WorldWideScience

Sample records for back contact solar cells

  1. Interdigitated back contact solar cells

    Science.gov (United States)

    Lundstrom, M. S.; Schwartz, R. J.

    1980-08-01

    The interdigitated back contact solar cell (IBC cell) was shown to possess a number of advantages for silicon solar cells, which operate at high concentration. A detailed discussion of the factors which need to be considered in the analysis of semiconducting devices which utilize heavily doped regions such as those which are found in solar cells in both the emitter and in the back surface field regions is given. This discussion covers the questions of: how to handle degeneracy, how to compute carrier concentrations in the absence of knowledge of the details of the band structure under heavily doped conditions, and how to reconcile the usual interpretation of heavy doping as a rigid shift of the bands with the band tailing and impurity level conduction models. It also discusses the reasons for the observed discrepancies between various experimental measurements of bandgap narrowing.

  2. Solar cell with back side contacts

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  3. Hybrid emitter all back contact solar cell

    Science.gov (United States)

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

  4. Screen printed interdigitated back contact solar cell

    Science.gov (United States)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T.

    1984-10-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  5. Screen printed interdigitated back contact solar cell

    Science.gov (United States)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T. (Inventor)

    1984-01-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  6. Ion Implanted Passivated Contacts for Interdigitated Back Contacted Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Reedy, Robert; Bateman, Nicholas; Stradins, Pauls

    2015-06-14

    We describe work towards an interdigitated back contacted (IBC) solar cell utilizing ion implanted, passivated contacts. Formation of electron and hole passivated contacts to n-type CZ wafers using tunneling SiO2 and ion implanted amorphous silicon (a-Si) are described. P and B were ion implanted into intrinsic amorphous Si films at several doses and energies. A series of post-implant anneals showed that the passivation quality improved with increasing annealing temperatures up to 900 degrees C. The recombination parameter, Jo, as measured by a Sinton lifetime tester, was Jo ~ 14 fA/cm2 for Si:P, and Jo ~ 56 fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts, as measured by TLM patterns, was 14 milliohm-cm2 for the n-type contact and 0.6 milliohm-cm2 for the p-type contact. These Jo and pcontact values are encouraging for forming IBC cells using ion implantation to spatially define dopants.

  7. Cadmium Telluride Solar Cells with PEDOT:PSS Back Contact

    Science.gov (United States)

    Mount, Michael; Duarte, Fernanda; Paudel, Naba; Yan, Yanfa; Wang, Weining

    Cadmium Telluride (CdTe) solar cell is one of the most promising thin film solar cells and its highest efficiency has reached 21%. To keep improving the efficiency of CdTe solar cells, a few issues need to be addressed, one of which is the back contact. The back contact of CdTe solar cells are mostly Cu-base, and the problem with Cu-based back contact is that Cu diffuses into the grain boundary and into the CdS/CdTe junction, causing degradation problem at high temperature and under illumination. To continue improving the efficiency of CdTe/CdS solar cells, a good ohmic back contact with high work function and long term stability is needed. In this work, we report our studies on the potential of conducting polymer being used as the back contact of CdTe/CdS solar cells. Conducting polymers are good candidates because they have high work functions and high conductivities, are easy to process, and cost less, meeting all the requirements of a good ohmic back contact for CdTe. In our studies, we used poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with different conductivities and compared them with traditional Cu-based back contact. It was observed that the CdTe solar cell performance improves as the conductivity of the PEDOT:PSS increase, and the efficiency (9.1%) is approaching those with traditional Cu/Au back contact (12.5%). Cadmium Telluride Solar Cells with PEDOT:PSS Back Contact.

  8. Thin foil silicon solar cells with coplanar back contacts

    Science.gov (United States)

    Ho, F.; Iles, P. A.; Baraona, C. R.

    1981-01-01

    To fabricate 50 microns thick, coplanar back contact (CBC) silicon solar cells, wraparound junction design was selected and proved to be effective. The process sequence used, the cell design, and the cell performance are described. CBC cells with low solar absorptance have shown AMO efficiencies to 13%, high cells up to 14%; further improvements are projected with predictable optimization.

  9. Study of Back Contacts for CdTe Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    ZnTe/ZnTe∶Cu layer is used as a complex back contact. The parameters of CdTe solar cells with and without the complex back contacts are compared. The effects of un-doped layer thickness, doped concentration and post-deposition annealing temperature of the complex layer on solar cells performance are investigated.The results show that ZnTe/ZnTe∶Cu layer can improve back contacts and largely increase the conversion efficiency of CdTe solar cells. Un-doped layer and post-deposition annealing of high temperature can increase open voltage. Using the complex back contact, a small CdTe cell with fill factor of 73.14% and conversion efficiency of 12.93% is obtained.

  10. Back-Contacted Silicon Heterojunction Solar Cells With Efficiency >21%

    OpenAIRE

    Tomasi, Andrea; Paviet-Salomon, Bertrand Yves Paul; Lachenal, Damien; Martin de Nicolas Agut, Silvia; Descoeudres, Antoine; Geissbühler, Jonas; De Wolf, Stefaan; Ballif, Christophe

    2014-01-01

    We report on the fabrication of back-contacted silicon heterojunction solar cells with conversion efficiencies above 21%. Our process technology relies solely on simple and size-scalable patterning methods, with no high-temperature steps. Using in situ shadow masks, doped hydrogenated amorphous silicon layers are patterned into two interdigitated combs. Transparent conductive oxide and metal layers, forming the back electrodes, are patterned by hot melt inkjet printing. With this process, we ...

  11. High efficiency interdigitated back contact silicon solar cells

    Science.gov (United States)

    Verlinden, P.; van de Wiele, F.; Stehelin, G.; Floret, F.; David, J. P.

    Interdigitated back contact (IBC) silicon solar cells with 25.6 percent efficiency at 10 W/sq cm and 24.4 percent at 30 W/ sq cm were fabricated. The authors report on the technological process, which produces a high effective carrier lifetime in the bulk (780 microsec), and on the characterization of the cells. The front side of these cells is textured and has an efficient polka-dot floating tandem junction. IBC and point-contact (PC) cells are fabricated on the same substrate and their efficiencies are compared. The possiblity of reaching 29 percent efficiency at 300X is shown.

  12. Coplanar back contacts for thin silicon solar cells

    Science.gov (United States)

    Storti, G.; Scheinine, A.; Whitehouse, D.; Wohlgemuth, J.; Wrigley, C.; Giuliano, M.

    1981-01-01

    The type of coplanar back contact solar cell described was constructed with interdigitated n(+) and p(+) type regions on the back of the cell, such that both contacts are made on the back with no metallization grid on the front. This cell construction has several potential advantages over conventional cells for space use namely, convenience of interconnects, lower operating temperatures and higher efficiency due to the elimination of grid shadowing. However, the processing is more complex, and the cell is inherently more radiation sensitive. The latter problem can be reduced substantially by making the cells very thin (approximately 50 micrometers). Two types of interdigitated back contact cells are possible, the types being dependent on the character of the front surface. The front surface field cell has a front surface region that is of the same conductivity type as the bulk but is more heavily doped. This creates an electric field at the surface which repels the minority carriers. The tandem junction cell has a front surface region of a conductivity type that is opposite to that of the bulk. The junction thus created floats to open circuit voltage on illumination and injects carriers into the bulk which then can be collected at the rear junction. For space use, the front surface field cell is potentially more radiation resistant than the tandem junction cell because the flow of minority carriers (electrons) into the bulk will be less sensitive to the production of recombination centers, particularly in the space charge region at the front surface.

  13. Laser fired back contact for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tucci, M. [ENEA Research Center Casaccia via Anguillarese 301, 00123 Roma (Italy)], E-mail: mario.tucci@casaccia.enea.it; Talgorn, E.; Serenelli, L.; Salza, E.; Izzi, M.; Mangiapane, P. [ENEA Research Center Casaccia via Anguillarese 301, 00123 Roma (Italy)

    2008-08-30

    To get high efficiency c-Si solar cells reduction of surface recombination losses and good surface passivation and/or Back Surface Field (BSF) formation are needed. Most industrial solar cells are made covering the back area with screen-printed Al, forming an Al-BSF upon firing step, with a Back Reflectance of 65% and a Back Surface Recombination Velocity (BSRV) of 1000 cm/s on 1 {omega}cm Si wafer. Simulations reveal that PV efficiency can increase up to 18% after improving the BSRV to {<=} 200 cm/s and the BR to > 95%. The aim of this work is to get these goals by a laser fired back contact with low temperature passivation of the remainder of the back. This can be obtained by a double layer of PECVD Amorphous Silicon and Silicon Nitride, on which a spin-on Boron dopant layer is deposited. The structure is completed by 2 {mu}m thick e-beam evaporated Al. The formation of an improved local BSF is obtained using a Nd:YAG pulsed laser, which promotes an Al and B simultaneous diffusion trough the passivation layers. Several cells, using this structure, have been fabricated on different substrates. By fitting procedure of cell Internal Quantum Efficiency we have extracted several parameters as surface recombination velocity, diffusion length and internal reflection that are comparable with the state of art of the cells having effective back surface field.

  14. Simulation of interdigitated back contact solar cell with trench structure

    Science.gov (United States)

    Kim, Soo Min; Chun, Seungju; Kang, Min Gu; Song, Hee-Eun; Lee, Jong-Han; Boo, Hyunpil; Bae, Soohyun; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2015-02-01

    We performed two-dimensional technology computer-aided design simulations for interdigitated back contact (IBC) solar cells with rear trench structures (TS), denoted here as TS-IBC solar cells. First, we calculated a reference simulation model for conventional IBC solar cells. We then assumed a trench structure at the rear surface of the IBC solar cell. For this structure, we analyzed solar cell performance as a function of various trench depths and type. It was found that emitter trench formation affects minority carrier collection, such that the short-circuit current density increases with increasing trench depth. However, the back-surface field (BSF) trench exhibited poor minority carrier collection, which reduced the conversion efficiency of the TS-IBC solar cells. It was also found that for the same trench depth (30 μm), the difference in conversion efficiencies of an IBC solar cell with an emitter trench and that with a BSF trench was 0.6%. We are thus convinced that the emitter trench structure is more important than the BSF trench structure.

  15. Behavior of interdigitated back-contact solar cells

    Science.gov (United States)

    Cheng, L. J.; Leung, D. C.

    1980-01-01

    This paper presents experimental data concerning operation mechanisms of two versions of interdigitated back-contact solar cells: the tandem junction cell and the front-surface field cell. It is shown that a photogenerated forward bias at the front junction of a tandem junction cell is a critical parameter for cell performance which not only causes photogenerated carriers to migrate to the back junction, but also eliminates the reduction in photoresponse over back p(+) metallization regions. However, no similar light effects are observed in the performance of front-surface field cells. Finally, a discussion on mechanisms concerning the performance of front-surface field and tandem junction cells along with their merits is given.

  16. Interdigitated back contact solar cell with high-current collection

    Science.gov (United States)

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    Internal current collection efficiencies greater than 90% and energy conversion efficiencies of 18 % at 30 suns were measured on a laboratory version of the interdigitated back contact (IBC) solar cell. A phosphorous gettering diffusion was performed on the front surface and then etched off to achieve these high current collection efficiencies. Thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. It is suggested that this should result in higher efficiencies at high concentration.

  17. Efficient interdigitated back-contacted silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mingirulli, Nicola; Haschke, Jan; Schulze, Tim F.; Duesterhoeft, J.; Korte, Lars; Rech, Bernd [Helmholtz-Zentrum Berlin (HZB), Institute of Silicon Photovoltaics, Kekulestrasse 5, 12489 Berlin (Germany); Gogolin, Ralf; Ferre, Rafel; Harder, Nils-Peter; Brendel, Rolf [Institute for Solar Energy Research Hameln (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany)

    2011-04-15

    We present back-contacted amorphous/crystalline silicon heterojunction solar cells (IBC-SHJ) on n-type substrates with fill factors exceeding 78% and high current densities, the latter enabled by a SiN{sub x} /SiO{sub 2} passivated phosphorus-diffused front surface field. V{sub oc} calculations based on carrier lifetime data of reference samples indicate that for the IBC architecture and the given amorphous silicon layer qualities an emitter buffer layer is crucial to reach a high V{sub oc}, as known for both-side contacted silicon heterojunction solar cells. A back surface field buffer layer has a minor influence. We observe a boost in solar cell V{sub oc} of 40 mV and a simultaneous fill factor reduction introducing the buffer layer. The aperture-area efficiency increases from 19.8 {+-} 0.4% to 20.2 {+-} 0.4%. Both, efficiencies and fill factors constitute a significant improvement over previously reported values. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. BEHIND (Back Enhanced Heterostructure with Interdigitated contact) Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Tucci, M.; Serenelli, L.; Salza, E.; Pirozzi, L. [ENEA Research Center Casaccia, Via Anguillarese 301, 00123 Roma (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M.; Martufi, P. [Electronic Engineering University of Rome ' Sapienza' , via Eudossiana 18, 00184 Roma (Italy); De Iuliis, S.; Geerligs, L.J. [ECN Solar Energy, P.O. Box 1, NL-1755 ZG Petten (Netherlands)

    2008-09-15

    In this paper we investigate in detail how the heterostructure concept can be implemented in an interdigitated back contact solar cell, in which both the emitters are formed on the back side of the c-Si wafer by amorphous/crystalline silicon heterostructure, and at the same time the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire process, held at temperature below 300C, is photolithography-free, using a metallic self-aligned mask to create the interdigitated pattern. An open-circuit voltage of 695 mV has been measured on this device fabricated. The mask assisted deposition process does not influence the uniformity of the deposited amorphous silicon layers. Several technological aspects that limit the fill factor are considered and discussed.

  19. Interdigitated back contact solar cell with high-current collection

    Energy Technology Data Exchange (ETDEWEB)

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    1981-01-01

    Internal current-collection efficiencies greater than 90 percent and energy-conversion efficiencies of 18 percent at 30 suns have been measured on a laboratory version of the interdigitated back contact (IBC) solar cell. The quantum efficiency at 600 nm was greater than 90 percent which implies a minority carrier lifetime of greater than 350 ..mu..sec and a front surface recombination velocity of less than 30 cm/sec on the better devices. To achieve these high-current collection efficiencies, a phosphorous gettering diffusion was performed on the front surface and then etched off. Also, thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. This should result in higher efficiencies at high concentration.

  20. Review of Back Contact Silicon Solar Cells for Low-Cost Application

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David D.

    1999-08-04

    Back contact solar cells hold significant promise for increased performance in photovoltaics for the near future. Two major advantages which these cells possess are a lack of grid shading loss and coplanar interconnection. Front contacted cells can have up to 10% shading loss when using screen printed metal grids. A front contact cell must also use solder connections which run from the front of one cell to the back of the next for series interconnection. This procedure is more difficult to automate than the case of co-planar contacts. The back contact cell design is not a recent concept. The earliest silicon solar cell developed by Bell Labs was a back contact device. There have been many design modifications to the basic concept over the years. To name a few, there is the Interdigitated Back Contact (IBC) cell, the Stanford Point contact solar cell, the Emitter Wrap Through (EWT), and its many variations. A number of these design concepts have demonstrated high efficiency. The SunPower back contact solar cell holds the efficiency record for silicon concentrator cells. The challenge is to produce a high efficiency cell at low cost using high throughput techniques. This has yet to be achieved with a back contact cell design. The focus of this paper will be to review the relevant features of back contact cells and progress made toward the goal of a low cost version of this device.

  1. Loss analysis of back-contact back-junction thin-film monocrystalline silicon solar cells

    Science.gov (United States)

    Haase, F.; Eidelloth, S.; Horbelt, R.; Bothe, K.; Garralaga Rojas, E.; Brendel, R.

    2011-12-01

    We investigate power losses in back-contact back-junction monocrystalline thin-film silicon solar cells fabricated using the porous silicon layer transfer process. Our loss analysis combines two-dimensional finite element modeling and resistance network simulations. The input parameters of the finite element modeling are determined experimentally by measuring saturation current densities and sheet resistances on test samples prepared identically to the solar cells. Characteristic solar cell parameters such as short circuit current, open circuit voltage, fill factor, and efficiency of measured and network simulated current voltage characteristics investigated in this study match within an uncertainty of 5%. Free energy loss analysis serves as comparison of all losses in units of power per area at the maximum power point. The largest loss is bulk recombination due to a carrier lifetime of 2 μs in the epitaxial Si layer. Further significant losses result from recombination at the base contacts characterized by a diode saturation current density of 50 000 fA cm-2 as well as resistive losses due to lateral majority carrier current flows within the solar cell base and contact resistance losses.

  2. Back contact buffer layer for thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

    A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

  3. Analysis of high efficiency back point contact silicon solar cells

    Science.gov (United States)

    Luque, Antonio

    1988-01-01

    A model has been developed for the analysis of Back Point-Contact (BPC) cells under variable injection level. The analysis has been applied to an experimental cell from Stanford University to allow the extraction of the recombination parameters of this cell. While the bulk SRH recombination and the recombination in the surface and in the emitters are those expected, the Auger constant takes a higher value (2.1 × 10 -30 cm 6/s), than the one usually accepted, and in agreement with the measurements by the Stanford group, for the carrier density involved here. The analysis indicates that best efficiency results are obtained with cells with finely designed emitter dots and well passivated surfaces, made on high resistivity substrates, leading to an upper limit of efficiency obtained at 20 W/cm 2 of about 30.4%. If our technology prevents us from a fine dot delineation (below 5-10 μm) then the highest efficiency is to be expected from the more conventional Interdigitated Back Contact cells with a limit (with our fitted Auger constant) of about 30%. Finally, if the commonly accepted value of the Auger constant (3.8 × 10 -31 cm 6/s) is used this limit is obtained at 50 W/cm 2 and is of 33.1% with a strongly idealized cell. All the efficiencies are at 25°C.

  4. Aluminum–Titanium Alloy Back Contact Reducing Production Cost of Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Hsin-Yu Wu

    2016-11-01

    Full Text Available In this study, metal films are fabricated by using an in-line reactive direct current magnetron sputtering system. The aluminum–titanium (AlTi back contacts are prepared by changing the pressure from 10 mTorr to 25 mTorr. The optical, electrical and structural properties of the metal back contacts are investigated. The solar cells with the AlTi had lower contact resistance than those with the silver (Ag back contact, resulting in a higher fill factor. The AlTi contact can achieve a solar cell conversion efficiency as high as that obtained from the Ag contact. These findings encourage the potential adoption of AlTi films as an alternative back contact to silver for silicon thin-film solar cells.

  5. Cu{sub 2}S as ohmic back contact for CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Türck, Johannes; Siol, Sebastian; Mayer, Thomas; Klein, Andreas; Jaegermann, Wolfram, E-mail: jaegermann@surface.tu-darmstadt.de

    2015-05-01

    We prepared a back contact for CdTe solar cells with Cu{sub 2}S as primary contact. Cu{sub 2}S was evaporated on CdCl{sub 2} treated CdTe solar cells in superstrate configuration. The CdTe and CdS layers were deposited by Closed Space Sublimation. Direct interface studies with X-ray photoelectron spectroscopy have revealed a strongly reactive interface between CdTe and Cu{sub 2}S. A valence band offset of 0.4-0.6 eV has been determined. The performance of solar cells with Cu{sub 2}S back contacts was studied in comparison to cells with an Au contact that deposited onto a CdCl{sub 2}-treated CdTe surface that was chemically etched using a nitric-phosphoric etch. The solar cells were analyzed by current-voltage curves and external quantum efficiency measurements. After several post deposition annealing steps, 13% efficiency was reached with the Cu{sub 2}S back contact, which was significantly higher than the ones obtained for the NP-etched back contacts. - Highlights: • A new back contact for CdTe solar out of Cu{sub 2}S has been tested. • With a direct interface experiment the valence band offset was determined. • Post deposition heat treatment has been carried out for the solar cells. • 13% efficiency has been reached with the Cu{sub 2}S back contact.

  6. Fabrication of back-contacted silicon solar cells using thermomigration to create conductive vias

    Science.gov (United States)

    Gee, James M; Schmit, Russell R.

    2007-01-30

    Methods of manufacturing back-contacted silicon solar cells fabricated using a gradient-driven solute transport process, such as thermomigration or electromigration, to create n-type conductive vias connecting the n-type emitter layer on the front side to n-type ohmic contacts located on the back side.

  7. Method of manufacturing a hybrid emitter all back contact solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Loscutoff, Paul; Rim, Seung

    2017-02-07

    A method of manufacturing an all back contact solar cell which has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. A second emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The method further includes forming contact holes that allow metal contacts to connect to corresponding emitters.

  8. High efficiency back-contact back-junction thin-film monocrystalline silicon solar cells from the porous silicon process

    Science.gov (United States)

    Haase, F.; Kajari-Schröder, S.; Brendel, R.

    2013-11-01

    This work demonstrates the fabrication of a 45 μm thick back-contact back-junction thin-film monocrystalline silicon solar cell from the porous silicon process with an energy conversion efficiency of 18.9%. We demonstrate an efficiency improvement of 5.4% absolute compared to our prior record of 13.5% for back-contact back-junction thin-film monocrystalline silicon solar cells. This increase in efficiency is achieved by reducing the recombination at the base contact using a back surface field and by increasing the generation with a front texture. We investigate the loss mechanisms in the cell using finite element simulations. A free energy loss analysis based on experiments and simulations determines the dominating loss mechanisms. The efficiency loss by base recombination is 0.8% absolute and the loss by base contact recombination is 0.5% absolute in the 18.9% efficiency cell.

  9. Back-Contacted Silicon Heterojunction Solar Cells: Optical-Loss Analysis and Mitigation

    OpenAIRE

    Paviet-Salomon, Bertrand; Tomasi, Andrea; Descoeudres, Antoine; Barraud, Loris; Nicolay, Sylvain; Despeisse, Matthieu; De Wolf, Stefaan; Ballif, Christophe

    2015-01-01

    We analyze the optical losses that occur in interdigitated back-contacted amorphous/crystalline silicon heterojunction solar cells. We show that in our devices, the main loss mechanisms are similar to those of two-side contacted heterojunction solar cells. These include reflection and escape-light losses, as well as parasitic absorption in the front passivation layers and rear contact stacks. We then provide practical guidelines to mitigate such reflection and parasitic absorption losses at t...

  10. Interdigitated back-surface-contact solar cell modeling using Silvaco Atlas

    OpenAIRE

    Green, Shawn E.

    2015-01-01

    Approved for public release; distribution is unlimited The Silvaco Atlas semiconductor modeling software was used to simulate an interdigitated back-surface-contact solar cell. The cell is modeled after the silicon-based Sunpower Corporation A-300 solar cell, which contains a number of unique features that give it advantages over conventional solar cells. This simulation attempted to match as closely as possible the results measured by the National Renewable Energy Laboratory from the A-30...

  11. CdS/CdTe solar cells with MoOx as back contact buffers

    Science.gov (United States)

    Lin, Hao; Xia, Wei; Wu, Hsiang N.; Tang, Ching W.

    2010-09-01

    Ohmic back contacts for CdS/CdTe solar cells with MoOx as the contact buffer have been demonstrated. With contacts such as MoOx/Ni and MoOx/Al, cell efficiencies comparable to those with conventional back contacts have been produced. Thermal stress tests indicate that MoOx is effective in suppressing metal diffusion into p-CdTe. The usefulness of MoOx is attributed to its unusually high work function which is needed to match that of p-type CdTe in producing contacts of low resistance.

  12. Nickel Phosphide as a Copper Free Back Contact for CdTe-Based Solar Cells

    Science.gov (United States)

    Sunderland, Brian; Gupta, Akhlesh; Compaan, Alvin D.

    2002-03-01

    Nickel phosphide back contacts were deposited onto polycrystalline, thin-film, CdS/CdTe solar cells using DC magnetron sputtering. The effects of the etching procedure, substrate temperature, deposition duration, post-deposition diffusion temperature, and ambient on the initial performance and on the long term stability of the devices were studied. We found that the initial performance of nickel phosphide contacts was lower than typical Cu-based back contacts. However, the stability of the cells at open circuit under one-sun light soak for several months is better than for our standard contact with evaporated Cu and Au. The use of sputtered graphite as an interfacial layer improved the performance. Average efficiencies of over 8.6were achieved. The excellent stability makes Ni2P an attractive candidate for a Cu-free back contact to CdTe-based solar cells. Work supported by NREL and by NSF-REU.

  13. High-temperature stability of molybdenum (Mo) back contacts for CIGS solar cells: a route towards more robust back contacts

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ju-Heon; Yoon, Kwan-Hee; Jeong, Jeung-hyun [Solar Cell Research Center, Korea Institute of Science and Technology, 39-1, Seoul 136-791 (Korea, Republic of); Kim, Won Mok; Park, Jong-Keuk; Baik, Young-Joon [Electronic Materials Research Center, Korea Institute of Science and Technology, 39-1, Seoul 136-791 (Korea, Republic of); Seong, Tae-Yeon, E-mail: jhjeong@kist.re.kr [Department of Materials Science and Engineering, College of Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2011-10-26

    The thermal stability of Mo thin films is indispensable to Cu(In,Ga)Se{sub 2} (CIGS) solar cells: CIGS films are deposited above 500 deg. C. The thermal stabilities of Mo thin films with dense to porous Mo microstructures, which are varied by controlling the sputtering pressure, are investigated. Interface failures are found to occur in buckling mode in denser Mo films, whereas cracking arises in less dense films. The failure modes are apparently dependent on the sign of the residual stress: the former is due to compressive stress, whereas the latter is due to tensile stress. Interestingly, the softening of soda-lime glass at high temperatures reconfigures the film stresses to be more compressive after annealing, which in turn triggers buckling even in films that are tensile-stressed in the as-deposited states. We conclude that the appropriate processing conditions for thermally stable back contacts cannot be obtained with the simple single layer approach. On the basis of this relationship between microstructure, residual stress and the failure modes, it is shown that improvements in film adhesion can widen the processing window for the preparation of robust back contacts, i.e. with a conventional bilayer approach and substrate roughening. Since the bilayer approach employed more compliant porous structures in the bottom layer, back contacts that are better suited to higher stress and temperature can be produced. Furthermore, substrate roughening might make the back contact more conductive as well as more stable because adhesion can be enhanced without the use of an electrically resistive buffer layer.

  14. Two-dimensional analysis of the interdigited back-contact solar cell

    Science.gov (United States)

    Chin, D. J.; Navon, D. H.

    1981-02-01

    The behavior of the interdigited back-contact solar cell (IBC) under high illuminating levels has been analyzed by two-dimensional numerical techniques. The effects of cell geometry and surface recombination on efficiency are examined. The IBC cell with a doping gradient at the front surface is also considered.

  15. Method of fabricating a back-contact solar cell and device thereof

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo; Smith, David; Cousins, Peter

    2016-08-02

    Methods of fabricating back-contact solar cells and devices thereof are described. A method of fabricating a back-contact solar cell includes forming an N-type dopant source layer and a P-type dopant source layer above a material layer disposed above a substrate. The N-type dopant source layer is spaced apart from the P-type dopant source layer. The N-type dopant source layer and the P-type dopant source layer are heated. Subsequently, a trench is formed in the material layer, between the N-type and P-type dopant source layers.

  16. Post passivation light trapping back contacts for silicon heterojunction solar cells.

    Science.gov (United States)

    Smeets, M; Bittkau, K; Lentz, F; Richter, A; Ding, K; Carius, R; Rau, U; Paetzold, U W

    2016-11-10

    Light trapping in crystalline silicon (c-Si) solar cells is an essential building block for high efficiency solar cells targeting low material consumption and low costs. In this study, we present the successful implementation of highly efficient light-trapping back contacts, subsequent to the passivation of Si heterojunction solar cells. The back contacts are realized by texturing an amorphous silicon layer with a refractive index close to the one of crystalline silicon at the back side of the silicon wafer. As a result, decoupling of optically active and electrically active layers is introduced. In the long run, the presented concept has the potential to improve light trapping in monolithic Si multijunction solar cells as well as solar cell configurations where texturing of the Si absorber surfaces usually results in a deterioration of the electrical properties. As part of this study, different light-trapping textures were applied to prototype silicon heterojunction solar cells. The best path length enhancement factors, at high passivation quality, were obtained with light-trapping textures based on randomly distributed craters. Comparing a planar reference solar cell with an absorber thickness of 280 μm and additional anti-reflection coating, the short-circuit current density (JSC) improves for a similar solar cell with light-trapping back contact. Due to the light trapping back contact, the JSC is enhanced around 1.8 mA cm(-2) to 38.5 mA cm(-2) due to light trapping in the wavelength range between 1000 nm and 1150 nm.

  17. Influence of black silicon surfaces on the performance of back-contacted back silicon heterojunction solar cells.

    Science.gov (United States)

    Ziegler, Johannes; Haschke, Jan; Käsebier, Thomas; Korte, Lars; Sprafke, Alexander N; Wehrspohn, Ralf B

    2014-10-20

    The influence of different black silicon (b-Si) front side textures prepared by inductively coupled reactive ion etching (ICP-RIE) on the performance of back-contacted back silicon heterojunction (BCB-SHJ) solar cells is investigated in detail regarding their optical performance, black silicon surface passivation and internal quantum efficiency. Under optimized conditions the effective minority carrier lifetime measured on black silicon surfaces passivated with Al(2)O(3) can be higher than lifetimes measured for the SiO(2)/SiN(x) passivation stack used in the reference cells with standard KOH textures. However, to outperform the electrical current of silicon back-contact cells, the black silicon back-contact cell process needs to be optimized with aspect to chemical and thermal stability of the used dielectric layer combination on the cell.

  18. Interdigitated back contact silicon heterojunction solar cell and the effect of front surface passivation

    Science.gov (United States)

    Lu, Meijun; Bowden, Stuart; Das, Ujjwal; Birkmire, Robert

    2007-08-01

    This letter reports interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells which combine the performance benefits of both back contact and heterojunction technologies while reducing their limitations. Low temperature (interdigitated heteroemitter and contacts in the rear preserves substrate lifetime while minimizes optical losses in the front. The IBC-SHJ structure is ideal for diagnosing surface passivation quality, which is analyzed and measured by internal quantum efficiency and minority carrier lifetime measurements. Initial cells have independently confirmed efficiency of 11.8% under AM1.5 illumination. Simulations indicate efficiencies greater than 20% after optimization.

  19. Nitrogen Doped Zinc Telluride Back Contact to CdS/CdTe Solar Cells

    Science.gov (United States)

    Drayton, J.; Makhratchev, K.; Price, K. J.; Ma, X.; Simmons, D. A.; Ludwig, K.; Gupta, A.; Bohn, R. G.; Compaan, A. D.

    2000-10-01

    We describe the development of the Nitrogen doped ZnTe for the back contacts of CdS/CdTe solar cell. Reproducible p-ZnTe films were obtained using RF magnetron sputtering technique with Ar/N2 gas mixture. Both, intrinsic and nitrogen doped, ZnTe films were investigated for electronic properties. The conductivity of the N:ZnTe films was about five orders of magnitude higher than that of intrinsic ones. A bilayer of intrinsic and doped ZnTe films were used in back contact structure of CdS/CdTe solar cells. The ZnTe/N:ZnTe/Ni structure showed slightly lower initial performance but better stability in comparison to evaporated Cu/Au back contacts.

  20. Admittance spectroscopy characterize graphite paste for back contact of CdTe thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    CdTe thin film solar cells with a doped-graphite paste back contact layer were studied using admittance spectroscopy technology.The positions and the capture cross sections of energy level in the forbidden band were calculated,which are the important parameters to affect solar cell performance.The results showed that there were three defects in the CdTe thin films solar cells with the doped-graphite paste back contact layer,whose positions in the forbidden band were close to 0.34,0.46 and 0.51 eV,respectively above the valence band,and capture cross sections were 2.23×10-16,2.41×10-14,4.38×10-13 cm2,respectively.

  1. Back-Contact Vertical-Junction Solar Cell

    Science.gov (United States)

    1988-03-01

    Without this process, 11-28 5C AM’ 5 S 300 InP GaAs 40 CdTe Ge A~ 30 C=(OOO Cu2 C z Li0 Li. C= GaP L1_u20 CdS * 10- 0 12 3 Eg (eV) Figure 2-11. Ideal solar...equations [19:386-388]: Cs(t) = S/(7rDt) 1 / 2 cm - 3 (43) and S = 2(Dt/77)’/ 2 Css cm - 2 (44) where Cs(t) is the surface impurity concentration at t, Cas

  2. Low resistivity molybdenum thin film towards the back contact of dye-sensitized solar cell

    Indian Academy of Sciences (India)

    Vuong Son; Tran Thi Ha; Luong T Thu Thuy; Nguyen Ngoc Ha; Nguyen Duc Chien; Mai Anh Tuan

    2015-12-01

    This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150Wat 18 sccm flow rate of Ar. At such sputtering parameters, the Mo film can reach the lowest resistivity of 1.28E−6 cm at 400 nm thick. And the reflection of Mo membrane was 82%. This value is considered as a very good result for preparation of the back contact of DSSC.

  3. Optimisation of interdigitated back contacts solar cells by two-dimensional numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, O.; Kaminski, A.; Lemiti, M.; Fave, A. [Instituit National des Sciences Appliquees Lyon, Villeurbanne (France). Lab. de Physique de la Matiere; Skryshevsky, V. [National Taras Shevchenko Univ., Kiev (Ukraine). Radiophysics Dept.

    2005-04-01

    In this paper we present the results of the simulation of interdigitated back contacts solar cell on thin-film ({approx}{mu}m) silicon layer. The influence of several parameters (surface recombination rate, substrate thickness and type, diffusion length, device geometry, doping levels) on device characteristics are simulated using the accurate two-dimensional numerical simulator DESSIS that allows to optimise the cell design. (Author)

  4. Optimized Interdigitated Back Contact (IBC) solar cell for high concentrated sunlight

    Science.gov (United States)

    Verlinden, P.; van de Wiele, F.; Stehelin, G.; David, J. P.

    A one-dimensional analytical model for Interdigitated Back Contact solar cells (IBC), also applicable to Front Surface Field (FSF) and Tandem Junction (TJ) solar cells, is presented. The quantum efficiency, generation current, dark current, and conversion efficiency are calculated as a function of the physical parameters of the cell (doping levels, junction depths, thickness, and lifetime). The proposed model simulates the response of FSF and TJ solar cells more accurately than models using the concept of effective surface recombination velocity. The optimization of parameters (doping level and dimension of each region) is discussed. It is shown that a conversion efficiency of 24.8 percent can be reached under 50 suns. IBC solar cells were fabricated with different substrate resistivities and thicknesses. The experimental results are compared to the theoretical predictions.

  5. Localized plasmonic losses at metal back contacts of thin-film silicon solar cells

    Science.gov (United States)

    Paetzold, U. W.; Hallermann, F.; Pieters, B. E.; Rau, U.; Carius, R.; von Plessen, G.

    2010-05-01

    Investigations of optical losses induced by localized plasmons in protrusions on silver back contacts of thin-film silicon solar cells are presented. The interaction of electromagnetic waves with nanoprotrusions on flat silver layers is simulated with a three-dimensional numerical solver of Maxwell's equations. Spatial absorption profiles and spatial electric field profiles as well as the absorption inside the protrusions are calculated. The results presented here show that the absorption of irradiated light at nanorough silver layers can be strongly enhanced by localized plasmonic resonances in Ag nanoprotrusions. Especially, localized plasmons in protrusions with a radius below 60 nm induce strong absorption, which can be several times the energy irradiated on the protrusion's cross section. The localized plasmonic resonances in single protrusions on Ag layers are observed to shift to longer wavelengths with increasing refractive index of the surrounding material. At wavelengths above 500 nm localized plasmonic resonances will increase the absorption of nanorough μc-Si:H/Ag interfaces. The localized plasmon induced absorption at nanorough ZnO/Ag interfaces lies at shorter wavelengths due to the lower refractive index of ZnO. For wavelengths above 500 nm, a high reflectivity of the silver back contacts is essential for the light-trapping of thin-film silicon solar cells. Localized-plasmon induced losses at silver back contacts can explain the experimentally observed increase of the solar cell performance when applying a ZnO/Ag back contact in comparison to a μc-Si:H/Ag back contact.

  6. Physical model of back line-contact front-junction solar cells

    Science.gov (United States)

    Cuevas, Andres

    2013-04-01

    The analysis of advanced front-junction solar cells where the metal contact to the base region is locally formed on the back surface in the shape of lines usually requires numerical simulations. Here, we describe an approach based on a geometric formulation of carrier crowding towards the localized contact, in conjunction with a partition of the device in two distinct regions. This permits a one dimensional analysis of carrier flow, both in the region immediately adjacent to the contact and in the peripheral region surrounding it. The resulting model is simple enough to provide insight into the physics of device operation and reasonably accurate in cases of practical interest. By applying it to different cases, we identify unexpected anomalies and explain them in terms of the peculiar interplay between carrier transport and recombination that takes place in this type of solar cell.

  7. Tuning back contact property via artificial interface dipoles in Si/organic hybrid solar cells

    Science.gov (United States)

    Wang, Dan; Sheng, Jiang; Wu, Sudong; Zhu, Juye; Chen, Shaojie; Gao, Pingqi; Ye, Jichun

    2016-07-01

    Back contact property plays a key role in the charge collection efficiency of c-Si/poly(3,4-ethylthiophene):poly(styrenesulfonate) hybrid solar cells (Si-HSCs), as an alternative for the high-efficiency and low-cost photovoltaic devices. In this letter, we utilize the water soluble poly (ethylene oxide) (PEO) to modify the Al/Si interface to be an Ohmic contact via interface dipole tuning, decreasing the work function of the Al film. This Ohmic contact improves the electron collection efficiency of the rear electrode, increasing the short circuit current density (Jsc). Furthermore, the interface dipoles make the band bending downward to increase the total barrier height of built-in electric field of the solar cell, enhancing the open circuit voltage (Voc). The PEO solar cell exhibits an excellent performance, 12.29% power conversion efficiency, a 25.28% increase from the reference solar cell without a PEO interlayer. The simple and water soluble method as a promising alternative is used to develop the interfacial contact quality of the rear electrode for the high photovoltaic performance of Si-HSCs.

  8. Optimization of substrate thickness for interdigitated back contact silicon solar cells

    Science.gov (United States)

    Verlinden, P.; van de Wiele, F.

    1983-08-01

    A computer model for the computation of the optimum substrate thickness of interdigitated-back-contact (IBC) Si solar cells is developed and demonstrated. The one-dimensional model assumes that solar-cell quantum efficiency is fully determined by minority-carrier diffusion length, surface recombination velocity, and substrate thickness, and hence unaffected by back-diffused layers. The maximum thickness allowable for a 10-percent reduction in short-circuit current density can also be determined. Optimum and maximum-allowable thicknesses are plotted as functions of diffusion length for different recombination velocities, using input parameters typical of lightly doped n-type and p-type backlit IBC cells under AM 1.5 illumination at 300 K. Good agreement is found with empirical parameter values determined by curve fitting.

  9. Exploiting metallic glasses for 19.6% efficient back contact solar cell

    Science.gov (United States)

    Kim, Suk Jun; Kim, Se Yun; Park, Jin Man; Heo, Jung Na; Lee, Jun Ho; Lee, Sang Mock; Kim, Do Hyang; Kim, Won Tae; Lim, Ka Ram; Kim, Donghwan; Park, Sung Chan; Kim, Hyoeng Ki; Song, Min Chul; Park, Jucheol; Jee, Sang Soo; Lee, Eun-Sung

    2012-08-01

    An interdigitated back contact silicon solar cell with conversion efficiency of 19.6% was fabricated by screen-printing the Ag paste. In the Ag paste, oxide glass frits were totally replaced by Al85Ni5Y8Co2, Al-based metallic glass (MG) ones. The thermoplastic forming of the MG in the super cooled liquid region led to large contact area at the interface between Ag electrodes and Si layers and thus to specific contact resistance (ρc) as low as 0.86 mΩ cm2. The specific contact resistance was a function of both contact area and thickness of the interlayer formed at the interface working as a tunneling barrier.

  10. Study of copper-free back contacts to thin film cadmium telluride solar cells

    Science.gov (United States)

    Viswanathan, Vijay

    The goals of this project are to study Cu free back contact alternatives for CdS/CdTe thin film solar cells, and to research dry etching for CdTe surface preparation before contact application. In addition, an attempt has been made to evaluate the stability of some of the contacts researched. The contacts studied in this work include ZnTe/Cu2Te, Sb2Te 3, and Ni-P alloys. The ZnTe/Cu2Te contact system is studied as basically an extension of the earlier work done on Cu2Te at USF. RF sputtering from a compound target of ZnTe and Cu2Te respectively deposits these layers on etched CdTe surface. The effect of Cu2Te thickness and deposition temperature on contact and cell performance will be studied with the ZnTe depositions conditions kept constant. C-V measurements to study the effect of contact deposition conditions on CdTe doping will also be performed. These contacts will then be stressed to high temperatures (70--100°C) and their stability with stress time is analyzed. Sb2Te3 will be deposited on glass using RF sputtering, to study film properties with deposition temperature. The Sb2Te 3 contact performance will also be studied as a function of the Sb 2Te3 deposition temperature and thickness. The suitability of Ni-P alloys for back contacts to CdTe solar cells was studied by forming a colloidal mixture of Ni2P in graphite paste. The Ni-P contacts, painted on Br-methanol etched CdTe surface, will be studied as a function of Ni-P concentration (in the graphite paste), annealing temperature and time. Some of these cells will undergo temperature stress testing to determine contact behavior with time. Dry etching of CdTe will be studied as an alternative for wet etching processes currently used for CdTe solar cells. The CdTe surface is isotropically etched in a barrel reactor in N2, Ar or Ar:O 2 ambient. The effect of etching ambient, pressure, plasma power and etch time on contact performance will be studied.

  11. Influence of CuxS back contact on CdTe thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    Lei Zhi; Feng Lianghuan; Zeng Guanggen; Li Wei; Zhang Jingquan; Wu Lili; Wang Wenwu

    2013-01-01

    We present a detailed study on CuxS polycrystalline thin films prepared by chemical bath method and utilized as back contact material for CdTe solar cells.The characteristics of the films deposited on Si-substrate are studied by XRD.The results show that as-deposited CuxS thin film is in an amorphous phase while after annealing,samples are in polycrystalline phases with increasing temperature.The thickness of CuxS thin films has great impact on the performance of CdS/CdTe solar cells.When the thickness of the film is about 75 nm the performance of CdS/CdTe thin film solar cells is found to be the best.The energy conversion efficiency can be higher than 12.19%,the filling factor is higher than 68.82% and the open-circuit voltage is more than 820 mV.

  12. Influence of CuxS back contact on CdTe thin film solar cells

    Science.gov (United States)

    Zhi, Lei; Lianghuan, Feng; Guanggen, Zeng; Wei, Li; Jingquan, Zhang; Lili, Wu; Wenwu, Wang

    2013-01-01

    We present a detailed study on CuxS polycrystalline thin films prepared by chemical bath method and utilized as back contact material for CdTe solar cells. The characteristics of the films deposited on Si-substrate are studied by XRD. The results show that as-deposited CuxS thin film is in an amorphous phase while after annealing, samples are in polycrystalline phases with increasing temperature. The thickness of CuxS thin films has great impact on the performance of CdS/CdTe solar cells. When the thickness of the film is about 75 nm the performance of CdS/CdTe thin film solar cells is found to be the best. The energy conversion efficiency can be higher than 12.19%, the filling factor is higher than 68.82% and the open-circuit voltage is more than 820 mV.

  13. Back-contacted and small form factor GaAs solar cell.

    Energy Technology Data Exchange (ETDEWEB)

    Clews, Peggy Jane; Wanlass, Mark W. (National Renewable Energy Laboratory, Golden, CO); Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

    2010-07-01

    We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

  14. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cudzinovic, M.; Sopori, B. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  15. Simulation of interdigitated back-contact silicon heterojunction solar cells with quantum transport model

    Science.gov (United States)

    Kamioka, Takefumi; Hayashi, Yutaka; Nakamura, Kyotaro; Ohshita, Yoshio

    2015-08-01

    A simulation of interdigitated back-contact silicon heterojunction (IBC-SHJ) solar cells was performed using a quantum transport model to consider the quantum effect at the crystalline/amorphous (c/a) heterojunction interface. It was found that the impact of the quantum effect on the open-circuit voltage is comparable to that of the interface defect density at the c/a interface, indicating the importance of implementation of the quantum model. The optimal back-contact design was also discussed from the viewpoint of mass production, in which the design rule is relaxed. The degradation of the conversion efficiency by widening the gap between the p- and n-aSi:H layers can be compensated by improving passivation quality at the c/a interface.

  16. Laser assisted patterning of hydrogenated amorphous silicon for interdigitated back contact silicon heterojunction solar cell

    Science.gov (United States)

    De Vecchi, S.; Desrues, T.; Souche, F.; Muñoz, D.; Lemiti, M.

    2012-10-01

    This work reports on the elaboration of a new industrial process based on laser selective ablation of dielectric layers for Interdigitated Back Contact Silicon Heterojunction (IBC Si-HJ) solar cells fabrication. Choice of the process is discussed and cells are processed to validate its performance. A pulsed green laser (515nm) with 10-20ns pulse duration is used for hydrogenated amorphous silicon (a-Si:H) layers patterning steps, whereas metallization is made by screen printed. High Open-Circuit Voltage (Voc=699mV) and Fill Factor (FF=78.5%) values are obtained simultaneously on IBC Si-HJ cells, indicating a high surface passivation level and reduced resistive losses. An efficiency of 19% on non textured 26 cm² solar cells has been reached with this new industrial process.

  17. RF Sputtered ZnTe:N as CdS/CdTe Solar Cell Back-Contact Material

    Science.gov (United States)

    Ma, X.

    1999-04-01

    The most frequently used electrical contact to CdTe thin-film polycrystalline solar cells on glass involves the use of copper. However, Cu is known to be a fast diffuser in many semiconductors and is suspected of leading to some deterioration of performance of CdTe solar cells under extreme conditions. In this work we report on the development of a reactively sputtered ZnTe:N back contact on solar cells. Promising low-resistive nitrogen-doped ZnTe films were obtained. Efficiencies up to 10.8 percent were obtained for solar cells fabricated with a ZnTe:N/Au back contact scheme. Comparison of cell performances using ZnTe:N and Cu/Au back-contacts is presented.

  18. Optimization of interdigitated back contact silicon heterojunction solar cells by two-dimensional numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Meijun; Das, Ujjwal; Bowden, Stuart; Hegedus, Steven; Birmire, Robert

    2009-06-09

    In this paper, two-dimensional (2D) simulation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells is presented using Sentaurus Device, a software package of Synopsys TCAD. A model is established incorporating a distribution of trap states of amorphous-silicon material and thermionic emission across the amorphous-silicon / crystalline-silicon heterointerface. The 2D nature of IBC-SHJ device is evaluated and current density-voltage (J-V) curves are generated. Optimization of IBC-SHJ solar cells is then discussed through simulation. It is shown that the open circuit voltage (VOC) and short circuit current density (JSC) of IBC-SHJ solar cells increase with decreasing front surface recombination velocity. The JSC improves further with the increase of relative coverage of p-type emitter contacts, which is explained by the simulated and measured position dependent laser beam induced current (LBIC) line scan. The S-shaped J-V curves with low fill factor (FF) observed in experiments are also simulated, and three methods to improve FF by modifying the intrinsic a-Si buffer layer are suggested: (i) decreased thickness, (ii) increased conductivity, and (iii) reduced band gap. With all these optimizations, an efficiency of 26% for IBC-SHJ solar cells is potentially achievable.

  19. Interdigitated back contact silicon solar cell analysis and design recommendations for space use

    Science.gov (United States)

    Marvin, Dean C.; Froedge, Sharon L.

    1989-09-01

    The Interdigitated Back Contact (IBC) solar cell is a relatively new design which has shown unprecedentedly high efficiencies. Silicon Interdigitated Back Contact cells have been fabricated that show greater than 25 percent efficiency at 100 suns Air Mass 1.5. This is far superior to conventional silicon concentrator cells which are approximately 18 percent efficient. The purpose of this report is to describe briefly the differences between this technology and conventional cells, demonstrate a near optimum design achieved by two-dimensional numerical simulation, and assess the utility of these cells for space application. The end of life (EOL) performance of this cell design in the radiation environment of space is a critical issue since the high efficiency of the design is predicated on the use of very high quality, long-diffusion length silicon. The radiation-induced degradation of this material is expected to lead to severe efficiency losses. The optimization of cell design to minimize these losses was carried out using a modified version of the two-dimensional PISCES semiconductor simulator. The final designs presented here show that the performance of IBC cells in space can significantly exceed that of conventional cells.

  20. Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency

    Science.gov (United States)

    Savin, Hele; Repo, Päivikki; von Gastrow, Guillaume; Ortega, Pablo; Calle, Eric; Garín, Moises; Alcubilla, Ramon

    2015-07-01

    The nanostructuring of silicon surfaces—known as black silicon—is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at the nanostructured surface. Here, we show that a conformal alumina film can solve the issue of surface recombination in black silicon solar cells by providing excellent chemical and electrical passivation. We demonstrate that efficiencies above 22% can be reached, even in thick interdigitated back-contacted cells, where carrier transport is very sensitive to front surface passivation. This means that the surface recombination issue has truly been solved and black silicon solar cells have real potential for industrial production. Furthermore, we show that the use of black silicon can result in a 3% increase in daily energy production when compared with a reference cell with the same efficiency, due to its better angular acceptance.

  1. Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency.

    Science.gov (United States)

    Savin, Hele; Repo, Päivikki; von Gastrow, Guillaume; Ortega, Pablo; Calle, Eric; Garín, Moises; Alcubilla, Ramon

    2015-07-01

    The nanostructuring of silicon surfaces--known as black silicon--is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at the nanostructured surface. Here, we show that a conformal alumina film can solve the issue of surface recombination in black silicon solar cells by providing excellent chemical and electrical passivation. We demonstrate that efficiencies above 22% can be reached, even in thick interdigitated back-contacted cells, where carrier transport is very sensitive to front surface passivation. This means that the surface recombination issue has truly been solved and black silicon solar cells have real potential for industrial production. Furthermore, we show that the use of black silicon can result in a 3% increase in daily energy production when compared with a reference cell with the same efficiency, due to its better angular acceptance.

  2. Back Enhanced Heterostructure with InterDigitated contact - BEHIND - solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Tucci, M.; Serenelli, L.; Salza, E.; Pirozzi, L. [ENEA Research Center Casaccia, Via Anguillarese 301, 00123 Roma (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M.; Martufi, P. [Electronic Engineering University of Rome ' Sapienza' , via Eudossiana 18, 00184 Roma (Italy); De Iuliis, S.; Geerligs, L.J. [ECN Solar Energy, P.O. Box 1, NL-1755 ZG Petten (Netherlands)

    2008-09-15

    In this paper we investigate in detail how the heterostructure concept can be implemented in an interdigitated back contact solar cell, in which both the emitters are formed on the back side of the c-Si wafer by amorphous/crystalline silicon heterostructure, and at the same time the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire process, held at temperature below 300C, is photolithographyfree, using a metallic self-aligned mask to create the interdigitated pattern. An open-circuit voltage of 695 mV has been measured on this device fabricated. The mask-assisted deposition process does not influence the uniformity of the deposited amorphous silicon layers. Several technological aspects that limit the fill factor are considered and discussed.

  3. From front contact to back contact in cadmium telluride/cadmium sulfide solar cells: Buffer layer and interfacial layer

    Science.gov (United States)

    Roussillon, Yann

    Cadmium telluride (CdTe) polycrystalline thin film solar cells, with their near optimum direct band-gap of 1.4 eV matching almost perfectly the sun radiation spectrum, are a strong contender as a less expensive alternative, among photovoltaic materials, than the more commonly used silicon-based cells. Polycrystalline solar cells are usually deposited over large areas. Such devices often exhibit strong fluctuations (nonuniformities) in electronic properties, which originate from deposition and post-deposition processes, and are detrimental to the device performance. Therefore their effects need to be constrained. A new approach in this work was, when a CdS/CdTe solar cell is exposed to light and immersed in a proper electrolyte, fluctuations in surface potential can drive electrochemical reactions which result in a nonuniform interfacial layer that could balance the original nonuniformity. This approach improved the device efficiency for CdS/CdTe photovoltaic devices from 1--3% to 11--12%. Cadmium sulfide (CdS), used as a window layer and heterojunction partner to CdTe, is electrically inactive and absorb light energies above its band-gap of 2.4 eV. Therefore, to maximize the device efficiency, a thin US layer needs to be used. However, more defects, such as pinholes, are likely to be present in the film, leading to shunts. A resistive transparent layer, called buffer layer, is therefore deposited before CdS. A key observation was that the open-circuit voltage (Voc) for cells made using a buffer layer was high, around 800 mV, similar to cells without buffer layer after Cu doping. The standard p-n junction theory cannot explain this phenomena, therefore an alternative junction mechanism, similar to metal-insulator-semiconductor devices, was developed. Furthermore, alternative Cu-free back-contacts were used in conjunction with a buffer layer. The Voc of the devices was found to be dependent of the back contact used. This change occurs as the back-contact junction

  4. Molybdenum oxide and molybdenum oxide-nitride back contacts for CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Drayton, Jennifer A., E-mail: drjadrayton@yahoo.com; Geisthardt, Russell M., E-mail: Russell.Geisthardt@gmail.com; Sites, James R., E-mail: james.sites@colostate.edu [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); Williams, Desiree D., E-mail: daisyw@rams.colostate.edu; Cramer, Corson L., E-mail: clcramer@rams.colostate.edu; Williams, John D., E-mail: john.d.williams@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

    2015-07-15

    Molybdenum oxide (MoO{sub x}) and molybdenum oxynitride (MoON) thin film back contacts were formed by a unique ion-beam sputtering and ion-beam-assisted deposition process onto CdTe solar cells and compared to back contacts made using carbon–nickel (C/Ni) paint. Glancing-incidence x-ray diffraction and x-ray photoelectron spectroscopy measurements show that partially crystalline MoO{sub x} films are created with a mixture of Mo, MoO{sub 2}, and MoO{sub 3} components. Lower crystallinity content is observed in the MoON films, with an additional component of molybdenum nitride present. Three different film thicknesses of MoO{sub x} and MoON were investigated that were capped in situ in Ni. Small area devices were delineated and characterized using current–voltage (J-V), capacitance–frequency, capacitance–voltage, electroluminescence, and light beam-induced current techniques. In addition, J-V data measured as a function of temperature (JVT) were used to estimate back barrier heights for each thickness of MoO{sub x} and MoON and for the C/Ni paint. Characterization prior to stressing indicated the devices were similar in performance. Characterization after stress testing indicated little change to cells with 120 and 180-nm thick MoO{sub x} and MoON films. However, moderate-to-large cell degradation was observed for 60-nm thick MoO{sub x} and MoON films and for C/Ni painted back contacts.

  5. Fabrication of back contacts using laser writer and photolithography for inscribing textured solar cells

    Indian Academy of Sciences (India)

    Murugaiya Sridar Ilango; Vijay Monterio; Sheela K Ramasesha

    2015-02-01

    Semiconductor fabrication process begins with photolithography. Preparing a photo mask is the key process step in photolithography. The photo mask was fabricated by inscribing patterns directly onto a soda lime glass with the help of a laser beam, as it is easily controllable. Laser writer LW405-A was used for preparing the mask in this study. Exposure wavelength of 405 nm was used, with which 1.2 m feature size can be written in direct write-mode over the soda lime glass plate. The advantage of using the fabricated mask is that it can be used to design back contacts for thin film Photovoltaic (PV) solar cells. To investigate the process capability of LW405-A, same pattern with different line widths was written on soda lime glass samples at different writing speeds. The pattern was inscribed without proximity effect and stitching errors, which was characterized using optical microscope and field emission scanning electron microscope (FE-SEM). It was proven that writing speed of a mask-writer is decided according to the intended feature size and line width. As the writing speed increases, the edges of the patterns become rougher due to uneven scattering of the laser beam. From the fabricated mask, the solar cell can be developed embedding both the contacts at the bottom layer, to increase the absorption of solar radiation on the top surface effectively by increasing light absorption area.

  6. A simulation study on the electrical structure of interdigitated back-contact silicon solar cells

    Science.gov (United States)

    Kang, Min Gu; Song, Hee-eun; Kim, Soo Min; Kim, Donghwan

    2015-05-01

    In this paper, a simulation for interdigitated back-contact (IBC) silicon solar cells was performed by using Silvaco TCAD ATLAS to investigate the cell's electrical properties. The impacts of various parameters, including the depth of the front surface field(FSF), the FSF peak doping concentration, the depths of the emitter and the back surface field(BSF), the peak doping concentrations of the emitter and BSF, the base doping, and the bulk lifetime on the output characteristics like the light current-voltage curves and the internal quantum efficiency of the IBC solar cell, were investigated. The light absorption was determined by adjusting the antireflection coating and the Al thickness. The FSF must be thin and have a low doping concentration for high-efficiency IBC cells. If the conversion efficiency is to be improved, a thick emitter and a high doping concentration are needed. Because of the low resistivity of the Si substrate, the series resistance was reduced, but recombination was increased. With a high-resistivity Si substrate, the opposite trends were observed. By counter-balancing the series resistance and the recombination, we determined by simulation that the optimized resistivity for the IBC cells was 1 Ω·cm. Because all metal electrodes in the IBC cells are located on the back side, a higher minority carrier lifetime showed a higher efficiency. After the various parameters had been optimized, texturing and surface recombination were added into the simulation. The simulated IBC cells showed a short-circuit current density of 42.89 mA/cm2, an open-circuit voltage of 714.8 mV, a fill factor of 84.04%, and a conversion efficiency of 25.77%.

  7. A simulation study of the micro-grooved electrode structure for back-contact back-junction silicon solar cell

    Science.gov (United States)

    Zhang, Bo; Yang, Jianfeng

    2015-01-01

    A micro-grooved electrode structure is investigated to illustrate its advantages when applied to the back-contact back-junction (BC-BJ) silicon solar cell. The finite element analysis shows that the micro-grooved electrodes enhances the photo-carrier collection and weakens the dependence of collection ability on pitch distance. The geometries of micro-groove are found to have little impact on the cell performance. These advantages open possibilities for the implementation of low cost fabrication methods. As a demonstration, a process involving laser doping and screen printing techniques are proposed and analyzed. The simulation results show that the laser induced lattice damage causes negligible deterioration of device electrical properties and the presence of parasitic metal insulator semiconductor structure near the screen printed electrodes actually leads to a performance improvement rather than degradation. Our preliminary results indicate that the micro-grooved electrode structure is promising for fabricating low cost high efficiency BC-BJ silicon solar cells.

  8. The Emitter Having Microcrystalline Surface in Silicon Heterojunction Interdigitated Back Contact Solar Cells

    Science.gov (United States)

    Ji, Kwang-sun; Syn, Hojung; Choi, Junghoon; Lee, Heon-Min; Kim, Donghwan

    2012-10-01

    In producing the Si heterojunction interdigitated backcontact solar cells, we investigated the feasibility of applying amorphous Si emitter having considerable crystalline Si phase at the facing to transparent conducting oxide (TCO) layer. Prior to evaluating electrical property, we characterized material nature of hydrogenated microcrystalline p-type silicon (µc-p-Si:H) as crystallized fraction, surface morphology, bonding kinds in thin films and then surface passivation quality finally. The diode and interface contact characteristics were induced by the simple test device and then current-voltage (I-V) curve showed more linearity in µc/hydrogenated amorphous silicon (a-Si:H) emitter case. We fabricated heterojunction back contact (HBC) solar cells using p/n interdigitated structure and acquired the 23.4% efficiency in cell size with performance parameters as open-circuit voltage (Voc) 723 mV, short-circuit current density (Jsc) 41.8 mA/cm2, fill factor (FF) 0.774, in the cell size (at 2×2 cm2).

  9. Plasma Immersion Ion Implantation for Interdigitated Back Passivated Contact (IBPC) Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Page, Matthew R.; Theingi, San; Young, Matthew; Aguiar, Jeffery; Lee, Benjamin G.; Stradins, Paul

    2016-11-21

    We present progress to develop low-cost interdigitated back contact solar cells with pc-Si/SiO2/c-Si passivated contacts formed by plasma immersion ion implantation (PIII). PIII is a lower-cost implantation technique than traditional beam-line implantation due to its simpler design, lower operating costs, and ability to run high doses (1E14-1E18 cm-2) at low ion energies (20 eV-10 keV). These benefits make PIII ideal for high throughput production of patterned passivated contacts, where high-dose, low-energy implantations are made into thin (20-200 nm) a-Si layers instead of into the wafer itself. For this work symmetric passivated contact test structures grown on n-Cz wafers with PH3 PIII doping gave implied open circuit voltage (iVoc) values of 730 mV with Jo values of 2 fA/cm2. Samples doped with B2H6 gave iVoc values of 690 mV and Jo values of 24 fA/cm2, outperforming BF3 doping, which gave iVoc values in the 660-680 mV range. Samples were further characterized by photoluminescence and SIMS depth profiles. Initial IBPC cell results are presented.

  10. Low-cost plasma immersion ion implantation doping for Interdigitated back passivated contact (IBPC) solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Page, Matthew R.; Theingi, San; Aguiar, Jeffery; Lee, Benjamin G.; Stradins, Paul

    2016-12-01

    We present progress to develop low-cost interdigitated back contact solar cells with pc-Si/SiO2/c-Si passivated contacts formed by plasma immersion ion implantation (PIII). PIII is a lower-cost implantation technique than traditional beam line implantation due to its simpler design, lower operating costs, and ability to run high doses (1E14-1E18 cm-2) at low ion energies (20 eV-10 keV). These benefits make PIII ideal for high throughput production of patterned passivated contacts, where high-dose, low-energy implantations are made into thin (20-200 nm) a-Si layers instead of into the wafer itself. For this work symmetric passivated contact test structures (~100 nm thick) grown on n-Cz wafers with pH3 PIII doping gave implied open circuit voltage (iVoc) values of 730 mV with Jo values of 2 fA/cm2. Samples doped with B2H6 gave iVoc values of 690 mV and Jo values of 24 fA/cm2, outperforming BF3 doping, which gave iVoc values in the 660-680 mV range. Samples were further characterized by SIMS, photoluminescence, TEM, EELS, and post-metallization TLM to reveal micro- and macro-scopic structural, chemical and electrical information.

  11. Three dimensionally structured interdigitated back contact thin film heterojunction solar cells

    Science.gov (United States)

    Hangarter, C. M.; Hamadani, B. H.; Guyer, J. E.; Xu, H.; Need, R.; Josell, D.

    2011-04-01

    Three dimensionally structured thin film photovoltaic devices based on interdigitated arrays of microscale electrodes are examined by external quantum efficiency simulations, indicating considerable JSC enhancement is possible through elimination of the front contact and window layer required in planar geometry devices. Electrode parameters including, pitch, width, height, and material are modeled and experimentally probed, demonstrating experimentally and capturing in models dependence on intrinsic material properties and electrode dimensions. In contrast to analogous silicon wafer back contact solar cells where the electrodes are placed on the silicon absorber at the end of processing, in this design the semiconductor is deposited on the electrodes, taking advantage of the thin film processing already required. Electrodeposited CdS/CdTe heterojunction devices approach 1% efficiencies with simulations as well as optical measurements indicating significant potential for improvement. Suboptimal performance is attributed to unintended materials reactions that preclude annealing at the temperatures required for absorber optimization as well as the Schottky barrier formation on the nonoptimal electrode materials. The test bed structures and absorber synthesis processes are amenable to an array of deposition techniques for fabrication and measurements of three dimensionally structured semiconductors, contact materials, and photovoltaic devices subject to processing feasibility and materials compatibility.

  12. Measurement of diffusion length and surface recombination velocity in Interdigitated Back Contact (IBC) and Front Surface Field (FSF) solar cells

    Science.gov (United States)

    Verlinden, Pierre; Van de Wiele, Fernand

    1985-03-01

    A method is proposed for measuring the diffusion length and surface recombination velocity of Interdigitated Back Contact (IBC) solar cells by means of a simple linear regression on experimental quantum efficiency values versus the inverse of the absorption coefficient. This method is extended to the case of Front Surface Field (FSF) solar cells. Under certain conditions, the real or the effective surface recombination velocity may be measured.

  13. Plasma-induced TCO texture of ZnO:Ga back contacts on silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Kuang-Chieh; Houng, Mau-Phon [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, No. 1, Dasyue Rd., East District, Tainan City 701 (China); Wang, Jen-Hung; Lu, Chun-hsiung; Tsai, Fu-Ji; Yeh, Chih-Hung [NexPower Technology Corporation, Taichung County 421 (China)

    2011-02-15

    This paper considers texturing of ZnO:Ga (GZO) films used as back contacts in amorphous silicon (a-Si) thin film solar cells. GZO thin films are first prepared by conventional methods. The as-deposited GZO surface properties are modified so that their use as back contacts on a-Si solar cells is enhanced. Texturing is performed by simple dry plasma etching in a CVD process chamber,at power=100 W, substrate temperature=190 C (temperature is held at 190 C because thin film solar cells are damaged above 200 C), pressure=400 Pa and process gas H{sub 2} flow=700 sccm. Conventional a-Si solar cells are fabricated with and without GZO back contact surface treatment. Comparison of the with/without texturing GZO films shows that plasma etching increases optical scattering reflectance and reflection haze. SEM and TEM are used to evaluate the morphological treatment-induced changes in the films. Comparison of the a-Si solar cells with/without texturing shows that the plasma treatment increases both the short-circuit current density and fill factor. Consequently, a-Si solar cell efficiency is relatively improved by 4.6%. (author)

  14. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  15. Evaluation of back contact in spray deposited SnS thin film solar cells by impedance analysis.

    Science.gov (United States)

    Patel, Malkeshkumar; Ray, Abhijit

    2014-07-09

    The role of back metal (M) contact in sprayed SnS thin film solar cells with a configuration Glass/F:SnO2/In2S3/SnS/M (M = Graphite, Cu, Mo, and Ni) was analyzed and discussed in the present study. Impedance spectroscopy was employed by incorporating constant phase elements (CPE) in the equivalent circuit to investigate the degree of inhomogeneity associated with the heterojunction and M/SnS interfaces. A best fit to Nyquist plot revealed a CPE exponent close to unity for thermally evaporated Cu, making it an ideal back contact. The Bode phase plot also exhibited a higher degree of disorders associated with other M/SnS interfaces. The evaluation scheme is useful for other emerging solar cells developed from low cost processing schemes like spray deposition, spin coating, slurry casting, electrodeposition, etc.

  16. Influence of Mo Back-Contact Oxidation on Properties of CIGSe(2) Thin Film Solar Cells on Glass Substrates

    OpenAIRE

    Rissom, T.; Kaufmann, C.A.; Caballero, R.; J. Schniebs; H. W. Schock; Michael Wiedenbeck

    2012-01-01

    Copper indium gallium diselenide (CIGSe) solar cells grown on glass substrates have reached an efficiency of 20.3%. Their industrial production is becoming increasingly relevant. While various deposition techniques for the fabrication of the absorber are used by different groups and corporations, molybdenum (Mo) has become the back contact material of choice. Oxidation of the bare Mo layer prior to absorber deposition is a phenomenon that is generally hard to control or to avoid. Since the in...

  17. Laser Fired Local Back Contact C-Si Solar Cells Using Phosphoric Acid for Back Surface Field

    Science.gov (United States)

    Balaji, Nagarajan; Park, Cheolmin; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Chung, Sungyoun; Raja, Jayapal; Yi, Junsin

    2015-04-01

    We report on a laser doping process for the formation of a local back surface field (BSF) using phosphoric acid (H3PO4) for n-type passivated emitter rear totally diffused silicon solar cells. The sheet resistance of the BSF layer was varied by changing the H3PO4 concentration. The BSF layer was passivated using SiN x . With the passivated BSF, the LBC solar cell shows an improved open circuit voltage. A laser power of 44 mW with 10 kHz resulted in a 45-Ω/sq BSF layer with effective lifetime of 290 μs and a higher V oc of 623 mV. With the optimized laser parameters, devices with the best electrical results yielded a short circuit current density of 36 mA/cm2 and an efficiency of 18.26%.

  18. Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Ralph, E-mail: ralph.mueller@ise.fraunhofer.de; Schrof, Julian; Reichel, Christian; Benick, Jan; Hermle, Martin [Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, Freiburg D-79110 (Germany)

    2014-09-08

    The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implanted phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.

  19. Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

    Science.gov (United States)

    Müller, Ralph; Schrof, Julian; Reichel, Christian; Benick, Jan; Hermle, Martin

    2014-09-01

    The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implanted phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.

  20. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  1. Degradation mechanisms studies in CdS/CdTe solar cells with ZnTe:Cu/Au back contact

    Science.gov (United States)

    Morgan, D.; Tang, J.; Kaydanov, V.; Ohno, T. R.; Trefny, J. U.

    1999-03-01

    CdS/CdTe/ZnTe:Cu/Au solar cells were fabricated and tested under stressed conditions including enhanced temperature, forward and reverse bias, open circuit, dark and light. Discussion of results was focused mostly on the development of the back contact Schottky diode (increase in series resistance). Changes in the cell parameters were detected based on the analysis of the dynamic resistance of a cell (dV/dJ) at forward biases. A possible role of electromigration of the Cu dopant was discussed.

  2. Degradation mechanisms studies in CdS/CdTe solar cells with ZnTe:Cu/Au back contact

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, D.; Tang, J.; Kaydanov, V.; Ohno, T.R.; Trefny, J.U. [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States)

    1999-03-01

    CdS/CdTe/ZnTe:Cu/Au solar cells were fabricated and tested under stressed conditions including enhanced temperature, forward and reverse bias, open circuit, dark and light. Discussion of results was focused mostly on the development of the back contact Schottky diode (increase in series resistance). Changes in the cell parameters were detected based on the analysis of the dynamic resistance of a cell (dV/dJ) at forward biases. A possible role of electromigration of the Cu dopant was discussed. {copyright} {ital 1999 American Institute of Physics.}

  3. Performance of Graphite Pastes Doped with Various Materials as Back Contact for CdS/CdTe Solar Cell

    Science.gov (United States)

    Hanafusa, Akira; Aramoto, Tetsuya; Morita, Akikatsu

    2001-12-01

    To date the problem of developing a suitable back contact for CdS/CdTe solar cells has yet to be resolved. The Cu-doped graphite paste that is widely used as a back contact is associated with degradation problems due to possible Cu diffusion across the CdS/CdTe junction. This study was designed to find ways to improve the graphite paste for superior electrical contacts. Mixtures of graphite paste with various material constituents and dopants consisting of silver-, lead-, nickel-, antimony-, bismuth-, or phosphor-based compounds, were studied. Results show that the performances of solar cells fabricated from these graphite pastes vary with the change in the composition. In the cases of Ag2Te and Ni2P, we studied their relationship with the solar cell characteristics with regard to dopant quantity, and furthermore in the case of Ag2Te, with regard to the sintering temperature of the graphite electrode. A fill factor (F.F.) of over 0.65 and efficiencies over 13% were obtained with Ag2Te, Ag3PO4, Ag2MoO4, and NiTe, and efficiencies over 12% were obtained with AgF, AgCl, Ni2P, and Ni3P.

  4. Band diagrams and performance of CdTe solar cells with a Sb2Te3 back contact buffer layer

    Directory of Open Access Journals (Sweden)

    Songbai Hu

    2011-12-01

    Full Text Available Sb2Te3 thin films were prepared by vacuum co-evaporation and the crystallinity of the films was greatly improved after annealing at 573 K in N2 ambient. Then they were deposited on the CdTe thick films. Band diagrams of the as-deposited and annealed CdTe/Sb2Te3 interfaces were constructed. Consequently, Sb2Te3 was used as a back contact layer for CdTe thin film solar cells and the cell performance was investigated. It was found that the Sb impurities accumulated in the CdTe grain boundaries diffuse deeply in the CdTe layer, and more photogenerated electrons and holes are separated by the segregated SbCd+ donors into the GBs. What is more, the doping concentration in the vicinity of the CdTe/CdS heterojunction increases for the formation of substitutional SbTe- acceptors under the Cd-rich conditions. For the introduction of the p-type Sb2Te3 layers as the back contact to the CdTe thin film solar cells, the performance of CdTe thin film solar cells has been greatly improved and an efficiency of 13.1% (FF=62.3%, Jsc=25.8 mA/cm2, Voc= 815.8 mV obtained.

  5. Simplified module assembly using back-contact crystalline-silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gee, J.M.; Garrett, S.E.; Morgan, W.P.

    1997-11-01

    The authors are developing new module concepts that encapsulate and electrically connect all the crystalline-silicon (c-Si) photovoltaic (PV) cells in a module in a single step. The new assembly process (1) uses back-contact c-Si cells, (2) uses a module backplane that has both the electrical circuit, encapsulant, and backsheet in a single piece, and (3) uses a single-step process for assembly of these components into a module. This new process reduces module assembly cost by using planar processes that are easy to automate, by reducing the number of steps, and by eliminating low-throughput (e.g., individual cell tabbing, cell stringing, etc.) steps. The authors refer to this process as monolithic module assembly since it translates many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Preliminary development of the new module assembly process, and some estimations of the cost potential of the new process, are presented.

  6. Impact of back-contact materials on performance and stability of cadmium sulfide/cadmium telluride solar cells

    Science.gov (United States)

    Demtsu, Samuel H.

    Thin-film CdTe based solar cells are one of the leading contenders for providing lowcost and pollution-free energy, The formation of a stable, low resistance, non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with this technology in the fabrication of efficient and stable solar cells. The premise of this thesis is a systematic study of the impact of back-contact materials on the initial performance and the degradation of CdS/CdTe solar cells. Two different back-contact structures that incorporate Cu as a key element are investigated in this study: (a) Cu1.4Te:HgTe-doped graphite and (b) evaporated-Cu back contacts. The effect of Cu inclusion is not limited to the back-contact layer where it is deposited. Cu is a known fast diffuser in p-CdTe, and therefore, a significant amount of Cu reaches both the CdTe and US layers. Hence, the effect of the presence of Cu on the individual layers: back-contact, the absorber (CdTe), and the window (CdS) layers is discussed respectively. The effect of different metals used to form the current-carrying electrode following the Cu layer is also evaluated. Devices are studied through current-voltage (JV) measurements at different temperatures and intensities, quantum efficiency (QE) measurements under light and voltage bias, capacitance-voltage (CV), drive-level-capacitance-profiling (DLCP), and time-resolved photoluminescence (TRPL) measurements. Numerical simulation is also used to reproduce and explain some of the experimental results. In devices made without Cu, a current-limiting effect, rollover (distortion) in the current-voltage characteristic, was observed. With the inclusion of a small amount of Cu (5-nm), however, the distortion disappeared, and higher FF was obtained. The performance of these devices was comparable to devices made with the standard Cu-doped graphite paste contacts when the same CdTe absorber is used. Small amount of Cu (5-20 nm) partially diffused into the

  7. Photo-assisted electrodeposition of polypyrrole back contact to CdS/CdTe solar cell structures

    Energy Technology Data Exchange (ETDEWEB)

    Jarkov, A., E-mail: aleksjarkov@gmail.com [Tallinn University of Technology, Department of Materials Science, Ehitajate tee 5, 19086 Tallinn (Estonia); Bereznev, S.; Volobujeva, O. [Tallinn University of Technology, Department of Materials Science, Ehitajate tee 5, 19086 Tallinn (Estonia); Traksmaa, R. [Tallinn University of Technology, Materials Research Center, Ehitajate tee 5, 19086 Tallinn (Estonia); Tverjanovich, A. [Saint-Petersburg State University, 198503 Saint-Petersburg, Staryj Petergof, Ulyanovskaya 5 (Russian Federation); Öpik, A.; Mellikov, E. [Tallinn University of Technology, Department of Materials Science, Ehitajate tee 5, 19086 Tallinn (Estonia)

    2013-05-01

    Glass/indium tin oxide/CdS/CdTe photovoltaic structures were prepared using the high vacuum evaporation method, followed by a typical activation procedure, which involves annealing of the structures at 415–430 °C in the presence of CdCl{sub 2} in air. The main purpose of this work was to prepare and evaluate the performance of complete CdS/CdTe solar cell structures with polypyrrole (PPy) back contact and compare it to the structures with standard, copper containing back contact. Back contact layers of PPy doped with ß-naphthalene sulfonate were deposited onto activated CdTe layers by photo-assisted electrodeposition technique in a three-electrode electrochemical cell. It was found that intensive white light illumination from a xenon lamp facilitates PPy deposition at a lower applied potential range and improves quality of obtained polymer films. Applied technique gives the possibility to deposit the PPy layer strictly onto illuminated photoactive CdTe surface eliminating possible short-circuiting through pinholes and cracks in CdTe photoabsorber layer. Furthermore, relatively low deposition potential values give the possibility to reduce electrochemical degradation of CdS/CdTe photovoltaic structure in an electrochemical cell. - Highlights: ► Polypyrrole (PPy) conductive polymer back contact (BC) to CdTe semiconductor. ► Hybrid organic/inorganic photovoltaic structures. ► PPy layer to CdTe by photo-assisted electrodeposition technique ► Comparable efficiency of cells with PPy and conventional inorganic Cu{sub x}Te BC.

  8. Interdigitated Back-Surface-Contact Solar Cell Modeling Using Silvaco Atlas

    Science.gov (United States)

    2015-06-01

    the Solar Portable Alternative Communications Energy System (SPACES). SPACES consist of a 0.73 m2 solar panel and power module [1]. It is capable...to provide electrical power to Marines in the field (see Figure 1). The Solar Portable Alternative Communications Energy System consists of a 0.73...investigations into using materials other than silicon, which may further improve power output. 14. SUBJECT TERMS Solar cell

  9. Sputtered CdTe thin film solar cells with Cu{sub 2}Te/Au back contact

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yongseob [Department of Photoelectronics Information, Chosun College of Science and Technology, Pilmudaero 309-1, Dong-gu, Gwangju 501-744 (Korea, Republic of); Lee, Suho; Yi, Junsin; Choi, Byung-Duck [School of Electronic and Electrical Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of); Kim, Doyoung [School of Electricity and Electronics, Ulsan College, Daehak-ro 57, Nam-gu, Ulsan 680-749 (Korea, Republic of); Lee, Jaehyeong, E-mail: jaehyeong@skku.edu [School of Electronic and Electrical Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2013-11-01

    In this work, Cu{sub 2}Te/Au back contact for CdTe thin film solar cells were prepared by vacuum evaporation. Influence of annealing temperature on the structure and electrical properties of Cu{sub 2}Te films were investigated by field emission scanning electron microscope, X-ray diffraction, and Hall effect measurement. Also, CdS/CdTe thin film solar cells were fabricated by magnetron sputtering process, which is favorable for large area deposition and mass production, and the photovoltaic characteristics were studied. As the annealing temperature was increased, the crystal structure transformed from Cu{sub 2}Te for as-deposited film to Cu{sub 2−x}Te hexagonal phase, and the grains in the film became bigger. The electrical resistivity was slightly higher by the annealing. The cell efficiency was significantly improved by the heat treatment, and showed a maximum value of 9.14% at 180 °C. From these results, Cu{sub 2}Te/Au contact acts as the proper pseudo-ohmic contact onto CdTe film. However, further increase of annealing temperature caused the deterioration of cell performance. - Highlights: • Annealing effects of the vacuum evaporated Cu{sub 2}Te films were investigated. • The transformation from Cu{sub 2}Te to Cu{sub 2−x}Te hexagonal phase occurred by annealing. • The performance of the solar cell was highly increased by annealing at 180 °C. • Cu{sub 2}Te/Au contact acts as the proper pseudo-ohmic contact onto CdTe film.

  10. Bragg reflector and laser fired back contact in a-Si:H/c-Si heterostructure solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Tucci, M. [ENEA, Research Center Casaccia, via Anguillarese 301, S. Maria di Galeria 00123, Rome (Italy)], E-mail: mario.tucci@casaccia.enea.it; Serenelli, L.; Salza, E.; Pirozzi, L. [ENEA, Research Center Casaccia, via Anguillarese 301, S. Maria di Galeria 00123, Rome (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M. [Department of Electronic Engineering, University ' Sapienza' , via Eudossiana 18 00184, Rome (Italy)

    2009-03-15

    The amorphous/crystalline silicon (a-Si/c-Si) heterostructure has recently attracted new interest due to higher open circuit voltage V{sub oc} and low temperature fabrication processes. By reducing the wafer thickness all these characteristics become a necessity, together with the requirement of a back reflecting mirror, to obtain an effective optical confinement. To this aim dielectric mirrors can be adopted in the rear side of the solar cells, together with a local process of laser fired back Al contact. Taking advantage of a-Si/SiN{sub x} passivation properties of c-Si surface a Bragg reflector configuration can be formed on the rear side of the c-Si wafer by Plasma Enhanced Chemical Vapor Deposition (PECVD) alternating several couples of a-Si/SiN{sub x} and choosing their thicknesses to maximize the reflectance inward the c-Si wafer in the NIR spectrum. In this work we have adopted this mirror on the rear side of an n-a-Si/i-a-Si/p-c-Si heterostructure solar cell to obtain a full low temperature process. The cell back contact has been ensured by an Al diffusion into the c-Si wafer promoted by Nd-YAG pulsed laser. The front cell contact has been enhanced by chromium silicide CrSi formation on top of the n-a-Si layer and ITO deposition followed by an Ag grid. A V{sub oc} of 681 mV and 94% of IQE at 1000 nm have been reached.

  11. Analysis of the interdigitated back contact solar cells: The n-type substrate lifetime and wafer thickness

    Science.gov (United States)

    Zhang, Wei; Chen, Chen; Jia, Rui; Sun, Yun; Xing, Zhao; Jin, Zhi; Liu, Xin-Yu; Liu, Xiao-Wen

    2015-10-01

    The n-type silicon integrated-back contact (IBC) solar cell has attracted much attention due to its high efficiency, whereas its performance is very sensitive to the wafer of low quality or the contamination during high temperature fabrication processing, which leads to low bulk lifetime τbulk. In order to clarify the influence of bulk lifetime on cell characteristics, two-dimensional (2D) TCAD simulation, combined with our experimental data, is used to simulate the cell performances, with the wafer thickness scaled down under various τbulk conditions. The modeling results show that for the IBC solar cell with high τbulk, (such as 1 ms-2 ms), its open-circuit voltage Voc almost remains unchanged, and the short-circuit current density Jsc monotonically decreases as the wafer thickness scales down. In comparison, for the solar cell with low τbulk (for instance, Solar Energy Action Plan from the Chinese Academy of Sciences (Grant Nos. Y3ZR044001 and Y2YF014001).

  12. Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency

    OpenAIRE

    Savin, Hele; Repo, Päivikki; Von Gastrow, Guillaume; Ortega, Pablo; Calle, Eric; Garín, Moises; Alcubilla, Ramon

    2015-01-01

    The nanostructuring of silicon surfaces—known as black silicon—is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at t...

  13. Prospects of novel front and back contacts for high efficiency cadmium telluride thin film solar cells from numerical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Matin, M.A. [Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Electrical and Electronics Engineering, Chittagong University of Engineering and Technology (CUET), Chittagong (Bangladesh); Mannir Aliyu, M.; Quadery, Abrar H. [Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Amin, Nowshad [Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Center of Excellence for Research in Engineering Materials (CEREM), College of Engineering, King Saud University, Riyadh 11421 (Saudi Arabia)

    2010-09-15

    Cadmium telluride (CdTe) thin film solar cell has long been recognized as a leading photovoltaic candidate for its high efficiency and low cost. A numerical simulation has been performed using AMPS-1D simulator to explore the possibility of higher efficiency and stable CdS/CdTe cell among several cell structures with indium tin oxide (ITO) and cadmium stannate (Cd{sub 2}SnO{sub 4}) as front contact material, tin oxide (SnO{sub 2}), zinc oxide (ZnO) and zinc stannate (Zn{sub 2}SnO{sub 4}) as buffer layer, and silver (Ag) or antimony telluride (Sb{sub 2}Te{sub 3}) with molybdenum (Mo) or zinc telluride (ZnTe) with aluminium (Al) as back contact material. The cell structure ITO/i-ZnO/CdS/CdS{sub x}Te{sub 1-x}/CdTe/Ag has shown the best conversion efficiency of 16.9% (Voc=0.9 V, Jsc=26.35 mA/cm{sup 2}, FF=0.783). This analysis has shown that ITO as front contact material, ZnO as buffer layer and ZnTe or Sb{sub 2}Te{sub 3} back surface reflector (BSR) are suitable material system for high efficiency (>15%) and stable CdS/CdTe cells. The cell normalized efficiency linearly decreased at a temperature gradient of -0.25%/ C for ZnTe based cells, and at -0.40%/ C for other cells. (author)

  14. Analysis of the interdigitated back contact solar cells:The n-type substrate lifetime and wafer thickness

    Institute of Scientific and Technical Information of China (English)

    张巍; 陈晨; 贾锐; 孙昀; 邢钊; 金智; 刘新宇; 刘晓文

    2015-01-01

    The n-type silicon integrated-back contact (IBC) solar cell has attracted much attention due to its high efficiency, whereas its performance is very sensitive to the wafer of low quality or the contamination during high temperature fab-rication processing, which leads to low bulk lifetimeτbulk. In order to clarify the influence of bulk lifetime on cell char-acteristics, two-dimensional (2D) TCAD simulation, combined with our experimental data, is used to simulate the cell performances, with the wafer thickness scaled down under variousτbulk conditions. The modeling results show that for the IBC solar cell with highτbulk, (such as 1 ms–2 ms), its open-circuit voltage Voc almost remains unchanged, and the short-circuit current density Jsc monotonically decreases as the wafer thickness scales down. In comparison, for the solar cell with lowτbulk (for instance,<500 µs) wafer or the wafer contaminated during device processing, the Voc increases monotonically but the Jsc first increases to a maximum value and then drops off as the wafer’s thickness decreases. A model combing the light absorption and the minority carrier diffusion is used to explain this phenomenon. The research results show that for the wafer with thinner thickness and high bulk lifetime, the good light trapping technology must be developed to offset the decrease in Jsc.

  15. Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangtao; Ingenito, Andrea; Hameren, Nienke van; Isabella, Olindo; Zeman, Miro [PVMD, Delft University of Technology, P.O. Box 5031, 2600 GA Delft (Netherlands)

    2016-01-18

    Ion-implanted passivating contacts based on poly-crystalline silicon (polySi) are enabled by tunneling oxide, optimized, and used to fabricate interdigitated back contact (IBC) solar cells. Both n-type (phosphorous doped) and p-type (boron doped) passivating contacts are fabricated by ion-implantation of intrinsic polySi layers deposited via low-pressure chemical vapor deposition and subsequently annealed. The impact of doping profile on the passivation quality of the polySi doped contacts is studied for both polarities. It was found that an excellent surface passivation could be obtained by confining as much as possible the implanted-and-activated dopants within the polySi layers. The doping profile in the polySi was controlled by modifying the polySi thickness, the energy and dose of ion-implantation, and the temperature and time of annealing. An implied open-circuit voltage of 721 mV for n-type and 692 mV for p-type passivating contacts was achieved. Besides the high passivating quality, the developed passivating contacts exhibit reasonable high conductivity (R{sub sh n-type} = 95 Ω/□ and R{sub sh p-type} = 120 Ω/□). An efficiency of 19.2% (V{sub oc} = 673 mV, J{sub sc} = 38.0 mA/cm{sup 2}, FF = 75.2%, and pseudo-FF = 83.2%) was achieved on a front-textured IBC solar cell with polySi passivating contacts as both back surface field and emitter. By improving the front-side passivation, a V{sub OC} of 696 mV was also measured.

  16. Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

    Science.gov (United States)

    Yang, Guangtao; Ingenito, Andrea; van Hameren, Nienke; Isabella, Olindo; Zeman, Miro

    2016-01-01

    Ion-implanted passivating contacts based on poly-crystalline silicon (polySi) are enabled by tunneling oxide, optimized, and used to fabricate interdigitated back contact (IBC) solar cells. Both n-type (phosphorous doped) and p-type (boron doped) passivating contacts are fabricated by ion-implantation of intrinsic polySi layers deposited via low-pressure chemical vapor deposition and subsequently annealed. The impact of doping profile on the passivation quality of the polySi doped contacts is studied for both polarities. It was found that an excellent surface passivation could be obtained by confining as much as possible the implanted-and-activated dopants within the polySi layers. The doping profile in the polySi was controlled by modifying the polySi thickness, the energy and dose of ion-implantation, and the temperature and time of annealing. An implied open-circuit voltage of 721 mV for n-type and 692 mV for p-type passivating contacts was achieved. Besides the high passivating quality, the developed passivating contacts exhibit reasonable high conductivity (Rsh n-type = 95 Ω/□ and Rsh p-type = 120 Ω/□). An efficiency of 19.2% (Voc = 673 mV, Jsc = 38.0 mA/cm2, FF = 75.2%, and pseudo-FF = 83.2%) was achieved on a front-textured IBC solar cell with polySi passivating contacts as both back surface field and emitter. By improving the front-side passivation, a VOC of 696 mV was also measured.

  17. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2015-07-21

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  18. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  19. Solar cell contact formation using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  20. Influence of Mo Back-Contact Oxidation on Properties of CIGSe2 Thin Film Solar Cells on Glass Substrates

    Science.gov (United States)

    Rissom, Thorsten; Kaufmann, Christian A.; Caballero, Raquel; Schniebs, Jan; Schock, Hans-Werner; Wiedenbeck, Michael

    2012-10-01

    Copper indium gallium diselenide (CIGSe) solar cells grown on glass substrates have reached an efficiency of 20.3%. Their industrial production is becoming increasingly relevant. While various deposition techniques for the fabrication of the absorber are used by different groups and corporations, molybdenum (Mo) has become the back contact material of choice. Oxidation of the bare Mo layer prior to absorber deposition is a phenomenon that is generally hard to control or to avoid. Since the incorporation of sodium (Na) into the absorber layer is commonly achieved by diffusion from a glass substrate through the Mo layer, oxidation of the back contact will influence the diffusion, and thus the availability of Na during the CIGSe growth process. In order to investigate this effect, Na containing glass substrates with Mo layers in different stages of oxidation have been prepared using a damp heat treatment. The samples were coated with CIGSe by physical vapor deposition in a multistage co-evaporation process. The CIGSe/Mo-interface is investigated by Raman spectroscopy and secondary ion mass spectroscopy, using a lift-off technique. The damp heat treatment led to the formation of an oxide layer (presumably MoO2) and an increase of the sodium content in the grown absorber layers.

  1. Opto-Electronic Characterization CdTe Solar Cells from TCO to Back Contact with Nano-Scale CL Probe

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John; Al-Jassim, Mowafak M.; Paudel, Naba; Mahabaduge, Hasitha; Kuciauskas, Darius; Guthrey, Harvey L.; Duenow, Joel; Yan, Yanfa; Metzger, Wyatt K.; Ahrenkiel, Richard K.

    2015-06-14

    We used cathodoluminescence (CL) (spectrum-per-pixel) imaging on beveled CdTe solar cell sections to investigate the opto-electronic properties of these devices from the TCO to the back contact. We used a nano-scale CL probe to resolve luminescence from grain boundary (GB) and grain interior (GI) locations near the CdS/CdTe interface where the grains are very small. As-deposited, CdCl2-treated, Cu-treated, and (CdCl2+Cu)-treated cells were analyzed. Color-coded CL spectrum imaging maps on bevels illustrate the distribution of the T=6 K luminescence transitions through the depth of devices with unprecedented spatial resolution. The CL at the GBs and GIs is shown to vary significantly from the front to the back of devices and is a sensitive function of processing. Supporting D-SIMS depth profile, TRPL lifetime, and C-V measurements are used to link the CL data to the J-V performance of devices.

  2. Development of Screen-Printed Texture-Barrier Paste for Single-Side Texturization of Interdigitated Back-Contact Silicon Solar Cell Applications

    OpenAIRE

    Chi-Cheng Chen; Chin-Lung Cheng; Thou-Jen Whang; Yu-Shun Chiu

    2013-01-01

    Continuous cost reduction of silicon-based solar cells is needed to lower the process time and increase efficiency. To achieve lower costs, screen-printed texture-barrier (SPTB) paste was first developed for single-side texturization (ST) of the interdigitated back-contact (IBC) for silicon-based solar cell applications. The SPTB paste was screen-printed on silicon substrates. The SPTB paste was synthesized from intermixed silicate glass (75 wt %), a resin binder (ethyl cellulose ethoce: 20 w...

  3. Potential of ITO nanoparticles formed by hydrogen treatment in PECVD for improved performance of back grid contact crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Sourav; Mitra, Suchismita; Dhar, Sukanta; Ghosh, Hemanta; Banerjee, Chandan, E-mail: chandanbanerjee74@gmail.com; Datta, Swapan K.; Saha, Hiranmoy

    2015-09-15

    Highlights: • Indium tin oxide (ITO) nanoparticles as back scatterers in c-Si solar cells. • ITO NP have comparatively low dissipative losses and tunable optical properties. • ITO NP formed by hydrogen plasma treatment on sputtered ITO film. • Enhanced absorption and carrier collection at longer wavelengths due to enhanced light trapping. - Abstract: This paper discusses the prospect of using indium tin oxide (ITO) nanoparticles as back scatterers in crystalline silicon solar cells instead of commonly used metal nanoparticles as ITO nanoparticles have comparatively low dissipative losses and tunable optical properties. ITO nanoparticles of ∼5–10 nm size is developed on the rear side of the solar cell by deposition of ∼5–10 nm thick ITO layer by DC magnetron sputtering followed by hydrogen treatment in PECVD. The silicon solar cell is fabricated in the laboratory using conventional method with grid metal contact at the back surface. Various characterizations like FESEM, TEM, AFM, XRD, EQE and IV characteristics are performed to analyze the morphology, chemical composition, optical characteristics and electrical performance of the device. ITO nanoparticles at the back surface of the solar cell significantly enhances the short circuit current, open circuit voltage and efficiency of the solar cell. These enhancements may be attributed to the increased absorption and carrier collection at longer wavelengths of solar spectrum due to enhanced light trapping by the ITO nanoparticles and surface passivation by the hydrogen treatment of the back surface.

  4. Heavily doped polysilicon-contact solar cells

    Science.gov (United States)

    Lindholm, F. A.; Neugroschel, A.; Arienzo, M.; Iles, P. A.

    1985-01-01

    The first use of a (silicon)/heavily doped polysilicon)/(metal) structure to replace the conventional high-low junction or back-surface-field (BSF) structure of silicon solar cells is reported. Compared with BSF and back-ohmic-contact (BOC) control samples, the polysilicon-back solar cells show improvements in red spectral response (RSR) and open-circuit voltage. Measurement reveals that a decrease in effective surface recombination velocity S is responsible for this improvement. Decreased S results for n-type (Si:As) polysilicon, consistent with past findings for bipolar transistors, and for p-type (Si:B) polysilicon, reported here for the first time. Though the present polysilicon-back solar cells are far from optimal, the results suggest a new class of designs for high efficiency silicon solar cells. Detailed technical reasons are advanced to support this view.

  5. Transparent conducting oxide contacts and textured metal back reflectors for thin film silicon solar cells

    NARCIS (Netherlands)

    Franken, R.H.-J.

    2006-01-01

    With the growing population and the increasing environmental problems of the 'common' fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic (PV) systems, can play a major role in the urgently needed energy

  6. Deep level transient spectroscopy investigation of deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact

    Science.gov (United States)

    Wang, Zhao; Li, Bing; Zheng, Xu; Xie, Jing; Huang, Zheng; Liu, Cai; Feng, Liang-Huan; Zheng, Jia-Gui

    2010-02-01

    Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep defects in the CdTe thin film. With the help of deep level transient spectroscopy (DLTS), we study the deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact. One hole trap and one electron trap are observed. The hole trap H1, localized at Ev + 0.128 eV, originates from the vacancy of Cd (VCd). The electron trap E1, found at Ec -0.178 eV, is considered to be correlated with the interstitial Cuj+ in CdTe.

  7. Ultraviolet laser ablation of fluorine-doped tin oxide thin films for dye-sensitized back-contact solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Huan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Fu, Dongchuan [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia); Jiang, Ming [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Duan, Jun, E-mail: duans@hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Zhang, Fei; Zeng, Xiaoyan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Bach, Udo [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia)

    2013-03-01

    In this study, laser ablation of a fluorine-doped tin oxide (FTO) thin film on a glass substrate was conducted using a 355 nm Nd:YVO{sub 4} ultraviolet (UV) laser to obtain a 4 × 4 mm microstructure. The microstructure contains a symmetric set of interdigitated FTO finger electrodes of a monolithic back-contact dye-sensitized solar cell (BC-DSC) on a common substrate. The effects of UV laser ablation parameters (such as laser fluence, repetition frequency, and scanning speed) on the size precision and quality of the microstructure were investigated using a 4 × 4 orthogonal design and an assistant experimental design. The incident photon-to-electron conversion efficiency and the current–voltage characteristics of the BC-DSC base of the interdigitated FTO finger electrodes were also determined. The experimental results show that an FTO film microstructure with high precision and good quality can be produced on a glass substrate via laser ablation with high scanning speed, high repetition frequency, and appropriate laser fluence. - Highlights: ► The ablation width and depth generally depend on the laser fluence. ► The scanning speed and the repetition frequency must match each other. ► Slight ablation of the glass substrate can completely remove F-doped tin oxide.

  8. The Effect of Sputtering Parameters on the Film Properties of Molybdenum Back Contact for CIGS Solar Cells

    Directory of Open Access Journals (Sweden)

    Peng-cheng Huang

    2013-01-01

    Full Text Available Molybdenum (Mo thin films are widely used as a back contact for CIGS-based solar cells. This paper determines the optimal settings for the sputtering parameters for an Mo thin film prepared on soda lime glass substrates, using direct current (dc magnetron sputtering, with a metal Mo target, in an argon gas environment. A Taguchi method with an L9 orthogonal array, the signal-to-noise ratio, and an analysis of variances is used to determine the performance characteristics of the coating operation. The main sputtering parameters, such as working pressure (mTorr, dc power (W, and substrate temperature (°C, are optimized with respect to the structural features, surface morphology, and electrical properties of the Mo films. An adhesive tape test is performed on each film to determine the adhesion strength of the films. The experimental results show that the working pressure has the dominant effect on electrical resistivity and reflectance. The intensity of the main peak (110 for the Mo film increases and the full width at half maximum decreases gradually as the sputtering power is increased. Additionally, the application of an Mo bilayer demonstrates good adherence and low resistivity.

  9. Superior stability of ultra thin CdTe solar cells with simple Cu/Au back contact

    Energy Technology Data Exchange (ETDEWEB)

    Rimmaudo, Ivan; Salavei, Andrei; Xu, Bing Lei; Di Mare, Simone; Romeo, Alessandro, E-mail: alessandro.romeo@univr.it

    2015-05-01

    Due to its high scalability and low production cost, CdTe has shown a significant potential for high mass production, resulting to be one of the cheapest photovoltaic technologies available. Efficiencies exceeding 20% have been obtained by the application of high temperature CdTe deposition. However tellurium scarcity is a limitation for mass production and one of the possibilities to overcome this is the reduction of absorber thickness. We have already demonstrated efficiencies above 11% for devices with 1.5 μm thick CdTe. Nowadays we have fabricated ultra-thin absorber devices performing more than 13% efficiencies. But what is most interesting is that we have observed a different electrical operation and stability, connected to the fact that the depletion region takes a very large part of the device. In this work many CdTe solar cells with a standard Cu/Au back contact, made with different absorber thicknesses, were prepared, stored in dark and tested at different aging times, showing different reactions to the aging and in particular a remarkable stability as CdTe thickness reduces. - Highlights: • CdTe/CdS devices with 0.7, 1 and 1.8 μm thick absorbers have been prepared. • Superior stability in dark aging of ultra thin CdTe devices has been registered. • Electrical analysis shows different behaviors and nature of defects for thin CdTe samples. • For 6 μm CdTe samples degradation is driven mainly by defect compensation. • For ultra thin CdTe samples, degradation is dominated by impurities from the front contact.

  10. Two-dimensional simulation of interdigitated back contact silicon heterojunction solar cells having overlapped p/i and n/i a-Si:H layers

    Science.gov (United States)

    Noge, Hiroshi; Saito, Kimihiko; Sato, Aiko; Kaneko, Tetsuya; Kondo, Michio

    2015-08-01

    The performance of interdigitated back contact silicon heterojunction solar cells having overlapped p/i and n/i a-Si:H layers on the back has been investigated by two-dimensional simulation in comparison with the conventional cell structure having a gap between p/i and n/i layers. The results show that narrower overlap width leads to higher short circuit current and conversion efficiency, especially for poor heterojunction interface and thinner silicon substrate of the cells in addition to narrower uncovered width of p/i layer by a metal electrode. This is similar to the gap width dependence in the conventional cells, since both overlap and gap act as dead area for diffused excess carriers in the back contacts.

  11. Front surface field formation and diffusion profiles for industrial interdigitated back contact solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cascant, M.; Morecroft, D.; Boulif, K.; Vauche, L.; Yuste, H.; Castano, F.J. [Siliken, High efficiency solar cell pilot line, R and D department, Ciudad Politecnica de la Innovacion- UPV Camino de Vera 14, 46022 Valencia, (Spain); Bende, E.E. [ECN Solar Energy, Petten (Netherlands)

    2012-09-15

    Optimization of the Front Surface Field (FSF) for IBC cells is important for passivation, lowering series resistance and reducing UV light degradation. This work presents results for optimizing the FSF diffusion from an industrial perspective, focusing on optimizing the process flow to achieve excellent FSF performance, whilst at the same time reducing the number of process steps. The ideal FSF profile is a compromise since a lightly doped deep diffusion reduces recombination losses close the cell surface where the light is captured, whilst increased doping reduces series resistance. This work investigates diffusing the FSF (1) at the beginning, (2) in the middle and (3) towards the end of the IBC process flow. The advantage of the first option is that the diffusion depth can be increased by subsequent thermal steps. However a diffusion barrier is required to protect the FSF throughout the subsequent processing, which increases the number of process steps and results in increased costs. By placing the FSF diffusion later in the process flow it is possible to simplify the process reducing the number of steps. Experimental results show excellent FSF diffusion passivation performance over 156mm, with lifetime values of over 500 {mu}s. Simulations confirm that high current generation can be achieved with a short circuit current of over 40 mA cm-{sup 2}.

  12. Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells

    Science.gov (United States)

    Haschke, Jan; Amkreutz, Daniel; Rech, Bernd

    2016-04-01

    Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.

  13. Optimization of Metal Coverage on the Emitter in n-Type Interdigitated Back Contact Solar Cells Using a PC2D Simulation

    Science.gov (United States)

    Zhang, Wei; Chen, Chen; Jia, Rui; Janssen, G. J. M.; Zhang, Dai-Sheng; Xing, Zhao; Bronsveld, P. C. P.; Weeber, A. W.; Jin, Zhi; Liu, Xin-Yu

    2013-07-01

    In interdigitated back contact (IBC) solar cells, the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation. The result shows that the variation of the metal coverage ratio (MCR) will affect both the surface passivation and the electrode-contact properties for the p-type emitter in IBC solar cells. We find that when Rc ranges from 0.08 to 0.16Ω·cm2, the MCR is optimized with a value of 25% and 33%, resulting in a highest energy-conversion efficiency. The dependences of both Voc and fill factor on MCR are simulated in order to explore the mechanism of the IBC solar cells.

  14. Effects of the Au/CdTe back contact on IV and CV characteristics of Au/CdTe/CdS/TCO solar cells

    Science.gov (United States)

    Niemegeers, Alex; Burgelman, Marc

    1997-03-01

    A simple analytical theory is presented to explain the measured roll over and cross over behaviour of the IV characteristics of thin film CdTe solar cells. It involves a classical description of the CdS/CdTe junction and the CdTe/back contact structure and is extended with a new description of minority carrier current in the CdTe contact region. This extension is crucial in describing the light dependence of the forward IV curves, and hence cross over. The same model also explains the measured CV curves. It is shown that analysis of the capacitance measurement can yield additional information about the doping density of CdTe in the vicinity of the contact. A relationship between the fill factor of the solar cell and the barrier height of the back contact is derived; this relation is useful as a new, practical criterion for the quality of the back contact. The results of this simple analytical model are confirmed by full numerical calculations of the dc and ac characteristics.

  15. The optimization of molybdenum back contact films for Cu(In,Ga)Se{sub 2} solar cells by the cathodic arc ion plating method

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yong Ki, E-mail: choyk@kitech.re.kr [Heat Treatment and Surface Engineering R and D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Gang Sam; Song, Young Sik; Lim, Tae Hong [Heat Treatment and Surface Engineering R and D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Jung, Donggeun [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2013-12-02

    Molybdenum back contact films for Cu(In,Ga)Se{sub 2} (CIGS) solar cells have been deposited using DC magnetron sputtering methods. The electronic pathway properties of the molybdenum film have been highly dependent on the working gas pressure in magnetron sputtering, which should be carefully controlled to obtain high conductivity and adhesion. A coating method, cathodic arc ion plating, was used for molybdenum back contact electrode fabrication. The aim of this work was to find a metallization method for CIGS solar cells, which has less sensitivity on the working pressure. The resistivity, grain size, growth structures, stress, and efficiency of the films in CIGS solar cells were investigated. The results reveal that the growth structures of the molybdenum films mainly affect the conductivity. The lowest electrical resistivity of the ion-plated molybdenum films was 6.9 μΩ-cm at a pressure of 0.7 Pa. The electrical resistivity variation showed a gently increasing slope with linearity under a working gas pressure of 13.3 Pa. However, a high value of the residual stress of over 1.3 GPa was measured. In order to reduce stress, titanium film was selected as the buffer layer material, and the back contact films were optimized by double-layer coating of two kinds of hetero-materials with arc ion plating. CIGS solar cells prepared molybdenum films to measure the efficiency and to examine the effects of the back contact electrode. The resistivity, grain size, and surface morphology of molybdenum films were measured by four-point probe, X-ray diffraction, and a scanning electron microscope. The residual stress of the films was calculated from differences in bending curvatures measured using a laser beam. - Highlights: • Molybdenum back contact films for Cu(In,Ga)Se{sub 2} solar cells were prepared by the cathodic arc ion plating. • The lowest electrical resistivity of molybdenum film was 6.9 μΩ-cm. • Titanium buffer layer reduced the compressive residual stress

  16. Analysis of the back contact properties of Cu(In,Ga)Se{sub 2} solar cells employing the thermionic emission model

    Energy Technology Data Exchange (ETDEWEB)

    Neugebohrn, Nils, E-mail: nils.neugebohrn@uni-oldenburg.de; Hammer, Maria S.; Neerken, Janet; Parisi, Jürgen; Riedel, Ingo

    2015-05-01

    Despite 20 years of research on Cu(In,Ga)Se{sub 2} (CIGSe) solar cells there is still no conclusive model to explain the electronic properties of the back contact between the CIGSe absorber and the molybdenum electrode. For this interface, Schottky-type as well as ohmic behavior has been reported previously. In particular, the intermediate MoSe{sub 2} layer which forms between the absorber and the metal during growth of the CIGSe layer determines the contact characteristics and might be critical for the device performance. In this study two types of samples were prepared from complete solar cells: MoSe{sub 2}/Mo samples by lift-off of the CIGSe layer and CIGSe/MoSe{sub 2}/Mo samples either via etch-removal of ZnO/CdS or etching including thickness reduction of the CIGSe layer. Au contacts were deposited on top of the CIGSe layer. To study a potential barrier-induced current limitation we performed temperature-dependent current-voltage measurements between 80 K and 300 K on both samples. We observed a limitation of the injection current following the thermionic emission model only for the latter sample, indicating the presence of a contact barrier with a barrier height between 0.21 eV and 0.24 eV at the CIGSe/MoSe{sub 2} interface. On the basis of a qualitative simulation a band diagram for the CIGSe/MoSe{sub 2} interface is proposed. - Highlights: • An analysis of properties of the back contact of CIGSe solar cells is presented. • An injection barrier at the CIGSe/MoSe{sub 2} interface can be concluded. • A band diagram for the CIGSe/MoSe{sub 2} on the basis of simulations is proposed. • The back contact barrier is unlikely to impact device performance negatively.

  17. Development of Screen-Printed Texture-Barrier Paste for Single-Side Texturization of Interdigitated Back-Contact Silicon Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Chi-Cheng Chen

    2013-10-01

    Full Text Available Continuous cost reduction of silicon-based solar cells is needed to lower the process time and increase efficiency. To achieve lower costs, screen-printed texture-barrier (SPTB paste was first developed for single-side texturization (ST of the interdigitated back-contact (IBC for silicon-based solar cell applications. The SPTB paste was screen-printed on silicon substrates. The SPTB paste was synthesized from intermixed silicate glass (75 wt %, a resin binder (ethyl cellulose ethoce: 20 wt %, and a dispersing agent (fatty acid: 5 wt %. The silicate glass is a necessity for contact formation during firing. A resin binder and a dispersing agent determine the rheology of the SPTB paste. In this work, by modulating various parameters, including post SPTB firing, alkali texturing, and removal of the SPTB, the ST of IBC silicon solar cells was achieved. Since the advantages of the SPTB paste include low toxicity and prompt formation of the texture-barrier, SPTB is potentially suited for simple fabrication at low-cost for solar cell applications. The cost of the SPTB is around $100/kg which is lower than the SiH4/NH3 gas ambient used in plasma-enhanced chemical vapor deposition (PECVD. Thus, the expensive Si3N4 film deposited by PECVD using SiH4 and NH3 gas ambient for silicon solar cells can be replaced by this SPTB.

  18. Fabrication of CdS/CdTe solar cells with transparent p-type conductive BaCuSeF back contact

    Science.gov (United States)

    Yamamoto, Koichi; Sakakima, Hiroshi; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Wada, Takahiro

    2015-08-01

    BaCuSeF films were applied to CdS/CdTe solar cells as back electrodes. The interfaces between the CdTe and BaCuSeF layers in the CdS/CdTe solar cells with BaCuSeF back contact deposited at substrate temperatures (TS) of 200 and 300 °C were analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). We clearly observed many dislocations in the CdTe layer in the CdS/CdTe solar cell with the BaCuSeF layer deposited at TS = 300 °C. We also observed a reaction layer of Cu2.72Te2 between the BaCuSeF and CdTe layers in both solar cells. We concluded that (1) the substrate temperature for the pulsed laser deposition of the BaCuSeF layer and (2) the interface between the CdTe and BaCuSeF layers are important factors for the performance of the CdTe solar cells. We obtained high conversion efficiency of 8.31% for a solar cell with a BaCuSeF layer deposited at TS = 200 °C on a CdTe surface etched in a NH3 aqueous solution. The highest conversion efficiency of 9.91% was obtained for a solar cell with a CdTe surface etched in a bromide-bromate solution.

  19. Improving Efficiency of Evaporated Cu2ZnSnS4 Thin Film Solar Cells by a Thin Ag Intermediate Layer between Absorber and Back Contact

    Directory of Open Access Journals (Sweden)

    Hongtao Cui

    2015-01-01

    Full Text Available A 20 nm Ag coating on Mo back contact was adopted to improve the back contact of evaporated Cu2ZnSnS4 (CZTS solar cells. The Ag layer helped reduce the thickness of MoS2 which improves fill factor (FF significantly; additionally, it reduced secondary phases ZnS and SnS2−x, which may help carrier transport; it was also involved in the doping of the absorber layer, which compensated the intrinsic p-type doping and therefore drags down the doping level. The doping involvement may enlarge the depletion region and improve lifetime of the absorber, which led to enhancing open circuit voltage (VOC, short circuit current density (JSC, and efficiency significantly. However, it degrades the crystallinity of the material slightly.

  20. Simultaneous shunt protection and back contact formation for CdTe solar cells with single wall carbon nanotube layers

    Science.gov (United States)

    Phillips, Adam B.; Khanal, Rajendra R.; Song, Zhaoning; Watthage, Suneth C.; Kormanyos, Kenneth R.; Heben, Michael J.

    2015-12-01

    Thin film photovoltaic (PV) devices and modules prepared by commercial processes can be severely compromised by through-device low resistance electrical pathways. The defects can be due to thin or missing semiconductor material, metal diffusion along grain boundaries, or areas containing diodes with low turn-on potentials. We report the use of single wall carbon nanotube (SWCNT) layers to enable both protection against these defects and back contact formation for CdTe PV devices. Samples prepared with a SWCNT back contact exhibited good efficiency and did not require shunt protection, while devices prepared without shunt protection using a standard metal back contact performed poorly. We describe the mechanism by which the SWCNT layer functions. In addition to avoiding the need for shunt protection by other means, the SWCNT film also provides a route to higher short circuit currents.

  1. Impact of DC-power during Mo back contact sputtering on the alkali distribution in Cu(In,Ga)Se{sub 2}-based thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lepetit, T., E-mail: thomas.lepetit@cnrs-imn.fr [Institut des Matériaux Jean Rouxel (IMN), UMR 6502 CNRS, 2 rue de la Houssinière BP 32229, 44322 Nantes Cedex 3 (France); Mangin, D. [Institut Jean Lamour, UMR 7198 CNRS — Université de Lorraine, Parc de Saurupt, CS 50840, 54011 Nancy Cedex (France); Gautron, E.; Tomassini, M.; Harel, S.; Arzel, L.; Barreau, N. [Institut des Matériaux Jean Rouxel (IMN), UMR 6502 CNRS, 2 rue de la Houssinière BP 32229, 44322 Nantes Cedex 3 (France)

    2015-05-01

    DC-sputtered Mo back contact layers were deposited on soda-lime glass (SLG) with different power densities applied on the Mo target to study its influence on the photovoltaic performance of Cu(In,Ga)Se{sub 2}-based (CIGSe) solar cell. CIGSe absorber was then deposited simultaneously on these SLG/Mo, following the 3-stage process. These devices have good but different photovoltaic performance (> 16% efficiency without MgF{sub 2} coating). To find a material origin, secondary ion mass spectroscopy (SIMS) profiles were carried out on complete cells, revealing that Na and K content and distribution in each layer depend on the deposition conditions of the back contact. Even before the CIGSe deposition and despite similar morphologies, Na content can vary 10-fold from one Mo layer to another. The same applies to the absorber; when grown on a different Mo they present the same grain boundary density but different alkali contents in bulk or at interfaces. This has an influence on the compositional grading in absorber, confirmed by X-ray diffraction and SIMS. - Highlights: • Mo films synthesized at different DC-power applied on the target during sputtering. • Similar macroscopic properties of Mo back contacts • The lowest alkali content in absorber with the highest DC-power applied during Mo sputtering.

  2. Rectification and tunneling effects enabled by Al{sub 2}O{sub 3} atomic layer deposited on back contact of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jun; Lin, Qinxian; Li, Hao; Su, Yantao; Yang, Xiaoyang; Wu, Zhongzhen; Zheng, Jiaxin; Wang, Xinwei; Lin, Yuan; Pan, Feng, E-mail: panfeng@pkusz.edu.cn [School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen 518055 (China)

    2015-07-06

    Atomic layer deposition (ALD) of Aluminum oxide (Al{sub 2}O{sub 3}) is employed to optimize the back contact of thin film CdTe solar cells. Al{sub 2}O{sub 3} layers with a thickness of 0.5 nm to 5 nm are tested, and an improved efficiency, up to 12.1%, is found with the 1 nm Al{sub 2}O{sub 3} deposition, compared with the efficiency of 10.7% without Al{sub 2}O{sub 3} modification. The performance improvement stems from the surface modification that optimizes the rectification and tunneling of back contact. The current-voltage analysis indicates that the back contact with 1 nm Al{sub 2}O{sub 3} maintains large tunneling leakage current and improves the filled factor of CdTe cells through the rectification effect. XPS and capacitance-voltage electrical measurement analysis show that the ALD-Al{sub 2}O{sub 3} modification layer features a desired low-density of interface state of 8 × 10{sup 10 }cm{sup −2} by estimation.

  3. Flexible CIGS solar cells on large area polymer foils with in-line deposition methods and application of alternative back contacts - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, A. N.

    2009-08-15

    This illustrated report for the Swiss Federal Office of Energy (SFOE) summarises the work performed within this project and also reports on synergies with other projects that helped to make a significant contribution to the development of CIGS thin film solar cells on flexible substrates such as polymer foils. The project's aims were to learn more about up-scaling issues and to demonstrate the abilities required for the processing of layers on large area polyimide foils for flexible CIGS solar cells. Custom-built evaporators that were designed and constructed in-house are described. A CIGS system for in-line deposition was also modified for roll-to-roll deposition and alternative electrical back contacts to conventional ones were evaluated on flexible polyimide foils. The objectives of the project and the results obtained are looked at and commented on in detail.

  4. Development and analysis of Cu-doped ZnTe for use as a back contact interface for CdS/CdTe solar cells

    Science.gov (United States)

    Gessert, T. A.; Coutts, T. J.

    1994-06-01

    It is well known that the losses associated with the back contact of typical CdS/CdTe solar cell devices can be a substantial part of the total external loss. Previous modeling has indicated that these losses will be significant, unless the value of specific contact resistance (rc) at this interface is reduced to ˜0.10 Ω-cm2 or less. Although several studies have inferred values of rc near this level, few have attempted to measure directly the value of rc as a function of various processing conditions. One reason for this situation is the difficulty in fabricating the appropriate patterns for direct analysis of rc. In the following paper, initial characterization studies of sputter-deposited, Cu-doped ZnTe are documented. Additionally, recent attempts to measure directly the contact resistance associated with the two interfaces of the Ni/ZnTe/CdTe contact stack, are presented and discussed. Preliminary testing of these processes has been conducted using sputter-deposited test structures representing the individual interfaces of a typical Ni/ZnTe/CdTe contact stack. Contact resistance analysis of these structures has allowed for the estimation of rc suggesting that, for the conditions studied, the contact stack appears to meet the criterion of yielding an rc value <0.1 Ω-cm2.

  5. Low temperature surface passivation of crystalline silicon and its application to interdigitated back contact silicon heterojunction (ibc-shj) solar cell

    Science.gov (United States)

    Shu, Zhan

    With the absence of shading loss together with improved quality of surface passivation introduced by low temperature processed amorphous silicon crystalline silicon (a-Si:H/c-Si) heterojunction, the interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell exhibits a potential for higher conversion efficiency and lower cost than a traditional front contact diffused junction solar cell. In such solar cells, the front surface passivation is of great importance to achieve both high open-circuit voltage (Voc) and short-circuit current (Jsc). Therefore, the motivation of this work is to develop a low temperature processed structure for the front surface passivation of IBC-SHJ solar cells, which must have an excellent and stable passivation quality as well as a good anti-reflection property. Four different thin film materials/structures were studied and evaluated for this purpose, namely: amorphous silicon nitride (a-SiNx:H), thick amorphous silicon film (a-Si:H), amorphous silicon/silicon nitride/silicon carbide (a-Si:H/a-SiN x:H/a-SiC:H) stack structure with an ultra-thin a-Si:H layer, and zinc sulfide (ZnS). It was demonstrated that the a-Si:H/a-SiNx:H/a-SiC:H stack surpasses other candidates due to both of its excellent surface passivation quality (SRVsolar cells using the stack structure for front surface passivation. Direct comparison shows that such low temperature deposited stack structure developed in this work achieves comparable device performance to the high temperature processed front surface passivation structure used in other high efficiency IBC solar cells. However, the lower fill factor (FF) of IBC-SHJ solar cell as compared with traditional front a-Si:H/c-Si heterojunction cell (HIT cell) greatly limits the overall performance of these devices. Two-dimensional (2D) simulations were used to comparatively model the HIT and IBC-SHJ solar cells to understand the underlying device physics which controls cell performance. The effects of a wide

  6. Electron Barrier Formation at the Organic-Back Contact Interface is the First Step in Thermal Degradation of Polymer Solar Cells

    KAUST Repository

    Sachs-Quintana, I. T.

    2014-03-24

    Long-term stability of polymer solar cells is determined by many factors, one of which is thermal stability. Although many thermal stability studies occur far beyond the operating temperature of a solar cell which is almost always less than 65 °C, thermal degradation is studied at temperatures that the solar cell would encounter in real-world operating conditions. At these temperatures, movement of the polymer and fullerenes, along with adhesion of the polymer to the back contact, creates a barrier for electron extraction. The polymer barrier can be removed and the performance can be restored by peeling off the electrode and depositing a new one. X-ray photoelectron spectroscopy measurements reveal a larger amount of polymer adhered to electrodes peeled from aged devices than electrodes peeled from fresh devices. The degradation caused by hole-transporting polymer adhering to the electrode can be suppressed by using an inverted device where instead of electrons, holes are extracted at the back metal electrode. The problem can be ultimately eliminated by choosing a polymer with a high glass transition temperature. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Low cost back contact heterojunction solar cells on thin c-Si wafers. integrating laser and thin film processing for improved manufacturability

    Energy Technology Data Exchange (ETDEWEB)

    Hegedus, Steven S. [Univ. of Delaware, Newark, DE (United States)

    2015-09-08

    An interdigitated back contact (IBC) Si wafer solar cell with deposited a-Si heterojunction (HJ) emitter and contacts is considered the ultimate single junction Si solar cell design. This was confirmed in 2014 by both Panasonic and Sharp Solar producing IBC-HJ cells breaking the previous record Si solar cell efficiency of 25%. But manufacturability at low cost is a concern for the complex IBC-HJ device structure. In this research program, our goals were to addressed the broad industry need for a high-efficiency c-Si cell that overcomes the dominant module cost barriers by 1) developing thin Si wafers synthesized by innovative, kerfless techniques; 2) integrating laser-based processing into most aspects of solar cell fabrication, ensuring high speed and low thermal budgets ; 3) developing an all back contact cell structure compatible with thin wafers using a simplified, low-temperature fabrication process; and 4) designing the contact patterning to enable simplified module assembly. There were a number of significant achievements from this 3 year program. Regarding the front surface, we developed and applied new method to characterize critical interface recombination parameters including interface defect density Dit and hole and electron capture cross-section for use as input for 2D simulation of the IBC cell to guide design and loss analysis. We optimized the antireflection and passivation properties of the front surface texture and a-Si/a-SiN/a-SiC stack depositions to obtain a very low (< 6 mA/cm2) front surface optical losses (reflection and absorption) while maintaining excellent surface passivation (SRV<5 cm/s). We worked with kerfless wafer manufacturers to apply defect-engineering techniques to improve bulk minority-carrier lifetime of thin kerfless wafers by both reducing initial impurities during growth and developing post-growth gettering techniques. This led insights about the kinetics of nickel, chromium, and dislocations in PV-grade silicon and to

  8. Low cost back contact heterojunction solar cells on thin c-Si wafers. Integrating laser and thin film processing for improved manufacturability

    Energy Technology Data Exchange (ETDEWEB)

    Hegedus, Steven S. [Univ. of Delaware, Newark, DE (United States)

    2015-09-08

    An interdigitated back contact (IBC) Si wafer solar cell with deposited a-Si heterojunction (HJ) emitter and contacts is considered the ultimate single junction Si solar cell design. This was confirmed in 2014 by both Panasonic and Sharp Solar producing IBC-HJ cells breaking the previous record Si solar cell efficiency of 25%. But manufacturability at low cost is a concern for the complex IBC-HJ device structure. In this research program, our goals were to addressed the broad industry need for a high-efficiency c-Si cell that overcomes the dominant module cost barriers by 1) developing thin Si wafers synthesized by innovative, kerfless techniques; 2) integrating laser-based processing into most aspects of solar cell fabrication, ensuring high speed and low thermal budgets ; 3) developing an all back contact cell structure compatible with thin wafers using a simplified, low-temperature fabrication process; and 4) designing the contact patterning to enable simplified module assembly. There were a number of significant achievements from this 3 year program. Regarding the front surface, we developed and applied new method to characterize critical interface recombination parameters including interface defect density Dit and hole and electron capture cross-section for use as input for 2D simulation of the IBC cell to guide design and loss analysis. We optimized the antireflection and passivation properties of the front surface texture and a-Si/a-SiN/a-SiC stack depositions to obtain a very low (< 6 mA/cm2) front surface optical losses (reflection and absorption) while maintaining excellent surface passivation (SRV<5 cm/s). We worked with kerfless wafer manufacturers to apply defect-engineering techniques to improve bulk minority-carrier lifetime of thin kerfless wafers by both reducing initial impurities during growth and developing post-growth gettering techniques. This led insights about the kinetics of nickel, chromium, and dislocations in PV-grade silicon and to

  9. Effect of ZnTe and CdZnTe Alloys at the Back Contact of 1-μm-Thick CdTe Thin Film Solar Cells

    Science.gov (United States)

    Amin, Nowshad; Yamada, Akira; Konagai, Makoto

    2002-05-01

    N2-doped ZnTe was introduced onto 1-μm-thick CdTe absorbers in order to reduce the carrier recombination at the back contact of CdS/CdTe/C/Ag configuration solar cells. ZnTe films were grown by molecular beam epitaxy (MBE) on GaAs and Corning glass substrates to investigate the characteristics of the films. Epitaxial growth of ZnTe was realized on GaAs substrates and a hole concentration of 8 × 1018 cm-3 with a resistivity of 0.045 Ω \\cdotcm was achieved as a result of nitrogen doping. In contrast, polycrystalline ZnTe films were grown on Corning glass and CdTe thin films. Dark and photoconductivity of ZnTe films increased to 1.43 × 10-5 S/cm and 1.41 × 10-4 S/cm, respectively, while the Zn to Te ratio was decreased to 0.25 during MBE growth. These ZnTe films with different thicknesses were inserted into close-spaced sublimation (CSS)-grown 1-μm-thick CdTe solar cells. A conversion efficiency of 8.31% (Voc: 0.74 V, Jsc: 22.98 mA/cm2, FF: 0.49, area: 0.5 cm2) was achieved for a 0.2-μm-thick ZnTe layer with a cell configuration of CdS/CdTe/ZnTe/Cu-doped-C/Ag. Furthermore, to overcome the problem of possible recombination loss in the interface layer of CdTe and ZnTe, the intermediate ternary CdZnTe is investigated. The compositional factor in Cd1-xZnxTe:N alloy is varied and the dependence of the conductivity is evaluated. For instance, Cd0.5Zn0.5Te:N, with dark and photoconductivity of 2.13 × 10-6 and 2.9 × 10-5 S/cm, respectively, is inserted at the back contact of a 1-μm-thick CdTe solar cell. A conversion efficiency of 7.46% (Voc: 0.68 V, Jsc: 22.60 mA/cm2, FF: 0.49, area: 0.086 cm2) was achieved as the primary result for a 0.2-μm-thick Cd0.5Zn0.5Te:N layer with the cell configuration of CdS/CdTe/Cd0.5Zn0.5Te:N/Au.

  10. Interdigitated back contact silicon solar cells%叉指背接触硅太阳电池

    Institute of Scientific and Technical Information of China (English)

    张伟康; 陈群; 王敏; 陈小源; 杨立友; 鲁林峰; 李东栋; 朱绪飞

    2016-01-01

    发展高效晶体硅太阳电池是前沿研究和产业发展的重要趋势.其中叉指背接触(Interdigitated back contact,IBC)硅太阳电池是克服了传统硅太阳电池中栅线电极的遮光损失,具有优异的光电转换效率.IBC电池的核心是界面调控、背部图形化设计和相应的场效应调控,以及寻找低成本的生产方案.本文结合国内外研究现状,系统地介绍了IBC硅太阳电池的结构和界面特点,以及生产制备中涉及的一系列工艺方法.文章最后展望了IBC太阳电池的发展趋势和应用前景.

  11. /Au Back Contacts

    Science.gov (United States)

    Paudel, Naba R.; Compaan, Alvin D.; Yan, Yanfa

    2014-08-01

    We report on the fabrication and characterization of CdTe thin-film solar cells with Cu-free MoO3- x /Au back contacts. CdTe solar cells with sputtered CdTe absorbers of thicknesses from 0.5 to 1.75 μm were fabricated on Pilkington SnO2:F/SnO2-coated soda-lime glasses coated with a 60- to 80-nm sputtered CdS layer. The MoO3- x /Au back contact layers were deposited by thermal evaporation. The incorporation of MoO3- x layer was found to improve the open circuit voltage ( V OC) but reduce the fill factor of the ultrathin CdTe cells. The V OC was found to increase as the CdTe thickness increased.

  12. Windowless CdSe/CdTe solar cells with differentiated back contacts: J-V, EQE, and photocurrent mapping.

    Science.gov (United States)

    Josell, Daniel; Debnath, Ratan; Ha, Jong Y; Guyer, Jonathan; Sahiner, Mehmet A; Reehil, Christopher J; Manners, William A; Nguyen, Nhan V

    2014-09-24

    This study presents windowless CdSe/CdTe thin film photovoltaic devices with in-plane patterning at a submicrometer length scale. The photovoltaic cells are fabricated upon two interdigitated comb electrodes prepatterned at micrometer length scale on an insulating substrate. CdSe is electrodeposited on one electrode, and CdTe is deposited by pulsed laser deposition over the entire surface of the resulting structure. Previous studies of symmetric devices are extended in this study. Specifically, device performance is explored with asymmetric devices having fixed CdTe contact width and a range of CdSe contact widths, and the devices are fabricated with improved dimensional tolerance. Scanning photocurrent microscopy (also known as laser beam induced current mapping) is used to examine local current collection efficiency, providing information on the spatial variation of performance that complements current-voltage and external quantum efficiency measurements of overall device performance. Modeling of carrier transport and recombination indicates consistency of experimental results for local and blanket illumination. Performance under simulated air mass 1.5 illumination exceeds 5% for all dimensions examined, and the best-performing device achieved 5.9% efficiency.

  13. Emitter study of front junction back contact crystalline silicon solar cells%前结背接触晶硅太阳电池发射区研究

    Institute of Scientific and Technical Information of China (English)

    周涛; 陆晓东; 吴元庆; 刘兴辉; 吴春瑜

    2015-01-01

    利用Silvaco-TCAD仿真软件全面系统地分析了发射区表面浓度(cE)、结深(xj)及发射区覆盖比率(EF)对P型前结背接触晶硅太阳电池输出特性的影响。结果表明:基于常规低成本P型晶硅衬底(利用直拉法生长,电阻率为1.5Ω·cm,少子寿命为10μs)的前结背接触太阳电池,其上表面发射区表面浓度及结深对太阳电池的输出特性产生显著影响。上表面发射区表面浓度和结深越大,短波入射光外量子效率越小。当上表面发射区表面浓度为1×1019 cm–3,结深为0.2μm时,电池效率高达20.72%。侧面和下表面发射区表面浓度及结深对太阳电池输出特性的影响较小。但侧面和下表面发射区覆盖比率对太阳电池的输出特性产生显著影响。侧面和下表面发射区覆盖比率越大,太阳电池外量子效率和转换效率越高。%By using Silvaco-TCAD simulation software, the influences of the emitter surface concentration (cE), the junction depth (xj) and the emitter fraction (EF) on the output characteristics of P-type front junction back contact crystalline silicon solar cell was analyzed. The results show that the upper surface emitter surface concentration and the junction depth of the front junction back contact crystalline silicon solar cell based on conventional low-cost P-type silicon substrate (CZ growth method, the resistivity is 1.5Ω·cm, the minority carrier life is 10μs) have a noticeable effect on output characteristics of solar cells. The higher the upper surface emitter surface concentration, the deeper the junction depth, the lower the short wavelength incident light external quantum efficiency. When the upper surface emitter surface concentration is 1×1019 cm–3 and the junction depth is 0.2μm,the solar cell conversion efficiency reaches 20.72%. The side-surface and under-surface emitter surface concentration and the junction depth have a slight effect on output

  14. Back contact to film silicon on metal for photovoltaic cells

    Science.gov (United States)

    Branz, Howard M.; Teplin, Charles; Stradins, Pauls

    2013-06-18

    A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

  15. Wiring-up carbon single wall nanotubes to polycrystalline inorganic semiconductor thin films: low-barrier, copper-free back contact to CdTe solar cells.

    Science.gov (United States)

    Phillips, Adam B; Khanal, Rajendra R; Song, Zhaoning; Zartman, Rosa M; DeWitt, Jonathan L; Stone, Jon M; Roland, Paul J; Plotnikov, Victor V; Carter, Chad W; Stayancho, John M; Ellingson, Randall J; Compaan, Alvin D; Heben, Michael J

    2013-11-13

    We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.

  16. Optimization of substrate resistivity and light intensity of concentrator back junction back contact solar cell%聚光背结背接触太阳电池衬底电阻率和光强的优化研究

    Institute of Scientific and Technical Information of China (English)

    周涛; 陆晓东; 吴元庆; 李媛

    2016-01-01

    利用 TCAD 半导体器件仿真软件对中低倍聚光光伏系统中应用的 N 型插指背接触(Interdigitated Back Contact,IBC)单晶硅太阳电池的电学性能进行了仿真研究,全面系统地分析了不同衬底电阻率和光强对电池短路电流密度、开路电压、填充因子及转换效率的影响。结果表明:IBC太阳电池的电学性能受到衬底电阻率和光强的显著影响。当光强较小(0.1 W/cm2)时,随着衬底电阻率的增大,IBC太阳电池转换效率随之降低,最优的衬底电阻率为0.5Ω·cm。当光强较高(0.5~5 W/cm2)时,随着衬底电阻率的增大,IBC太阳电池转换效率随之增大,最优的衬底电阻率为3Ω·cm。当光强进一步增大(10~50 W/cm2)时,随着衬底电阻率的增大,IBC太阳电池转换效率呈现出先增大后减小的变化特点,最优的衬底电阻率为2Ω·cm。%The electrical properties of N-type interdigitated back contact mono-crystalline silicon solar cell used in medium and low CPV systems were studied by using TCAD semiconductor device simulation software. The influences of substrate resistivity and light intensity on IBC solar cell’s short-circuit current density, open-circuit voltage, filling factor and conversion efficiency were studied comprehensively and systematically. The research shows that the IBC solar cell’s electrical properties are affected by the substrate resistivity and light intensity significantly. When the light intensity is low (0.1 W/cm2), the IBC solar cell conversion efficiency decreases with the increase of substrate resistivity, and the optimum substrate resistivity is 0.5Ω·cm. When the light intensity is higher (0.5~5 W/cm2), the IBC solar cell conversion efficiency increases with the increase of substrate resistivity, and the optimum substrate resistivity is 3Ω·cm. When the light intensity increases further (10~50 W/cm2), the IBC solar cell conversion efficiency presents first

  17. Theory of back-surface-field solar cells

    Science.gov (United States)

    Vonroos, O.

    1979-01-01

    Report describes simple concise theory of back-surface-field (BSF) solar cells (npp + junctions) based on Shockley's depletion-layer approximation and cites superiority of two-junction devices over conventional unijunction cells.

  18. Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells with a ZnTe:Cu Back Contact: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. V.; Duenow, J. N.; Kuciauskas, D.; Kanevce, A.; Dhere, R. G.; Young, M. R.; Levi, D. H.

    2012-07-01

    We study the effects of Cu composition on the CdTe/ZnTe:Cu back contact and the bulk CdTe. For the back contact, its potential barrier decreases with Cu concentration while its saturation current density increases. For the bulk CdTe, the hole density increases with Cu concentration. We identify a Cu-related deep level at {approx}0.55 eV whose concentration is significant when the Cu concentration is high. The device performance, which initially increases with Cu concentration then decreases, reflects the interplay between the positive influences and negative influences (increasing deep levels in CdTe) of Cu.

  19. Inkjet Printing of Back Electrodes for Inverted Polymer Solar cells

    DEFF Research Database (Denmark)

    Angmo, Dechan; Sweelssen, Jorgen; Andriessen, Ronn;

    2013-01-01

    in an otherwise fast roll-to-roll production line. In this paper, the applicability of inkjet printing in the ambient processing of back electrodes in inverted polymer solar cells with the structure ITO/ZnO/P3HT:PCBM/PEDOT:PSS/ Ag is investigated. Furthermore, the limitation of screen printing, the commonly......Evaporation is the most commonly used deposition method in the processing of back electrodes in polymer solar cells used in scientifi c studies. However, vacuum-based methods such as evaporation are uneconomical in the upscaling of polymer solar cells as they are throughput limiting steps...... employed method in the ambient processing of back electrode, is demonstrated and discussed. Both inkjet printing and screen printing of back electrodes are studied for their impact on the photovoltaic properties of the polymer solar cells measured under 1000 Wm−2 AM1.5. Each ambient processing technique...

  20. 具有复合背接触层的 CdTe多晶薄膜太阳电池%Polycrystalline CdTe thin- film solar cells with complex back contact layers

    Institute of Scientific and Technical Information of China (English)

    覃文治; 夏庚培; 郑家贵; 李卫; 蔡伟; 冯良桓; 蔡亚平; 黎兵; 张静全; 武莉莉

    2005-01-01

    To improve the properties of back contacts of CdTe solar cells, ZnTe:Cu and polycrystalline Cd1- xZnxTe films were deposited by simultaneous evaporation. Investigative data of the configuration and performance indicate that energy gap of Cd1- xZnxTe films assume quadratic connection with zinc content. With increasing of Cu content, energy gap of polycrystalline ZnTe:Cu will decrease. ZnTe/ZnTe:Cu or Cd1- xZnxTe/ZnTe:Cu back contacted cells can reduce the heterogeneous interface state density and modify the structure of energy band of the solar cells. Furthermore, diffusion of Cu can avoid by this compound films in CdTe solar cells. An efficiency of 13.38% of solar cell with dimension of 0.502cm2was fabricated.%为了提高 CdTe太阳电池的背接触性能,用共蒸发法制备了 ZnTe:Cu和 Cd1- xZnxTe多晶薄膜. 研究结果表明: Cd1- xZnxTe多晶薄膜的能隙与锌含量呈二次方关系, ZnTe:Cu多晶薄膜能隙随着掺 Cu浓度的增加而减小.分别用 ZnTe/ZnTe:Cu和 Cd1- xZnxTe/ZnTe:Cu复合膜作为背接触层,既能 修饰异质结界面,改善电池的能带结构,又能防止 Cu原子向电池内部扩散.因此获得了面积 0.502cm2,转换效率为 13.38%的 CdTe多晶薄膜太阳电池.

  1. Fabrication of interdigitated back-contact silicon heterojunction solar cells on a 53-µm-thick crystalline silicon substrate by using the optimized inkjet printing method for etching mask formation

    Science.gov (United States)

    Takagishi, Hideyuki; Noge, Hiroshi; Saito, Kimihiko; Kondo, Michio

    2017-04-01

    Inkjet-printing-based fabrication process of the interdigitated back-contact silicon heterojunction solar cells has the potential to reduce the manufacturing costs because of its low machine and material costs and its applicability to thinner fragile silicon substrates than 100 µm. In this study, ink and printing parameters were investigated to obtain the desirable fine patterns and the resultant accuracy of the linewidths was less than ±0.05 mm on a flat surface. The completed cells using inkjet-printing showed almost the same performance of that fabricated by photolithography. In addition, flexible and free-standing cell on a 53-µm-thick Si substrate has been successfully fabricated.

  2. Effect of ZnTe/ZnTe:Cu complex back-contact on device characteristics of CdTe solar cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    ZnTe/ZnTe:Cu complex layers deposited by vacuum co-evaporation have been in- troduced to CdS/CdTe solar cells. The C-V and I-V curves have been investigated and the effects of un-doped ZnTe layer thickness as well as annealing temperatures on I-V characteristics of CdTe solar cells have been studied. The results show that the “roll over” and “cross over” phenomena of dark and light I-V curves can be eliminated by use of ZnTe/ZnTe:Cu layer and the fill factor for a typical sample has increased to 73%, where there is no high resistance transparent layer. The reasons have been discussed combined with the energy band diagram of CdTe solar cells.

  3. Optical modeling of graphene contacted CdTe solar cells

    Science.gov (United States)

    Aldosari, Marouf; Sohrabpoor, Hamed; Gorji, Nima E.

    2016-04-01

    For the first time, an optical model is applied on CdS/CdTe thin film solar cells with graphene front or back contact. Graphene is highly conductive and is as thin as a single atom which reduces the light reflection and absorption, and thus enhances the light transmission to CdTe layer for a wide range of wavelengths including IR. Graphene as front electrode of CdTe devices led to loss in short circuit current density of 10% ΔJsc ≤ 15% compared to the conventional electrodes of TCO and ITO at CdS thickness of dCdS = 100 nm. In addition, all the multilayer graphene electrodes with 2, 4, and 7 graphene layers led to Jsc ≤ 20 mA/cm2. Therefore, we conclude that a single monolayer graphene with hexagonal carbon network reduces optical losses and enhances the carrier collection measured as Jsc. In another structure design, we applied the optical model to graphene back contacted CdS/CdTe device. This scheme allows double side irradiation of the cell which is expected to enhance the Jsc. We obtained 1 ∼ 6 , 23, and 38 mA/cm2 for back, front and bifacial illumination of graphene contacted CdTe cell with CdS = 100 nm. The bifacial irradiated cell, to be efficient, requires an ultrathin CdTe film with dCdTe ≤ 1 μm. In this case, the junction electric field extends to the back region and collects out the generated carriers efficiently. This was modelled by absorptivity rather than transmission rate and optical losses. Since the literature suggest that ZnO can increase the graphene conductivity and enhance the Jsc, we performed our simulations for a graphene/ZnO electrode (ZnO = 100 nm) instead of a single graphene layer.

  4. Design and fabrication of wraparound contact silicon solar cells

    Science.gov (United States)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1972-01-01

    Both dielectric insulation and etched junction contact techniques were evaluated for use in wraparound contact cell fabrication. Since a suitable process for depositing the dielectrics was not achieved, the latter approach was taken. The relationship between loss of back contact and power degradation due to increased series resistance was established and used to design a simple contact configuration for 10 ohm-cm etched wraparound junction contact N/P cells. A slightly deeper junction significantly improved cell curve shape and the associated loss of current was regained by using thinner contact grid fingers. One thousand cells with efficiencies greater than 10.5% were fabricated to demonstrate the process.

  5. Simulation, elaboration and analysis of inter-digitated back-contacts photovoltaic cells; Simulation, fabrication et analyse de cellules photovoltaiques a contacts arrieres interdigites

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, O

    2005-05-15

    Solar energy is the most promising and powerful energy source among renewable energies. Photovoltaic electricity is obtained by direct transformation of the sunlight into electricity by means of photovoltaic cells. The objective of this work is to develop photovoltaic cells with back inter-digitated contacts. In the first chapter, we recall the principle of operation and the fundamental parameters of a photovoltaic cell. In a second part, we explain specificities of the inter-digitated back-contact solar cells, as well as the advantages and the disadvantages of such cells. In the second chapter we study the operation of inter-digitated back-contacts solar cells by two dimensional numerical simulation in order to optimize the geometry and doping profiles of the cell. The third chapter relates to the techniques and the methods of characterization of photovoltaic devices and components. In the fourth chapter, we describe the elaboration of inter-digitated back-contact cells. Three technological processes are presented in order to develop a simple technology for cells realization. In particular, we develop the auto-aligned technological process, which enables to elaborate the cells by using only one lithography step. In the last chapter we examine various approaches to reduce the surface recombination: SiO{sub 2}, silicon nitride deposited by UVCVD, hydrogen annealing, etc... (author)

  6. Simulation, elaboration and analysis of inter-digitated back contacts photovoltaic cells; Simulation, fabrication et analyse de cellules photovoltaiques a contacts arrieres interdigites

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, O

    2005-05-15

    Solar energy is the most promising and powerful energy source among renewable energies. Photovoltaic electricity is obtained by direct transformation of the sunlight into electricity by means of photovoltaic cells. The objective of this work is to develop photovoltaic cells with back inter-digitated contacts. In the first chapter, we recall the principle of operation and the fundamental parameters of a photovoltaic cell. In a second part, we explain specificities of the inter-digitated back-contact solar cells, as well as the advantages and the disadvantages of such cells. In the second chapter we study the operation of inter-digitated back-contacts solar cells by two dimensional numerical simulation in order to optimize the geometry and doping profiles of the cell. The third chapter relates to the techniques and the methods of characterization of photovoltaic devices and components. In the fourth chapter, we describe the elaboration of inter-digitated back-contact cells. Three technological processes are presented in order to develop a simple technology for cells realization. In particular, we develop the auto-aligned technological process, which enables to elaborate the cells by using only one lithography step. In the last chapter we examine various approaches to reduce the surface recombination: SiO{sub 2}, silicon nitride deposited by UVCVD, hydrogen annealing, etc.. (author)

  7. Back surface studies of Cu(In,Ga)Se2 thin film solar cells

    Science.gov (United States)

    Simchi, Hamed

    Cu(In,Ga)Se2 thin film solar cells have attracted a lot of interest because they have shown the highest achieved efficiency (21%) among thin film photovoltaic materials, long-term stability, and straightforward optical bandgap engineering by changing relative amounts of present elements in the alloy. Still, there are several opportunities to further improve the performance of the Cu(In,Ga)Se2 devices. The interfaces between layers significantly affect the device performance, and knowledge of their chemical and electronic structures is essential in identifying performance limiting factors. The main goal of this research is to understand the characteristics of the Cu(In,Ga)Se2-back contact interface in order to design ohmic back contacts for Cu(In,Ga)Se2-based solar cells with a range of band gaps and device configurations. The focus is on developing either an opaque or transparent ohmic back contact via surface modification or introduction of buffer layers in the back surface. In this project, candidate back contact materials have been identified based on modeling of band alignments and surface chemical properties of the absorber layer and back contact. For the first time, MoO3 and WO 3 transparent back contacts were successfully developed for Cu(In,Ga)Se 2 solar cells. The structural, optical, and surface properties of MoO 3 and WO3 were optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. Valence band edge energies were also obtained by analysis of the XPS spectra and used to characterize the interface band offsets. As a result, it became possible to illuminate of the device from the back, resulting in a recently developed "backwall superstrate" device structure that outperforms conventional substrate Cu(In,Ga)Se2 devices in the absorber thickness range 0.1-0.5 microm. Further enhancements were achieved by introducing moderate amounts of Ag into the Cu(In,Ga)Se2 lattice during the co-evaporation method

  8. Characteristics of Ga-Rich Cu(In, Ga)Se2 Solar Cells Grown on Ga-Doped ZnO Back Contact.

    Science.gov (United States)

    Sun, Qian; Kim, Kyoung-Bo; Jeon, Chan-Wook

    2016-05-01

    Wide bandgap Cu(In,Ga)Se2 (CIGS) thin films were deposited on Ga-rich Ga:ZnO (GZO) or MoN/GZO by single-stage co-evaporation. CIGS/TCO interface phases, such as resistive n-type Ga2O3, which are likely to have formed during the high temperature growth of Ga-rich CIGS, can deteriorate the solar cell performance. Although some Ga accumulation was observed in both of the CIGS/GZO and CIGS/MoN/GZO interfaces formed at 520 degrees C, the Ga oxide layer was absent. On the other hand, their current-voltage characteristics showed strong roll-over behavior regardless of the MoN diffusion barrier. The strong Schottky barrier formation at the CLGS/GZO junction due to the low work function of GZO, was attributed to current blocking at a high forward bias.

  9. On the kinetics of MoSe2 interfacial layer formation in chalcogen-based thin film solar cells with a molybdenum back contact

    Science.gov (United States)

    Shin, Byungha; Bojarczuk, Nestor A.; Guha, Supratik

    2013-03-01

    We have studied the temperature dependent kinetics of MoSe2 formation between molybdenum and Cu2ZnSnSe4 (CZTSe) films during annealing in the presence of Se. CZTSe is an emerging light-absorbing material for thin film solar cell applications, and thermal treatment of this layer constitutes a critical part of the device processing. The formation of MoSe2 in this system is modeled using a three step mechanism—diffusion of Se through CZTSe, diffusion of Se through MoSe2, and reaction between Se and Mo. Applying the results of the model to experimental results reveals that the MoSe2 formation is limited by the diffusion of Se through the CZTSe layer.

  10. Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M.; Metzger, W. K.; Li, X.; Al-Jassim, M. M.

    2006-05-01

    We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated at grains boundaries, and may short circuit the device if the CdTe is too thin. The etching process facilitates the Cu diffusion and results in thicker conductive layers. The existence of this inhomogeneous conductive layer directly affects the current transport and is probably the reason for needing thick CdTe in these devices.

  11. The reverse thermal breakdown characteristics of high efficiency back contact Solar cells%高效背接触太阳电池反向热击穿特性研究

    Institute of Scientific and Technical Information of China (English)

    周涛; 陆晓东; 吴元庆; 李媛

    2015-01-01

    Based on the non-isothermal energy balance transfer model, a simulation study of the reverse out characteris-tics of n-type interdigitated back contact ( IBC ) monocrystalline silicon solar cells was conducted by using the TCAD semiconductor devices simulation software.The performance of IBC solar cells was synthetically evaluated by using the photoelectric conversion efficiency and reverse thermal breakdown characteristic.The influences of the substrate resistivity, emitter surface concentration and emitter junction depth on IBC solar cells’ reverse thermal breakdown characteristic and conversion efficiency were studied in detail.The influence of the edge etching struc-ture of the emitter on the characteristics of reverse thermal breakdown of IBC solar cells was analyzed in detail by drawing on the technique of resisting secondary breakdown for bipolar power semiconductor devices and by applying this technique to IBC solar cells.The simulation results show that high crystalline silicon resistivity and low emitter surface concentration help to improve IBC solar cells’ reverse thermal breakdown characteristics, but can not help to improve the cell conversion efficiency;The deeper emitter junction is beneficial to improving the thermal break-down characteristic of IBC cells, as well as the solar cell conversion efficiency; When the emitter edge cylinder junction is incompletely etched, emitter edge’ s etching structure can not improve IBC solar cells’ thermal break-down characteristic;When the emitter edge cylinder junction is completely etched, the thermal breakdown thresh-old voltage increases with the increase of lateral etching distance.%基于非等温能量平衡传输模型,利用TCAD半导体器件仿真软件对N型插指背接触(IBC)单晶硅太阳电池反向输出特性进行了仿真研究。通过光电转换效率和反向热击穿特性对IBC太阳电池的性能进行综合评价。全面系统地分析了不同衬底电阻率、发

  12. Optimization of Rear Local Contacts on High Efficiency PERC Solar Cells Structures

    Directory of Open Access Journals (Sweden)

    Kapila Wijekoon

    2013-01-01

    Full Text Available A local contact formation process and integration scheme have been developed for the fabrication of rear passivated point contact solar cells. Conversion efficiency of 19.6% was achieved using  mm, pseudo square, p-type single crystalline silicon wafers. This is a significant improvement when compared to unpassivated, full area aluminum back surface field solar cells, which exhibit only 18.9% conversion efficiency on the same wafer type. The effect of rear contact formation on cell efficiency was studied as a function of contact area and contact pitch, hence the metallization fraction. Contact shape and the thickness of Al-BSF layer were found to be heavily dependent on the laser ablation pattern and contact area. Simulated cell parameters as a function of metallization showed that there is a tradeoff between open circuit voltage and fill factor gains as the metallization fraction varies. The rear surface was passivated with an Al2O3 layer and a capping layer. The rear surface contact pattern was created by laser ablation and the contact geometry was optimized to obtain voids free contact filling, resulting in a uniform back surface field. The efficiency gain in rear passivated cells over the reference cells is mainly due to improved short circuit current and open circuit voltage.

  13. Ion implantation into amorphous Si layers to form carrier-selective contacts for Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feldmann, Frank; Mueller, Ralph; Reichel, Christian; Hermle, Martin [Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110, Freiburg (Germany)

    2014-09-15

    This paper reports our findings on the boron and phosphorus doping of very thin amorphous silicon layers by low energy ion implantation. These doped layers are implemented into a so-called tunnel oxide passivated contact structure for Si solar cells. They act as carrier-selective contacts and, thereby, lead to a significant reduction of the cell's recombination current. In this paper we address the influence of ion energy and ion dose in conjunction with the obligatory high-temperature anneal needed for the realization of the passivation quality of the carrier-selective contacts. The good results on the phosphorus-doped (implied V{sub oc} = 725 mV) and boron-doped passivated contacts (iV{sub oc} = 694 mV) open a promising route to a simplified interdigitated back contact (IBC) solar cell featuring passivated contacts. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Tunnel oxide passivated contacts formed by ion implantation for applications in silicon solar cells

    Science.gov (United States)

    Reichel, Christian; Feldmann, Frank; Müller, Ralph; Reedy, Robert C.; Lee, Benjamin G.; Young, David L.; Stradins, Paul; Hermle, Martin; Glunz, Stefan W.

    2015-11-01

    Passivated contacts (poly-Si/SiOx/c-Si) doped by shallow ion implantation are an appealing technology for high efficiency silicon solar cells, especially for interdigitated back contact (IBC) solar cells where a masked ion implantation facilitates their fabrication. This paper presents a study on tunnel oxide passivated contacts formed by low-energy ion implantation into amorphous silicon (a-Si) layers and examines the influence of the ion species (P, B, or BF2), the ion implantation dose (5 × 1014 cm-2 to 1 × 1016 cm-2), and the subsequent high-temperature anneal (800 °C or 900 °C) on the passivation quality and junction characteristics using double-sided contacted silicon solar cells. Excellent passivation quality is achieved for n-type passivated contacts by P implantations into either intrinsic (undoped) or in-situ B-doped a-Si layers with implied open-circuit voltages (iVoc) of 725 and 720 mV, respectively. For p-type passivated contacts, BF2 implantations into intrinsic a-Si yield well passivated contacts and allow for iVoc of 690 mV, whereas implanted B gives poor passivation with iVoc of only 640 mV. While solar cells featuring in-situ B-doped selective hole contacts and selective electron contacts with P implanted into intrinsic a-Si layers achieved Voc of 690 mV and fill factor (FF) of 79.1%, selective hole contacts realized by BF2 implantation into intrinsic a-Si suffer from drastically reduced FF which is caused by a non-Ohmic Schottky contact. Finally, implanting P into in-situ B-doped a-Si layers for the purpose of overcompensation (counterdoping) allowed for solar cells with Voc of 680 mV and FF of 80.4%, providing a simplified and promising fabrication process for IBC solar cells featuring passivated contacts.

  15. Simulation and Optimization of Silicon Solar Cell Back Surface Field

    Directory of Open Access Journals (Sweden)

    Souad TOBBECHE

    2015-11-01

    Full Text Available In this paper, TCAD Silvaco (Technology Computer Aided Design software has been used to study the Back Surface Field (BSF effect of a p+ silicon layer for a n+pp+ silicon solar cell. To study this effect, the J-V characteristics and the external quantum efficiency (EQE are simulated under AM 1.5 illumination for two types of cells. The first solar cell is without BSF (n+p structure while the second one is with BSF (n+pp+ structure. The creation of the BSF on the rear face of the cell results in efficiency h of up to 16.06% with a short-circuit current density Jsc = 30.54 mA/cm2, an open-circuit voltage Voc = 0.631 V, a fill factor FF = 0.832 and a clear improvement of the spectral response obtained in the long wavelengths range. An electric field and a barrier of potential are created by the BSF and located at the junction p+/p with a maximum of 5800 V/cm and 0.15 V, respectively. The optimization of the BSF layer shows that the cell performance improves with the p+ thickness between 0.35 – 0.39 µm, the p+ doping dose is about 2 × 1014 cm-2, the maximum efficiency up to 16.19 %. The cell efficiency is more sensitive to the value of the back surface recombination velocity above a value of 103 cm/s in n+p than n+pp+ solar cell.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9565

  16. Carrier-selective contacts for Si solar cells

    Science.gov (United States)

    Feldmann, F.; Simon, M.; Bivour, M.; Reichel, C.; Hermle, M.; Glunz, S. W.

    2014-05-01

    Carrier-selective contacts (i.e., minority carrier mirrors) are one of the last remaining obstacles to approaching the theoretical efficiency limit of silicon solar cells. In the 1980s, it was already demonstrated that n-type polysilicon and semi-insulating polycrystalline silicon emitters form carrier-selective emitters which enabled open-circuit voltages (Voc) of up to 720 mV. Albeit promising, to date a polysilicon emitter solar cell having a high fill factor (FF) has not been demonstrated yet. In this work, we report a polysilicon emitter related solar cell achieving both a high Voc = 694 mV and FF = 81%. The passivation mechanism of these so-called tunnel oxide passivated contacts will be outlined and the impact of TCO (transparent conductive oxide) deposition on the injection-dependent lifetime characteristic of the emitter as well as its implications on FF will be discussed. Finally, possible transport paths across the tunnel oxide barrier will be discussed and it will be shown that the passivating oxide layer does not lead to a relevant resistive loss and thus does not limit the solar cell's carrier transport. Contrary to amorphous silicon-based heterojunction solar cells, this structure also shows a good thermal stability and, thus, could be a very appealing option for next generation high-efficiency silicon solar cells.

  17. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  18. Total Internal Reflection for Effectively Transparent Solar Cell Contacts

    CERN Document Server

    Jahelka, Phillip; Atwater, Harry

    2016-01-01

    A new strategy for eliminating photocurrent losses due to the metal contacts on the front of a solar cell was proposed, simulated, and tested. By placing triangular cross-section lines of low refractive index on top of the contacts, total-internal reflection at the interface of the low-index triangles and the surrounding material can direct light away from the metal and into the photoactive absorber. Simulations indicated that losses can be eliminated for any incident angle, and that yearly energy production improvements commensurate with the metallized area are possible. Proof of principle experiments were carried out to eliminate the reflective losses of a commercial solar cell's busbar contact. Spatially resolved laser beam induced current measurements demonstrated that reflection losses due to the busbar were reduced by voids with triangular cross-section.

  19. INKJET PRINTING OF NICKEL AND SILVER METAL SOLAR CELL CONTACTS

    Energy Technology Data Exchange (ETDEWEB)

    Pasquarelli, R.; Curtis, C.; Van Hest, M.

    2008-01-01

    With about 125,000 terawatts of solar power striking the earth at any given moment, solar energy may be the only renewable energy resource with enough capacity to meet a major portion of our future energy needs. Thin-fi lm technologies and solution deposition processes seek to reduce manufacturing costs in order to compete with conventional coal-based electricity. Inkjet printing, as a derivative of the direct-write process, offers the potential for low-cost, material-effi cient deposition of the metals for photovoltaic contacts. Advances in contact metallizations are important because they can be employed on existing silicon technology and in future-generation devices. We report on the atmospheric, non-contact deposition of nickel (Ni) and silver (Ag) metal patterns on glass, Si, and ZnO substrates at 180–220°C from metal-organic precursor inks using a Dimatix inkjet printer. Near-bulk conductivity Ag contacts were successfully printed up to 4.5 μm thick and 130 μm wide on the silicon nitride antirefl ective coating of silicon solar cells. Thin, high-resolution Ni adhesion-layer lines were printed on glass and zinc oxide at 80 μm wide and 55 nm thick with a conductivity two orders of magnitude less than the bulk metal. Additionally, the ability to print multi-layered metallizations (Ag on Ni) on transparent conducting oxides was demonstrated and is promising for contacts in copper-indium-diselenide (CIS) solar cells. Future work will focus on further improving resolution, printing full contact devices, and investigating copper inks as a low-cost replacement for Ag contacts.

  20. Optimization of tapered busses for solar cell contacts

    Science.gov (United States)

    Landis, G. A.

    1979-01-01

    Some fraction of the power produced by a solar cell is necessarily lost by series resistance associated with the metallized contact grid and by shadowing of cell active area by the grid. There are several approaches to reducing these losses, such as choosing a more efficient pattern, optimizing line spacing, and using tapered buses. The present paper analyzes tapered lines and derives from this analysis a theoretical lower bound to metallization power loss, independent of pattern chosen.

  1. Nickel Silicide Metallization for Passivated Tunneling Contacts for Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Alexander; Florent, Karine; Tapriya, Astha; Lee, Benjamin G.; Kurinec, Santosh K.; Young, David L.

    2016-11-21

    Passivated tunneling contacts offer promise for applications in Interdigitated Back Passivated Contact (IBPC) high efficiency silicon solar cells. Metallization of these contacts remains a key research topic. This paper investigates NiSi/poly-Si/SiO2/c-Si passivated contacts using photoluminescence and contact resistivity measurements. An amorphous Si interlayer between the NiSi and poly-Si is observed to improve passivation, decreasing recombination. The overall recombination loss has a linear trend with the NiSi thickness. Implied Voc values close to 700 mV and contact resistivities below 10 mohm-cm2 have been achieved in NiSi/poly-Si:P/SiO2/c-Si contacts.

  2. Study of back reflectors for thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, H.; Mai, Y. [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China); Wan, M. [Department of Chemistry and Material Science, Hunan Institute of Humanities, Science and Technology, Loudi 417000 (China); Gao, J.; Wang, Y.; He, T.; Feng, Y.; Yin, J.; Du, J.; Wang, J.; Sun, R. [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China); Huang, Y., E-mail: y.huang@btw-solarfilms.com [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China)

    2013-07-31

    In this study, the reflection properties of transparent conductive oxide (TCO) films i.e. aluminum doped zinc oxide (ZnO:Al) and boron doped zinc oxide (ZnO:B) films plus aluminum (Al) films or white polyvinyl butyral (PVB) foils, which are usually used as the combined back reflectors of thin film silicon solar cells, are investigated. Sputtered ZnO:Al films were etched in diluted hydrochloric acid (1%) to achieve rough surface structures while textured ZnO:B films were directly prepared by a low pressure chemical vapor deposition technique. It is found that the rough TCO/Al reflectors show a low total reflection, which is mainly due to the parasitic absorption by the surface plasmons at the rough TCO/Al interfaces as well as the absorption in the TCO films. Differently, the rough TCO/white PVB foil reflectors display a slightly high light reflection regardless of the influence of the rough interface without the excitation of surface plasmons. Thus, the TCO/white PVB foil back reflectors could be a good candidate with respect to light utilization when they are applied in thin film silicon solar cells. - Highlights: • White polyvinyl butyral and transparent conductive oxide materials are used. • The reflection properties of TCO/Al and TCO/white PVB foil reflectors are studied. • The ZnO:Al and ZnO:B films are used as two types of TCO materials. • TCO/white PVB foil reflector shows a high reflection compared to TCO/Al reflector.

  3. Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures

    Science.gov (United States)

    Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, Senpo; Xiu, Fei; Ho, Johnny C.

    2016-09-01

    Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices.

  4. Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures

    Science.gov (United States)

    Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, SenPo; Xiu, Fei; Ho, Johnny C.

    2016-01-01

    Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices. PMID:27671709

  5. Colloidal plasmonic back reflectors for light trapping in solar cells

    Science.gov (United States)

    Mendes, Manuel J.; Morawiec, Seweryn; Simone, Francesca; Priolo, Francesco; Crupi, Isodiana

    2014-04-01

    A novel type of plasmonic light trapping structure is presented in this paper, composed of metal nanoparticles synthesized in colloidal solution and self-assembled in uniform long-range arrays using a wet-coating method. The high monodispersion in size and spherical shape of the gold colloids used in this work allows a precise match between their measured optical properties and electromagnetic simulations performed with Mie theory, and enables the full exploitation of their collective resonant plasmonic behavior for light-scattering applications. The colloidal arrays are integrated in plasmonic back reflector (PBR) structures aimed for light trapping in thin film solar cells. The PBRs exhibit high diffuse reflectance (up to 75%) in the red and near-infrared spectrum, which can pronouncedly enhance the near-bandgap photocurrent generated by the cells. Furthermore, the colloidal PBRs are fabricated by low-temperature (<120 °C) processes that allow their implementation, as a final step of the cell construction, in typical commercial thin film devices generally fabricated in a superstrate configuration.

  6. Tunnel oxide passivated contacts formed by ion implantation for applications in silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, Christian, E-mail: christian.reichel@ise.fraunhofer.de [Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrasse 2, 79110 Freiburg (Germany); National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Feldmann, Frank; Müller, Ralph; Hermle, Martin; Glunz, Stefan W. [Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrasse 2, 79110 Freiburg (Germany); Reedy, Robert C.; Lee, Benjamin G.; Young, David L.; Stradins, Paul [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, Colorado 80401 (United States)

    2015-11-28

    Passivated contacts (poly-Si/SiO{sub x}/c-Si) doped by shallow ion implantation are an appealing technology for high efficiency silicon solar cells, especially for interdigitated back contact (IBC) solar cells where a masked ion implantation facilitates their fabrication. This paper presents a study on tunnel oxide passivated contacts formed by low-energy ion implantation into amorphous silicon (a-Si) layers and examines the influence of the ion species (P, B, or BF{sub 2}), the ion implantation dose (5 × 10{sup 14 }cm{sup −2} to 1 × 10{sup 16 }cm{sup −2}), and the subsequent high-temperature anneal (800 °C or 900 °C) on the passivation quality and junction characteristics using double-sided contacted silicon solar cells. Excellent passivation quality is achieved for n-type passivated contacts by P implantations into either intrinsic (undoped) or in-situ B-doped a-Si layers with implied open-circuit voltages (iV{sub oc}) of 725 and 720 mV, respectively. For p-type passivated contacts, BF{sub 2} implantations into intrinsic a-Si yield well passivated contacts and allow for iV{sub oc} of 690 mV, whereas implanted B gives poor passivation with iV{sub oc} of only 640 mV. While solar cells featuring in-situ B-doped selective hole contacts and selective electron contacts with P implanted into intrinsic a-Si layers achieved V{sub oc} of 690 mV and fill factor (FF) of 79.1%, selective hole contacts realized by BF{sub 2} implantation into intrinsic a-Si suffer from drastically reduced FF which is caused by a non-Ohmic Schottky contact. Finally, implanting P into in-situ B-doped a-Si layers for the purpose of overcompensation (counterdoping) allowed for solar cells with V{sub oc} of 680 mV and FF of 80.4%, providing a simplified and promising fabrication process for IBC solar cells featuring passivated contacts.

  7. Design of a plasmonic back reflector for silicon nanowire decorated solar cells.

    Science.gov (United States)

    Ren, Rui; Guo, Yongxin; Zhu, Rihong

    2012-10-15

    This Letter presents a crystalline silicon thin film solar cell model with Si nanowire arrays surface decoration and metallic nanostructure patterns on the back reflector. The nanostructured Ag back reflector can significantly enhance the absorption in the near-infrared spectrum. Furthermore, by inserting a ZnO:Al layer between the silicon substrate and nanostructured Ag back reflector, the absorption loss in the Ag back reflector can be clearly depressed, contributing to a maximum J(sc) of 28.4 mA/cm(2). A photocurrent enhancement of 22% is achieved compared with a SiNW solar cell with a planar Ag back reflector.

  8. Back surface cell structures for reducing recombination in CZ silicon solar cells

    Science.gov (United States)

    King, R. R.; Mitchell, K. W.; Gee, J. M.

    1994-12-01

    Mass-produced terrestrial CZ silicon solar cells are currently entering the domain in which bulk diffusion length is comparable to the cell thickness, so that recombination at the back surface can have a significant effect on device performance. Three manufacturable processes that address the problem of back recombination are examined here: boron diffusion from a deposited doped SiO2, layer; Al-alloyed layers using screen-printed paste; and use of a collecting n* layer on the back interdigitated with the positive electrode. 104 sq cm cells fabricated at Siemens Solar Industries using these back surface structures are characterized by current-voltage, spectral response, photoconductivity decay, and SIMS measurements.

  9. Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact

    Science.gov (United States)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-01

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. This work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  10. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  11. Three-dimensional numerical analysis of hybrid heterojunction silicon wafer solar cells with heterojunction rear point contacts

    Directory of Open Access Journals (Sweden)

    Zhi Peng Ling

    2015-07-01

    Full Text Available This paper presents a three-dimensional numerical analysis of homojunction/heterojunction hybrid silicon wafer solar cells, featuring front-side full-area diffused homojunction contacts and rear-side heterojunction point contacts. Their device performance is compared with conventional full-area heterojunction solar cells as well as conventional diffused solar cells featuring locally diffused rear point contacts, for both front-emitter and rear-emitter configurations. A consistent set of simulation input parameters is obtained by calibrating the simulation program with intensity dependent lifetime measurements of the passivated regions and the contact regions of the various types of solar cells. We show that the best efficiency is obtained when a-Si:H is used for rear-side heterojunction point-contact formation. An optimization of the rear contact area fraction is required to balance between the gains in current and voltage and the loss in fill factor with shrinking rear contact area fraction. However, the corresponding optimal range for the rear-contact area fraction is found to be quite large (e.g. 20-60 % for hybrid front-emitter cells. Hybrid rear-emitter cells show a faster drop in the fill factor with decreasing rear contact area fraction compared to front-emitter cells, stemming from a higher series resistance contribution of the rear-side a-Si:H(p+ emitter compared to the rear-side a-Si:H(n+ back surface field layer. Overall, we show that hybrid silicon solar cells in a front-emitter configuration can outperform conventional heterojunction silicon solar cells as well as diffused solar cells with rear-side locally diffused point contacts.

  12. Solar LBIC scanning of high-efficiency point-contact silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Vorster, F.J.; Dyk, E.E. van [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University (NMMU), Port Elizabeth (South Africa)

    2008-07-01

    The induced current response from a High Efficiency Concentrator (HECO) monocrystaline Si solar cell was mapped as a function of surface position and cell bias by using a solar light beam induced current (S-LBIC) mapping system while at the same time dynamically biasing the whole cell with an external voltage. Recombination accounts for a major portion of the reduction in quantum efficiency in these cells. This paper examines the spatial distribution of defect mechanisms causing a reduction of collected photocurrent of the backside point-contact device structure while under spot illumination. By examining the bias dependence of the S-LBIC maps, the identification of current loss mechanisms of solar cells under concentrated solar irradiance may be improved. The techniques employed to interpret the spatially distributed I-V curves are discussed and results presented. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Al-Si alloy point contact formation and rear surface passivation for silicon solar cells using double layer porous silicon

    Science.gov (United States)

    Moumni, Besma; Ben Jaballah, Abdelkader; Bessais, Brahim

    2012-10-01

    Lowering the rear surface recombination velocities by a dielectric layer has fascinating advantages compared with the standard fully covered Al back-contact silicon solar cells. In this work the passivation effect by double layer porous silicon (PS) (wide band gap) and the formation of Al-Si alloy in narrow p-type Si point contact areas for rear passivated solar cells are analysed. As revealed by Fourier transform infrared spectroscopy, we found that a thin passivating aluminum oxide (Al2O3) layer is formed. Scanning electron microscopy analysis performed in cross sections shows that with bilayer PS, liquid Al penetrates into the openings, alloying with the Si substrate at depth and decreasing the contact resistivity. At the solar cell level, the reduction in the contact area and resistivity leads to a minimization of the fill factor losses.

  14. Ink-Jet Printer Forms Solar-Cell Contacts

    Science.gov (United States)

    Alexander, Paul, Jr.; Vest, R. W.; Binford, Don A.; Tweedell, Eric P.

    1988-01-01

    Contacts formed in controllable patterns with metal-based inks. System forms upper metal contact patterns on silicon photovoltaic cells. Uses metallo-organic ink, decomposes when heated, leaving behind metallic, electrically conductive residue in printed area.

  15. The role of oxide interlayers in back reflector configurations for amorphous silicon solar cells

    NARCIS (Netherlands)

    Demontis, V.; Sanna, C.; Melskens, J.; Santbergen, R.; Smets, A.H.M.; Damiano, A.; Zeman, M.

    2013-01-01

    Thin oxide interlayers are commonly added to the back reflector of thin-film silicon solar cells to increase their current. To gain more insight in the enhancement mechanism, we tested different back reflector designs consisting of aluminium-doped zinc oxide (ZnO:Al) and/or hydrogenated silicon oxid

  16. A simple theory of back surface field /BSF/ solar cells

    Science.gov (United States)

    Von Roos, O.

    1978-01-01

    A theory of an n-p-p/+/ junction is developed, entirely based on Shockley's depletion layer approximation. Under the further assumption of uniform doping the electrical characteristics of solar cells as a function of all relevant parameters (cell thickness, diffusion lengths, etc.) can quickly be ascertained with a minimum of computer time. Two effects contribute to the superior performance of a BSF cell (n-p-p/+/ junction) as compared to an ordinary solar cell (n-p junction). The sharing of the applied voltage among the two junctions (the n-p and the p-p/+/ junction) decreases the dark current and the reflection of minority carriers by the builtin electron field of the p-p/+/ junction increases the short-circuit current. The theory predicts an increase in the open-circuit voltage (Voc) with a decrease in cell thickness. Although the short-circuit current decreases at the same time, the efficiency of the cell is virtually unaltered in going from a thickness of 200 microns to a thickness of 50 microns. The importance of this fact for space missions where large power-to-weight ratios are required is obvious.

  17. Process and structures for fabrication of solar cells with laser ablation steps to form contact holes

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2013-11-19

    Contact holes of solar cells are formed by laser ablation to accomodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thickness.

  18. Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact

    OpenAIRE

    Hongmei Dang; Singh, Vijay P

    2015-01-01

    Using a 10 nm thick molybdenum oxide (MoO3−x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3−x/Au side, the nanowire solar cells yielded Jsc of 21 mA...

  19. Determination of the specific shunt resistances under and away from the front contacts of solar cell

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    New structure of front contacts was devised and fabricated for accurately measuring the resistances under and away from the front contacts of silicon solar cell with the results showing that the former was much worse. The sample preparing sequence was completely compatible with the conventional solar cell manufacturing process, which demonstrated the convenience of this approach. With the aid of this characterization technique, detailed information can be obtained on the solar cell structure, material ingredients and process parameters, especially the sintering process.

  20. The role of front and back electrodes in parasitic absorption in thin-film solar cells

    Directory of Open Access Journals (Sweden)

    Boccard Mathieu

    2014-07-01

    Full Text Available When it comes to parasitic absorption in thin-film silicon solar cells, most studies focus on one electrode only, most of the time the substrate (in n-i-p configuration or superstrate (in p-i-n configuration. We investigate here simultaneously the influence of the absorption in both front and back electrodes on the current density of tandem micromorph solar cells in p-i-n configuration. We compare four possible combinations of front and back electrodes with two different doping levels, but identical sheet resistance and identical light-scattering properties. In the infrared part of the spectrum, parasitic absorption in the front or back electrode is shown to have a similar effect on the current generation in the cell, which is confirmed by modeling. By combining highly transparent front and back ZnO electrodes and high-quality silicon layers, a micromorph device with a stabilized efficiency of 11.75% is obtained.

  1. Thermal decomposition of silver acetate in silver paste for solar cell metallization: An effective route to reduce contact resistance

    Science.gov (United States)

    Jun Kim, Suk; Yun Kim, Se; Man Park, Jin; Hwan Park, Keum; Ho Lee, Jun; Mock Lee, Sang; Taek Han, In; Hyang Kim, Do; Ram Lim, Ka; Tae Kim, Won; Cheol Park, Ju; Soo Jee, Sang; Lee, Eun-Sung

    2013-08-01

    A screen printed silver/metallic glass (MG) paste formulated with Ag acetate resulted in a specific contact resistance in the range of 0.6-0.7 mΩ.cm2 on both the n- and p-type Si emitters of interdigitated back-contact solar cells. Silver nanocrystallites resulting from thermally decomposed Ag acetate prevented the Al MG frits from directly interacting with the Si emitter, thus reducing the amount of Al diffused into the Si emitters, and subsequently, the contact resistance. A photovoltaic conversion efficiency of 20.3% was achieved using this technique.

  2. Buried contact multijunction thin film silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Green, M. [Univ. of New South Wales, Sydney (Australia)

    1995-08-01

    In early 1994, the Center for Photovoltaic Devices and Systems announced the filing of patent applications on an improved silicon thin film photovoltaic module approach. With material costs estimated to be about 20 times lower than those in present silicon solar cell modules along with other production advantages, this technology appears likely to make low cost, high performance solar modules available for the first time. This paper describes steps involved in making a module and module performance.

  3. Fabrication of Polymer Solar Cells Using Aqueous Processing for All Layers Including the Metal Back Electrode

    DEFF Research Database (Denmark)

    Søndergaard, Roar; Helgesen, Martin; Jørgensen, Mikkel;

    2011-01-01

    The challenges of printing all layers in polymer solar cells from aqueous solution are met by design of inks for the electron-, hole-, active-, and metallic back electrode-layers. The conversion of each layer to an insoluble state after printing enables multilayer formation from the same solvent...

  4. Modulated photonic-crystal structures as broadband back reflectors in thin-film solar cells

    NARCIS (Netherlands)

    Krc, J.; Zeman, M.; Luxembourg, S.L.; Topic, M.

    2009-01-01

    A concept of a modulated one-dimensional photonic-crystal (PC) structure is introduced as a back reflector for thin-film solar cells. The structure comprises two PC parts, each consisting of layers of different thicknesses. Using layers of amorphous silicon and amorphous silicon nitride a reflectanc

  5. An optimized top contact design for solar cell concentrators

    Science.gov (United States)

    Desalvo, Gregory C.; Barnett, Allen M.

    1985-01-01

    A new grid optimization scheme is developed for point focus solar cell concentrators which employs a separated grid and busbar concept. Ideally, grid lines act as the primary current collectors and receive all of the current from the semiconductor region. Busbars are the secondary collectors which pick up current from the grids and carry it out of the active region of the solar cell. This separation of functions leads to a multithickness metallization design, where the busbars are made larger in cross section than the grids. This enables the busbars to carry more current per unit area of shading, which is advantageous under high solar concentration where large current densities are generated. Optimized grid patterns using this multilayer concept can provide a 1.6 to 20 percent increase in output power efficiency over optimized single thickness grids.

  6. N型背接触晶硅太阳电池前表面场研究%Front surface field on N type back contact crystalline silicon solar cell

    Institute of Scientific and Technical Information of China (English)

    周涛; 赵洋; 陆晓东; 张鹏; 李媛

    2015-01-01

    利用Silvaco公司的Athena工艺仿真软件和Atlas器件仿真软件,对N型插指背结背接触(Interdigitated Back Contact,IBC)晶硅太阳电池普遍采用的前表面场(FSF)结构进行研究,详细分析了IBC晶硅电池FSF表面掺杂浓度及扩散深度对电池性能的影响.结果表明:具有不同表面掺杂浓度和扩散深度的FSF对IBC晶硅太阳电池短路电流密度(Jsc)、开路电压(Voc)和填充因子(FF)产生显著影响,从而影响电池的转换效率(Eff).具有较低表面浓度、深扩散FSF结构的IBC晶硅太阳电池可获得较高转换效率,当表面掺杂浓度为5×1017 cm-3时,电池转换效率Eff最高,且随FSF扩散深度增加略有增加,最高转换效率可达22.3%.

  7. Numerical study on short-circuit current of single layer organic solar cells with Schottkey contacts

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The influence of the cathode work function,carriers mobilities and temperature on the short-circuit current of single layer organic solar cells with Schottkey contacts was numerically studied,and the quantitative dependences of the short-circuit current on these quantities were obtained.The results provide the theoretical foundation for experimental study of single layer organic solar cells with Schottkey contacts.

  8. Improvement to thin film CdTe solar cells with controlled back surface oxidation

    OpenAIRE

    Rugen-Hankey, S.L.; Clayton, Andrew J; Barrioz, Vincent; Kartopu, Giray; Irvine, Stuart J; McGettrick, J.D.; Hammond, D.

    2015-01-01

    Thin film CdTe solar cells were produced by MOCVD, at atmospheric pressure, under a hydrogen atmosphere (i.e. oxygen-free). Window layer alloying with zinc (forming Cd1−xZnxS) and extrinsic p-type doping with arsenic (giving CdTe:As) have been used to improve photovoltaic solar cell performances, but as-grown MOCVD-CdTe PV cells are still typically characterised by low Voc (~620–690 mV). Post-deposition annealing in air for 30 min at low temperature (170 °C) prior to evaporation of the back c...

  9. Upscaling of Perovskite Solar Cells: Fully Ambient Roll Processing of Flexible Perovskite Solar Cells with Printed Back Electrodes

    DEFF Research Database (Denmark)

    Schmidt, Thomas Mikael; Larsen-Olsen, Thue Trofod; Carlé, Jon Eggert

    2015-01-01

    A scaling effort on perovskite solar cells is presented where the device manufacture is progressed onto fl exible substrates using scalable techniques such as slot-die roll coating under ambient conditions. The printing of the back electrode using both carbon and silver is essential to the scaling...... effort. Both normal and inverted device geometries are explored and it is found that the formation of the correct morphology for the perovskite layer depends heavily on the surface upon which it is coated and this has signifi cant implications for manufacture. The time it takes to form the desired layer...... morphology falls in the range of 5–45 min depending on the perovskite precursor, where the former timescale is compatible with mass production and the latter is best suited for laboratory work. A signifi cant loss in solar cell performance of around 50% is found when progressing to using a fully scalable...

  10. High resolution, low cost solar cell contact development

    Science.gov (United States)

    Mardesich, N.

    1981-01-01

    The MIDFILM cell fabrication and encapsulation processes were demonstrated as a means of applying low-cost solar cell collector metallization. The average cell efficiency of 12.0 percent (AM1, 28 C) was achieved with fritted silver metallization with a demonstration run of 500 starting wafers. A 98 percent mechanical yield and 80 percent electrical yield were achieved through the MIDFILM process. High series resistance was responsible for over 90 percent of the electrical failures and was the major factor causing the low average cell efficiency. Environmental evaluations suggest that the MIDFILM cells do not degrade. A slight degradation in power was experienced in the MIDFILM minimodules when the AMP Solarlok connector delaminated during the environmental testing.

  11. Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se2 solar cells

    Science.gov (United States)

    Yin, Guanchao; Steigert, Alexander; Andrae, Patrick; Goebelt, Manuela; Latzel, Michael; Manley, Phillip; Lauermann, Iver; Christiansen, Silke; Schmid, Martina

    2015-11-01

    Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se2 (CIGSe) solar cells is investigated. X-ray photoelectron spectroscopy results show that Ag nanoparticles underneath a Sn:In2O3 back contact could not be thermally passivated even at a low substrate temperature of 440 °C during CIGSe deposition. It is shown that a 50 nm thick Al2O3 film prepared by atomic layer deposition is able to block the diffusion of Ag, clearing the thermal obstacle in utilizing Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. Via 3-D finite element optical simulation, it is proved that the Ag nanoparticles show the potential to contribute the effective absorption in CIGSe solar cells.

  12. A study of nickel silicide in a conventional furnace for Ni/Cu contact monocrystalline-silicon solar cells

    Science.gov (United States)

    Min, Seon Kyu; Lee, Soo Hong

    2013-01-01

    High-conductivity contacts in place of screen-printed contacts are in demand for commercial solar cells. Also, simplifying the process steps is required for commercial solar cells. In addition, very expensive metals are necessary improved efficiency without using scarce. In this research, we replaced screen-printed contacts with Ni/Cu contacts in passivated emitter solar cells. A layer of nickel was used as the seed and the adhesion layer. The main contact was formed by plating with copper. Firing conditions in a conventional furnace were varied so as to form nickel silicide. The best cell showed a solar cell efficiency of 18.76%.

  13. Multi-Material Front Contact for 19% Thin Film Solar Cells

    NARCIS (Netherlands)

    Deelen, J. van; Tezsevin, Y.; Barink, M.

    2016-01-01

    The trade-off between transmittance and conductivity of the front contact material poses abottleneck for thin film solar panels. Normally, the front contact material is a metal oxide and the optimal cell configuration and panel efficiency were determined for various band gap materials, representing

  14. Passivated Tunneling Contacts to N-Type Wafer Silicon and Their Implementation into High Performance Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stradins, P.; Essig, S.; Nemeth, W.; Lee, B. G.; Young, D.; Norman, A.; Liu, Y.; Luo, J.-W.; Warren, E.; Dameron, A.; LaSalvia, V.; Page, M.; Rohatgi, A.; Upadhyaya, A.; Rounsaville, B.; Ok, Y.-W.; Glunz, S.; Benick, J.; Feldmann, F.; Hermle, M.

    2014-12-01

    We present a case that passivated contacts based on a thin tunneling oxide layer, combined with a transport layer with properly selected work function and band offsets, can lead to high efficiency c-Si solar cells. Passivated contacts contribute to cell efficiency as well as design flexibility, process robustness, and a simplified process flow. Material choices for the transport layer are examined, including transparent n-type oxides and n+-doped poly-Si. SiO2/n+-poly-Si full-area, induced-junction back surface field contacts to n-FZ and n-Cz Si are incorporated into high efficiency cells with deep, passivated boron emitters.

  15. Tunnel oxide passivated rear contact for large area n-type front junction silicon solar cells providing excellent carrier selectivity

    Directory of Open Access Journals (Sweden)

    Yuguo Tao

    2016-01-01

    Full Text Available Carrier-selective contact with low minority carrier recombination and efficient majority carrier transport is mandatory to eliminate metal-induced recombination for higher energy conversion efficiency for silicon (Si solar cells. In the present study, the carrier-selective contact consists of an ultra-thin tunnel oxide and a phosphorus-doped polycrystalline Si (poly-Si thin film formed by plasma enhanced chemical vapor deposition (PECVD and subsequent thermal crystallization. It is shown that the poly-Si film properties (doping level, crystallization and dopant activation anneal temperature are crucial for achieving excellent contact passivation quality. It is also demonstrated quantitatively that the tunnel oxide plays a critical role in this tunnel oxide passivated contact (TOPCON scheme to realize desired carrier selectivity. Presence of tunnel oxide increases the implied Voc (iVoc by ~ 125 mV. The iVoc value as high as 728 mV is achieved on symmetric structure with TOPCON on both sides. Large area (239 cm2 n-type Czochralski (Cz Si solar cells are fabricated with homogeneous implanted boron emitter and screen-printed contact on the front and TOPCON on the back, achieving 21.2% cell efficiency. Detailed analysis shows that the performance of these cells is mainly limited by boron emitter recombination on the front side.

  16. Thin, Lightweight Solar Cell

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Weinberg, Irving

    1991-01-01

    Improved design for thin, lightweight solar photovoltaic cells with front contacts reduces degradation of electrical output under exposure to energetic charged particles (protons and electrons). Increases ability of cells to maintain structural integrity under exposure to ultraviolet radiation by eliminating ultraviolet-degradable adhesives used to retain cover glasses. Interdigitated front contacts and front junctions formed on semiconductor substrate. Mating contacts formed on back surface of cover glass. Cover glass and substrate electrostatically bonded together.

  17. Understanding and development of cost-effective industrial aluminum back surface field (Al-BSF) silicon solar cells

    Science.gov (United States)

    Chen, Nian

    For the long-term strategy of gradual decarbonization of the world's energy supply, high penetration of PV electricity is critical in the future world energy landscape. In order to achieve this, solar electricity with competitive cost to fossil fuel energy is necessary. To be able to obtain high efficiency solar cells, many advanced cell architectures have been developed commercially by PV industry. However, the fabrication of these cells necessitates complex processing steps and high requirements on semiconductor materials, which make it not as cost-effective as the state-of-the-art conventional Al-BSF structure. In order to keep the cost of PV cell low and improve on the efficiency with fewer processing steps, this thesis work focuses on the understanding of the conventional Al-BSF solar cell structure. The research work therefore, focuses on the (i) design, and modeling of front metal electrodes including the use of multi-bus-bar capable of decreasing the gridline resistance, (ii) fine-line printing and (iii) metal contact co-firing using high belt speed that is not common to the solar industry to achieve ~20% efficient industrial Al-BSF silicon solar cells. In order to achieve the objectives of this thesis work, firstly, the appropriate Al paste was investigated for lowest back surface recombination velocity (BSRV), which gives high open circuit voltage (Voc). Secondly, the impact of emitter sheet resistance on solar cell performance was modeled to determine the optimal sheet resistance, and the uniformity of emitter was also investigated. Thirdly, modeling on the front metal electrodes was carried out to investigate the optimal number of busbars, and determine the optimum number of gridlines and gridline geometries that would result in low series resistance (Rs), high fill factor (FF) and hence high efficiency. Fourthly, the modeled results were experimentally validated through fine-line printing and optimized contact co-firing. By combining each layer to make

  18. Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

    Science.gov (United States)

    Yang, Weiquan; Becker, Jacob; Liu, Shi; Kuo, Ying-Shen; Li, Jing-Jing; Landini, Barbara; Campman, Ken; Zhang, Yong-Hang

    2014-05-01

    This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In0.49Ga0.51P/GaAs/In0.49Ga0.51P double-heterostructure PN junction with an ultra-thin 300 nm thick GaAs absorber, combined with a 5 μm thick Al0.52In0.48P layer with a textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF2/ZnS anti-reflective coating demonstrated open-circuit voltages (Voc) up to 1.00 V, short-circuit current densities (Jsc) up to 24.5 mA/cm2, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated Jsc and conversion efficiency of these devices are expected to reach 26.6 mA/cm2 and 20.7%, respectively.

  19. Electroplated contacts and porous silicon for silicon based solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Kholostov, Konstantin, E-mail: kholostov@diet.uniroma1.it [Department of information engineering, electronics and telecommunications, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome (Italy); Serenelli, Luca; Izzi, Massimo; Tucci, Mario [Enea Casaccia Research Centre Rome, via Anguillarese 301, 00123 Rome (Italy); Balucani, Marco [Department of information engineering, electronics and telecommunications, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome (Italy); Rise Technology S.r.l., Lungomare Paolo Toscanelli 170, 00121 Rome (Italy)

    2015-04-15

    Highlights: • Uniformity of the Ni–Si interface is crucial for performance of Cu–Ni contacts on Si. • Uniformly filled PS is the key to obtain the best performance of Cu–Ni contacts on Si. • Optimization of anodization and electroplating allows complete filling of PS layer. • Highly adhesive and low contact resistance Cu–Ni contacts are obtained on Si. - Abstract: In this paper, a two-layer metallization for silicon based solar cells is presented. The metallization consists of thin nickel barrier and thick copper conductive layers, both obtained by electrodeposition technique suitable for phosphorus-doped 70–90 Ω/sq solar cell emitter formed on p-type silicon substrate. To ensure the adhesion between metal contact and emitter a very thin layer of mesoporous silicon is introduced on the emitter surface before metal deposition. This approach allows metal anchoring inside pores and improves silicon–nickel interface uniformity. Optimization of metal contact parameters is achieved varying the anodization and electrodeposition conditions. Characterization of contacts between metal and emitter is carried out by scanning electron microscopy, specific contact resistance and current–voltage measurements. Mechanical strength of nickel–copper contacts is evaluated by the peel test. Adhesion strength of more than 4.5 N/mm and contact resistance of 350 μΩ cm{sup 2} on 80 Ω/sq emitter are achieved.

  20. Advances in the theory and application of BSF cells. [Back Surface Field solar cells

    Science.gov (United States)

    Mandelkorn, J.; Lamneck, J. H.

    1975-01-01

    A study to determine the influence of fabrication processes and bulk material properties on the behavior of back surface field (BSF) cells is reported. It is concluded that a photovoltage is generated at the p(+), p back junction of the cell. The concept of majority carrier collection is proposed as a possible mechanism for this generation. Advantages accruing to the advent of BSF cells are outlined.

  1. Multi-Material Front Contact for 19% Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Joop van Deelen

    2016-02-01

    Full Text Available The trade-off between transmittance and conductivity of the front contact material poses a bottleneck for thin film solar panels. Normally, the front contact material is a metal oxide and the optimal cell configuration and panel efficiency were determined for various band gap materials, representing Cu(In,GaSe2 (CIGS, CdTe and high band gap perovskites. Supplementing the metal oxide with a metallic copper grid improves the performance of the front contact and aims to increase the efficiency. Various front contact designs with and without a metallic finger grid were calculated with a variation of the transparent conductive oxide (TCO sheet resistance, scribing area, cell length, and finger dimensions. In addition, the contact resistance and illumination power were also assessed and the optimal thin film solar panel design was determined. Adding a metallic finger grid on a TCO gives a higher solar cell efficiency and this also enables longer cell lengths. However, contact resistance between the metal and the TCO material can reduce the efficiency benefit somewhat.

  2. Design of Semiconductor-Based Back Reflectors for High Voc Monolithic Multijunction Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, I.; Geisz, J.; Steiner, M.; Olson, J.; Friedman, D.; Kurtz, S.

    2012-06-01

    State-of-the-art multijunction cell designs have the potential for significant improvement before going to higher number of junctions. For example, the Voc can be substantially increased if the photon recycling taking place in the junctions is enhanced. This has already been demonstrated (by Alta Devices) for a GaAs single-junction cell. For this, the loss of re-emitted photons by absorption in the underlying layers or substrate must be minimized. Selective back surface reflectors are needed for this purpose. In this work, different architectures of semiconductor distributed Bragg reflectors (DBR) are assessed as the appropriate choice for application in monolithic multijunction solar cells. Since the photon re-emission in the photon recycling process is spatially isotropic, the effect of the incident angle on the reflectance spectrum is of central importance. In addition, the DBR structure must be designed taking into account its integration into the monolithic multijunction solar cells, concerning series resistance, growth economics, and other issues. We analyze the tradeoffs in DBR design complexity with all these requirements to determine if such a reflector is suitable to improve multijunction solar cells.

  3. Ni/Cu/Ag plated contacts: A study of resistivity and contact adhesion for crystalline-Si solar cells

    Science.gov (United States)

    ur Rehman, Atteq; Lee, Sang Hee; Bhopal, Muhammad Fahad; Lee, Soo Hong

    2016-07-01

    Ni/Cu/Ag plated contacts were examined as an alternate to Ag screen printed contacts for silicon (Si) solar cell metallization. To realize a reliable contact for industrial applications, the contact resistance and its adhesion to Si substrates were evaluated. Si surface roughness by picosecond (ps) laser ablation of silicon-nitride (SiNx) antireflection coating (ARC) was done in order to prepare the patterns. The sintering process after Ni/Cu/Ag full metallization in the form of the post-annealing process was applied to investigate the contact resistivity and adhesion. A very low contact resistivity of approximately 0.5 mΩcm2 has been achieved with measurements made by the transfer length method (TLM). Thin finger lines of about 26 μm wide and a line resistance of 0.51 Ω/cm have been realized by plating technology. Improved contact adhesion by combining the ps-laser-ablation and post-annealing process has been achieved. We have shown the peel-off strengths >1 N/mm with a higher average adhesion of 1.9 N/mm. Our pull-tab adhesion tests demonstrate excellent strength well above the wafer breakage force. [Figure not available: see fulltext.

  4. Si/PEDOT:PSS Hybrid Solar Cells with Advanced Antireflection and Back Surface Field Designs

    Science.gov (United States)

    Sun, Yiling; Yang, Zhenhai; Gao, Pingqi; He, Jian; Yang, Xi; Sheng, Jiang; Wu, Sudong; Xiang, Yong; Ye, Jichun

    2016-08-01

    Molybdenum oxide (MoO3) is one of most suitable antireflection (AR) layers for silicon/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (Si/PEDOT:PSS) hybrid solar cells due to its well-matched refractive index (2.1). A simulation model was employed to predict the optical characteristics of Si/PEDOT:PSS hybrid solar cells with the MoO3 layers as antireflection coatings (ARCs), as well as to analyze the loss in current density. By adding an optimum thickness of a 34-nm-thick ARC of MoO3 on the front side and an effective rear back surface field (BSF) of phosphorus-diffused N + layer at the rear side, the hybrid cells displayed higher light response in the visible and near infrared regions, boosting a short-circuit current density ( J sc) up to 28.7 mA/cm2. The average power conversion efficiency (PCE) of the Si/PEDOT:PSS hybrid solar cells was thus increased up to 11.90 %, greater than the value of 9.23 % for the reference devices.

  5. Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance

    Science.gov (United States)

    Desta, Derese; Ram, Sanjay K.; Rizzoli, Rita; Bellettato, Michele; Summonte, Caterina; Jeppesen, Bjarke R.; Jensen, Pia B.; Tsao, Yao-Chung; Wiggers, Hartmut; Pereira, Rui N.; Balling, Peter; Larsen, Arne Nylandsted

    2016-06-01

    A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering. The n-i-p amorphous silicon thin-film solar cells grown on such a back-reflector show enhanced light absorption resulting in improved external quantum efficiency. The benefit of the light trapping in those solar cells is evidenced by the gains in short-circuit current density and efficiency up to 15.6% and 19.3% respectively, compared to the reference flat solar cells. This improvement in the current generation in the solar cells grown on the flat-topped (buried pyramid) back-reflector is observed even when the irradiation takes place at large oblique angles of incidence. Finite-difference-time-domain simulation results of optical absorption and ideal short-circuit current density values agree well with the experimental findings. The proposed approach uses a low cost and simple fabrication technique and allows effective light manipulation by utilizing the optical properties of micro-scale structures and nanoscale constituent particles.

  6. Universal Features of Electron Dynamics in Solar Cells with TiO2 Contact: From Dye Solar Cells to Perovskite Solar Cells.

    Science.gov (United States)

    Todinova, Anna; Idígoras, Jesús; Salado, Manuel; Kazim, Samrana; Anta, Juan A

    2015-10-01

    The electron dynamics of solar cells with mesoporous TiO2 contact is studied by electrochemical small-perturbation techniques. The study involved dye solar cells (DSC), solid-state perovskite solar cells (SSPSC), and devices where the perovskite acts as sensitizer in a liquid-junction device. Using a transport-recombination continuity equation we found that mid-frequency time constants are proper lifetimes that determine the current-voltage curve. This is not the case for the SSPSC, where a lifetime of ∼1 μs, 1 order of magnitude longer, is required to reproduce the current-voltage curve. This mismatch is attributed to the dielectric response on the mid-frequency component. Correcting for this effect, lifetimes lie on a common exponential trend with respect to open-circuit voltage. Electron transport times share a common trend line too. This universal behavior of lifetimes and transport times suggests that the main difference between the cells is the power to populate the mesoporous TiO2 contact with electrons.

  7. Efficiency improvement of dye-sensitized tandem solar cell by increasing the photovoltage of the back sub-cell

    Energy Technology Data Exchange (ETDEWEB)

    Fan Shengqiang [Department of Advanced Materials Chemistry, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of); Department of Applied Chemistry, School of Science, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Fang Baizeng, E-mail: shengqiang_fan@sohu.co [Department of Advanced Materials Chemistry, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of); Choi, Hyunbong; Paik, Sanghyun; Kim, Chulwoo; Jeong, Ban-Seok; Kim, Jeum-Jong [Department of Advanced Materials Chemistry, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of); Ko, Jaejung, E-mail: jko@korea.ac.k [Department of Advanced Materials Chemistry, Korea University, Jochiwon, Chungnam 339-700 (Korea, Republic of)

    2010-06-01

    In tandem-structured dye-sensitized solar cell (DSSC) composed of two parallel-connected sub-cells, the photovoltage (V{sub oc}) generated by the back sub-cell is usually rather low, resulting in low V{sub oc} and conversion efficiency (eta) of the tandem cell. To solve this issue, two simple but very efficient strategies, namely, the filling of Li{sup +}-absent electrolyte and/or coating Al{sub 2}O{sub 3} on TiO{sub 2} electrode surface in the back sub-cell, were explored to enhance the V{sub oc} of the back sub-cell and hence that of the tandem cell. The former strategy was expected to heighten the energy level of TiO{sub 2} conduction band, and the latter one to retard the charge recombination. The photovoltaic performance measurements reveal that in the both cases, although there was a slight decrease in the photocurrent (J{sub sc}), an obvious rise in the V{sub oc} was achieved for the tandem cells, leading to significant improvements in eta of the tandem cells. Compared to the individual organic dye-sensitized solar cell (the highest eta is 7.58%), the tandem cell with two organic dyes having complementary absorption spectra demonstrates an improved efficiency of up to 8.33% by a combinational application of Li{sup +}-absent electrolyte and Al{sub 2}O{sub 3} overcoat. The results presented in this study highlight that the efficiency of a parallel-connected tandem-structured DSSC can be improved significantly through enhancing the photovoltage of the back sub-cell, which is first time reported.

  8. Improving the durability of dye-sensitized solar cells through back illumination

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Lu-Yin; Lee, Chuan-Pei; Vittal, R. [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Ho, Kuo-Chuan [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617 (China)

    2011-02-01

    Highly efficient and stable back illumination dye-sensitized solar cell (BIL-DSSC) is developed using its Pt-counter electrode (Pt-CE) as the light-irradiating surface. Photovoltaic parameters are measured for DSSCs with Pt-CEs obtained with different sputtering periods of platinum layer. By optimizing the transmittance and catalytic property of the platinum layer on the counter electrode, a light-to-electricity conversion efficiency ({eta}) of 7.54% is achieved with back illumination at 100 mW cm{sup -2}, when the platinum deposition time is 30 s. The effects of platinum layers with different sputtering periods on the photovoltaic characteristics of the respective DSSCs are explained in terms of transmittance and catalytic activity of the layers. A comparative study is also made on the durability of the DSSCs with BIL and front illumination (FIL), in which the respective DSSCs are previously subjected to UV-soaking for different periods of time under simulated conditions of back and front illuminations; at-rest stability tests for such UV-soaked DSSCs carried out through BIL and FIL suggest a far higher stability in favor of the BIL-DSSC, compared to that of the FIL-DSSC. Explanations are substantiated with transmittance spectra, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and absorption spectra. (author)

  9. Implementation of Tunneling Passivated Contacts into Industrially Relevant n-Cz Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Nemeth, William; LaSalvia, Vincenzo; Page, Matthew R.; Warren, Emily L.; Dameron, Arrelaine; Norman, Andrew G.; Lee, Benjamin G.; Young, David L.; Stradins, Paul

    2015-06-14

    We identify bottlenecks, and propose solutions, to implement a B-diffused front emitter and a backside pc-Si/SiO2 pasivated tunneling contact into high efficiency n-Cz Si cells in an industrially relevant way. We apply an O-precipitate dissolution treatment to make n-Cz wafers immune to bulk lifetime process degradation, enabling robust, passivated B front emitters with J0 <; 20fA/cm2. Adding ultralow recombination n+ pc-Si/SiO2 back contacts enables pre-metallized cells with iVoc=720 mV and J0=8.6 fA/cm2. However, metallization significantly degrades performance of these contacts due to pinholes and possibly, grain boundary diffusion of primary metal and source contaminates such as Cu. An intermediate, doped a-Si:H capping layer is found to significantly block the harmful metal penetration into pc-Si.

  10. Numerical Analysis of Novel Back Surface Field for High Efficiency Ultrathin CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    M. A. Matin

    2013-01-01

    Full Text Available This paper numerically explores the possibility of high efficiency, ultrathin, and stable CdTe cells with different back surface field (BSF using well accepted simulator AMPS-1D (analysis of microelectronics and photonic structures. A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/BSF/BC has been proposed over reference structure SnO2/Zn2SnO4/CdS/CdTe/Cu. Both higher bandgap materials like ZnTe and Cu2Te and low bandgap materials like As2Te3 and Sb2Te3 have been used as BSF to reduce minority carrier recombination loss at the back contact in ultra-thin CdTe cells. In this analysis the highest conversion efficiency of CdTe based PV cell without BSF has been found to be around 17% using CdTe absorber thickness of 5 μm. However, the proposed structures with different BSF have shown acceptable efficiencies with an ultra-thin CdTe absorber of only 0.6 μm. The proposed structure with As2Te3 BSF showed the highest conversion efficiency of 20.8% ( V,  mA/cm2, and . Moreover, the proposed structures have shown improved stability in most extents, as it was found that the cells have relatively lower negative temperature coefficient. However, the cell with ZnTe BSF has shown better overall stability than other proposed cells with temperature coefficient (TC of −0.3%/°C.

  11. Aspects of designing an optimized molybdenum back contact in CIGS-technology

    Energy Technology Data Exchange (ETDEWEB)

    Oertel, Michael; Goetz, Stefan; Haarstrich, Jakob; Metzner, Heinrich; Reisloehner, Udo; Ronning, Carsten; Wesch, Werner [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany)

    2011-07-01

    In Cu(In,Ga)Se{sub 2}(CIGS)-solar cell and module production, the sputtering of the molybdenum back contact is the first step in nearly all process lines. We present our results of experiments to elucidate the different aspects which have to be kept in mind when depositing the molybdenum back contact by dc-magnetron sputtering. These aspects include: I) The adhesion of the molybdenum to the glass substrate as well as the adhesion of the CIGS-layer to the molybdenum, II) electrical conductivity, III) sodium diffusion and IV) the specific contact resistance of the molybdenum to the aluminium doped zinc oxide (Al:ZnO) window layer. We present our three layer design of the back contact which combines an optimized adhesion to both the substrate and the absorber and also a high electrical conductivity. X-ray diffraction measurements (XRD) are employed to characterize each single layer. We also discuss I-U-measurements of CuInSe{sub 2}-solar cells made in a sequential absorber layer process in order to study the sodium transport behaviour of molybdenum back contacts sputtered at different argon sputter pressures. The sodium content in the absorber and the different back contact layers is measured by secondary ion mass spectroscopy (SIMS). A lowest value of the specific contact resistance between the Mo and the Al:ZnO of (1.37{+-}0.14).10{sup 5} {omega}cm{sup 2} was determined.

  12. Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, L. [Arizona State Univ., Tempe, AZ (United States); Boccard, Matthieu [Arizona State Univ., Tempe, AZ (United States); Holman, Zachary [Arizona State Univ., Tempe, AZ (United States); Bertoni, M. [Arizona State Univ., Tempe, AZ (United States)

    2015-04-06

    "Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical band alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface

  13. Passivation of the surface of rear contact solar cells by porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, O. [Radiophysics Department, Taras Shevchenko National University, 64 Vladimirskaya, 01033, Kiev (Ukraine) and Laboratoire de Physique de la Matiere, UMR 5511, INSA de Lyon, Bat. Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France)]. E-mail: oleksiy.nichiporuk@insa-lyon.fr; Kaminski, A. [Laboratoire de Physique de la Matiere, UMR 5511, INSA de Lyon, Bat. Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Lemiti, M. [Laboratoire de Physique de la Matiere, UMR 5511, INSA de Lyon, Bat. Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Fave, A. [Laboratoire de Physique de la Matiere, UMR 5511, INSA de Lyon, Bat. Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Litvinenko, S. [Radiophysics Department, Taras Shevchenko National University, 64 Vladimirskaya, 01033, Kiev (Ukraine); Skryshevsky, V. [Radiophysics Department, Taras Shevchenko National University, 64 Vladimirskaya, 01033, Kiev (Ukraine)

    2006-07-26

    In this paper we analyse the passivation of the front surface of p-Si interdigitated rear contacts solar cell (IBC) by a thin porous silicon (PS) layer. Effectively, an efficiency improvement of 87% in relative was observed after porous silicon layer formation on the front surface of the IBC cell. The origin of surface passivation by the PS layer was studied by Laser Beam Induced Current (LBIC) method. The front surface of rear contacts cell with thin porous silicon layer was scanned by a modulated red laser beam in presence of a permanent light with different wavelengths and intensities. It was shown that without permanent illumination, the photocurrent of the cell with PS layer is very low, even lower than for a cell with unpassivated surface. However with short permanent wavelength illumination a strong increase of photocurrent was observed (8-10 times{exclamation_point}). The light-dependent porous silicon passivation phenomenon is explained by a significant negative charge accumulation at the PS/p-Si interface traps under illumination. This leads to the formation of a hi-low (p{sup +}/p) junction at the front surface of the cell and to the reduction of the front surface recombination rate, like in Front Surface Field Solar Cell.

  14. Design and optimization of ultrathin crystalline silicon solar cells using an efficient back reflector

    Directory of Open Access Journals (Sweden)

    S. Saravanan

    2015-05-01

    Full Text Available Thin film solar cells are cheaper but having low absorption in longer wavelength and hence, an effective light trapping mechanism is essential. In this work, we proposed an ultrathin crystalline silicon solar cell which showed extraordinary performance due to enhanced light absorption in visible and infrared part of solar spectrum. Various designing parameters such as number of distributed Bragg reflector (DBR pairs, anti-reflection layer thickness, grating thickness, active layer thickness, grating duty cycle and period were optimized for the optimal performance of solar cell. An ultrathin silicon solar cell with 40 nm active layer could produce an enhancement in cell efficiency ∼15 % and current density ∼23 mA/cm2. This design approach would be useful for the realization of new generation of solar cells with reduced active layer thickness.

  15. Optimization of multi-layer front-contact grid patterns for solar cells

    Science.gov (United States)

    Flat, A.; Milnes, A. G.

    1979-01-01

    In a front-contact grid pattern for a solar cell there is a trade-off necessary between shadowing loss and excessive power loss due to voltage drop in the metalization itself. If the metalization is too little there may be excessive contact resistance to the underlying semiconductor and insufficient coverage to control losses in the thin front-surface layer of the solar cell. Optimization of grid pattern area and geometry is considered analytically to minimize total losses. Worthwhile performance advantages are shown to be possible, particularly in concentrator systems, if multi-layer grid patterns are used. The current carrying fingers should be approximately square in metal cross section and the main current feedout bars should not only be wider but also thicker than the primary collecting fingers. This is termed multi-level metalization. Effective use of multi-level grid metalization allows much greater concentration-to-loss ratio for a cell of large area and permits good performance from cells of high front-layer sheet resistance.

  16. Self-assembly method for controlling spatial frequency response of plasmonic back reflectors in organic thin-film solar cells

    Science.gov (United States)

    Okamoto, Takayuki; Shinotsuka, Kei; Kawamukai, Etsuko; Ishibashi, Koji

    2017-01-01

    We propose a novel colloidal lithography technique that uses a mixture of colloidal particles with a few different diameters. This technique can be used for fabricating quasi-random nanostructures whose k-space spectra can be easily controlled by using an appropriate combination of particles. We introduced such nanostructures into the back reflectors of organic thin-film solar cells, where they serve as plasmonic back reflectors for recycling the nonabsorbed transmitted light into surface plasmons. The obtained photon-to-current efficiency was enhanced by 14-20% compared with that of a flat cell.

  17. Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

    Energy Technology Data Exchange (ETDEWEB)

    Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.; Burst, James M.; Reese, Matthew O.; Wolden, C. A.; Gessert, Timothy A.; Metzger, Wyatt K.; Garner, S.; Barnes, Teresa M.

    2015-06-14

    Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the device performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.

  18. Improving the organic/Si heterojunction hybrid solar cell property by optimizing PEDOT:PSS film and with amorphous silicon as back surface field

    Science.gov (United States)

    Wen, Hongbin; Cai, Hongkun; Du, Yangyang; Dai, Xiaowan; Sun, Yun; Ni, Jian; Li, Juan; Zhang, Dexian; Zhang, Jianjun

    2017-01-01

    Organic/Si hybrid heterojunction hybrid solar cells have got a great progress. The hybrid device may be promising in terms of reducing cost due to its simple technological process. It is crucial for high efficiency solar cells to form better coating films on the Si substrate. Here, the performance of organic/Si heterojunction hybrid solar cells is obviously enhanced by adding surfactant (FS300) into poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) film and the device with amorphous silicon as back surface field is successfully fabricated. The proper amount of surfactant addition improves the uniformity and homogeneous of the polymer film that can be reflected by scanning electron microscope and atomic force microscope, which allows good contact on the texture-Si substrate resulting in excellent device property. Also, the power conversion efficiency of cells is boosted to 9.37 from 7.31% displayed a 28% enhancement by embedding amorphous silicon thin film layer at rear interface as holes blocking layer. The insertion layer of amorphous silicon enhances the extraction of photon-generated carrier and suppresses the recombination of hole-electron at the rear cathode. Which results all improvement in the short-circuit current density, the open-circuit voltage and the fill factor. By optimizing the polymer film property and inserting the hole blocking layer, the performance of hybrid Si/organic hybrid solar cells is greatly improved.

  19. Combinatorial sputtering of Ga-doped (Zn,Mg)O for contact applications in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rajbhandari, Pravakar P.; Bikowski, André; Perkins, John D.; Dhakal, Tara P.; Zakutayev, Andriy

    2017-01-01

    Development of tunable contact materials based on environmentally friendly chemical elements using scalable deposition approaches is necessary for existing and emerging solar energy conversion technologies. In this paper, the properties of ZnO alloyed with magnesium (Mg), and doped with gallium (Ga) are studied using combinatorial thin film experiments. As a result of these studies, the optical band gap of the sputtered Zn1-xMgxO thin films was determined to vary from 3.3 to 3.6 eV for a compositional spread of Mg content in the 0.04 < x < 0.17 range. Depending on whether or not Ga dopants were added, the electron concentrations were on the order of 1017 cm-3 or 1020 cm-3, respectively. Based on these results and on the Kelvin Probe work function measurements, a band diagram was derived using basic semiconductor physics equations. The quantitative determination of how the energy levels of Ga-doped (Zn, Mg)O thin films change as a function of Mg composition presented here, will facilitate their use as optimized contact layers for both Cu2ZnSnS4 (CZTS), Cu(In, Ga)Se2 (CIGS) and other solar cell absorbers.

  20. Operando XPS Characterization of Selective Contacts: The Case of Molybdenum Oxide for Crystalline Silicon Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Laura; Harvey, Stephen P.; Teeter, Glenn; Bertoni, Mariana I.

    2016-11-21

    We demonstrate the potential of X-ray photoelectron spectroscopy (XPS) to characterize new carrier-selective contacts (CSC) for solar cell application. We show that XPS not only provides information about the surface chemical properties of the CSC material, but that operando XPS, i.e. under light bias condition, can also directly measure the photovoltage that develops at the CSC/absorber interface, revealing device relevant information without the need of assembling a full solar cell. We present the application of the technique to molybdenum oxide hole-selective contact films on a crystalline silicon absorber.

  1. Effects of contact electrode size on the characteristics of polycrystalline-Si p-i-n solar cells

    Institute of Scientific and Technical Information of China (English)

    M. H. Juang; H. Y. Huang; S. L. Jang

    2011-01-01

    The effects of contact electrode size on the photo-voltaic characteristics of polycrystalline-Si p-i-n solar cells have been studied,with respect to a unit-cell pitch size of 1 μm width.For the non-transparent A1 contact electrode with a contact width of 0.05-0.2 μm,the short-circuit current is obviously reduced with increasing contact width,due to a larger area of optical reflection by the electrode.On the other hand,even when using a transparent ITO (indium-tin-oxide) electrode,a larger width of contact electrode may also cause a smaller short-circuit current,due to a larger area of optical absorption by the electrode.However,for this ITO electrode,the contact electrode of 0.05 μm width causes a smaller short-circuit current than that of 0.1 μm width,primarily ascribed to a smaller area for collecting carrier and a larger contact resistance.As a result,while using the ITO contact electrode to enhance the conversion efficiency of the solar cell,a proper width of contact electrode should be employed to optimize the photo-voltaic characteristics.

  2. Optical Evaluation of the Rear Contacts of Crystalline Silicon Solar Cells by Coupled Electromagnetic and Statistical Ray-Optics Modeling

    KAUST Repository

    Dabirian, Ali

    2017-02-15

    High-efficiency crystalline silicon (c-Si) solar cells increasingly feature sophisticated electron and hole contacts aimed at minimizing electronic losses. At the rear of photovoltaic devices, such contacts—usually consisting of stacks of functional layers—offer opportunities to enhance the infrared response of the solar cells. Here, we propose an accurate and simple modeling procedure to evaluate the infrared performance of rear contacts in c-Si solar cells. Our method combines full-wave electromagnetic modeling of the rear contact with a statistical ray optics model to obtain the fraction of optical energy dissipated from the rear contact relative to that absorbed by the Si wafer. Using this technique, we study the impact of the refractive index, extinction coefficient, and thickness of the rear-passivating layer and establish basic design rules. In addition, we evaluate novel optical structures, including stratified thin films, nanoparticle composites, and conductive nanowires embedded in a low-index dielectric matrix, for integration into advanced rear contacts in c-Si photovoltaic devices. From an optical perspective, nanowire structures preserving low contact resistance appear to be the most effective approach to mitigating dissipation losses from the rear contact.

  3. Effect of electroless nickel on the series resistance of high-efficiency inkjet printed passivated emitter rear contacted solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lenio, Martha A.T. [REC Technology US, Inc., 1159 Triton Dr., Foster City, CA 94301 (United States); Lennon, A.J.; Ho-Baillie, A.; Wenham, S.R. [ARC Photovoltaics Centre of Excellence, University of NSW, Sydney, NSW 2052 (Australia)

    2010-12-15

    Many existing and emerging solar cell technologies rely on plated metal to form the front surface contacts, and aluminium to form the rear contact. Interactions between the metal plating solutions and the aluminium rear can have a significant impact on cell performance. This paper describes non-uniform nickel deposition on the sintered aluminium rear surface of passivated emitter and rear contacted (PERC) cells patterned using an inkjet printing technique. Rather than being plated homogeneously over the entire rear surface as is observed on an alloyed aluminium rear, the nickel is plated only in the vicinity of the point openings in the rear surface silicon dioxide dielectric layer. Furthermore, this non-uniform nickel deposition was shown to increase the contact resistance of the rear point contacts by an order of magnitude, resulting in higher series resistance values for these fabricated PERC cells. (author)

  4. Transparency Effect of Electrolyte on Light Back-Scattering in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    N. Sharifi

    2015-12-01

    Full Text Available Conventionally, a film of TiO2 particles of ~300 nm size is employed in DSCs as the back reflector film to enhance the light harvesting. In this study, two electrolytes with different transparencies, iodide-based and cobalt-based electrolytes, were used to investigate the transparency effect of electrolytes on light back-scattering from back scattering layer and also to study its effect on the performance of DSCs. The use of cobalt-based electrolyte is recommended from the view point of optical properties as due to the light absorption in electrolytes, the current density losses are 2.9mA/cm2 and 4.2 mA/cm2 in cobalt- and iodide-based electrolytes, respectively, and the transmission of 100% is observed for cobalt-based electrolyte in 500-600 nm in spite of iodide-based electrolyte. Use of light back-scattering layer, unlike iodide-based cell, causes external quantum efficiency in cobalt-base cell to increase for the wavelengths lower than 350 nm since cobalt-base electrolyte has transparency in this region. In addition, optical calculations demonstrate that in the range 400-500 nm, in which dye has a noticeable absorption, absorption loss is 40% and 30% for iodide- and cobalt-based electrolytes, respectively.

  5. Transparent Ohmic Contacts for Solution-Processed, Ultrathin CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kurley, J. Matthew; Panthani, Matthew G.; Crisp, Ryan W.; Nanayakkara, Sanjini U.; Pach, Gregory F.; Reese, Matthew O.; Hudson, Margaret H.; Dolzhnikov, Dmitriy S.; Tanygin, Vadim; Luther, Joseph M.; Talapin, Dmitri V.

    2017-01-13

    Recently, solution-processing became a viable route for depositing CdTe for use in photovoltaics. Ultrathin (~500 nm) solar cells have been made using colloidal CdTe nanocrystals with efficiencies exceeding 12% power conversion efficiency (PCE) demonstrated by using very simple device stacks. Further progress requires an effective method for extracting charge carriers generated during light harvesting. Here, we explored solution-based methods for creating transparent Ohmic contacts to the solution-deposited CdTe absorber layer and demonstrated molecular and nanocrystal approaches to Ohmic hole-extracting contacts at the ITO/CdTe interface. We used scanning Kelvin probe microscopy to further show how the above approaches improved carrier collection by reducing the potential drop under reverse bias across the ITO/CdTe interface. Other methods, such as spin-coating CdTe/A2CdTe2 (A = Na, K, Cs, N2H5), can be used in conjunction with current/light soaking to improve PCE further.

  6. Perovskite/silicon-based heterojunction tandem solar cells with 14.8% conversion efficiency via adopting ultrathin Au contact

    Science.gov (United States)

    Fan, Lin; Wang, Fengyou; Liang, Junhui; Yao, Xin; Fang, Jia; Zhang, Dekun; Wei, Changchun; Zhao, Ying; Zhang, Xiaodan

    2017-01-01

    A rising candidate for upgrading the performance of an established narrow-bandgap solar technology without adding much cost is to construct the tandem solar cells from a crystalline silicon bottom cell and a high open-circuit voltage top cell. Here, we present a four-terminal tandem solar cell architecture consisting of a self-filtered planar architecture perovskite top cell and a silicon heterojunction bottom cell. A transparent ultrathin gold electrode has been used in perovskite solar cells to achieve a semi-transparent device. The transparent ultrathin gold contact could provide a better electrical conductivity and optical reflectance-scattering to maintain the performance of the top cell compared with the traditional metal oxide contact. The four-terminal tandem solar cell yields an efficiency of 14.8%, with contributions of the top (8.98%) and the bottom cell (5.82%), respectively. We also point out that in terms of optical losses, the intermediate contact of self-filtered tandem architecture is the uppermost problem, which has been addressed in this communication, and the results show that reducing the parasitic light absorption and improving the long wavelength range transmittance without scarifying the electrical properties of the intermediate hole contact layer are the key issues towards further improving the efficiency of this architecture device. Project supported by the International Cooperation Projects of the Ministry of Science and Technology (No. 2014DFE60170), the National Natural Science Foundation of China (Nos. 61474065, 61674084), the Tianjin Research Key Program of Application Foundation and Advanced Technology (No. 15JCZDJC31300), the Key Project in the Science & Technology Pillar Program of Jiangsu Province (No. BE2014147-3), and the 111 Project (No. B16027).

  7. Modeling light trapping in nanostructured solar cells.

    Science.gov (United States)

    Ferry, Vivian E; Polman, Albert; Atwater, Harry A

    2011-12-27

    The integration of nanophotonic and plasmonic structures with solar cells offers the ability to control and confine light in nanoscale dimensions. These nanostructures can be used to couple incident sunlight into both localized and guided modes, enhancing absorption while reducing the quantity of material. Here we use electromagnetic modeling to study the resonances in a solar cell containing both plasmonic metal back contacts and nanostructured semiconductor top contacts, identify the local and guided modes contributing to enhanced absorption, and optimize the design. We then study the role of the different interfaces and show that Al is a viable plasmonic back contact material.

  8. A simple theory of back-surface-field /BSF/ solar cells

    Science.gov (United States)

    Von Roos, O.

    1979-01-01

    An earlier calculation of the I-V characteristics of solar cells contains a mistake. The current generated by light within the depletion layer is too large by a factor of 2. When this mistake is corrected, not only are all previous conclusions unchanged, but the agreement with experiment becomes better. Results are presented in graphical form of new computations which not only take account of the factor of 2, but also include more recent data on material parameters.

  9. Application Of Artificial Neural Networks In Modeling Of Manufactured Front Metallization Contact Resistance For Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Musztyfaga-Staszuk M.

    2015-09-01

    Full Text Available This paper presents the application of artificial neural networks for prediction contact resistance of front metallization for silicon solar cells. The influence of the obtained front electrode features on electrical properties of solar cells was estimated. The front electrode of photovoltaic cells was deposited using screen printing (SP method and next to manufactured by two methods: convectional (1. co-fired in an infrared belt furnace and unconventional (2. Selective Laser Sintering. Resistance of front electrodes solar cells was investigated using Transmission Line Model (TLM. Artificial neural networks were obtained with the use of Statistica Neural Network by Statsoft. Created artificial neural networks makes possible the easy modelling of contact resistance of manufactured front metallization and allows the better selection of production parameters. The following technological recommendations for the screen printing connected with co-firing and selective laser sintering technology such as optimal paste composition, morphology of the silicon substrate, co-firing temperature and the power and scanning speed of the laser beam to manufacture the front electrode of silicon solar cells were experimentally selected in order to obtain uniformly melted structure well adhered to substrate, of a small front electrode substrate joint resistance value. The prediction possibility of contact resistance of manufactured front metallization is valuable for manufacturers and constructors. It allows preserving the customers’ quality requirements and bringing also measurable financial advantages.

  10. Degradation of ultrathin CdTe films with SWCNT or Graphene back contact

    Science.gov (United States)

    Gorji, Nima E.

    2015-06-01

    The degradation of ultrathin film solar cells based on CdS/CdTe materials and back contacted with nanolayers are analysed using SCAPS. The ultrathin films suffer from uncompleted photo-absorption and fast degradation. The instability in performance was mainly attributed to the back contact materials which cause roll-over and cause mobile ions inter-diffusion. Thus, in this work, three different nanolayers such as single walled carbon nanotubes and Graphene are considered as the metal-free back contacts with wide controllable work function for the CdTe films. The simulations show that the roll-over in characteristics of the device disappears when the work function of the nanolayer increases by a proper doping. The current density-voltage curves showed promising results when the CdTe thickness was thinned down to 0.7 μm. Surface coverage of the grain boundaries at the interface of CdTe/nanolayer can reduce the contact series resistance and improve the carrier collection. However, the inter-sheet resistance of the nanolayers should be re-optimized. Finally, the time dependent approach was applied to simulate the defect generation under stress condition where the Cu-doped nanolayers showed faster degradation while the nanolayer back contacted devices showed higher stability.

  11. Design of anti-ring back reflectors for thin-film solar cells based on three-dimensional optical and electrical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Hui-Hsin; Wu, Yuh-Renn, E-mail: yrwu@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan (China); Chang, Hung-Chun [Graduate Institute of Photonics and Optoelectronics, Graduate Institute of Communication Engineering, and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China)

    2014-08-11

    The optical and electrical properties of a photonic-plasmonic nanostructure on the back contact of thin-film solar cells were investigated numerically through the three-dimensional (3D) finite-difference time-domain method and the 3D Poisson and drift-diffusion solver. The focusing effect and the Fabry-Perot resonances are identified as the main mechanisms for the enhancement of the optical generation rate as well as the short circuit current density. However, the surface topography of certain nanopattern structures is found to reduce the internal electrostatic field of the device, thus limiting charge collection. The optimized conditions for both optics and electronics have been analyzed in this paper.

  12. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Hyun-Sik; Khang, Dahl-Young, E-mail: dykhang@yonsei.ac.kr

    2015-08-31

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s.

  13. Terrestrial solar cell module automated array assembly, task 4

    Science.gov (United States)

    1978-01-01

    A cost effective design and manufacturing process which would produce solar cell modules capable of meeting qualification test criteria was developed. Emphasis was placed on the development of an aluminum paste back contact process.

  14. Numerical Analysis of Novel Back Surface Field for High Efficiency Ultrathin CdTe Solar Cells

    OpenAIRE

    Matin, M.A.; Tomal, M. U.; A. M. Robin; N. Amin

    2013-01-01

    This paper numerically explores the possibility of high efficiency, ultrathin, and stable CdTe cells with different back surface field (BSF) using well accepted simulator AMPS-1D (analysis of microelectronics and photonic structures). A modified structure of CdTe based PV cell SnO2/Zn2SnO4/CdS/CdTe/BSF/BC has been proposed over reference structure SnO2/Zn2SnO4/CdS/CdTe/Cu. Both higher bandgap materials like ZnTe and Cu2Te and low bandgap materials like As2Te3 and Sb2Te3 have been used as BSF ...

  15. Microstructural characterization and current conduction mechanisms of front-side contact of n-type crystalline Si solar cells with Ag/Al pastes

    Science.gov (United States)

    Liang, L.; Li, Z. G.; Cheng, L. K.; Takeda, N.; Carroll, A. F.

    2015-06-01

    Recently, high efficiency n-type crystalline Si cells made with the screen printed Ag/Al metallization have received considerable attention. We report here our microstructural investigations of the critical interfacial region between the front-side contact and the Si wafer of n-type cells fired under progressively higher temperatures. Our study revealed that the key characteristic microstructures of the interfacial region changed from one with a large fraction of residual SiNx, to one consisting of a thin glass layer with nano-Ag colloids, and finally to one decorated with Ag and Ag/Al crystallites attached to the emitter surface for cells with under-, optimally-, and over-fired conditions, respectively. We did not find any Al-Si eutectic layer on the emitter surface that would support a silicon dissolution and re-growth mechanism, which is operative in the back surface field formation process for the Al back contact of p-type industrial solar cells. The presence of the SiNx antireflection coating has likely altered the chemistry between Si and Al significantly. The observed microstructures lead us to conclude that the main current conduction mechanism in optimally-fired n-type cells is tunneling through those areas of thin interfacial glass containing nano-Ag colloids. This mechanism is similar to the current conduction model we have proposed previously for optimally-fired p-type crystalline Si solar cells. We believe that the intrusion of Ag/Al (and/or Ag) crystallites into the p+-Si emitter in over-fired cells is one of the major sources of metallization-induced recombination losses, which degrades cell performance.

  16. Light trapping efficiency of periodic and quasiperiodic back-reflectors for thin film solar cells: A comparative study

    Science.gov (United States)

    Micco, A.; Ricciardi, A.; Pisco, M.; La Ferrara, V.; Mercaldo, L. V.; Delli Veneri, P.; Cutolo, A.; Cusano, A.

    2013-08-01

    Recently, great efforts have been carried out to design optimized metallic nano-grating back-reflectors to improve the light absorption in thin film solar cells. In this work, we compare the performances of deterministic aperiodic backreflectors in the form of 1-D nanogratings based on the generalized Fibonacci deterministic aperiodic sequence with a standard periodic one. The case of study here analyzed relies on a realistic solar cell model, where light absorption is evaluated only in the intrinsic region of an amorphous silicon P-I-N junction. We found that the results of comparison are strongly influenced by the amorphous silicon extinction coefficient within the near-infrared wavelength range, where most photonic-plasmonic modes (responsible for the light absorption enhancement typically observed when structured metal nanogratings are employed) are excited. In particular, with device-grade hydrogenated amorphous silicon, we demonstrate that Fibonacci-like backreflectors are able to provide an absorption enhancement of about 4% and 20% with respect to periodic and flat metallic backreflectors, respectively. We also found that aperiodic gratings guarantee better results in terms of robustness to the incident angle of the incoming radiation. Overall, our results confirm that aperiodic geometries are effectively able to offer some intriguing perspectives to enhance light trapping capability in thin film solar cells especially thanks to the large set of patterns employable to enable a proper design of resonant modes number and their spectral locations.

  17. Resonant tunneling diodes as energy-selective contacts used in hot-carrier solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Yasuhiko, E-mail: takeda@mosk.tytlabs.co.jp; Sugimoto, Noriaki [Toyota Central Research and Development Laboratories, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 (Japan); Ichiki, Akihisa [Green Mobility Collaborative Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Kusano, Yuya [Green Mobility Collaborative Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Toyota Motor Corp., 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan); Motohiro, Tomoyoshi [Toyota Central Research and Development Laboratories, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 (Japan); Green Mobility Collaborative Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan)

    2015-09-28

    Among the four features unique to hot-carrier solar cells (HC-SCs): (i) carrier thermalization time and (ii) carrier equilibration time in the absorber, (iii) energy-selection width and (iv) conductance of the energy-selective contacts (ESCs), requisites of (i)-(iii) for high conversion efficiency have been clarified. We have tackled the remaining issues related to (iv) in the present study. The detailed balance model of HC-SC operation has been improved to involve a finite value of the ESC conductance to find the required values, which in turn has been revealed to be feasible using resonant tunneling diodes (RTDs) consisting of semiconductor quantum dots (QDs) and quantum wells (QWs) by means of a formulation to calculate the conductance of the QD- and QW-RTDs derived using the rigorous solutions of the effective-mass Hamiltonians. Thus, all of the four requisites unique to HC-SCs to achieve high conversion efficiency have been elucidated, and the two requisites related to the ESCs can be fulfilled using the QD- and QW-RTDs.

  18. CAB-DWTM for 5 μm trace-width deposition of solar cell metallization top-contacts

    Energy Technology Data Exchange (ETDEWEB)

    Justin Hoey; Drew Thompson; Matt Robinson; Zakaria Mahmud; Orven F. Swenson; Iskander S. Akhatov; Douglas L. Schulz

    2009-06-08

    This paper reviews methods for creating solar cell grid contacts and explores how cell efficiency can be increased using CAB-DW{trademark}. Specifically, the efficiency of p-i-n structure solar cells built in-house with 90 {micro}m sputtered lines and 5 {micro}m CAB-DW lines were compared. Preliminary results of the comparison show a marked improvement in solar cell efficiency using CAB-DW. In addition to this, a theoretical and experimental analysis of the dynamics of particle impaction on a substrate (i.e. whether particle stick or bounce) will be discussed including how this analysis may lead to further improvement of CAB-DW.

  19. Influence of the ARC patterning method and annealing on the contact adhesion of Ni/Cu-plated solar cells

    Science.gov (United States)

    Baik, Jong Wook; Lee, Sang Hee; Lee, Doo Won; Lee, Soo Hong

    2016-05-01

    Ni/Cu two-step plating is a promising metallization technique because low contact resistance and improved contact adhesion can be achieved after the Ni annealing process. Also, narrow fingers, which are required for high-efficiency solar cells, can be formed by plating. However, the reliability of contact adhesion is still considered one obstacle to industrializing solar cells with plated metal contacts. In this experiment, the influence of ARC opening methods on plated contact adhesion was investigated because the roughnesses of the Si surfaces produced by using pico-second laser ablation and photolithography may be different. Also, the annealing process was conducted before and after plating Cu/Ag metal stacks. The sequence of the annealing can be significant for efficient production because plating is a wet process while annealing is a dry process. The contact adhesion was measured by using a peel-off test. The test was conducted on a 1.5-mm-wide by a 60 ~ 70- mm-long bus bar area. A 3.2-N/mm adhesion force was recorded as a highest average value along the bus bar.

  20. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  1. Measuring The Contact Resistances Of Photovoltaic Cells

    Science.gov (United States)

    Burger, D. R.

    1985-01-01

    Simple method devised to measure contact resistances of photovoltaic solar cells. Method uses readily available equipment and applicable at any time during life of cell. Enables evaluation of cell contact resistance, contact-end resistance, contact resistivity, sheet resistivity, and sheet resistivity under contact.

  2. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    Energy Technology Data Exchange (ETDEWEB)

    Pathirane, M., E-mail: minoli.pathirane@uwaterloo.ca; Iheanacho, B.; Lee, C.-H.; Wong, W. S. [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Tamang, A.; Knipp, D. [Research Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Bremen 28759 (Germany); Lujan, R. [Electronic Materials and Devices Laboratory, Palo Alto Research Center, Palo Alto, California 93003 (United States)

    2015-10-05

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  3. Enhancement of photovoltaic properties of multicrystalline silicon solar cells by combination of buried metallic contacts and thin porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, M.; Bessais, B. [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

    2010-03-15

    Photovoltaic properties of buried metallic contacts (BMCs) with and without application of a front porous silicon (PS) layer on multicrystalline silicon (mc-Si) solar cells were investigated. A Chemical Vapor Etching (CVE) method was used to perform front PS layer and BMCs of mc-Si solar cells. Good electrical performance for the mc-Si solar cells was observed after combination of BMCs and thin PS films. As a result the current-voltage (I-V) characteristics and the internal quantum efficiency (IQE) were improved, and the effective minority carrier diffusion length (Ln) increases from 75 to 110 {mu}m after BMCs achievement. The reflectivity was reduced to 8% in the 450-950 nm wavelength range. This simple and low cost technology induces a 12% conversion efficiency (surface area = 3.2 cm{sup 2}). The obtained results indicate that the BMCs improve charge carrier collection while the PS layer passivates the front surface. (author)

  4. The investigation of ZnO:Al2O3/metal composite back reflectors in amorphous silicon germanium thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    Wang Guang-Hong; Zhao Lei; Yan Bao-Jun; Chen Jing-Wei; Wang Ge; Diao Hong-Wei; Wang Wen-Jing

    2013-01-01

    Different aluminum-doped ZnO (AZO)/metal composite thin films,including AZO/Ag/Al,AZO/Ag/nickelchromium alloy (NiCr),and AZO/Ag/NiCr/Al,are utilized as the back reflectors of p-i-n amorphous silicon germanium thin film solar cells.NiCr is used as diffusion barrier layer between Ag and Al to prevent mutual diffusion,which increases the short circuit current density of solar cell.NiCr and NiCr/Al layers are used as protective layers of Ag layer against oxidation and sulfurization,the higher efficiency of solar cell is achieved.The experimental results show that the performance of a-SiGe solar cell with AZO/Ag/NiCr/Al back reflector is best.The initial conversion efficiency is achieved to be 8.05%.

  5. Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells.

    Science.gov (United States)

    Nogay, Gizem; Stuckelberger, Josua; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Niquille, Xavier; Debrot, Fabien; Despeisse, Matthieu; Haug, Franz-Josef; Löper, Philipp; Ballif, Christophe

    2016-12-28

    The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiCx(p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiCx(p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiCx(p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm(-2) on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a Voc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p(+)/p-wafer full-side-passivated rear-side scheme shown here.

  6. Fluorinated tin oxide back contact for AZTSSe photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Gershon, Talia S.; Gunawan, Oki; Haight, Richard A.; Lee, Yun Seog

    2017-03-28

    A photovoltaic device includes a substrate, a back contact comprising a stable low-work function material, a photovoltaic absorber material layer comprising Ag.sub.2ZnSn(S,Se).sub.4 (AZTSSe) on a side of the back contact opposite the substrate, wherein the back contact forms an Ohmic contact with the photovoltaic absorber material layer, a buffer layer or Schottky contact layer on a side of the absorber layer opposite the back contact, and a top electrode on a side of the buffer layer opposite the absorber layer.

  7. Design of periodic metal-insulator-metal waveguide back structures for the enhancement of light absorption in thin-film solar cells

    Institute of Scientific and Technical Information of China (English)

    Zheng Gai-Ge; Jiang Jian-Li; Xian Feng-Lin; Qiang Hai-Xia; Wu Hong; Li Xiang-Yin

    2011-01-01

    To increase the absorption in a thin layer of absorbing material (amorphous silicon,arSi),a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic (TM)-polarized light,but also for transverse electric (TE)-polarized light. No plasmonic modes can be excited in TE-polarization,but because of the coupling into the a.Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders,the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices.

  8. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

    Institute of Scientific and Technical Information of China (English)

    YANG Cheng; ZHANG Gang; LEE Dae-Young; LI Hua-Min; LIM Young-Dae; Y00 Won Jong; PARK Young-Jun; KIM Jong-Min

    2011-01-01

    Self-assembly of silicon nanowire(SiNW)arrays is studied using SF6/02 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained. The conducting transparent indium-tin-oxide(ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.

  9. Efficient and stable solution-processed planar perovskite solar cells via contact passivation

    Science.gov (United States)

    Tan, Hairen; Jain, Ankit; Voznyy, Oleksandr; Lan, Xinzheng; García de Arquer, F. Pelayo; Fan, James Z.; Quintero-Bermudez, Rafael; Yuan, Mingjian; Zhang, Bo; Zhao, Yicheng; Fan, Fengjia; Li, Peicheng; Quan, Li Na; Zhao, Yongbiao; Lu, Zheng-Hong; Yang, Zhenyu; Hoogland, Sjoerd; Sargent, Edward H.

    2017-02-01

    Planar perovskite solar cells (PSCs) made entirely via solution processing at low temperatures (areas of 0.049 and 1.1 square centimeters, respectively, achieved via low-temperature solution processing. Solar cells with efficiency greater than 20% retained 90% (97% after dark recovery) of their initial performance after 500 hours of continuous room-temperature operation at their maximum power point under 1-sun illumination (where 1 sun is defined as the standard illumination at AM1.5, or 1 kilowatt/square meter).

  10. Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Siol, Sebastian; Dhakal, Tara P.; Gudavalli, Ganesh S.; Rajbhandari, Pravakar P.; DeHart, Clay; Baranowski, Lauryn L.; Zakutayev, Andriy

    2016-06-08

    High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in ..beta..-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization techniques. It is demonstrated that, by tuning the sulfur partial pressure, phase pure ..beta..-In2S3 could be deposited using a broad range of substrate temperatures between 500 degrees C and ambient temperature. Combinatorial photovoltaic device libraries with Al/ZnO/In2S3/Cu2ZnSnS4/Mo/SiO2 structure were built at optimal processing conditions to investigate the feasibility of the sputtered In2S3 buffer layers and of an accelerated optimization of the device structure. The performance of the resulting In2S3/Cu2ZnSnS4 photovoltaic devices is on par with CdS/Cu2ZnSnS4 reference solar cells with similar values for short circuit currents and open circuit voltages, despite the overall quite low efficiency of the devices (-2%). Overall, these results demonstrate how a high-throughput experimental approach can be used to accelerate the development of contact materials and facilitate the optimization of thin film solar cell devices.

  11. Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells.

    Science.gov (United States)

    Siol, Sebastian; Dhakal, Tara P; Gudavalli, Ganesh S; Rajbhandari, Pravakar P; DeHart, Clay; Baranowski, Lauryn L; Zakutayev, Andriy

    2016-06-08

    High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in β-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization techniques. It is demonstrated that, by tuning the sulfur partial pressure, phase pure β-In2S3 could be deposited using a broad range of substrate temperatures between 500 °C and ambient temperature. Combinatorial photovoltaic device libraries with Al/ZnO/In2S3/Cu2ZnSnS4/Mo/SiO2 structure were built at optimal processing conditions to investigate the feasibility of the sputtered In2S3 buffer layers and of an accelerated optimization of the device structure. The performance of the resulting In2S3/Cu2ZnSnS4 photovoltaic devices is on par with CdS/Cu2ZnSnS4 reference solar cells with similar values for short circuit currents and open circuit voltages, despite the overall quite low efficiency of the devices (∼2%). Overall, these results demonstrate how a high-throughput experimental approach can be used to accelerate the development of contact materials and facilitate the optimization of thin film solar cell devices.

  12. Toward High-Performance Organic-Inorganic Hybrid Solar Cells: Bringing Conjugated Polymers and Inorganic Nanocrystals in Close Contact.

    Science.gov (United States)

    He, Ming; Qiu, Feng; Lin, Zhiqun

    2013-06-06

    Organic-inorganic hybrid solar cells composed of conjugated polymers (CPs) and inorganic nanocrystal (NC) semiconductors have garnered considerable attention as a potential alternative to traditional silicon solar cells due to the capacity of producing high-efficiency solar energy in a cost-effective manner. The combination of advantageous characteristics of CPs and NCs enables the construction of nanostructured high-performance, lightweight, flexible, large-area, and low-cost hybrid solar cells. However, it remains a grand challenge to control the film morphology and interfacial structure of such organic/inorganic semiconductor blends on the nanoscale. In this Perspective, we highlight the strategies of implementing close contact between CPs and NCs by tailoring the colloidal synthesis, the coordination reaction, and the chemical modification of CPs. As such, they offer promising opportunities for rationally controlling the phase separation between electron-donating CPs and electron-accepting NCs, increasing the interfacial areas between them, enhancing their electronic interaction, and thus substantially promoting the photovoltaic performance of the resulting organic-inorganic hybrid solar cells.

  13. Decrease of back recombination rate in CdS quantum dots sensitized solar cells using reduced graphene oxide

    Institute of Scientific and Technical Information of China (English)

    Ali Badawi

    2015-01-01

    The photovoltaic performance of CdS quantum dots sensitized solar cells (QDSSCs) using the 0.2 wt%of reduced graphene oxide and TiO2 nanoparticles (RGO+TiO2 nanocomposite) photoanode is investigated. CdS QDs are adsorbed onto RGO+TiO2 nanocomposite films by the successive ionic layer adsorption and reaction (SILAR) technique for several cycles. The current density–voltage (J–V ) characteristic curves of the assembled QDSSCs are measured at AM1.5 sim-ulated sunlight. The optimal photovoltaic performance for CdS QDSSC was achieved for six SILAR cycles. Solar cells based on the RGO+TiO2 nanocomposite photoanode achieve a 33%increase in conversion efficiency (η) compared with those based on plain TiO2 nanoparticle (NP) photoanodes. The electron back recombination rates decrease significantly for CdS QDSSCs based on RGO+TiO2 nanocomposite photoanodes. The lifetime constant (τ) for CdS QDSSC based on the RGO+TiO2 nanocomposite photoanode is at least one order of magnitude larger than that based on the bare TiO2NPs photoanode.

  14. Decrease of back recombination rate in CdS quantum dots sensitized solar cells using reduced graphene oxide

    Science.gov (United States)

    Badawi, Ali

    2015-04-01

    The photovoltaic performance of CdS quantum dots sensitized solar cells (QDSSCs) using the 0.2 wt% of reduced graphene oxide and TiO2 nanoparticles (RGO+TiO2 nanocomposite) photoanode is investigated. CdS QDs are adsorbed onto RGO+TiO2 nanocomposite films by the successive ionic layer adsorption and reaction (SILAR) technique for several cycles. The current density-voltage (J-V) characteristic curves of the assembled QDSSCs are measured at AM1.5 simulated sunlight. The optimal photovoltaic performance for CdS QDSSC was achieved for six SILAR cycles. Solar cells based on the RGO+TiO2 nanocomposite photoanode achieve a 33% increase in conversion efficiency (η) compared with those based on plain TiO2 nanoparticle (NP) photoanodes. The electron back recombination rates decrease significantly for CdS QDSSCs based on RGO+TiO2 nanocomposite photoanodes. The lifetime constant (τ) for CdS QDSSC based on the RGO+TiO2 nanocomposite photoanode is at least one order of magnitude larger than that based on the bare TiO2 NPs photoanode. Project supported by the Fund from Taif University, Saudi Arabia (Grant No. 1/435/3524).

  15. Efficiency loss prevention in monolithically integrated thin film solar cells by improved front contact

    NARCIS (Netherlands)

    Deelen, J. van; Barink, M.; Klerk, L.; Voorthuijzen, P.; Hovestad, A.

    2015-01-01

    Modeling indicates a potential efficiency boost of 17% if thin-film solar panels are featured with a metallic grid. Variations of transparent conductive oxide sheet resistance, cell length, and grid dimensions are discussed. These parameters were optimized simultaneously to obtain the best result. M

  16. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NARCIS (Netherlands)

    Lipovšek, B.; Krč, J.; Isabella, O.; Zeman, M.; Topič, M.

    2010-01-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-fi

  17. Efficiency Enhancement in Plasmonic IBC Solar Cells

    OpenAIRE

    Christian Chaverri-Ramos; J. Ayúcar; L. Bellières; Guillermo Sánchez Plaza; James Connolly

    2012-01-01

    Silicon solar cells dominate photovoltaics but suffer from poor interaction with light. This work reports on progress regarding both spectral conversion and improved light interaction with the LIMA design [1]. This combines an efficient interdigitated back-contact (IBC) solar cell [2] with a silicon quantum dot (Si-QD) [3] to optimize the spectral distribution of the incident spectrum, and finally a front-side plasmon layer to optimize light interaction. Reflectivity after thickness and proce...

  18. Applications of ``PV Optics`` for solar cell and module design

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B.L.; Madjdpour, J.; Chen, W. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper describes some applications of a new optics software package, PV Optics, developed for the optical design of solar cells and modules. PV Optics is suitable for the analysis and design of both thick and thin solar cells. It also includes a feature for calculation of metallic losses related to contacts and back reflectors.

  19. Selective emitters in buried contact silicon solar cells. Some low-cost solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pirozzi, L.; Arabito, G.; Artuso, F.; Barbarossa, V.; Besi-Vetrella, U.; Loreti, S.; Mangiapane, P.; Salza, E. [ENEA Casaccia, Via Anguillarese 301, 00060 Roma (Italy)

    2001-01-01

    We present the results of our study on the formation of selective emitter structures in buried contact cells. In particular, our attention has been focused on those processes that seem to be scalable to industry. To this aim, specific dopant sources and fabrication steps have been selected.Two different kinds of dopants have been considered: the P-doped SOD and the screen-printed dopant paste. For both sources we have tested the feasibility of the selective diffusion formation in a single step, together with the application of suitable techniques to get selective doping, such as laser enhanced diffusion into the grooves, or selective deposition of screen printed paste in buried grid pattern. SEM and SEM-EBIC analyses have been used to investigate the occurrence of doping. Several batches of buried contact, mechanically grooved cells have prepared and tested.

  20. High Efficiency Inverted Planar Perovskite Solar Cells with Solution-Processed NiOx Hole Contact.

    Science.gov (United States)

    Yin, Xuewen; Yao, Zhibo; Luo, Qiang; Dai, Xuezeng; Zhou, Yu; Zhang, Ye; Zhou, Yangying; Luo, Songping; Li, Jianbao; Wang, Ning; Lin, Hong

    2017-01-25

    NiOx is a promising hole-transporting material for perovskite solar cells due to its high hole mobility, good stability, and easy processability. In this work, we employed a simple solution-processed NiOx film as the hole-transporting layer in perovskite solar cells. When the thickness of the perovskite layer increased from 270 to 380 nm, the light absorption and photogenerated carrier density were enhanced and the transporting distance of electron and hole would also increase at the same time, resulting in a large charge transfer resistance and a long hole-extracted process in the device, characterized by the UV-vis, photoluminescence, and electrochemical impedance spectroscopy spectra. Combining both of these factors, an optimal thickness of 334.2 nm was prepared with the perovskite precursor concentration of 1.35 M. Moreover, the optimal device fabrication conditions were further achieved by optimizing the thickness of NiOx hole-transporting layer and PCBM electron selective layer. As a result, the best power conversion efficiency of 15.71% was obtained with a Jsc of 20.51 mA·cm(-2), a Voc of 988 mV, and a FF of 77.51% with almost no hysteresis. A stable efficiency of 15.10% was caught at the maximum power point. This work provides a promising route to achieve higher efficiency perovskite solar cells based on NiO or other inorganic hole-transporting materials.

  1. All-back-Schottky-contact thin-film photovoltaics

    Science.gov (United States)

    Nardone, Marco

    2016-02-01

    The concept of All-Back-Schottky-Contact (ABSC) thin-film photovoltaic (TFPV) devices is introduced and evaluated using 2D numerical simulation. Reach-through Schottky junctions due to two metals of different work functions in an alternating, side-by-side pattern along the non-illuminated side generate the requisite built-in field. It is shown that our simulation method quantitatively describes existing data for a recently demonstrated heterojunction thin-film cell with interdigitated back contacts (IBCs) of one metal type. That model is extended to investigate the performance of ABSC devices with bimetallic IBCs within a pertinent parameter space. Our calculations indicate that 20% efficiency is achievable with micron-scale features and sufficient surface passivation. Bimetallic, micron-scale IBCs are readily fabricated using photo-lithographic techniques and the ABSC design allows for optically transparent surface passivation layers that need not be electrically conductive. The key advantages of the ABSC-TFPV architecture are that window layers, buffer layers, heterojunctions, and module scribing are not required because both contacts are located on the back of the device.

  2. Development of low cost contacts to silicon solar cells. Final report, 15 October 1978-30 April 1980

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, D.P.; Iles, P.A.

    1980-01-01

    A summary of work done on the development of a copper based contact system for silicon solar cells is presented. The work has proceeded in three phases: (1) Development of a copper based contact system using plated Pd-Cr-Cu. Good cells were made but cells degraded under low temperature (300/sup 0/C) heat treatments. (2) The degradation in Phase I was identified as copper migration into the cells junction region. A paper study was conducted to find a proper barrier to the copper migration problem. Nickel was identified as the best candidate barrier and this was verified in a heat treatment study using evaporated metal layers. (3) An electroless nickel solution was substituted for the electroless chrominum solution in the original process. Efforts were made to replace the palladium bath with an appropriate nickel layer, but these were unsuccessful. 150 cells using the Pd-Ni-Cu contact system were delivered to JPL. Also a cost study was made on the plating process to assess the chance of reaching 5 cents/watt.

  3. Optimization of solar cell contacts by system cost-per-watt minimization

    Science.gov (United States)

    Redfield, D.

    1977-01-01

    New, and considerably altered, optimum dimensions for solar-cell metallization patterns are found using the recently developed procedure whose optimization criterion is the minimum cost-per-watt effect on the entire photovoltaic system. It is also found that the optimum shadow fraction by the fine grid is independent of metal cost and resistivity as well as cell size. The optimum thickness of the fine grid metal depends on all these factors, and in familiar cases it should be appreciably greater than that found by less complete analyses. The optimum bus bar thickness is much greater than those generally used. The cost-per-watt penalty due to the need for increased amounts of metal per unit area on larger cells is determined quantitatively and thereby provides a criterion for the minimum benefits that must be obtained in other process steps to make larger cells cost effective.

  4. Characterization of laser doped silicon and overcoming adhesion challenges of solar cells with nickel-copper plated contacts

    Energy Technology Data Exchange (ETDEWEB)

    Geisler, Christian

    2015-07-01

    The combination of localized laser patterning and metal plating allows to replace conventional silver screen printing with nickel-copper plating to form inexpensive front contacts for crystalline silicon solar cells. In this work, a focus is put on effects that could cause inhomogeneous metal deposition and low metal contact adhesion. A descriptive model of the silicon nitride ablation mechanism is derived from SEM imaging and a precise recombination analysis using QSSPC measurements. Surface sensitive XPS measurements are conducted to prove the existence of a parasitic surface layer, identified as SiO{sub x}N{sub y}. The dense SiO{sub x}N{sub y} layer is an effective diffusion barrier, hindering the formation of a nickel silicide interlayer. After removal of the SiO{sub x}N{sub y} layer, cells show severe degradation caused by metal-induced shunting. These shunts are imaged using reverse biased electroluminescence imaging. A shunting mechanism is proposed and experimentally verified. New laser process sequences are devised and proven to produce cells with adhering Ni-Cu contacts. Conclusively the developed processes are assessed based on their industrial feasibility as well as on their efficiency potential.

  5. Signature of a back contact barrier in DLTS spectra

    Science.gov (United States)

    Lauwaert, J.; Khelifi, S.; Decock, K.; Burgelman, M.; Vrielinck, H.

    2011-03-01

    The DLTS signal induced by a back contact barrier is studied both theoretically and through experiments on model circuits. A nonideal back contact is modeled either by a resistor and a capacitor, or by a germanium diode inversely polarized with respect to the junction diode. Depending on the back contact properties, this may result in a positive or negative capacitance transient. For these model circuits the capacitance transient time constants and amplitudes are studied as a function of voltage pulse height and compared with signals originating from emission and slow capture from a defect level. These two origins of DLTS signals present very different properties, which opens possibilities to distinguish between them.

  6. Electrochemical etching of molybdenum for shunt removal in thin film solar cells

    NARCIS (Netherlands)

    Hovestad, A.; Bressers, P.M.M.C.; Meertens, R.M.; Frijters, C.H.; Voorthuijzen, W.P.

    2015-01-01

    High yield and reproducible production is a major challenge in up-scaling thin film Cu(In,Ga)Se2(CIGS) solar cells to large area roll-to-roll industrial manufacturing. Pinholes enabling Ohmic contact between the ZnO:Al front-contact and Mo back contact of the CIGS cell create electrical shunts that

  7. Study of electrical transport properties of ZnO thin films used as front contact of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, C.; Gordillo, G.; Olarte, J. [Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)

    2005-07-01

    This work is focused on the study of possible mechanisms affecting the electrical transport properties of ZnO thin films. The films were deposited using the reactive evaporation technique, obtaining transmittances greater than 80% and resistivities of the order of 8 x 10{sup -4} {omega}cm without using extrinsic doping. This films are suitable for transparent front contact of solar cells. Measurements of resistivity and Hall coefficient, as a function of temperature, were performed on the films. The interpretation of these results was done with the help of a theoretical calculation of the carrier mobility as a function of the temperature. Several scattering mechanisms affecting the electrical transport in the temperature range studied (90 K-680 K) were found. The most important are processes occurring in the grain boundaries and interactions of free carriers with ionized impurities. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. High resolution, low cost solar cell contact development. Quarterly technical progress and schedule report, September 28, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Mardesich, N.

    1980-01-01

    The scope of the contract covers the development and evaluation of forming solar cell collector grid contacts by the MIDFILM process. This is a proprietary process developed by the Ferro Corporation which is a subcontractor for the program. The MIDFILM process attains line resolution characteristics of photoresist methods with processing related to screen printing. The surface to be processed is first coated with a thin layer of photoresist material. Upon exposure to ultraviolet light through a suitable mask, the resist in the non-pattern area cross-links and becomes hard. The unexposed pattern areas remain tacky. The conductor material is applied in the form of a dry mixture of metal and frit particles which adhere to the tacky pattern area. The assemblage is then fired to ash the photopolymer and sinter the fritted conductor powder. Effort was concentrated during this period on the establishment, optimization and identification of problem areas of the MIDFILM process. Progress is reported. (WHK)

  9. Silicon quantum dots in SiO{sub x} dielectrics as energy selective contacts in hot carrier solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kar, Debjit; Das, Debajyoti, E-mail: erdd@iacs.res.in [Nano-Science Group, Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata – 700032 (India)

    2015-06-24

    Thin films of c-Si QDs embedded in a-SiO{sub x} dielectric matrix was achieved at a low temperature ∼400°C, from one step process by reactive rf magnetron co-sputtering of c-Si wafer and pure SiO{sub 2} targets, in the (H{sub 2}+Ar)- plasma. Formation of a double-barrier structure has been primarily identified from the SAX data and exclusively confirmed from the resonant tunneling current appearing in the J-E characteristic curve peaks, determined by the discrete energy levels of c-Si QDs, at which it could be used as energy selective contacts in hot carrier solar cells.

  10. Photovoltaic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2013-11-26

    A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electicity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

  11. Photovoltaic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N; Cruz-Campa, Jose Luis; Okandan, Murat; Resnick, Paul J

    2014-05-20

    A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electricity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

  12. Flexible high power-per-weight perovskite solar cells with chromium oxide-metal contacts for improved stability in air

    Science.gov (United States)

    Kaltenbrunner, Martin; Adam, Getachew; Głowacki, Eric Daniel; Drack, Michael; Schwödiauer, Reinhard; Leonat, Lucia; Apaydin, Dogukan Hazar; Groiss, Heiko; Scharber, Markus Clark; White, Matthew Schuette; Sariciftci, Niyazi Serdar; Bauer, Siegfried

    2015-10-01

    Photovoltaic technology requires light-absorbing materials that are highly efficient, lightweight, low cost and stable during operation. Organolead halide perovskites constitute a highly promising class of materials, but suffer limited stability under ambient conditions without heavy and costly encapsulation. Here, we report ultrathin (3 μm), highly flexible perovskite solar cells with stabilized 12% efficiency and a power-per-weight as high as 23 W g-1. To facilitate air-stable operation, we introduce a chromium oxide-chromium interlayer that effectively protects the metal top contacts from reactions with the perovskite. The use of a transparent polymer electrode treated with dimethylsulphoxide as the bottom layer allows the deposition--from solution at low temperature--of pinhole-free perovskite films at high yield on arbitrary substrates, including thin plastic foils. These ultra-lightweight solar cells are successfully used to power aviation models. Potential future applications include unmanned aerial vehicles--from airplanes to quadcopters and weather balloons--for environmental and industrial monitoring, rescue and emergency response, and tactical security applications.

  13. Influence of wavelength on laser doping and laser-fired contact processes for c-Si solar cells

    Science.gov (United States)

    Molpeceres, Carlos; Sánchez-Aniorte, María. Isabel; Morales, Miguel; Muñoz, David; Martín, Isidro; Ortega, Pablo; Colina, Mónica; Voz, Cristóbal; Alcubilla, Ramón

    2012-10-01

    This work investigates the influence of the laser wavelength on laser doping (LD) and laser-fired contact (LFC) formation in solar cell structures. We compare the results obtained using the three first harmonics (corresponding to wavelengths of 1064 nm, 532 nm and 355 nm) of fully commercial solid state laser sources with pulse width in the ns range. The discussion is based on the impact on the morphology and electrical characteristics of test structures. In the case of LFC the study includes the influence of different passivation layers and the assessment of the process quality through electrical resistance measurements of an aluminium single LFC point for the different wavelengths. Values for the normalized LFC resistance far below 1.0 mΩcm2 have been obtained, with better results at shorter wavelengths. To assess the influence of the laser wavelength on LD we have created n+ regions into p-type c-Si wafers, using a dry LD approach to define punctual emitters. J-V characteristics show exponential trends at mid-injection for a broad parametric window in all wavelengths, with local ideality factors well below 1.5. In both processes the best results have been obtained using green (532 nm) and, specially, UV (355 nm). This indicates that to minimize the thermal damage in the material is a clear requisite to obtain the best electrical performance, thus indicating that UV laser shows better potential to be used in high efficiency solar cells.

  14. The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study.

    Science.gov (United States)

    Idígoras, J; Todinova, A; Sánchez-Valencia, J R; Barranco, A; Borrás, A; Anta, J A

    2016-05-11

    The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies. For all of them, we have investigated the influence of these substrate properties on perovskite formation and its degradation by humidity. The effect of selective-hole contact (Spiro-OmeTad and P3HT) layers on the degradation rate by moisture has also been studied. Our IR results reveal the existence of a strong interaction between perovskite and all ZnO materials considered, evidenced by a shift of the peaks related to the N-H vibrational modes. The interaction even induces a morphological change in ZnO nanoparticles after perovskite deposition, pointing to an acid-base reaction that takes place through the NH3(+) groups of the methylammonium cation. Our IR and X-ray diffraction results also indicate that this specific interaction favors perovskite decomposition and PbI2 formation for ZnO/perovskite films subjected to humid conditions. Although no interaction is observed for TiO2, Al2O3, and the hole selective contact, the morphology and chemical nature of both contacts appear to play an important role in the rate of degradation upon exposure to moisture.

  15. Absorption enhancement in CH3NH3PbI3 solar cell using a TiO2/MoS2 nanocomposite electron selective contact

    Science.gov (United States)

    Imran Ahmed, Muhammad; Hussain, Zakir; Khalid, Amir; Noman Amin, Hafiz Muhammad; Habib, Amir

    2016-04-01

    In the present contribution, perovskite absorbers have been combined with few layer thick MoS2 semiconductor to put together a solar cell allowing broad spectrum harvesting of solar radiations. Such modification allows to achieve solar light harvesting at the band edges, addressing a drawback of CH3NH3PbI3 absorbers. We recorded an improved efficiency from 3.7% to 4.3% on the back of this methodology. We have also worked out a novel methodology to synthesize TiO2/MoS2 nanocomposite by in situ dispersion of liquid exfoliated MoS2 sheets in the sol gel reaction.

  16. Planar multijunction high voltage solar cells

    Science.gov (United States)

    Evans, J. C., Jr.; Chai, A. T.; Goradia, C.

    1980-01-01

    Technical considerations, preliminary results, and fabrication details are discussed for a family of high-voltage planar multi-junction (PMJ) solar cells which combine the attractive features of planar cells with conventional or interdigitated back contacts and the vertical multijunction (VMJ) solar cell. The PMJ solar cell is internally divided into many voltage-generating regions, called unit cells, which are internally connected in series. The key to obtaining reasonable performance from this device was the separation of top surface field regions over each active unit cell. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per linear centimeter are possible. Analysis of the new device is complex, and numerous geometries are being studied which should provide substantial benefits in both normal sunlight usage as well as with concentrators.

  17. Study on the fabrication of back surface reflectors in nano-crystalline silicon thin-film solar cells by using random texturing aluminum anodization

    Science.gov (United States)

    Shin, Kang Sik; Jang, Eunseok; Cho, Jun-Sik; Yoo, Jinsu; Park, Joo Hyung; Byungsung, O.

    2015-09-01

    In recent decades, researchers have improved the efficiency of amorphous silicon solar cells in many ways. One of the easiest and most practical methods to improve solar-cell efficiency is adopting a back surface reflector (BSR) as the bottom layer or as the substrate. The BSR reflects the incident light back to the absorber layer in a solar cell, thus elongating the light path and causing the so-called "light trapping effect". The elongation of the light path in certain wavelength ranges can be enhanced with the proper scale of BSR surface structure or morphology. An aluminum substrate with a surface modified by aluminum anodizing is used to improve the optical properties for applications in amorphous silicon solar cells as a BSR in this research due to the high reflectivity and the low material cost. The solar cells with a BSR were formed and analyzed by using the following procedures: First, the surface of the aluminum substrate was degreased by using acetone, ethanol and distilled water, and it was chemically polished in a dilute alkali solution. After the cleaning process, the aluminum surface's morphology was modified by using a controlled anodization in a dilute acid solution to form oxide on the surface. The oxidized film was etched off by using an alkali solution to leave an aluminum surface with randomly-ordered dimple-patterns of approximately one micrometer in size. The anodizing conditions and the anodized aluminum surfaces after the oxide layer had been removed were systematically investigated according to the applied voltage. Finally, amorphous silicon solar cells were deposited on a modified aluminum plate by using dc magnetron sputtering. The surfaces of the anodized aluminum were observed by using field-emission scanning electron microscopy. The total and the diffuse reflectances of the surface-modified aluminum sheets were measured by using UV spectroscopy. We observed that the diffuse reflectances increased with increasing anodizing voltage. The

  18. Mo/Cu(In, Ga)Se{sub 2} back interface chemical and optical properties for ultrathin CIGSe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Erfurth, F.; Jehl, Z. [Institut de Recherche et Developpement sur l' Energie Photovoltaieque IRDEP (EDF/CNRS/Chimie-ParisTech UMR 7174), 6 quai Watier, 78401 Chatou (France); Bouttemy, M. [ILV - UMR 8180, Universite de Versailles St Quentin, 45 Av. des Etats Unis, 78035 Versailles (France); Dahan, N. [Institut d' Optique, CNRS, Campus Polytechnique, RD 128, 91127 Palaiseau Cedex (France); Tran-Van, P.; Gerard, I.; Etcheberry, A. [ILV - UMR 8180, Universite de Versailles St Quentin, 45 Av. des Etats Unis, 78035 Versailles (France); Greffet, J.-J. [Institut d' Optique, CNRS, Campus Polytechnique, RD 128, 91127 Palaiseau Cedex (France); Powalla, M. [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung (ZSW), Industriestr. 6, 70565 Stuttgart (Germany); Voorwinden, G. [Wuerth Elektronik Research GmbH, Industriestr. 4, 70565 Stuttgart (Germany); Lincot, D.; Guillemoles, J.F. [Institut de Recherche et Developpement sur l' Energie Photovoltaieque IRDEP (EDF/CNRS/Chimie-ParisTech UMR 7174), 6 quai Watier, 78401 Chatou (France); Naghavi, N., E-mail: negar.naghavi@edf.fr [Institut de Recherche et Developpement sur l' Energie Photovoltaieque IRDEP (EDF/CNRS/Chimie-ParisTech UMR 7174), 6 quai Watier, 78401 Chatou (France)

    2012-01-15

    Chemical and optical properties of the interface between a coevaporated Cu(In,Ga)Se{sub 2} (CIGSe) absorber thin film and the Mo back contact are investigated with the objective to reduce markedly the thickness of CIGSe layers from two microns down to about 100 nm. First a mechanical lift off technique allowed to separate Mo and CIGSe layers and perform X-ray photoelectron spectroscopy (XPS) and elipsometry studies on as prepared surfaces. On the Mo side small amounts of In and Ga are observed together with the formation of an MoSe{sub 2} layer. There is no evidence of the presence of Cu. On the opposite CIGSe side a clear depletion of Cu together with an enrichment of Ga is evidenced. There is no evidence of Mo. Optical reflectivity of the interface CIGSe/Mo is studied by ellipsometry showing a low reflectivity of the interface attributed to the formation of MoSe{sub 2} layer. The enhance light absorption in ultrathin absorbers using alternative, highly reflective back contacts are finally discussed.

  19. Mo/Cu(In, Ga)Se 2 back interface chemical and optical properties for ultrathin CIGSe solar cells

    Science.gov (United States)

    Erfurth, F.; Jehl, Z.; Bouttemy, M.; Dahan, N.; Tran-Van, P.; Gerard, I.; Etcheberry, A.; Greffet, J.-J.; Powalla, M.; Voorwinden, G.; Lincot, D.; Guillemoles, J. F.; Naghavi, N.

    2012-01-01

    Chemical and optical properties of the interface between a coevaporated Cu(In,Ga)Se2 (CIGSe) absorber thin film and the Mo back contact are investigated with the objective to reduce markedly the thickness of CIGSe layers from two microns down to about 100 nm. First a mechanical lift off technique allowed to separate Mo and CIGSe layers and perform X-ray photoelectron spectroscopy (XPS) and elipsometry studies on as prepared surfaces. On the Mo side small amounts of In and Ga are observed together with the formation of an MoSe2 layer. There is no evidence of the presence of Cu. On the opposite CIGSe side a clear depletion of Cu together with an enrichment of Ga is evidenced. There is no evidence of Mo. Optical reflectivity of the interface CIGSe/Mo is studied by ellipsometry showing a low reflectivity of the interface attributed to the formation of MoSe2 layer. The enhance light absorption in ultrathin absorbers using alternative, highly reflective back contacts are finally discussed.

  20. An efficient light trapping scheme based on textured conductive photonic crystal back reflector for performance improvement of amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Peizhuan; Hou, Guofu, E-mail: gfhou@nankai.edu.cn; Huang, Qian; Zhao, Jing; Zhang, Jianjun, E-mail: jjzhang@nankai.edu.cn; Ni, Jian; Zhang, Xiaodan; Zhao, Ying [Tianjin Key Laboratory of Photoelectronic Thin-Film Devices and Technique, Institute of Photoelectronics, Nankai University, Tianjin 300071 (China); Fan, QiHua [Department of Electrical Engineering and Computer Science, South Dakota State University, Brookings, South Dakota 57007 (United States)

    2014-08-18

    An efficient light trapping scheme named as textured conductive photonic crystal (TCPC) has been proposed and then applied as a back-reflector (BR) in n-i-p hydrogenated amorphous silicon (a-Si:H) solar cell. This TCPC BR combined a flat one-dimensional photonic crystal and a randomly textured surface of chemically etched ZnO:Al. Total efficiency enhancement was obtained thanks to the sufficient conductivity, high reflectivity and strong light scattering of the TCPC BR. Unwanted intrinsic losses of surface plasmon modes are avoided. An initial efficiency of 9.66% for a-Si:H solar cell was obtained with short-circuit current density of 14.74 mA/cm{sup 2}, fill factor of 70.3%, and open-circuit voltage of 0.932 V.

  1. Mismatched front and back gratings for optimum light trapping in ultra-thin crystalline silicon solar cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Branham, Matthew S.; Huang, Yi; Yerci, Selçuk; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    The implementation of a front and back grating in ultra-thin photovoltaic cells is a promising approach towards improving light trapping. A simple design rule was developed using the least common multiple (LCM) of the front and back grating periods. From this design rule, several optimal period combinations can be found, providing greater design flexibility for absorbers of indirect band gap materials. Using numerical simulations, the photo-generated current (Jph) for a 10-μm-thick crystalline silicon absorber was predicted to be as high as 38 mA/cm2, which is 11.74% higher than that of a single front grating (Jph=34 mA/cm2).

  2. Interdigitated Back Contact Silicon Solar Cell Analysis and Design Recommendations for Space Use

    Science.gov (United States)

    1989-09-30

    Paul M. Propp was the project officer for the Mission-Oriented Investigation and Experimentation (MOE) Program. This report has been reviewed by the...Air Force approval of the report’s findings or conclusions. It is published only for the exchange and stimulation of ideas. PAU M. PROPP , GM-14

  3. Comparison of Fast Roll-to-Roll Flexographic, Inkjet, Flatbed, and Rotary Screen Printing of Metal Back Electrodes for Polymer Solar Cells

    DEFF Research Database (Denmark)

    Hösel, Markus; Søndergaard, Roar R.; Angmo, Dechan

    2013-01-01

    be avoided and electrodes should be printable using methods that provide a high degree of accuracy and high technical yield. When considering large area polymer solar cells (i.e., not laboratory devices) a few reports have employed printable back electrodes mostly by use of silver formulations[1–4] but also...... carbon[5] and copper has been discussed whereas copper is unlikely to yield the necessary cost reduction and resistance to oxidation. Most reports have employed flatbed or rotary screen printing whereas other methods are available and described later on. The important question to answer is which...... printing techniques have proven excellent while they do present disadvantages in speed due to significant drying requirements but also they do require significant amounts of material.[2,6] In this paper we employ four different roll-to-roll (R2R) printing methods for printing silver back electrodes...

  4. Thin film CdTe solar cells by close spaced sublimation: Recent results from pilot line

    Energy Technology Data Exchange (ETDEWEB)

    Siepchen, B., E-mail: bastian.siepchen@ctf-solar.com [CTF Solar GmbH, Industriestraße 2, 65779 Kelkheim (Germany); Drost, C.; Späth, B.; Krishnakumar, V.; Richter, H.; Harr, M. [CTF Solar GmbH, Industriestraße 2, 65779 Kelkheim (Germany); Bossert, S.; Grimm, M. [Roth and Rau AG, An der Baumschule 6-8, 09337 Hohenstein-Ernstthal (Germany); Häfner, K.; Modes, T.; Zywitzki, O.; Morgner, H. [Fraunhofer Institute for Electron Beam and Plasma Technology FEP, Winterbergstrasse 28, 01277 Dresden (Germany)

    2013-05-01

    CdTe is an attractive material to produce high efficient and low cost thin film solar cells. The semiconducting layers of this kind of solar cell can be deposited by the Close Spaced Sublimation (CSS) process. The advantages of this technique are high deposition rates and an excellent utilization of the raw material, leading to low production costs and competitive module prices. CTF Solar GmbH is offering equipment and process knowhow for the production of CdTe solar modules. For further improvement of the technology, research is done at a pilot line, which covers all relevant process steps for manufacture of CdTe solar cells. Herein, we present the latest results from the process development and our research activities on single functional layers as well as for complete solar cell devices. Efficiencies above 13% have already been obtained with Cu-free back contacts. An additional focus is set on different transparent conducting oxide materials for the front contact and a Sb{sub 2}Te{sub 3} based back contact. - Highlights: ► Laboratory established on industrial level for CdTe solar cell research ► 13.0% cell efficiency with our standard front contact and Cu-free back contact ► Research on ZnO-based transparent conducting oxide and Sb{sub 2}Te{sub 3} back contacts ► High resolution scanning electron microscopy analysis of ion polished cross section.

  5. Direct electrical contact of slanted ITO film on axial p-n junction silicon nanowire solar cells.

    Science.gov (United States)

    Lee, Ya-Ju; Yao, Yung-Chi; Yang, Chia-Hao

    2013-01-14

    A novel scheme of direct electrical contact on vertically aligned silicon nanowire (SiNW) axial p-n junction is demonstrated by means of oblique-angle deposition of slanted indium-tin-oxide (ITO) film for photovoltaic applications. The slanted ITO film exhibits an acceptable resistivity of 1.07 x 10⁻³Ω-cm underwent RTA treatment of T = 450°C, and the doping concentration and carrier mobility by Hall measurement amount to 3.7 x 10²⁰ cm⁻³ and 15.8 cm²/V-s, respectively, with an n-type doping polarity. Because of the shadowing effect provided by the SiNWs, the incident ITO vapor-flow is deposited preferentially on the top of SiNWs, which coalesces and eventually forms a nearly continuous film for the subsequent fabrication of grid electrode. Under AM 1.5 G normal illumination, our axial p-n junction SiNW solar cell exhibits an open circuit voltage of VOC = 0.56 V, and a short circuit current of JSC = 1.54 mA/cm² with a fill factor of FF = 30%, resulting in a total power conversion efficiency of PEC = 0.26%.

  6. Impact of atmospheric species on copper indium gallium selenide solar cell stability: An overview

    NARCIS (Netherlands)

    Theelen, M.

    2016-01-01

    An overview of the measurement techniques and results of studies on the stability of copper indium gallium selenide (CIGS) solar cells and their individual layers in the presence of atmospheric species is presented: in these studies, Cu(In,Ga)Se2 solar cells, their molybdenum back contact, and their

  7. Crystalline Fraction and Doping Concentration Effect on Heterojunction Solar Cells n-Doped µc-Si:H Back Surface Field Layer.

    Science.gov (United States)

    Kim, Sangho; Shin, Chonghoon; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    The back surface field (BSF) plays a vital role for high efficiency in the Heterojunction Intrinsic Thin (HIT) film solar cell. This paper investigated the effect of crystalline volume fraction (Xc) and 1% hydrogen diluted phosphine (PH3) gas doping concentration of the n-type µc-Si:H back surface file (BSF) layer. Initially, the thickness of the n-type µc-Si:H BSF layer was optimized. With increase in Xc from 6% to 59%, the open circuit voltage (Voc) increased from 573 mV to 696 mV, and the fill factor (FF) also increased from 59% to 71%. In the long wavelengths region (≥ 950 nm), the QE of the solar cells decreased over the optimized Xc of the n-doped micro BSF layer, due to the defects of a film. In the second part of this paper, the effect of high conductivity n-type µc-Si:H BSF layer with optimized thickness on the performance of HIT solar cells was investigated, by doping gas ratio variation. Even though Xc decreased, conductivity was increased, with increasing PH3 doping concentration. Under the optimized condition, a n-µc-Si:H BSF layer has a dark conductivity of 2.59 S/cm, activation energy of 0.0519 eV, and X, of 52%. The conversion efficiency of 18.9% was achieved with a Voc of 706 mV, fill factor of 72%, and short circuit current density of 37.1 mW·cm(-2).

  8. Progress on the emitter wrap-through silicon solar cell

    Science.gov (United States)

    Gee, J. M.; Buck, M. E.; Schubert, W. K.; Basore, P. A.

    The Emitter Wrap-Through (EWT) solar cell is a back-contacted solar cell with a carrier-collection junction (emitter) on the front surface. Elimination of grids from the front surface allows for higher performance by eliminating grid-obscuration losses and reducing series resistance, while keeping an emitter on the front surface maintains high collection efficiency in solar-grade materials with modest diffusion lengths. The EWT cell uses laser-drilled vias to wrap the emitter diffusion on the front surface to interdigitated contacts on the back surface. We report on progress towards demonstration of two concepts for the EWT cell. The first EWT concept uses a fabrication sequence based on heavily diffused grooves and plated metallizations, and the second EWT concept uses a single furnace step and screen-printed metallizations. We also report on demonstration of double-sided carrier collection in the EWT cell.

  9. Application and analysis of silicon nitride films for surface passivation of high efficiency silicon solar cells

    NARCIS (Netherlands)

    Lamers, M.W.P.E.

    2015-01-01

    Two solar cell types are discussed in this thesis. Firstly, the Metal Wrap-Through cell, where the emitter-contact metallization of the front side is wrapped through holes in the wafer to the cell back. Optimization of several cell processing steps led to an increase of more than 2% absolute in cell

  10. Effect of TiO2 nanotube length and lateral tubular spacing on photovoltaic properties of back illuminated dye sensitized solar cell

    Indian Academy of Sciences (India)

    Shantikumar V Nair; A Balakrishnan; K R V Subramanian; A M Anu; A M Asha; B Deepika

    2012-08-01

    The main objective of this study is to show the effect of TiO2 nanotube length, diameter and intertubular lateral spacings on the performance of back illuminated dye sensitized solar cells (DSSCs). The present study shows that processing short TiO2 nanotubes with good lateral spacings could significantly improve the performance of back illuminated DSSCs. Vertically aligned, uniform sized diameter TiO2 nanotube arrays of different tube lengths have been fabricated on Ti plates by a controlled anodization technique at different times of 24, 36, 48 and 72 h using ethylene glycol and ammonium fluoride as an electrolyte medium. Scanning electron microscopy (SEM) showed formation of nanotube arrays spread uniformly over a large area. X-ray diffraction (XRD) of TiO2 nanotube layer revealed the presence of crystalline anatase phases. By employing the TiO2 nanotube array anodized at 24 h showing a diameter ∼80 nm and length ∼1.5 m as the photo-anode for back illuminated DSSCs, a full-sun conversion efficiency () of 3.5%was achieved, the highest value reported for this length of nanotubes.

  11. Optimization of solar cells for air mass zero operation and a study of solar cells at high temperatures, phase 3

    Science.gov (United States)

    Blakeslee, A. E.; Hovel, H. J.; Woodall, J. M.

    1977-01-01

    The etch-back epitaxy process is described for producing thin, graded composition GaAlAs layers. The palladium-aluminum contact system is discussed along with its associated problems. Recent solar cell results under simulated air mass zero light and at elevated temperatures are reported and the growth of thin polycrystalline GaAs films on foreign substrates is developed.

  12. Method for growing a back surface contact on an imaging detector used in conjunction with back illumination

    Science.gov (United States)

    Blacksberg, Jordana (Inventor); Hoenk, Michael Eugene (Inventor); Nikzad, Shouleh (Inventor)

    2010-01-01

    A method is provided for growing a back surface contact on an imaging detector used in conjunction with back illumination. In operation, an imaging detector is provided. Additionally, a back surface contact (e.g. a delta-doped layer, etc.) is grown on the imaging detector utilizing a process that is performed at a temperature less than 450 degrees Celsius.

  13. Carrier dynamics and design optimization of electrolyte-induced inversion layer carbon nanotube-silicon Schottky junction solar cell

    Science.gov (United States)

    Chen, Wenchao; Seol, Gyungseon; Rinzler, Andrew G.; Guo, Jing

    2012-03-01

    Carrier dynamics of the electrolyte-induced inversion layer carbon nanotube-silicon Schottky junction solar cells is explored by numerical simulations. Operation mechanisms of the solar cells with and without the electrolyte-induced inversion layer are presented and compared, which clarifies the current flow mechanisms in a solar cell with an induced inversion layer. A heavily doped back contact layer can behave as a hole block layer. In addition to lowering contact resistance and surface recombination, it is particularly useful for improving carrier separation in an electrolyte-induced inversion layer solar cell or a metal-insulator-semiconductor grating solar cell.

  14. Interface studies on the tunneling contact of a MOCVD-prepared tandem solar cell; Grenzflaechenuntersuchungen am Tunnelkontakt einer MOCVD-praeparierten Tandemsolarzelle

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, U.

    2007-07-10

    In this thesis a tandem solar cell with a novel tunneling contact was developed. For the development of the monolithic preparation especailly critical hetero-interfaces were studied in the region of the tunneling contact with surface-sensitive measuring method. The tandem solar cell consisted of single solar cells with absorber layers of In{sub 0.53}Ga{sub 0.47}As (E{sub g}=0.73 eV) and In{sub 0.78}Ga{sub 0.22}As{sub 0.491}P{sub 0.51} (E{sub g}=1.03 eV), the serial switching of which was pursued with a tunneling contact (ESAKI diode, which consisted of a very thin n-doped InGaAs and a p-doped GaAsSb layer. The III-V semiconductor layers were prepared by metalorganic gas phase epitaxy (MOCVD) monocrystallinely on an InP(100) substrate lattice-matchedly. Especially the influence of the preparation of InGaAs surfaces on the sharpness of the InGaAs/GaAsSb interface was in-situ studied by reflection-anisotropy spectroscopy and after a contamination-free transfer into the ultrahigh vacuum with photoelectron spectroscopy and with low-energetic electron diffraction (LEED). Thereby for the first time three different reconstructions of the MOCVD-prepared InGaAs surfaces could be observed, which were dependent on the heating temperature under pure hydrogen. The arsenic-rich InGaAs surface was observed for temperatures less than 300 C and showed in the LEED picture a (4 x 3) reconstruction. In the temperature range from 300 C until about 500 C a (2 x 4) reconstruction was observed, above 500 C the InGaAs surface 94 x 2)/c(8 x 2) was reconstructed. Subsequently the study of the growth of thin GaAsSb layers on these three InGaAs surface reconstructions followed. XPS measurements showed that the Sb/As ratio in GaAsSb at the growth on the As-rich (4 x 3) reconstructed surface in the first monolayers was too low. The preparation of the GaAsSb on the two other InGaAs surfaces yielded however in both cases a distinctly higher Sb/As ratio. Finally tandem solar cells with differently

  15. Concentration of solar radiation by white backed photovoltaic panels.

    Science.gov (United States)

    Smestad, G; Hamill, P

    1984-12-01

    In this paper, we present an analysis of the concentration achieved by white backed photovoltaic panels. Concentration is due to the trapping by light scattered in the refractive plate to which the solar cell is bonded. Using the reciprocity relation and assuming the ideal case of a Lambertian distribution, a detailed model is formulated that includes the effects of the thickness and walls of the concentrator. This model converges to the thermodynamic limit and is found to be consistent with experimental results for a wide range of cell sizes. Finally, the model is generalized to multiple-cell photovoltaic panels.

  16. Nanocrystal Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gur, Ilan [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.

  17. Effect of pre-cleaning treatment and contact wetting angle in the interface between P-doped Si surfaces and selective solar cell electrodes

    Science.gov (United States)

    Cui, Yinhua; Choi, Eunmi; Kim, Areum; Oh, Leeseul; Lee, Seon Jea; Ryang, Ayeon; Park, Hansoo; Lim, Kyunghee; Pyo, Sung Gyu

    2013-07-01

    Prior to electroless plating of the solar cell electrode, the sample was cleaned with a mixture of a sulfuric acid and peroxide solution and a H2NCH2CH2CH2Si(OC2H5) solution. We measured the de-wetting and contact angles of the solar cell thin film electrode. After SPM and APTES treatments, an excellent hydrophilic contact angle was observed. Our results show that it is more effective to remove oxidizer with SiO2 than HF mixed solutions. When comparing the efficiency, pre-treatment with a NH4F:HF mixed solution was more efficient than pre-treatment with a diluted HF solution. After NH4F:HF mixed solution cleaning, when the electrode was formed, the contact resistance that most directly affected the cleaning effect was 0.8194 ohm/sq, which had three times more improvement effect. It is expected that if an optimum cleaning time and process conditions for each cleaning chemical is developed, more improved contact resistance will be secured when each cleaning chemical is applied.

  18. Impact of built-in fields and contact configuration on the characteristics of ultra-thin GaAs solar cells

    CERN Document Server

    Aeberhard, Urs

    2016-01-01

    We discuss the effects of built-in fields and contact configuration on the photovoltaic characteristics of ultrathin GaAs solar cells. The investigation is based on advanced quantum-kinetic simulations reaching beyond the standard semi-classical bulk picture concerning the consideration of charge carrier states and dynamics in complex potential profiles. The thickness dependence of dark and photocurrent in the ultra-scaled regime is related to the corresponding variation of both, the built-in electric fields and associated modification of the density of states, and the optical intensity in the films. Losses in open-circuit voltage and short-circuit current due to leakage of electronically and optically injected carriers at minority carrier contacts are investigated for different contact configurations including electron and hole blocking barrier layers. The microscopic picture of leakage currents is connected to the effect of finite surface recombination velocities in the semi-classical description, and the i...

  19. Development of ZnTe:Cu Contacts for CdTe Solar Cells: Cooperative Research and Development Final Report, CRADA Number CRD-08-320

    Energy Technology Data Exchange (ETDEWEB)

    Dhere, R.

    2012-04-01

    The main focus of the work at NREL was on the development of Cu-doped ZnTe contacts to CdTe solar cells in the substrate configuration. The work performed under the CRADA utilized the substrate device structure used at NREL previously. All fabrication was performed at NREL. We worked on the development of Cu-doped ZnTe as well as variety of other contacts such as Sb-doped ZnTe, CuxTe, and MoSe2. We were able to optimize the contacts to improve device parameters. The improvement was obtained primarily through increasing the open-circuit voltage, to values as high as 760 mV, leading to device efficiencies of 7%.

  20. Fabrication of double barrier structures in single layer c-Si-QDs/a-SiOx films for realization of energy selective contacts for hot carrier solar cells

    Science.gov (United States)

    Kar, Debjit; Das, Debajyoti

    2017-01-01

    Thin films of c-Si-QDs embedded in an a-SiOx dielectric matrix forming arrays of double barrier structures have been fabricated by reactive rf-magnetron sputtering at ˜400 °C, without post-deposition annealing. The formation of larger size c-Si-QDs of reduced number density in homogeneous distribution within a less oxygenated a-SiOx matrix at higher plasma pressure introduces systematic widening of the average periodic distance between the adjacent `c-Si-QDs in a-SiOx', as obtained by X-ray reflectivity and transmission electron microscopy studies. A wave-like pattern in the J-E characteristics identifies the formation of periodic double-barrier structures along the path of the movement of charge carriers across the QDs and that those are originated by the a-SiOx dielectric matrix around the c-Si-QDs. A finite distribution of the size of c-Si-QDs introduces a broadening of the current density peak and simultaneously originates the negative differential resistance-like characteristics, which have suitable applications in the energy selective contacts that act as energy filters for hot carrier solar cells. A simple yet effective process technology has been demonstrated. Further initiative on tuning the energy selectivity by reducing the size and narrowing the size-distribution of Si-QDs can emerge superior energy selective contacts for hot carrier solar cells, paving ground for accomplishing all-Si solar cells.

  1. Cross-Linkable, Solvent-Resistant Fullerene Contacts for Robust and Efficient Perovskite Solar Cells with Increased JSC and VOC.

    Science.gov (United States)

    Watson, Brian L; Rolston, Nicholas; Bush, Kevin A; Leijtens, Tomas; McGehee, Michael D; Dauskardt, Reinhold H

    2016-10-05

    The active layers of perovskite solar cells are also structural layers and are central to ensuring that the structural integrity of the device is maintained over its operational lifetime. Our work evaluating the fracture energies of conventional and inverted solution-processed MAPbI3 perovskite solar cells has revealed that the MAPbI3 perovskite exhibits a fracture resistance of only ∼0.5 J/m(2), while solar cells containing fullerene electron transport layers fracture at even lower values, below ∼0.25 J/m(2). To address this weakness, a novel styrene-functionalized fullerene derivative, MPMIC60, has been developed as a replacement for the fragile PC61BM and C60 transport layers. MPMIC60 can be transformed into a solvent-resistant material through curing at 250 °C. As-deposited films of MPMIC60 exhibit a marked 10-fold enhancement in fracture resistance over PC61BM and a 14-fold enhancement over C60. Conventional-geometry perovskite solar cells utilizing cured films of MPMIC60 showed a significant, 205% improvement in fracture resistance while exhibiting only a 7% drop in PCE (13.8% vs 14.8% PCE) in comparison to the C60 control, enabling larger VOC and JSC values. Inverted cells fabricated with MPMIC60 exhibited a 438% improvement in fracture resistance with only a 6% reduction in PCE (12.3% vs 13.1%) in comparison to those utilizing PC61BM, again producing a higher JSC.

  2. Design requirements for high-efficiency high concentration ratio space solar cells

    Science.gov (United States)

    Rauschenbach, H.; Patterson, R.

    1980-01-01

    A miniaturized Cassegrainian concentrator system concept was developed for low cost, multikilowatt space solar arrays. The system imposes some requirements on solar cells which are new and different from those imposed for conventional applications. The solar cells require a circular active area of approximately 4 mm in diameter. High reliability contacts are required on both front and back surfaces. The back area must be metallurgically bonded to a heat sink. The cell should be designed to achieve the highest practical efficiency at 100 AMO suns and at 80 C. The cell design must minimize losses due to nonuniform illumination intensity and nonnormal light incidence. The primary radiation concern is the omnidirectional proton environment.

  3. High-flux solar furnace processing of silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S.; Pitts, J.R.; Landry, M.D.; Menna, P.; Bingham, C.E.; Lewandowski, A.; Ciszek, T.F. [National Renewable Energy Laboratory, Golden, CO (United States)

    1996-06-10

    We used a 10-kW, high-flux solar furnace (HFSF) to diffuse the front-surface n{sup +}-p junction and the back-surface p-p{sup +} junction of single-crystal silicon solar cells in one processing step. We found that all of these HFSF-processed cells have better conversion efficiencies than control cells of identical structures fabricated by conventional furnace diffusion methods. We also used the HFSF to crystallize a-Si:H thin films on glass, to texture crystalline silicon surfaces, to deposit gold contacts on silicon wafers, and to getter impurities from metallurgical grade silicon. HFSF processing offers several advantages over conventional furnace processing: (1) it provides a cold-wall process, which reduces contamination; (2) temperature versus time profiles can be precisely controlled; (3) wavelength, intensity, and spatial distribution of the incident solar flux can be controlled and changed rapidly; (4) a number of high-temperature processing steps can be performed simultaneously; and (5) combined quantum and thermal effects may benefit overall cell performance. We conclude that HFSF processing of silicon solar cells has the potential to improve cell efficiency, reduce cell fabrication costs, and also be an environmentally friendly manufacturing method. We have also demonstrated that the HFSF can be used to achieve solid-phase crystallization of a-Si:H at very high speed

  4. Concepts for thin-film GaAs concentrator cells. [for solar photovoltaic space power systems

    Science.gov (United States)

    Spitzer, M. B.; Gale, R. P.; Mcclelland, R.; King, B.; Dingle, J.

    1989-01-01

    The development of advanced GaAs concentrator solar cells, and in particular, the use of CLEFT (cleavage of lateral epitaxial films for transfer) processes for formation of thin-film structures is reported. The use of CLEFT has made possible processing of the back, and cells with back surface grids are discussed. Data on patterned junction development are presented; such junctions are expected to be useful in back surface applications requiring point contacts, grating structures, and interdigitated back contacts. CLEFT concentrator solar cells with grids on the front and back surfaces are reported here; these cells are 4 microns thick and are bonded to glass covers for support. Air mass zero efficiency of 18.8 percent has been obtained for a CLEFT concentrator operating at 18.5 suns.

  5. Device analysis methods for physical cell parameters of CdTe/CdS solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Baetzner, D.L. [Eidgenoessische Technische Hochschule, Zurich (Switzerland). Inst. fuer Quantenelektronik; Oezsan, M.E. [BP Solar Technology Centre, Sunbury-on-Thames, Middlesex (United Kingdom); Bonnet, D. [ANTEC Angewandte Neue Technologien GmbH, Kelkheim (Germany); Buecher, K. [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany). Abt. Thermische und Optische Systeme

    2000-02-21

    CdTe/CdS solar cells are thin film solar cells made of several different materials. As front contact serves a TCO, the p-n junction is an intermixed CdS/CdTe heterojunction and the metallization on the CdTe layer, which is needed for the back contact, usually shows a Schottky diode behaviour. Therefore the optoelectrical properties of the cells are complex and can often not be explained straight forward like in silicon solar cells. In order to determine the physical cell parameters like the Schottky barrier height and the minority carrier diffusion length in the absorber layer, we investigated the temperature dependence of the dark I-V characteristics and the spectral response. By modelling the temperature and wavelength dependence of the cell parameters, physical quantities such as the barrier height of the Schottky contact can be determined. (orig.)

  6. Results from Coupled Optical and Electrical Sentaurus TCAD Models of a Gallium Phosphide on Silicon Electron Carrier Selective Contact Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Limpert, Steven; Ghosh, Kunal; Wagner, Hannes; Bowden, Stuart; Honsberg, Christiana; Goodnick, Stephen; Bremner, Stephen; Green, Martin

    2014-06-09

    We report results from coupled optical and electrical Sentaurus TCAD models of a gallium phosphide (GaP) on silicon electron carrier selective contact (CSC) solar cell. Detailed analyses of current and voltage performance are presented for devices having substrate thicknesses of 10 μm, 50 μm, 100 μm and 150 μm, and with GaP/Si interfacial quality ranging from very poor to excellent. Ultimate potential performance was investigated using optical absorption profiles consistent with light trapping schemes of random pyramids with attached and detached rear reflector, and planar with an attached rear reflector. Results indicate Auger-limited open-circuit voltages up to 787 mV and efficiencies up to 26.7% may be possible for front-contacted devices.

  7. Improving low pressure chemical vapor deposited zinc oxide contacts for thin film silicon solar cells by using rough glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Steinhauser, J., E-mail: jerome.steinhauser@oerlikon.com; Boucher, J.-F.; Omnes, E.; Borrello, D.; Vallat-Sauvain, E.; Monteduro, G.; Marmelo, M.; Orhan, J.-B.; Wolf, B.; Bailat, J.; Benagli, S.; Meier, J.; Kroll, U.

    2011-12-01

    Compared to zinc oxide grown (ZnO) on flat glass, rough etched glass substrates decrease the sheet resistance (R{sub sq}) of zinc oxide layers grown on it. We explain this R{sub sq} reduction from a higher thickness and an improved electron mobility for ZnO layers deposited on rough etched glass substrates. When using this etched glass substrate, we also obtain a large variety of surface texture by changing the thickness of the ZnO layer grown on it. This new combination of etched glass and ZnO layer shows improved light trapping potential compared to ZnO films grown on flat glass. With this new approach, Micromorph thin film silicon tandem solar cells with high total current densities (sum of the top and bottom cell current density) of up to 26.8 mA cm{sup -2} were fabricated.

  8. Nanostructured Semiconductor Device Design in Solar Cells

    Science.gov (United States)

    Dang, Hongmei

    We demonstrate the use of embedded CdS nanowires in improving spectral transmission loss and the low mechanical and electrical robustness of planar CdS window layer and thus enhancing the quantum efficiency and the reliability of the CdS-CdTe solar cells. CdS nanowire window layer enables light transmission gain at 300nm-550nm. A nearly ideal spectral response of quantum efficiency at a wide spectrum range provides an evidence for improving light transmission in the window layer and enhancing absorption and carrier generation in absorber. Nanowire CdS/CdTe solar cells with Cu/graphite/silver paste as back contacts, on SnO2/ITO-soda lime glass substrates, yield the highest efficiency of 12% in nanostructured CdS-CdTe solar cells. Reliability is improved by approximately 3 times over the cells with the traditional planar CdS counterpart. Junction transport mechanisms are delineated for advancing the basic understanding of device physics at the interface. Our results prove the efficacy of this nanowire approach for enhancing the quantum efficiency and the reliability in windowabsorber type solar cells (CdS-CdTe, CdS-CIGS and CdS-CZTSSe etc) and other optoelectronic devices. We further introduce MoO3-x as a transparent, low barrier back contact. We design nanowire CdS-CdTe solar cells on flexible foils of metals in a superstrate device structure, which makes low-cost roll-to-roll manufacturing process feasible and greatly reduces the complexity of fabrication. The MoO3 layer reduces the valence band offset relative to the CdTe, and creates improved cell performance. Annealing as-deposited MoO3 in N 2 reduces series resistance from 9.98 O/cm2 to 7.72 O/cm2, and hence efficiency of the nanowire solar cell is improved from 9.9% to 11%, which efficiency comparable to efficiency of planar counterparts. When the nanowire solar cell is illuminated from MoO 3-x /Au side, it yields an efficiency of 8.7%. This reduction in efficiency is attributed to decrease in Jsc from 25.5m

  9. Analysis of one-sun monocrystalline rear-contacted silicon solar cells with efficiencies of 22.1%

    Science.gov (United States)

    Dicker, J.; Schumacher, J. O.; Warta, W.; Glunz, S. W.

    2002-04-01

    21.4% efficient rear-contacted cells (RCC) with interdigitated contact grids processed at the Fraunhofer ISE on 1.25 Ω cm float-zone (FZ) silicon are analyzed in detail. The comprehensive description does not only include a two-dimensional numerical device simulation, but also a detailed analysis of the optical carrier generation using optical ray tracing and determination of the losses due to distributed metal resistance and perimeter currents employing circuit simulation. Bulk and surface recombination losses are separated, combining carrier lifetime and open-circuit voltage measurements with numerical device simulation. The interface surface recombination velocity of the thermally oxidized emitter covering the front surface is deduced to be 1500 cm/s and the bulk diffusion length within the 1.25 Ω cm FZ silicon base is 1200 μm. Despite this excellent bulk diffusion length, the simulations reveal that at a maximum power point 80% of the total recombination is due to Shockley-Read-Hall recombination in the base. It was determined that losses due to the distributed metal resistance within the contact grid (including nongeneration losses) caused an fill factor decrease of 1% absolute. Loss currents flowing out of the cell perimeter caused an additional fill factor loss of 1.5% absolute. It was predicted that changing the surface concentration of the front and rear emitter diffusion from 5×1018 to 1×1018 cm-3, while keeping the sheet resistance constant, effected a relative improvement of 3% in the efficiency of the RCC structure. In fact, this modification has lead to an increase in the realized cell efficiency from 21.4% to 22.1% (VOC=697.6 mV, JSC=39.8 mA/cm2, and FF=79.4%), i.e., a relative improvement of 3.3%. This cell has an efficiency of 18.6% (VOC=696.5 mV, JSC=33.9 mA/cm2, and FF=78.8%) if illuminated from the rear side.

  10. Development of thin wraparound junction silicon solar cells

    Science.gov (United States)

    Ho, F.; Iles, P. A.

    1981-01-01

    The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

  11. A new model of organic solar cells reveals open circuit conditions and size dependent power loss induced by the finite conductivity of a transparent contact

    Science.gov (United States)

    Gotleyb, Dor; Shikler, Rafi

    2017-01-01

    We report on a new approach to modelling the effect of the size of organic solar cells on their efficiency. Experimental results show a drastic deterioration in performance when scaling up organic solar cells. This reduction reflects in key parameters such as the short circuit current (Is c ) , the maximum power point (Pm ) , and the Fill Factor (F F ) . It is attributed to the transparent anode that exhibits a relatively low conductivity (σ) . Our unique approach is to account for the interplay between the two sub-domains of the solar cell. In the first domain, containing the electro-optic active materials, we solve the drift-diffusion model using a simplified model for the recombination to emphasize the role of the anode resistance. In the second domain, representing the anode, we solve only the Laplace equation. We introduce the coupling between these layers using the current of the active layer as the boundary condition for the anode and the position dependent potential of the anode as the boundary condition for the active layer. Our results reveal that as the length of the cell increases, the parts that are farther from the contact exhibit near open circuit conditions and do not contribute to the current. We found that the efficiency of the cell altered from linear to sub-linear behavior already at cell lengths of a few millimeters. The transition point strongly depends on the conductivity of the anode. The sub-linearity starts at 0.4, 0.5, and 0.7 cm for σ=100 , 200 , and 500 S /cm , respectively. Additionally, the efficiency begins to saturate sooner than both the short circuit current and the Fill-Factor. The saturation is observed at device lengths of 0.8, 1.2, and 2.1 cm for σ=100 , 200 , and 500 S /cm , respectively.

  12. Nanostructured Solar Cells

    Science.gov (United States)

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-01-01

    We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  13. Amorphous silicon oxide layers for surface passivation and contacting of heterostructure solar cells of amorphous and crystalline silicon; Amorphe Siliziumoxidschichten zur Oberflaechenpassivierung und Kontaktierung von Heterostruktur-Solarzellen aus amorphen und kristallinem Silizium

    Energy Technology Data Exchange (ETDEWEB)

    Einsele, Florian

    2010-02-05

    films is dominated by the diffusion of atomic hydrogen being suitable for the saturation of interface defects. This shows in a distinct increase of the passivation quality of annealed films. The heterostructure back contact for solar cells on p-type c-Si consists of an undoped, full area passivation film, followed by a boron doped p-type contact layer. If highly doped, this layer generates a back surface field effect which decreases the recombination by reflecting minority charge carriers from the defect rich interface. An undoped passivation layer of a-Si:H improves the passivation by saturating interface defects. Effusion measurements on stacks of undoped and doped layers show an increase of the hydrogen diffusion in the undoped layer due to the presence of the doped layer. The doped layer shifts the Fermi level of the undoped layer towards the valence band edge. This shift increases the diffusion coefficient of hydrogen due to an effective reduction of the Si-H bond energy. As a consequence, the presence of the doped contact layer increases the mobility of atomic hydrogen in the passivation layer, with atomic hydrogen being necessary for the passivation of interface defects. The thickness of the passivation layer critically affects both the passivation and the electrical conductance of the back contact. Whereas the passivation quality steadily improves with increasing thickness, the conductance drops when exceeding a critical thickness in a range of 4 nm to 8 nm. Temperature dependent measurements yield a thermal activation of the conductance with an activation energy of E{sub A} {approx_equal} 0.5 eV, which is attributed to the valence band offset {Delta}E{sub V} between a-Si:H and c-Si. This high barrier requires a tunneling process for majority charge carriers and explains the abrupt decrease of conductance with increasing passivation layer thickness. Passivation layers of a-SiO{sub x}:H form a blocking junction on p-type c-Si, which is explained by an oxygen

  14. Perovskite Solar Cells with Large-Area CVD-Graphene for Tandem Solar Cells.

    Science.gov (United States)

    Lang, Felix; Gluba, Marc A; Albrecht, Steve; Rappich, Jörg; Korte, Lars; Rech, Bernd; Nickel, Norbert H

    2015-07-16

    Perovskite solar cells with transparent contacts may be used to compensate for thermalization losses of silicon solar cells in tandem devices. This offers a way to outreach stagnating efficiencies. However, perovskite top cells in tandem structures require contact layers with high electrical conductivity and optimal transparency. We address this challenge by implementing large-area graphene grown by chemical vapor deposition as a highly transparent electrode in perovskite solar cells, leading to identical charge collection efficiencies. Electrical performance of solar cells with a graphene-based contact reached those of solar cells with standard gold contacts. The optical transmission by far exceeds that of reference devices and amounts to 64.3% below the perovskite band gap. Finally, we demonstrate a four-terminal tandem device combining a high band gap graphene-contacted perovskite top solar cell (Eg = 1.6 eV) with an amorphous/crystalline silicon bottom solar cell (Eg = 1.12 eV).

  15. The planar multijunction cell - A new solar cell for earth and space

    Science.gov (United States)

    Evans, J. C., Jr.; Chai, A.-T.; Goradia, C.

    1980-01-01

    A new family of high-voltage solar cells, called the planar multijunction (PMJ) cell is being developed. The new cells combine the attractive features of planar cells with conventional or interdigitated back contacts and the vertical multijunction (VMJ) solar cell. The PMJ solar cell is internally divided into many voltage-generating regions, called unit cells, which are internally connected in series. The key to obtaining reasonable performance from this device was the separation of top surface field regions over each active unit cell area. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per linear centimeter are possible. Analysis of the new device is complex, and numerous geometries are being studied which should provide substantial benefits in both normal sunlight usage as well as with concentrators.

  16. Drain Back, Low Flow Solar Combi Systems

    DEFF Research Database (Denmark)

    Perers, Bengt; Furbo, Simon; Fan, Jianhua

    2014-01-01

    Drain Back systems with ETC collectors are tested and analyzed in a Danish - Chinese cooperation project. Experiences from early work at DTU, with drain back, low flow systems, was used to design two systems: 1) One laboratory system at DTU and 2) One demonstration system in a single family house...

  17. Optimization of Rear Local Al-Contacts on High Efficiency Commercial PERC Solar Cells with Dot and Line Openings

    Directory of Open Access Journals (Sweden)

    Peisheng Liu

    2014-01-01

    Full Text Available Crystalline silicon PERCs with dot or line openings on rear surface were studied here. By measuring the minor carrier lifetimes of the PERCs with dot and line openings, passivation effects of rear surface with dot and line openings were discussed. The performance affected by dot and line openings was analyzed in detail by testing the open-circuit voltages, short-circuit current densities, fill factors, and conversion efficiencies of the PERCs. The results show that the wider space resulted in better minor carrier lifetimes on the rear surface. And the cells with a line opening space of 0.5 mm had an average of 0.22% improvement of conversion efficiency, compared with the cells with full-area Al-BSF. On the other hand, the dot opening PERCs exhibited only a conversion efficiency of 17.4%, although there had been good rear surface reflectivity. The bad Al-Si alloy layer and large hollow densities in dot Al-contacts resulted in bad performance of the PERCs with dot openings.

  18. Application of laser technology in high efficiency silicon solar cell manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Long, W.X.; Tu, J.L.; Wang, Z.G.; Cui, H.Y.; Deng, J.L.; Liu, Z.M.; Liao, H. [Yunnan Normal Univ., Yunnan (China). Solar Energy Research Inst., Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology

    2008-07-01

    This paper examined the use of laser processing applications in solar cell fabrication. Laser processing is used to improve the electrical performance of solar cells as well as to reduce their manufacturing cost. Laser processes included laser scribing and cutting; laser fired contacts; wrap through technology; laser chemical processing; and the application of thin film devices. The study also examined the use of laser-fired contact (LFC) process schemes for the production of silicon (Si) Results of the study indicated that the lasers resulted in decreased wafer thickness and increased wafer sizes. LFC schemes can be applied on almost all advanced solar cell structures, including metal or emitter wrap-through cells and interdigitated back contact cells. Laser doping and via hole drilling techniques are also feasible in industrial applications. The use of laser technologies is expected to reduce costs. It was concluded that laser technologies are an appropriate choice for solar cell manufacturing processes. 12 refs., 8 figs.

  19. Effective plasma hydrogen passivation of mc-Si solar cells after finishing contacts%多晶硅太阳电池的有效等离子体氢钝化

    Institute of Scientific and Technical Information of China (English)

    胡志华; 刘祖明; 陈庭金; 廖显伯; 廖华

    2002-01-01

    A simple equipment and process for hydrogen passivation of multicrystalline silicon (mc-Si) solar cells are reported in this work. Hydrogen plasma is generated by means of AC glow discharge in hydrogen atmosphere. Hydrogen passivation is carried out with three different groups of mc-Si solar cells after finishing contacts. The experimental results demonstrate that the photovoltaic performances of the solar cell samples have been improved after hydrogen plasma treatment, with a relative increase in conversion efficiency up to 10.6%.

  20. Point-contacting by localised dielectric breakdown: Characterisation of a metallisation technique for the rear surface of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Western, Ned J., E-mail: n.western@unsw.edu.au; Perez-Wurfl, Ivan; Wenham, Stuart R.; Bremner, Stephen P. [Photovoltaics Centre of Excellence, UNSW, Sydney NSW 2052 (Australia)

    2015-07-28

    Characterisation results are presented for ohmic contacts to passivated crystalline silicon, formed using the point-contacting by localised dielectric breakdown technique. Self aligned contact is made between the metal and heavily doped surface regions through an intrinsic a-Si:H passivation layer. Local doping is provided by a laser using a standard technique identical to that for selective emitter formation. Our results for gate metals of Au, Al, and Ti show that the technique does not rely on reactivity between the dielectric and the metal, excluding metal induced crystallisation from the contacting process. Diffusion of the gate metal into the dielectric is observed in transmission electron microscope images suggesting high temperatures are present locally during the breakdown process. The technique is equally applicable to contacting of n and p-type silicon, making it a potential alternative for ohmic contacting to silicon to passivated rear surfaces.

  1. Development of solar cells with back surface field made by aluminum paste and belt furnace diffusion; Desenvolvimento de celulas solares com campo retrodifusor formado por pasta de aluminio e difusao em forno de esteira

    Energy Technology Data Exchange (ETDEWEB)

    Marcolino, Juliane Bernardes

    2011-01-15

    Photovoltaics is based on the direct conversion of solar energy into electricity and is a promising alternative to diversify the world's energy matrix. This work aims to develop and analyse the deposition of Al paste by screen printing and firing/diffusion in a belt furnace to produce a BSF region in monocrystalline Si wafers. The diffusion of Al into the substrate was implemented by two different processes. In the first process the diffusion/firing of the Al paste and the firing of the Ag paste was carried out in independent steps. In this case, solar cells with an average efficiency ({eta}{sub average}) of 11.5 % and a maximum of 12.0 % were produced, but with the formation Al clusters in the back surface of the devices. In the second process firing/diffusion of such pastes was done on the same step. In this case, the best results were obtained for a firing/diffusion temperature of 860 deg C and belt furnace speed (V{sub E}) of 150 cm/min and also for 890 deg C and 180 cm/min. For the former parameters, {eta}{sub average} was 12.4 % and the maximum was 12.8 %. For the later, {eta}{sub average} was 12.5 % and the maximum was 12.6 %. Considering a temperature of 900 deg C and V{sub E} of 190 cm/min, {eta}{sub average} was 12.4 %. It was observed that minority carriers diffusion lengths were smaller than the thickness of silicon wafers. Open circuit voltages were 30 mV lower than that from similar cells fabricated at NT-Solar by using high purity Al deposited by e-beam evaporation indicating that the developed process produced low quality BSF. (author)

  2. High efficiency micro solar cells integrated with lens array

    Science.gov (United States)

    Fidaner, Onur; Suarez, Ferran A.; Wiemer, Michael; Sabnis, Vijit A.; Asano, Tetsuya; Itou, Akihiro; Inoue, Daijiro; Hayashi, Nobuhiko; Arase, Hidekazu; Matsushita, Akio; Nakagawa, Tohru

    2014-03-01

    We demonstrate high efficiency triple junction solar cells with submillimeter dimensions in an all-back-contact architecture. 550 × 550 μm2 cells flash at 41.3% efficiency under the air mass 1.5 direct normal spectrum at 50 W/cm2 at 25 °C. Compared to standard size production cells, the micro cells have reduced performance at 1-sun due to perimeter recombination, but the performance gap closes at higher concentrations. Micro cells integrated with lens arrays were tested on-sun with an efficiency of 34.7%. All-back-contact architecture and submillimeter dimensions are advantageous for module integration and heat dissipation, allowing for high-performance, compact, lightweight, and cost-effective concentrated photovoltaic modules.

  3. Silicon heterojunction solar cell and crystallization of amorphous silicon

    Science.gov (United States)

    Lu, Meijun

    The rapid growth of photovoltaics in the past decade brings on the soaring price and demand for crystalline silicon. Hence it becomes necessary and also profitable to develop solar cells with over 20% efficiency, using thin (˜100mum) silicon wafers. In this respect, diffused junction cells are not the best choice, since the inescapable heating in the diffusion process not only makes it hard to handle thin wafers, but also reduces carriers' bulk lifetime and impairs the crystal quality of the substrate, which could lower cell efficiency. An alternative is the heterojunction cells, such as amorphous silicon/crystalline silicon heterojunction (SHJ) solar cell, where the emitter layer can be grown at low temperature (solar cell, including the importance of intrinsic buffer layer; the discussion on the often observed anomalous "S"-shaped J-V curve (low fill factor) by using band diagram analysis; the surface passivation quality of intrinsic buffer and its relationship to the performance of front-junction SHJ cells. Although the a-Si:H is found to help to achieve high efficiency in c-Si heterojuntion solar cells, it also absorbs short wavelength (cells. Considering this, heterojunction with both a-Si:H emitter and base contact on the back side in an interdigitated pattern, i.e. interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell, is developed. This dissertation will show our progress in developing IBC-SHJ solar cells, including the structure design; device fabrication and characterization; two dimensional simulation by using simulator Sentaurus Device; some special features of IBC-SHJ solar cells; and performance of IBC-SHJ cells without and with back surface buffer layers. Another trend for solar cell industry is thin film solar cells, since they use less materials resulting in lower cost. Polycrystalline silicon (poly-Si) is one promising thin-film material. It has the potential advantages to not only retain the performance and stability of c

  4. Quantum-Tuned Multijunction Solar Cells

    Science.gov (United States)

    Koleilat, Ghada I.

    Multijunction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun's broad spectrum. In this dissertation, we first report the systematic engineering of 1.6 eV PbS CQD solar cells, optimal as the front cell responsible for visible wavelength harvesting in tandem photovoltaics. We rationally optimize each of the device's collecting electrodes---the heterointerface with electron accepting TiO2 and the deep-work-function hole-collecting MoO3 for ohmic contact---for maximum efficiency. Room-temperature processing enables flexible substrates, and permits tandem solar cells that integrate a small-bandgap back cell atop a low thermal-budget larger-bandgap front cell. We report an electrode strategy that enables a depleted heterojunction CQD PV device to be fabricated entirely at room temperature. We develop a two-layer donor-supply electrode (DSE) in which a highly doped, shallow work function layer supplies a high density of free electrons to an ultrathin TiO2 layer via charge-transfer doping. Using the DSE we build all-room-temperature-processed small-bandgap (1 eV) colloidal quantum dot solar cells suitable for use as the back junction in tandem solar cells. We further report in this work the first efficient CQD tandem solar cells. We use a graded recombination layer (GRL) to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell. The recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We conclude our dissertation by presenting the generalized conditions for design of efficient graded recombination layer solar devices. We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the

  5. Three-Terminal Amorphous Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Cheng-Hung Tai

    2011-01-01

    Full Text Available Many defects exist within amorphous silicon since it is not crystalline. This provides recombination centers, thus reducing the efficiency of a typical a-Si solar cell. A new structure is presented in this paper: a three-terminal a-Si solar cell. The new back-to-back p-i-n/n-i-p structure increased the average electric field in a solar cell. A typical a-Si p-i-n solar cell was also simulated for comparison using the same thickness and material parameters. The 0.28 μm-thick three-terminal a-Si solar cell achieved an efficiency of 11.4%, while the efficiency of a typical a-Si p-i-n solar cell was 9.0%. Furthermore, an efficiency of 11.7% was achieved by thickness optimization of the three-terminal solar cell.

  6. Three-Terminal Amorphous Silicon Solar Cells

    OpenAIRE

    Cheng-Hung Tai; Chu-Hsuan Lin; Chih-Ming Wang; Chun-Chieh Lin

    2011-01-01

    Many defects exist within amorphous silicon since it is not crystalline. This provides recombination centers, thus reducing the efficiency of a typical a-Si solar cell. A new structure is presented in this paper: a three-terminal a-Si solar cell. The new back-to-back p-i-n/n-i-p structure increased the average electric field in a solar cell. A typical a-Si p-i-n solar cell was also simulated for comparison using the same thickness and material parameters. The 0.28 μm-thick three-terminal a-Si...

  7. Processing for high photocurrent in IBC solar cells

    Science.gov (United States)

    Sexton, F. W.; Garner, C. M.; Rodriquez, J. L.

    The fabrication process and performance characteristics and features of long bulk lifetime, low front and back surface recombination velocities, 10 ohm-cm FZ-grown single crystal Si solar cells are discussed. The cells are interdigitated back contact designs fabricated on 300 microns thick Si wafers, with phosphorus and boron dopants. Quantum efficiency data indicated a minority-carrier lifetime of 350 microsec and a maximum recombination velocity of 30 cm/sec. Laser scans, however, revealed a minimum minority carrier lifetime of 190 microsec. The difference is suggested to be due to front surface recombination reducing the short-circuit current during the laser scans. Back surface passivation is indicated for reducing back surface recombination losses, and a process using 500 A thick wet thermal oxides is recommended.

  8. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    Science.gov (United States)

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated.

  9. Reduction Bending of Thin Crystalline Silicon Solar Cells

    Institute of Scientific and Technical Information of China (English)

    SHEN Lan-xian; LIU Zu-ming; LIAO Hua; TU Jie-lei; DENG Shu-kang

    2009-01-01

    Reported are the results of reduction the bending of thin crystalline silicon solar ceils after printing and sintering of back electrode by changing the back electrode paste and adjusting the screen printing parameters without effecting the electrical properties of the cell. Theory and experiments showed that the bending of the cell is changed with its thickness of suhstrate, the thinner cell, the more serious bending. The bending of the cell is decreased with the thickness decrease of the back contact paste. The substrate with the thickness of 190μm printing with sheet aluminum paste shows a relatively lower bend compared with that of the substrate printing with ordinary aluminum paste, and the minimum bend is 0.55 mm which is reduced by52%.

  10. Sensitivity analysis of high-efficiency silicon solar-cell design parameters

    Science.gov (United States)

    Mokashi, A. R.

    1984-01-01

    Silicon solar cell design parameters were investigated to determine their bearing on cell efficiency. Among the parameters reviewed were: (1) bulk resistivity, (2) minority carrier lifetime cell thickness, (3) front junction depth, (4) front surface doping concentration, (5) front surface recombination velocity, and (6) back surface contact. The following were concluded: (1) there is good agreement between experimental and simulation results; (2) sheet material quality improvement is needed for high efficiency cells; (3) 20% cell of this design is feasible with 10 ms bulk lifetime material; and (4) for achieving efficiencies higher than 20% new cell designs including thin cells with light trapping and back surface field should be considered.

  11. Development and analysis of silicon solar cells with laser-fired contacts and silicon nitride laser ablation

    OpenAIRE

    Sauaia, Rodrigo Lopes

    2013-01-01

    O objetivo desta tese foi o desenvolvimento e análise de células solares em substrato de silício cristalino com processamento por radiação laser. Células solares com estrutura n+pp+ em substrato de CZ-Si tipo p foram fabricadas, analisadas e comparadas, com base em duas técnicas de processamento laser: contatos posteriores formados por laser (CFL) e ablação do filme antirreflexo frontal de nitreto de silício por processamento químico com laser (PQL) ou por processamento com laser guiado por g...

  12. Dendritic cells and contact dermatitis.

    Science.gov (United States)

    Sasaki, Yoshinori; Aiba, Setsuya

    2007-10-01

    Contact dermatitis is a biological response to simple chemicals in the skin. Although it is well known that allergic contact dermatitis is mediated by the immune system, it is still uncertain whether it is a kind of protective response or it is simply an unnecessary response. We have demonstrated the following: (1) haptens activate Langerhans cells in the initiation phase of murine allergic contact dermatitis in vivo, (2) haptens activate human monocyte-derived dendritic cells in vitro, (3) the activation of dendritic cells by haptens is primarily mediated by the activation of p38 mitogen-activated protein kinase (MAPK), and (4) the activation of p38 MAPK is mediated by stimulation related to an imbalance of intracellular redox. Based on these observations, we will discuss the biological significance of contact dermatitis. In addition, we will review some up-to-date findings on Langerhans cell biology.

  13. High-Work-Function Molybdenum Oxide Hole Extraction Contacts in Hybrid Organic–Inorganic Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Philip; Tiepelt, Jan O.; Christians, Jeffrey A.; Levine, Igal; Edri, Eran; Sanehira, Erin M.; Hodes, Gary; Cahen, David; Kahn, Antoine

    2016-11-23

    We investigate the effect of high work function contacts in halide perovskite absorber-based photovoltaic devices. Photoemission spectroscopy measurements reveal that band bending is induced in the absorber by the deposition of the high work function molybdenum trioxide (MoO3). We find that direct contact between MoO3 and the perovskite leads to a chemical reaction, which diminishes device functionality. Introducing an ultrathin spiro-MeOTAD buffer layer prevents the reaction, yet the altered evolution of the energy levels in the methylammonium lead iodide (MAPbI3) layer at the interface still negatively impacts device performance.

  14. Approaches to improve the Voc of CDTE devices: Device modeling and thinner devices, alternative back contacts

    Science.gov (United States)

    Walkons, Curtis J.

    An existing commercial process to develop thin film CdTe superstrate cells with a lifetime tau=1-3 ns results in Voc= 810-850 mV which is 350 mV lower than expected for CdTe with a bandgap EG = 1.5 eV. Voc is limited by 1.) SRH recombination in the space charge region; and 2.) the Cu2Te back contact to CdTe, which, assuming a 0.3 eV CdTe/Cu2Te barrier, exhibits a work function of phi Cu2Te= 5.5 eV compared to the CdTe valence band of Ev,CdTe=5.8 eV. Proposed solutions to develop CdTe devices with increased Voc are: 1.) reduce SRH recombination by thinning the CdTe layer to ≤ 1 mum; and 2.) develop an ohmic contact back contact using a material with phi BC≥5.8 eV. This is consistent with simulations using 1DSCAPS modeling of CdTe/CdS superstrate cells under AM 1.5 conditions. Two types of CdTe devices are presented. The first type of CdTe device utilizes a window/CdTe stack device with an initial 3-9 mum CdTe layer which is then chemically thinned resulting in regions of the CdTe film with thickness less than 1 mum. The CdTe surface was contacted with a liquid junction quinhydrone-Pt (QH-Pt) probe which enables rapid repeatable Voc measurements on CdTe before and after thinning. In four separate experiments, the window/CdTe stack devices with thinned CdTe exhibited a Voc increase of 30-170 mV, which if implemented using a solid state contact could cut the Voc deficit in half. The second type of CdTe device utilizes C61 PCBM as a back contact to the CdTe, selected since PCBM has a valence band maximum energy (VBM) of 5.8 eV. The PCBM films were grown by two different chemistries and the characterization of the film properties and device results are discussed. The device results show that PCBM exhibits a blocking contact with a 0.6 eV Schottky barrier and possible work function of phiPCBM = 5.2 eV.

  15. Reflectance improvement by thermal annealing of sputtered Ag/ZnO back reflectors in a-Si:H thin film silicon solar cells

    DEFF Research Database (Denmark)

    Haug, Franz-Josef; Söderström, Karin; Pahud, Céline

    2011-01-01

    reflector increases its reflectance drastically. The process is performed at low temperature (150°C) to allow the use of plastic sheets such as polyethylene naphthalate and increases the efficiency of single junction amorphous solar cells dramatically. We present the best result obtained on a flexible...

  16. High-efficiency silicon heterojunction solar cells: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    De Wolf, S.; Geissbuehler, J.; Loper, P.; Martin de Nicholas, S.; Seif, J.; Tomasi, A.; Ballif, C.

    2015-05-11

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on both-sides contacted n-type cells, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short-wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long- wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metallization grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical

  17. Rational Strategies for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Seo, Jangwon; Noh, Jun Hong; Seok, Sang Il

    2016-03-15

    A long-standing dream in the large scale application of solar energy conversion is the fabrication of solar cells with high-efficiency and long-term stability at low cost. The realization of such practical goals depends on the architecture, process and key materials because solar cells are typically constructed from multilayer heterostructures of light harvesters, with electron and hole transporting layers as a major component. Recently, inorganic-organic hybrid lead halide perovskites have attracted significant attention as light absorbers for the fabrication of low-cost and high-efficiency solar cells via a solution process. This mainly stems from long-range ambipolar charge transport properties, low exciton binding energies, and suitable band gap tuning by managing the chemical composition. In our pioneering work, a new photovoltaic platform for efficient perovskite solar cells (PSCs) was proposed, which yielded a high power conversion efficiency (PCE) of 12%. The platform consisted of a pillared architecture of a three-dimensional nanocomposite of perovskites fully infiltrating mesoporous TiO2, resulting in the formation of continuous phases and perovskite domains overlaid with a polymeric hole conductor. Since then, the PCE of our PSCs has been rapidly increased from 3% to over 20% certified efficiency. The unprecedented increase in the PCE can be attributed to the effective integration of the advantageous attributes of the refined bicontinuous architecture, deposition process, and composition of perovskite materials. Specifically, the bicontinuous architectures used in the high efficiency comprise a layer of perovskite sandwiched between mesoporous metal-oxide layer, which is a very thinner than that of used in conventional dye-sensitized solar cells, and hole-conducting contact materials with a metal back contact. The mesoporous scaffold can affect the hysteresis under different scan direction in measurements of PSCs. The hysteresis also greatly depends on

  18. A one-dimensional model for the quantum efficiency of front-surface-field solar cells

    Science.gov (United States)

    Yernaux, M. I.; Battochio, C.; Verlinden, P.; van de Wiele, F.

    1984-11-01

    A one-dimensional analytical model is proposed to calculate the photocurrent generated in interdigitated back contact solar cells with a high-low junction at the front illuminated surface. The high-low junction is simulated by constant doping levels, mobilities and lifetimes. A study of the quantum efficiency of front-surface-field (FSF) solar cells is made and the computer results are compared with experimental results. A method of determining the real and the effective surface recombination velocity of FSF solar cells is proposed.

  19. Fabricating solar cells with silicon nanoparticles

    Science.gov (United States)

    Loscutoff, Paul; Molesa, Steve; Kim, Taeseok

    2014-09-02

    A laser contact process is employed to form contact holes to emitters of a solar cell. Doped silicon nanoparticles are formed over a substrate of the solar cell. The surface of individual or clusters of silicon nanoparticles is coated with a nanoparticle passivation film. Contact holes to emitters of the solar cell are formed by impinging a laser beam on the passivated silicon nanoparticles. For example, the laser contact process may be a laser ablation process. In that case, the emitters may be formed by diffusing dopants from the silicon nanoparticles prior to forming the contact holes to the emitters. As another example, the laser contact process may be a laser melting process whereby portions of the silicon nanoparticles are melted to form the emitters and contact holes to the emitters.

  20. Status of the EU FP7 HERCULES project: what is the potential of n-type silicon solar cells in europe?

    OpenAIRE

    Muñoz Cervantes, Delfina; Ribeyron, P.J.; Harrison, S; Allebe, C.; Descoeudres, A.; Despeisse, M.; Reichel, C.; Glunz, S.W.; Peibst, R.; Merkle, A.; Nielsen, O; Martín García, Isidro; Mihailetchi, V.; Demaurex, B.; Wolf, S.

    2016-01-01

    The concept proposed by the HERCULES project is to develop innovative n-type monocrystalline c-Si device structures based on both sides' contacted silicon heterojunction (SHJ) solar cells, on interdigitated back-contact (IBC) solar cells with alternative junction formation, as well as on hybrid concepts (homo-heterojunction). These concepts are the most promising technologies to reach ultra-high efficiencies with industrially relevant processes. The HERCULES strategy is to transfer the ...

  1. Prospects of Back Surface Field Effect in Ultra-Thin High-Efficiency CdS/CdTe Solar Cells from Numerical Modeling

    OpenAIRE

    Nowshad Amin; Matin, M.A.; Aliyu, M. M.; M. A. Alghoul; Karim, M. R.; K. Sopian

    2010-01-01

    Polycrystalline CdTe shows greater promises for the development of cost-effective, efficient, and reliable thin film solar cells. Results of numerical analysis using AMPS-1D simulator in exploring the possibility of ultrathin, high efficiency, and stable CdS/CdTe cells are presented. The conventional baseline case structure of CdS/CdTe cell has been explored with reduced CdTe absorber and CdS window layer thickness, where 1 μm thin CdTe and 50 nm CdS layers showed reasonable efficiencies over...

  2. Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Narayanswamy, C. (Department of Physics & Astronomy, University of Toledo); Gessert, T. A. and Asher, S. E. (National Renewable Energy Laboratory)

    1998-10-27

    Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Ni metallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 C to 300 C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cu at the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.

  3. Overview of thick-film technology as applied to solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Firor, K.; Hogan, S.

    1980-01-01

    Thick-film technology was developed by the electronics industry as a means of fabricating components and miniature circuitry. Today, the solar cell industry is looking at screen printing as an alternate to more expensive, high-vacuum techniques in several of the production steps during the manufacture of silicon solar cells. Screen printing is already fairly well established as a means of providing electrical contact to a cell and for the formation of a back surface field. Now under investigation are the possibilities of non-noble metal contacts and protective and antireflective coatings applied to solar cells by the use of screen printing. Most exciting is the work being done in the non-silicon area on the fabrication of the active layers of a solar cell, using thick-film inks made up of II-VI semiconductors.

  4. Numerical Analysis of Copper-Indium-Gallium-Diselenide-Based Solar Cells by SCAPS-1D

    Directory of Open Access Journals (Sweden)

    S. Ouédraogo

    2013-01-01

    Full Text Available We used a one-dimensional simulation program Solar Cell Capacitance Simulator in 1 Dimension (SCAPS-1D to investigate Copper-Indium-Gallium-Diselenide- (CIGS- based solar cells properties. Starting with a conventional ZnO-B/i-ZnO/CdS/CIGS structure, we simulated the parameters of current-voltage characteristics and showed how the absorber layer thickness, hole density, and band gap influence the short-circuit current density (Jsc, open-circuit voltage (Voc, fill factor (FF, and efficiency of solar cell. Our simulation results showed that all electrical parameters are greatly affected by the absorber thickness (w below 1000 nm, due to the increase of back-contact recombination and very poor absorption. Increasing hole density (p or absorber band gap (Eg improves Voc and leads to high efficiency, which equals value of 16.1% when p = 1016 cm−3 and Eg=1.2 eV. In order to reduce back-contact recombination, the effect of a very thin layer with high band gap inserted near the back contact and acting as electrons reflector, the so-called back-electron reflector (EBR, has been investigated. The performances of the solar cells are significantly improved, when ultrathin absorbers (w < 500 nm are used; the corresponding gain of Jsc due to the EBR is 3 mA/cm2. Our results are in good agreement with those reported in the literature from experiments.

  5. Optical and Recombination Losses in Thin Film Solar Cells Based on Heterojunctions n-ZnS (n-CdS / p-CdTe with Current Collecting Contacts ITO and ZnO

    Directory of Open Access Journals (Sweden)

    O.A. Dobrozhan

    2014-11-01

    Full Text Available The optical and recombination losses in auxiliary and absorbing layers of solar cells based on heterojunctions n-ZnS / p-CdTe and n-CdS / p-CdTe with current collecting front sublayers ITO and ZnO were determined. As a result, spectral dependence of light transmittance (T of solar cells, taking into account its reflections from the boundaries of the contacting materials and in case of absorption in the auxiliary layers of solar cells was calculated. The influence of optical and recombination losses in the solar cell structure ITO (ZnO / CdS (ZnS / CdTe on the short circuit current (Jsc and efficiency (η of solar cells with different thickness of the window layer CdS (ZnS (50-300 nm and constant current collecting layer (200 nm was investigated. It has been established that the greatest efficiency values (15,9-16,1% solar cells have the structure of ZnO / ZnS / CdTe at a concentration of uncompensated acceptors in the absorbent layer (Na – Nd = 1015-1017 cm – 3 and the window layer thickness of 50 nm.

  6. Novel approach for characterizing the specific shunt resistance caused by the penetration of the front contact through the p-n junction in solar cell

    Institute of Scientific and Technical Information of China (English)

    Zhang Lucheng; Shen Hui

    2009-01-01

    on process was completely compatible with the industrial silicon fabrication sequence, which was of great convenience. The measurement results give informations on the solar cell structure, material ingredients, and process parameters.

  7. Nanostructured Organic Solar Cells

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Rubahn, Horst-Günter; Madsen, Morten

    Recent forecasts for alternative energy generation predict emerging importance of supporting state of art photovoltaic solar cells with their organic equivalents. Despite their significantly lower efficiency, number of application niches are suitable for organic solar cells. This work reveals...... the principles of bulk heterojunction organic solar cells fabrication as well as summarises major differences in physics of their operation....

  8. Solar Photovoltaic Cells.

    Science.gov (United States)

    Mickey, Charles D.

    1981-01-01

    Reviews information on solar radiation as an energy source. Discusses these topics: the key photovoltaic material; the bank theory of solids; conductors, semiconductors, and insulators; impurity semiconductors; solid-state photovoltaic cell operation; limitations on solar cell efficiency; silicon solar cells; cadmium sulfide/copper (I) sulfide…

  9. High-efficiency silicon heterojunction solar cells: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    De Wolf, S.

    2015-04-27

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on n-type wafers, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short- wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long-wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metalisation grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical transport requirements. The

  10. PEROVSKITE SOLAR CELLS (REVIEW ARTICLE)

    OpenAIRE

    Benli, Deniz Ahmet

    2015-01-01

    A solar cell is a device that converts sunlight into electricity. There are different types of solar cells but this report mainly focuses on a type of new generation solar cell that has the name organo-metal halide perovskite, shortly perovskite solar cells. In this respect, the efficiency of power conversion is taken into account to replace the dominancy of traditional and second generation solar cell fields by perovskite solar cells. Perovskite solar cell is a type of solar cell including a...

  11. Review of silicon solar cells for high concentrations

    Science.gov (United States)

    Schwartz, R. J.

    1982-06-01

    The factors that limit the performance of high concentration silicon solar cells are reviewed. The design of a conventional high concentration cell is discussed, together with the present state of the art. Unconventional cell designs that have been proposed to overcome the limitations of the conventional design are reviewed and compared. The current status of unconventional cells is reviewed. Among the unconventional cells discussed are the interdigitated back-contact cell, the double-sided cell, the polka dot cell, and the V-groove cell. It is noted that all the designs for unconventional cells require long diffusion lengths for high efficiency operation, even though the demands in this respect are less for those cells with the optical path longer than the diffusion path.

  12. An Investigation of High Performance Heterojunction Silicon Solar Cell Based on n-type Si Substrate

    Directory of Open Access Journals (Sweden)

    N. Memarian

    2016-12-01

    Full Text Available In this study, high efficient heterojunction crystalline silicon solar cells without using an intrinsic layer were systematically investigated. The effect of various parameters such as work function of transparent conductive oxide (ϕTCO, density of interface defects, emitter and crystalline silicon thickness on heterojunction silicon solar cell performance was studied. In addition, the effect of band bending and internal electric field on solar cell performance together with the dependency of cell performance on work function and reflectance of the back contact were investigated in full details. The optimum values of the solar cell properties for the highest efficiency are presented based on the results of the current study. The results represent a complete set of optimum values for a heterojunction solar cell with high efficiency up to the 24.1 % with VOC  0.87 V and JSC  32.69 mAcm – 2.

  13. Optimized analysis and experimental study for two-layer contact of crystalline silicon solar cells%晶体硅太阳电池双层电极优化分析与实验研究

    Institute of Scientific and Technical Information of China (English)

    李涛; 周春兰; 刘振刚; 赵雷; 李海玲; 刁宏伟; 王文静

    2012-01-01

    相对于单层电极结构,优化的前表面双层电极能够明显减小功率损失,改善晶体硅太阳电池的电学特性.本文对晶体硅太阳电池的双层电极进行了优化分析和实验研究.通过扫描电子显微镜观测将双层电极的截面抽象为更接近于实际的半椭圆型,建立了太阳电池前表面的双层电极模型,理论分析了双层电极的电学损失和光学损失.结合丝网印刷后光诱导电镀太阳电池的实验,得到了理论和实验上的最优化光诱导电镀增厚电极厚度与丝网印刷电极宽度的关系.所得到的理论和实验结果符合良好.由于并不涉及电极制备的具体技术,双层电极理论模型普遍适用于多种类型的双层电极结构.%Compared with single-layer contact,optimized two-layer contact of front side could diminish power losses distinctly and improve the electrical performance of crystalline silicon solar cell.In this paper,the optimized analysis and experimental study for two-layer contact of crystalline silicon solar cell are carried out.The model of two-layer contact is established by abstracting the crosssection of two-layer contact into semi-elliptical shape closer to the realistic situation according to the SEM observation.The electrical losses and the optical losses of two-layer contact are analyzed in theory.In combination with experimental screen-printed contact thickened by light-induced electroplating solar cell,the relationship between the optimum thickening contact thickness by light-induced electroplating and the screen-printed contact width is achieved in theory and experiment.The corresponding theory and experimental results are in good agreement with each other.Due to involving no concrete technology of contact preparation,the theoretical model of two-layer contact is generally appticable for many types of two-layer contact structures in consequence.

  14. Toward high efficiency ultra-thin CIGSe based solar cells using light management techniques

    Science.gov (United States)

    Naghavi, Negar; Jehl, Zacharie; Donsanti, Frederique; Guillemoles, Jean-François; Gérard, Isabelle; Bouttemy, Muriel; Etcheberry, Arnaud; Pelouard, Jean-Luc; Collin, Stéphane; Colin, Clément; Péré-Laperne, Nicolas; Dahan, Nir; Greffet, Jean-Jacques; Morel, Boris; Djebbour, Zakaria; Darga, Arouna; Mencaraglia, Denis; Voorwinden, Georg; Dimmler, Bernhard; Powalla, Micheal; Lincot, Daniel

    2012-02-01

    This study addresses the potential of different approaches to improve the generated current density in ultrathin Cu(In,Ga)Se2 (CIGSe) based solar cells down to 0.1 μm. Advanced photon management, involving both absorption enhancement and reflection reduction in the absorber, is studied. In this contribution, the three main approaches used are: - The reduction of the CIGSe thickness by chemical etching which combines thickness reduction and smoothing effect on the absorber. - Optical management by front contact engineering and by the replacement of the back contact by the "lift-off" of CIGSe layer from the Mo layer and the deposition of a new reflective back contact. - Application of plasmonic structures to CIGSe solar cells enabling light confinement at the subwavelength scale.

  15. 太阳能电池用多晶硅晶界的EBSD研究%Electron Back Scattered Diffraction Study on Grain Boundaries in Polycrystalline Silicon of Solar Cells

    Institute of Scientific and Technical Information of China (English)

    马会娜; 张智慧; 左玉婷; 杜风贞; 李继东

    2012-01-01

    利用电子背散射衍射(Electron back scattered diffraction,EBSD)对太阳能电池用多晶硅的晶界进行了研究.结果表明,太阳能电池用多晶硅中的大部分晶界为大角度晶界,且以特殊晶界∑3和普通晶界为主,同时还存在少量小角度晶界.在制作太阳能电池用多晶硅时,重点要降低小角度晶界和∑3的含量.%The grain boundary in polycrystalline silicon of solar cells was studied by electron back scattered diffraction (EBSD). The results show that most grain boundaries observed are large angle grain boundaries. ∑3 and common grain boundaries are the chief of these large angle grain boundaries. Small angle grain boundaries were also observed with a low ratio. Decrease the content of small angle grain boundaries and ∑3 in preparing polycrystalline silicon of solar cells is the emphasis.

  16. Infrared-Controlled Welding of Solar Cells

    Science.gov (United States)

    Paulson, R.; Finnell, S. E.; Decker, H. J.; Hodor, J. R.

    1982-01-01

    Proposed apparatus for welding large arrays of solar cells to flexible circuit substrates would sense infrared emission from welding spot. Emission would provide feedback for control of welding heat. Welding platform containing optical fibers moves upward through slots in movable holding fixture to contact solar cells. Fibers pick up infrared radiation from weld area.

  17. Industrial Silicon Wafer Solar Cells

    Directory of Open Access Journals (Sweden)

    Dirk-Holger Neuhaus

    2007-01-01

    Full Text Available In 2006, around 86% of all wafer-based silicon solar cells were produced using screen printing to form the silver front and aluminium rear contacts and chemical vapour deposition to grow silicon nitride as the antireflection coating onto the front surface. This paper reviews this dominant solar cell technology looking into state-of-the-art equipment and corresponding processes for each process step. The main efficiency losses of this type of solar cell are analyzed to demonstrate the future efficiency potential of this technology. In research and development, more various advanced solar cell concepts have demonstrated higher efficiencies. The question which arises is “why are new solar cell concepts not transferred into industrial production more frequently?”. We look into the requirements a new solar cell technology has to fulfill to have an advantage over the current approach. Finally, we give an overview of high-efficiency concepts which have already been transferred into industrial production.

  18. Tunnel junctions for InP-on-Si solar cells

    Science.gov (United States)

    Keavney, C.; Vernon, S.; Haven, V.

    1991-01-01

    Growing, by metalorganic chemical vapor deposition, a tunnel junction is described, which makes possible and ohmic back contact in an n-on-p InP solar cell on a silicon substrate. The junction between heavily doped layers of p-type InGaAs and n-type InP shows resistance low enough not to affect the performance of these cells. InP solar cells made on n-type Si substrates with this structure were measured with an efficiency of 9.9 percent. Controls using p-type GaAs substrates showed no significant difference in cell performance, indicating that the resistance associated with the tunnel junction is less than about 0.1 ohm/sq cm.

  19. Electron-beam-induced current at absorber back surfaces of Cu(In,Ga)Se{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kavalakkatt, J.; Abou-Ras, D., E-mail: daniel.abou-ras@helmholtz-berlin.de; Nichterwitz, M.; Caballero, R.; Rissom, T.; Unold, T.; Scheer, R.; Schock, H. W. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz. 1, 14109 Berlin (Germany); Haarstrich, J.; Ronning, C. [Institut für Festkörperphysik, Friedrich Schiller Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2014-01-07

    The present work reports on investigations of the influence of the microstructure on electronic properties of Cu(In,Ga)Se{sub 2} (CIGSe) thin-film solar cells. For this purpose, ZnO/CdS/CIGSe stacks of these solar cells were lifted off the Mo-coated glass substrates. The exposed CIGSe backsides of these stacks were investigated by means of electron-beam-induced current (EBIC) and cathodoluminescence (CL) measurements as well as by electron backscattered diffraction (EBSD). EBIC and CL profiles across grain boundaries (GBs), which were identified by EBSD, do not show any significant changes at Σ3 GBs. Across non-Σ3 GBs, on the other hand, the CL signals exhibit local minima with varying peak values, while by means of EBIC, decreased and also increased short-circuit current values are measured. Overall, EBIC and CL signals change across non-Σ3 GBs always differently. This complex situation was found in various CIGSe thin films with different [Ga]/([In]+[Ga]) and [Cu]/([In]+[Ga]) ratios. A part of the EBIC profiles exhibiting reduced signals across non-Σ3 GBs can be approximated by a simple model based on diffusion of generated charge carriers to the GBs.

  20. Electron-beam-induced current at absorber back surfaces of Cu(In,Ga)Se2 thin-film solar cells

    Science.gov (United States)

    Kavalakkatt, J.; Abou-Ras, D.; Haarstrich, J.; Ronning, C.; Nichterwitz, M.; Caballero, R.; Rissom, T.; Unold, T.; Scheer, R.; Schock, H. W.

    2014-01-01

    The present work reports on investigations of the influence of the microstructure on electronic properties of Cu(In,Ga)Se2 (CIGSe) thin-film solar cells. For this purpose, ZnO/CdS/CIGSe stacks of these solar cells were lifted off the Mo-coated glass substrates. The exposed CIGSe backsides of these stacks were investigated by means of electron-beam-induced current (EBIC) and cathodoluminescence (CL) measurements as well as by electron backscattered diffraction (EBSD). EBIC and CL profiles across grain boundaries (GBs), which were identified by EBSD, do not show any significant changes at Σ3 GBs. Across non-Σ3 GBs, on the other hand, the CL signals exhibit local minima with varying peak values, while by means of EBIC, decreased and also increased short-circuit current values are measured. Overall, EBIC and CL signals change across non-Σ3 GBs always differently. This complex situation was found in various CIGSe thin films with different [Ga]/([In]+[Ga]) and [Cu]/([In]+[Ga]) ratios. A part of the EBIC profiles exhibiting reduced signals across non-Σ3 GBs can be approximated by a simple model based on diffusion of generated charge carriers to the GBs.

  1. Optimization and performance of Space Station Freedom solar cells

    Science.gov (United States)

    Khemthong, S.; Hansen, N.; Bower, M.

    1991-01-01

    High efficiency, large area and low cost solar cells are the drivers for Space Station solar array designs. The manufacturing throughput, process complexity, yield of the cells, and array manufacturing technique determine the economics of the solar array design. The cell efficiency optimization of large area (8 x 8 m), dielectric wrapthrough contact solar cells are described. The results of the optimization are reported and the solar cell performance of limited production runs is reported.

  2. Process for high photocurrent in IBC solar cells

    Science.gov (United States)

    Sexton, F. W.; Garner, C. M.; Rodriguez, J. L.

    1982-11-01

    An interdigitated back contact solar cell fabrication process that yields cells with current-collection efficiencies in excess of 90% in n-type silicon is presented. This process maintains high bulk minority-carrier lifetime through the use of diffusion gettering steps and relatively low processing temperatures. Low front and back surface recombination velocities are achieved by growing thermal oxides on these surfaces followed by a forming gas anneal. Bulk lifetimes on the order of 350 microsec and front surface recombination velocities of less than 30 cm/sec are determined by comparing measured quantum efficiency data to calculated quantum efficiency using an analytical code which solves the transport equations in one dimension. These lifetimes are compared to values of 290-190 microsec measured for cells with and without a front surface n(+) layer, respectively. These were measured with a laser scanning technique using the 514 nm wavelength and are considered a lower limit to the lifetimes.

  3. Physics and technology of amorphous-crystalline heterostructure silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sark, Wilfried G.J.H.M. van [Utrecht Univ. (Netherlands). Copernicus Institute, Science Technology and Society; Roca, Francesco [Unita Tecnologie Portici, Napoli (Italy). ENEA - Agenzia Nazionale per le Nuove Tecnologie, l' Energia e lo Sviluppo Economico Sostenibile; Korte, Lars [Helmholtz-Zentrum Berlin fuer Materialien und Energie (Germany). Inst. Silizium-Photovoltaik

    2012-07-01

    The challenge of developing photovoltaic (PV) technology to a cost-competitive alternative for established energy sources can be achieved using simple, high-throughput mass-production compatible processes. Issues to be addressed for large scale PV deployment in large power plants or in building integrated applications are enhancing the performance of solar energy systems by increasing solar cell efficiency, using low amounts of materials which are durable, stable, and abundant on earth, and reducing manufacturing and installation cost. Today's solar cell multi-GW market is dominated by crystalline silicon (c-Si) wafer technology, however new cell concepts are entering the market. One very promising solar cell design to answer these needs is the silicon hetero-junction solar cell, of which the emitter and back surface field are basically produced by a low temperature growth of ultra-thin layers of amorphous silicon. In this design, amorphous silicon (a-Si:H) constitutes both ''emitter'' and ''base-contact/back surface field'' on both sides of a thin crystalline silicon wafer-base (c-Si) where the photogenerated electrons and holes are generated; at the same time, a Si:H passivates the c-Si surface. Recently, cell efficiencies above 23% have been demonstrated for such solar cells. In this book, the editors present an overview of the state-of-the-art in physics and technology of amorphous-crystalline heterostructure silicon solar cells. (orig.)

  4. Optimization of the front contact to minimize short-circuit current losses in CdTe thin-film solar cells

    Science.gov (United States)

    Kephart, Jason Michael

    With a growing population and rising standard of living, the world is in need of clean sources of energy at low cost in order to meet both economic and environmental needs. Solar energy is an abundant resource which is fundamentally adequate to meet all human energy needs. Photovoltaics are an attractive way to safely convert this energy to electricity with little to no noise, moving parts, water, or arable land. Currently, thin-film photovoltaic modules based on cadmium telluride are a low-cost solution with multiple GW/year commercial production, but have lower conversion efficiency than the dominant technology, crystalline silicon. Increasing the conversion efficiency of these panels through optimization of the electronic and optical structure of the cell can further lower the cost of these modules. The front contact of the CdTe thin-film solar cell is critical to device efficiency for three important reasons: it must transmit light to the CdTe absorber to be collected, it must form a reasonably passive interface and serve as a growth template for the CdTe, and it must allow electrons to be extracted from the CdTe. The current standard window layer material, cadmium sulfide, has a low bandgap of 2.4 eV which can block over 20% of available light from being converted to mobile charge carriers. Reducing the thickness of this layer or replacing it with a higher-bandgap material can provide a commensurate increase in device efficiency. When the CdS window is made thinner, a degradation in electronic quality of the device is observed with a reduction in open-circuit voltage and fill factor. One commonly used method to enable a thinner optimum CdS thickness is a high-resistance transparent (HRT) layer between the transparent conducting oxide electrode and window layer. The function of this layer has not been fully explained in the literature, and existing hypotheses center on the existence of pinholes in the window layer which are not consistent with observed results

  5. Cu(In,Ga)Se{sub 2} absorber thinning and the homo-interface model: Influence of Mo back contact and 3-stage process on device characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, E.; Arzel, L.; Tomassini, M.; Barreau, N., E-mail: nicolas.barreau@univ-nantes.fr [Institut des Matériaux Jean Rouxel (IMN)-UMR 6502, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Zabierowski, P. [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, PL 00-662 Warsaw (Poland); Fuertes Marrón, D. [Instituto de Energía Solar–ETSIT, Technical University of Madrid, Ciudad Universitaria s.n., 28040 Madrid (Spain)

    2014-08-21

    Thinning the absorber layer is one of the possibilities envisaged to further decrease the production costs of Cu(In,Ga)Se{sub 2} (CIGSe) thin films solar cell technology. In the present study, the electronic transport in submicron CIGSe-based devices has been investigated and compared to that of standard devices. It is observed that when the absorber is around 0.5 μm-thick, tunnelling enhanced interface recombination dominates, which harms cells energy conversion efficiency. It is also shown that by varying either the properties of the Mo back contact or the characteristics of 3-stage growth processing, one can shift the dominating recombination mechanism from interface to space charge region and thereby improve the cells efficiency. Discussions on these experimental facts led to the conclusions that 3-stage process implies the formation of a CIGSe/CIGSe homo-interface, whose location as well as properties rule the device operation; its influence is enhanced in submicron CIGSe based solar cells.

  6. Cu(In,Ga)Se2 absorber thinning and the homo-interface model: Influence of Mo back contact and 3-stage process on device characteristics

    Science.gov (United States)

    Leonard, E.; Arzel, L.; Tomassini, M.; Zabierowski, P.; Fuertes Marrón, D.; Barreau, N.

    2014-08-01

    Thinning the absorber layer is one of the possibilities envisaged to further decrease the production costs of Cu(In,Ga)Se2 (CIGSe) thin films solar cell technology. In the present study, the electronic transport in submicron CIGSe-based devices has been investigated and compared to that of standard devices. It is observed that when the absorber is around 0.5 μm-thick, tunnelling enhanced interface recombination dominates, which harms cells energy conversion efficiency. It is also shown that by varying either the properties of the Mo back contact or the characteristics of 3-stage growth processing, one can shift the dominating recombination mechanism from interface to space charge region and thereby improve the cells efficiency. Discussions on these experimental facts led to the conclusions that 3-stage process implies the formation of a CIGSe/CIGSe homo-interface, whose location as well as properties rule the device operation; its influence is enhanced in submicron CIGSe based solar cells.

  7. Amorphous silicon oxide layers for surface passivation and contacting of heterostructure solar cells of amorphous and crystalline silicon; Amorphe Siliziumoxidschichten zur Oberflaechenpassivierung und Kontaktierung von Heterostruktur-Solarzellen aus amorphen und kristallinem Silizium

    Energy Technology Data Exchange (ETDEWEB)

    Einsele, Florian

    2010-02-05

    films is dominated by the diffusion of atomic hydrogen being suitable for the saturation of interface defects. This shows in a distinct increase of the passivation quality of annealed films. The heterostructure back contact for solar cells on p-type c-Si consists of an undoped, full area passivation film, followed by a boron doped p-type contact layer. If highly doped, this layer generates a back surface field effect which decreases the recombination by reflecting minority charge carriers from the defect rich interface. An undoped passivation layer of a-Si:H improves the passivation by saturating interface defects. Effusion measurements on stacks of undoped and doped layers show an increase of the hydrogen diffusion in the undoped layer due to the presence of the doped layer. The doped layer shifts the Fermi level of the undoped layer towards the valence band edge. This shift increases the diffusion coefficient of hydrogen due to an effective reduction of the Si-H bond energy. As a consequence, the presence of the doped contact layer increases the mobility of atomic hydrogen in the passivation layer, with atomic hydrogen being necessary for the passivation of interface defects. The thickness of the passivation layer critically affects both the passivation and the electrical conductance of the back contact. Whereas the passivation quality steadily improves with increasing thickness, the conductance drops when exceeding a critical thickness in a range of 4 nm to 8 nm. Temperature dependent measurements yield a thermal activation of the conductance with an activation energy of E{sub A} {approx_equal} 0.5 eV, which is attributed to the valence band offset {Delta}E{sub V} between a-Si:H and c-Si. This high barrier requires a tunneling process for majority charge carriers and explains the abrupt decrease of conductance with increasing passivation layer thickness. Passivation layers of a-SiO{sub x}:H form a blocking junction on p-type c-Si, which is explained by an oxygen

  8. Understanding effects of TCO work function on the performance of organic solar cells by numerical simulation

    CERN Document Server

    Chen, Aqing; Shao, Qingyi; Ji, Zhenguo

    2016-01-01

    The influences of work function of transparent conducting oxides (TCO) on the per-formance of organic solar cells, including open circuit voltage, conversion efficiency and fill factor, has been simulated. It is obtained that for non-Ohmic contact the open circuit voltage and conversion efficiency increase monotonically with the TCO work function but keep constant for Ohmic contact. Fill factor decreases and increases with the electrode work function when the electrode work function is below and above a critical value (4.2 eV for TCO and 4.5 eV for back-contact), respectively. The results of this simulation are significant in the choice of TCO contacts to optimize organic planar heterojunction solar cells.

  9. Improved Performance of Electroplated CZTS Thin-Film Solar Cells with Bifacial Configuration

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Jie [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; Yu, Yue [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; Ke, Weijun [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; Li, Jian [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; Tan, Xinxuan [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; Wang, Zhiwei [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; National Renewable Energy Laboratory, Golden CO 80401 United States; Chu, Junhao [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, The Chinese Academy of Sciences, Shanghai 800081 China; Yan, Yanfa [Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States

    2016-07-11

    Annealing in S vapor greatly improves the performance of electroplated Cu2ZnSnS4 (CZTS) solar cells based on the bifacial configuration of Al-doped ZnO (AZO, front contact)/ZnO/CdS/CZTS/indium tin oxide (ITO, back contact), as compared to H2S annealing in our previous works. S-vapor annealing does not cause severe damage to the conductivity of the ITO back contact. The highest device efficiency of 5.8% was reached under 1 sun illumination from the AZO side. The well-preformed devices based on the ITO back contact demonstrate smaller series resistances and better fill factors, as compared to our substrate-type devices using Mo back contacts. An interfacial reaction at the ITO back contact has been revealed in experiments, which contributes to the formation of SnO2-enriched interfacial layer and diffusion of In from ITO into CZTS through the Sn sites. Incorporation of In does not significantly change the optical and structural properties or the grain size of CZTS absorbers.

  10. 交叉式背接触型光伏电池中国专利现状及其发展趋势%Current Status and Development Trend of ChinesePatents of Interdigitated Back Contact Photovoltaic Cell

    Institute of Scientific and Technical Information of China (English)

    刘国梁; 李晓明

    2016-01-01

    光伏电池是近年来节能减排技术的代表,而交叉式背接触型光伏电池(IBC,Interdigitated back contact,IBC)则是近年来光伏电池研究的热点领域.本文通过对交叉式背接触型光伏电池技术领域的专利进行研究,分析了中国专利申请的趋势、区域分布以及主要申请人等情况,以期为行业、研究机构以及政府相关部门提供参考.

  11. The properties of CdTe solar cells with ZnTe/ZnTe: Cu buffer layers

    Institute of Scientific and Technical Information of China (English)

    Song Huijin; Zheng Jiagui; Feng Lianghuan; Yan Qiang; Lei Zhi; Wu Lili; Zhang Jingquan; Li Wei; Li Bing

    2008-01-01

    CdS/CdTe solar cells with ZnTe/ZnTe:Cu buffer layers were fabricated and studied. The energy band structure of it was analyzed. The C-V, I-V characteristics and the spectral response show that the ZnTe/ZnTe:Cu buffer layers improve the back contact characteristic properties, the diode characteristics of the forward junction and the short-wave spectral response of the CdTe solar cells. The ZnTe/ZnTe:Cu buffer layers affect the solar cell conversion efficiency and its fill factor.

  12. Laser processing of solar cells with anti-reflective coating

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Gabriel; Smith, David D.; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2016-02-16

    Contact holes of solar cells are formed by laser ablation to accommodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thicknesses.

  13. Rectenna solar cells

    CERN Document Server

    Moddel, Garret

    2013-01-01

    Rectenna Solar Cells discusses antenna-coupled diode solar cells, an emerging technology that has the potential to provide ultra-high efficiency, low-cost solar energy conversion. This book will provide an overview of solar rectennas, and provide thorough descriptions of the two main components: the diode, and the optical antenna. The editors discuss the science, design, modeling, and manufacturing of the antennas coupled with the diodes. The book will provide concepts to understanding the challenges, fabrication technologies, and materials required to develop rectenna structures. Written by e

  14. The role of high work-function metallic nanodots on the performance of a-Si:H solar cells: offering ohmic contact to light trapping.

    Science.gov (United States)

    Kim, Jeehwan; Abou-Kandil, Ahmed; Fogel, Keith; Hovel, Harold; Sadana, Devendra K

    2010-12-28

    Addition of carbon into p-type "window" layers in hydrogenated amorphous silicon (a-Si:H) solar cells enhances short circuit currents and open circuit voltages by a great deal. However, a-Si:H solar cells with high carbon-doped "window" layers exhibit poor fill factors due to a Schottky barrier-like impedance at the interface between a-SiC:H windows and transparent conducting oxides (TCO), although they show maximized short circuit currents and open circuit voltages. The impedance is caused by an increasing mismatch between the work function of TCO and that of p-type a-SiC:H. Applying ultrathin high-work-function metals at the interface between the two materials results in an effective lowering of the work function mismatch and a consequent ohmic behavior. If the metal layer is sufficiently thin, then it forms nanodots rather than a continuous layer which provides light-scattering effect. We demonstrate 31% efficiency enhancement by using high-work-function materials for engineering the work function at the key interfaces to raise fill factors as well as photocurrents. The use of metallic interface layers in this work is a clear contrast to previous work where attempts were made to enhance the photocurrent using plasmonic metal nanodots on the solar cell surface.

  15. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.

    2016-11-30

    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  16. Overcoming degradation mechanisms in CdTe solar cells: First annual report, August 1998--August 1999

    Energy Technology Data Exchange (ETDEWEB)

    Cahen, D.; Gartsman, K.; Hodes, G.; Rotlevy, O.; Visoly-Fisher, I,; Dobson, K.

    2000-02-28

    The authors have studied the importance of chemical processes for the stability of CdTe solar cells, in particular, diffusion in the ohmic contact/absorber junction regions. Both whole cells and test systems containing only the ohmic contact and the absorber are used. They found several experimental methods to be useable tools to follow the effects of impurity diffusion on the CdTe grain boundaries, grain bulk, and surface. In addition, they have explored alternative contacting schemes. The first year of activities led to the following tentative conclusions: Grain boundaries in CdTe/CdS cells are NOT fully passivated and are expected to be electrically active; There appears to be fast ionic diffusion in the vicinity of the Cu/HgTe/graphite back-contact, possibly enhanced by grain boundary diffusion; The macroscopic response to stress is different for cells with identical back-contact, but from different manufacturers. Different factors and/or different reactions to identical factors are possibly at work here; and Ni-P appears to be a promising back-contact material.

  17. Superior light trapping in thin film silicon solar cells through nano imprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Soppe, W.J.; Dorenkamper, M.S.; Schropp, R.E.I.; Pex, P.P.A.C.

    2013-10-15

    ECN and partners have developed a fabrication process based on nanoimprint lithography (NIL) of textures for light trapping in thin film solar cells such as thin-film silicon, OPV, CIGS and CdTe. The process can be applied in roll-to-roll mode when using a foil substrate or in roll-to-plate mode when using a glass substrate. The lacquer also serves as an electrically insulating layer for cells if steel foil is used as substrate, to enable monolithic series interconnection. In this paper we will show the superior light trapping in thin film silicon solar cells made on steel foil with nanotextured back contacts. We have made single junction a-Si and {mu}c-Si and a-Si/{mu}c-Si tandem cells, where we applied several types of nano-imprints with random and periodic structures. We will show that the nano-imprinted back contact enables more than 30% increase of current in comparison with non-textured back contacts and that optimized periodic textures outperform state-of-the-art random textures. For a-Si cells we obtained Jsc of 18 mA/cm{sup 2} and for {mu}c-Si cells more than 24 mA/cm{sup 2}. Tandem cells with a total Si absorber layer thickness of only 1350 nm have an initial efficiency of 11%.

  18. Well-Controlled Dielectric Nanomeshes by Colloidal Nanosphere Lithography for Optoelectronic Enhancement of Ultrathin Cu(In,Ga)Se2 Solar Cells.

    Science.gov (United States)

    Yin, Guanchao; Song, Min; Duan, Shengkai; Manley, Phillip; Greiner, Dieter; Kaufmann, Christian A; Schmid, Martina

    2016-11-23

    Ultrathin Cu(In,Ga)Se2 (CIGSe) solar cells pose challenges of incomplete absorption and back contact recombination. In this work, we applied the simple collodial nanosphere lithography and fabricated 2D SiO2 nanomeshes (NMs), which simultaneously benefit ultrathin CIGSe solar cells electrically and optically. Electrically, the NMs are capable of passivating the back contact recombination and increasing the minimum bandgap of absorbers. Optically, the parasitic absorption in Mo as a main optical loss is reduced. Consequently, the SiO2 NMs give rise to an increase of 3.5 mA/cm(2) in short circuit current density (Jsc) and of 57 mV in open circuit voltage increase (Voc), leading to an absolute efficiency enhancement as high as 2.6% (relatively 30%) for CIGSe solar cells with an absorber thickness of only 370 nm and a steep back Ga/[Ga + In] grading.

  19. Achievements and Challenges of CdS/CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhou Fang

    2011-01-01

    Full Text Available Thin film CdS/CdTe has long been regarded as one promising choice for the development of cost-effective and reliable solar cells. Efficiency as high as 16.5% has been achieved in CdS/CdTe heterojunction structure in laboratory in 2001, and current techniques for CdS/CdTe solar cells gradually step toward commercialization. This paper reviews some novel techniques mainly within two years to solve this problem from aspects of promotion of fabrication technology, structural modification, and choice of back contact materials.

  20. Core-shell ITO/ZnO/CdS/CdTe nanowire solar cells

    Science.gov (United States)

    Williams, B. L.; Taylor, A. A.; Mendis, B. G.; Phillips, L.; Bowen, L.; Major, J. D.; Durose, K.

    2014-02-01

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was η = 2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (ϕB = 0.52 eV) and low shunt resistances (RSH < 500 Ω.cm2).

  1. Low-high junction theory applied to solar cells

    Science.gov (United States)

    Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

    1974-01-01

    Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open-circuit voltage and improved radiation resistance. Several analytical models for open-circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero surface recombination velocity (SRV) case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells.

  2. Dye sensitized solar cells.

    Science.gov (United States)

    Wei, Di

    2010-03-16

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO(2), ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed.

  3. Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Di Wei

    2010-03-01

    Full Text Available Dye sensitized solar cell (DSSC is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO2, ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed.

  4. Quantum dot solar cells

    CERN Document Server

    Wu, Jiang

    2013-01-01

    The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou

  5. Plasmonic Dye-Sensitized Solar Cells

    KAUST Repository

    Ding, I-Kang

    2010-12-14

    This image presents a scanning electron microscopy image of solid state dye-sensitized solar cell with a plasmonic back reflector, overlaid with simulated field intensity plots when monochromatic light is incident on the device. Plasmonic back reflectors, which consist of 2D arrays of silver nanodomes, can enhance absorption through excitation of plasmonic modes and increased light scattering, as reported by Michael D. McGehee, Yi Cui, and co-workers.

  6. Solar cell radiation handbook

    Science.gov (United States)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  7. Black Silicon Solar Cells with Black Ribbons

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io;

    2016-01-01

    We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies...... in the range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....

  8. Semiconductors for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, H.J. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering)

    1991-01-01

    This review covers the historical background of the solar cell development, the physical principles of photovoltaic energy conversion, technology of solar cell devices and the structural and physical properties of lattice defects in semiconductors. Single crystal and polycrystalline silicon, single crystal and epitaxial gallium arsenide, polycrystalline thin films and amorphous thin films are discussed in detail. Semiconductors have emerged as the most promising group of materials which can convert sunlight directly into electrical energy. They utilize the fundamental physical process that a photon that penetrates into the semiconductor and is absorbed can generate electron-hole pairs. Because of their opposite charges they can be separated by an internal electrical field and collected at two contacts thus giving rise to a voltage and photocurrent if the two contacts are connected externally. In semiconductors internal electric fields occur in connection with space charges at junctions and a variety of technological concepts are used to produce a built-in voltage. The most widely used device principle is the operation of a solar cell as a diode or p-n junction. Alternative concepts are heterojunction devices where the materials on either side of the junction are different semiconductors. (author).

  9. Advanced nanostructured materials and their application for improvement of sun-light harvesting and efficiency of solar cells

    Science.gov (United States)

    Dimova-Malinovska, D.

    2016-02-01

    This review describes the application of different nanostructured materials in solar cells technology for improvement of sun-light harvesting and their efficiency. Several approaches have recently been proposed to increase the efficiency of solar cells above the theoretical limit which are based on a “photon management” concept that employs such phenomena as: (i) down-conversion, and (ii) surface plasmon resonance effect (iii) decreasing of the loss due to the reflection of the radiation, (iv) increasing of the reflection from the back contact, v) increasing of the effective solar cells surface, etc. The results demonstrate the possibility for to increasing of light harvesting, short circuit current and efficiency by application of nanomaterials in thin film and hetero-junction (HJ) solar cells. The first promising results allow an expectation for application of advanced nanomaterials in the 3d generation solar cells.

  10. 17% mc-Si solar cell efficiency using completely in-line processing with improved texturing and screen-printed contacts on lowly doped emitters

    Energy Technology Data Exchange (ETDEWEB)

    Weeber, A.W.; Granek, F.J.; Hoornstra, J.; Koppes, M.; Kossen, E.J.; Rieffe, H.C.; Romijn, I.G.; Tool, C.J.J. [ECN Solar Energy, Petten (Netherlands)

    2005-06-01

    A simple in-line industrial process has been developed for commercial multicrystalline silicon (mc-Si) which results in solar cells with an average efficiency of 16.5%. The best cell has an independently confirmed efficiency of 17.0%. These are the highest efficiencies reported for full inline processing. The process consists of an acidic etch for texturing, homogeneous spin-on phosphorous and a belt furnace emitter diffusion, MicroWave PECVD of silicon nitride layers, and screen-printed metallization. The silicon nitride layer serves as antireflection coating and provides bulk and surface passivation. Detailed characterization and computer simulation show that implementation of already proven technologies in the current cell processing can lead to efficiencies around 18%.

  11. Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

    OpenAIRE

    Hamid Fardi; Fatima Buny

    2013-01-01

    Device simulation is used to investigate the current-voltage efficiency performance in CdTe/CdS photovoltaic solar cell. The role of several limiting factors such as back contact Schottky barrier and its relationship to the doping density and layer thickness is examined. The role of surface recombination velocity at back contact interface and extended CdTe layer is included. The base CdS/CdTe experimental device used in this study shows an efficiency of 16-17%. Simulation analysis is used to ...

  12. Process development for single-crystal silicon solar cells

    Science.gov (United States)

    Bohra, Mihir H.

    Solar energy is a viable, rapidly growing and an important renewable alternative to other sources of energy generation because of its abundant supply and low manufacturing cost. Silicon still remains the major contributor for manufacturing solar cells accounting for 80% of the market share. Of this, single-crystal solar cells account for half of the share. Laboratory cells have demonstrated 25% efficiency; however, commercial cells have efficiencies of 16% - 20% resulting from a focus on implementation processes geared to rapid throughput and low cost, thereby reducing the energy pay-back time. An example would be the use of metal pastes which dissolve the dielectric during the firing process as opposed to lithographically defined contacts. With current trends of single-crystal silicon photovoltaic (PV) module prices down to 0.60/W, almost all other PV technologies are challenged to remain cost competitive. This presents a unique opportunity in revisiting the PV cell fabrication process and incorporating moderately more expensive IC process practices into PV manufacturing. While they may drive the cost toward a 1/W benchmark, there is substantial room to "experiment", leading to higher efficiencies which will help maintain the overall system cost. This work entails a turn-key process designed to provide a platform for rapid evaluation of novel materials and processes. A two-step lithographic process yielding a baseline 11% - 13% efficient cell is described. Results of three studies have shown improvements in solar cell output parameters due to the inclusion of a back-surface field implant, a higher emitter doping and also an additional RCA Clean.

  13. Transparent Conductive Oxides for Thin-Film Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, J.

    2005-04-25

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150C and 350C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the

  14. Transparent conductive oxides for thin-film silicon solar cells

    Science.gov (United States)

    Löffler, J.

    2005-04-01

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150 º C and 350 º C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the cells

  15. Nanowire-based All Oxide Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

    2008-12-07

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  16. Welded solar cell interconnection

    Science.gov (United States)

    Stofel, E. J.; Browne, E. R.; Meese, R. A.; Vendura, G. J.

    1982-01-01

    The efficiency of the welding of solar-cell interconnects is compared with the efficiency of soldering such interconnects, and the cases in which welding may be superior are examined. Emphasis is placed on ultrasonic welding; attention is given to the solar-cell welding machine, the application of the welding process to different solar-cell configurations, producibility, and long-life performance of welded interconnects. Much of the present work has been directed toward providing increased confidence in the reliability of welding using conditions approximating those that would occur with large-scale array production. It is concluded that there is as yet insufficient data to determine which of three methods (soldering, parallel gap welding, and ultrasonic welding) provides the longest-duration solar panel life.

  17. High-flux solar furnace processing of crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S.; Pitts, J.R. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Menna, P. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)]|[ENEA-Centro Ricerche Fotovoltaiche, Portici 80055 (Italy); Landry, M.D. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Gee, J.M. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)]|[Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Ciszek, T.F. [National Renewable Energy Laboratory, Golden, Colorado, 80401 (United States)

    1997-02-01

    We studied the processing of crystalline-silicon solar cells using a 10-kW, high-flux solar furnace (HFSF). Major findings of this study include: (1) hydrogenated amorphous silicon films deposited on glass substrates can be converted to microcrystalline silicon by solid-phase crystallization in 5 seconds or less in the HFSF; (2) the presence of concentrated sunlight enhances the diffusion of phosphorus into silicon from a spin-on dopant source; (3) the combination of a porous-silicon surface layer and photo-enhanced impurity diffusion is very effective in gettering impurities from a metallurgical-grade silicon wafer or thin-layer silicon deposited using liquid-phase epitaxy; (4) a 14.1{percent}-efficient crystalline-silicon solar cell with an area of 4.6cm{sup 2} was fabricated using the HFSF for simultaneous diffusion of front n{sup +}-p and back p-p{sup +} junctions; and (5) we have shown that the HFSF can be used to texture crystalline-silicon surfaces and to anneal metal contacts printed on a silicon solar cell. {copyright} {ital 1997 American Institute of Physics.}

  18. High-flux solar furnace processing of crystalline silicon solar cells

    Science.gov (United States)

    Tsuo, Y. S.; Pitts, J. R.; Menna, P.; Landry, M. D.; Gee, J. M.; Ciszek, T. F.

    1997-02-01

    We studied the processing of crystalline-silicon solar cells using a 10-kW, high-flux solar furnace (HFSF). Major findings of this study include: (1) hydrogenated amorphous silicon films deposited on glass substrates can be converted to microcrystalline silicon by solid-phase crystallization in 5 seconds or less in the HFSF; (2) the presence of concentrated sunlight enhances the diffusion of phosphorus into silicon from a spin-on dopant source; (3) the combination of a porous-silicon surface layer and photo-enhanced impurity diffusion is very effective in gettering impurities from a metallurgical-grade silicon wafer or thin-layer silicon deposited using liquid-phase epitaxy; (4) a 14.1%-efficient crystalline-silicon solar cell with an area of 4.6 cm2 was fabricated using the HFSF for simultaneous diffusion of front n+-p and back p-p+ junctions; and (5) we have shown that the HFSF can be used to texture crystalline-silicon surfaces and to anneal metal contacts printed on a silicon solar cell.

  19. Towards upconversion for amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    de Wild, J.; Rath, J.K.; Schropp, R.E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Nanophotonics, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Meijerink, A. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Condensed Matter and Interfaces, P.O. Box 80000, 3508 TA Utrecht (Netherlands); van Sark, W.G.J.H.M. [Utrecht University, Copernicus Institute for Sustainable Development and Innovation, Science, Technology and Society, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)

    2010-11-15

    Upconversion of subbandgap light of thin film single junction amorphous silicon solar cells may enhance their performance in the near infrared (NIR). In this paper we report on the application of the NIR-vis upconverter {beta}-NaYF{sub 4}:Yb{sup 3+}(18%) Er{sup 3+}(2%) at the back of an amorphous silicon solar cell in combination with a white back reflector and its response to infrared irradiation. Current-voltage measurements and spectral response measurements were done on experimental solar cells. An enhancement of 10 {mu}A/cm{sup 2} was measured under illumination with a 980 nm diode laser (10 mW). A part of this was due to defect absorption in localized states of the amorphous silicon. (author)

  20. Test and Simulation of Drain-back Solar DHW System from SolarNor AS. Norway

    DEFF Research Database (Denmark)

    Qin, Lin

    1997-01-01

    A drain-back solar domestic hot water (DHW) system from SolarNor AS, Norway was built and tested in the laboratory’s test facility. The thermal performance of the system has been measured for the period from May to November 1997. A detailed simulation model have been developed for predicting...... the annually performance of the system. The simulation model was modified by means of comparison of the simulation results with the measurements. By using this simulation model the yearly thermal performance of the system have been investigated with the Danish Test Reference Year as the input weather data....

  1. Metallic Inks for Solar Cells: Cooperative Research and Development Final Report, CRADA Number CRD-10-370

    Energy Technology Data Exchange (ETDEWEB)

    van Hest, M.

    2013-04-01

    This document describes the statement of work for National Renewable Energy Laboratory (NREL) as a subcontractor for Applied Nanotech, Inc. (ANI) for the Phase II SBIR contract with the Department of Energy to build silicon solar cells using non-contact printed, nanoparticle-based metallic inks. The conductive inks are based upon ANI's proprietary method for nanoparticle dispersion. The primary inks under development are aluminum for silicon solar cell back plane contacts and copper for top interdigitated contacts. The current direction of silicon solar cell technology is to use thinner silicon wafers. The reduction in wafer thickness reduces overall material usage and can increase efficiency. These thin silicon wafers are often very brittle and normal methods used for conductive feed line application, such as screen-printing, are detrimental. The Phase II program will be focused on materials development for metallic inks that can be applied to a silicon solar cell using non-contact methods. Uniform BSF (Back Surface Field) formation will be obtained by optimizing ink formulation and curing conditions to improve cell efficiency.

  2. Heterogeneous integration of InGaAs nanowires on the rear surface of Si solar cells for efficiency enhancement.

    Science.gov (United States)

    Shin, Jae Cheol; Mohseni, Parsian K; Yu, Ki Jun; Tomasulo, Stephanie; Montgomery, Kyle H; Lee, Minjoo L; Rogers, John A; Li, Xiuling

    2012-12-21

    We demonstrate energy-conversion-efficiency (η) enhancement of silicon (Si) solar cells by the heterogeneous integration of an In(x)Ga(1-x)As nanowire (NW) array on the rear surface. The NWs are grown via a catalyst-free, self-assembled method on Si(111) substrates using metalorganic chemical vapor deposition (MOCVD). Heavily p-doped In(x)Ga(1-x)As (x ≈ 0.7) NW arrays are utilized as not only back-reflectors but also low bandgap rear-point-contacts of the Si solar cells. External quantum efficiency of the hybrid In(x)Ga(1-x)As NW-Si solar cell is increased over the entire solar response wavelength range; and η is enhanced by 36% in comparison to Si solar cells processed under the same condition without the NWs.

  3. Asymmetric tandem organic solar cells

    Science.gov (United States)

    Howells, Thomas J.

    Organic photovoltaics (OPVs) is an area that has attracted much attention recently as a potential low cost, sustainable source of energy with a good potential for full-scale commercialisation. Understanding the factors that determine the efficiency of such cells is therefore a high priority, as well as developing ways to boost efficiency to commercially-useful levels. In addition to an intensive search for new materials, significant effort has been spent on ways to squeeze more performance out of existing materials, such as multijunction cells. This thesis investigates double junction tandem cells in the context of small molecule organic materials. . Two different organic electron donor materials, boron subphthalocyanine chloride (SubPc) and aluminium phthalocyanine chloride (ClAlPc) were used as donors in heterojunctions with C60 to create tandem cells for this thesis. These materials have been previously used for solar cells and the absorption spectra of the donor materials complement each other, making them good candidates for tandem cell architectures. The design of the recombination layer between the cells is considered first, with silver nanoparticles demonstrated to work well as recombination centres for charges from the front and back sub-cells, necessary to avoid a charge build-up at the interface. The growth conditions for the nanoparticles are optimised, with the tandem cells outperforming the single heterojunction architecture. Optical modelling is considered as a method to improve the understanding of thin film solar cells, where interference effects from the reflective aluminium electrode are important in determining the magnitude of absorption a cell can achieve. The use of such modelling is first demonstrated in hybrid solar cells based on a SubPc donor with a titanium oxide (TiOx) acceptor; this system is ideal for observing the effects of interference as only the SubPc layer has significant absorption. The modelling is then applied to tandem cells

  4. Organic-inorganic halide perovskite/crystalline silicon four-terminal tandem solar cells.

    Science.gov (United States)

    Löper, Philipp; Moon, Soo-Jin; de Nicolas, Sílvia Martín; Niesen, Bjoern; Ledinsky, Martin; Nicolay, Sylvain; Bailat, Julien; Yum, Jun-Ho; De Wolf, Stefaan; Ballif, Christophe

    2015-01-21

    Tandem solar cells constructed from a crystalline silicon (c-Si) bottom cell and a low-cost top cell offer a promising way to ensure long-term price reductions of photovoltaic modules. We present a four-terminal tandem solar cell consisting of a methyl ammonium lead triiodide (CH3NH3PbI3) top cell and a c-Si heterojunction bottom cell. The CH3NH3PbI3 top cell exhibits broad-band transparency owing to its design free of metallic components and yields a transmittance of >55% in the near-infrared spectral region. This allows the generation of a short-circuit current density of 13.7 mA cm(-2) in the bottom cell. The four-terminal tandem solar cell yields an efficiency of 13.4% (top cell: 6.2%, bottom cell: 7.2%), which is a gain of 1.8%abs with respect to the reference single-junction CH3NH3PbI3 solar cell with metal back contact. We employ the four-terminal tandem solar cell for a detailed investigation of the optical losses and to derive guidelines for further efficiency improvements. Based on a power loss analysis, we estimate that tandem efficiencies of ∼28% are attainable using an optically optimized system based on current technology, whereas a fully optimized, ultimate device with matched current could yield up to 31.6%.

  5. Plastic solar cell interface and morphological characterization

    Science.gov (United States)

    Guralnick, Brett W.

    Plastic solar cell research has become an intense field of study considering these devices may be lightweight, flexible and reduce the cost of photovoltaic devices. The active layer of plastic solar cells are a combination of two organic components which blend to form an internal morphology. Due to the poor electrical transport properties of the organic components it is important to understand how the morphology forms in order to engineer these materials for increased efficiency. The focus of this thesis is a detailed study of the interfaces between the plastic solar cell layers and the morphology of the active layer. The system studied in detail is a blend of P3HT and PCBM that acts as the primary absorber, which is the electron donor, and the electron acceptor, respectively. The key morphological findings are, while thermal annealing increases the crystallinity parallel to the substrate, the morphology is largely unchanged following annealing. The deposition and mixing conditions of the bulk heterojunction from solution control the starting morphology. The spin coating speed, concentration, solvent type, and solution mixing time are all critical variables in the formation of the bulk heterojunction. In addition, including the terminals or inorganic layers in the analysis is critical because the inorganic surface properties influence the morphology. Charge transfer in the device occurs at the material interfaces, and a highly resistive transparent conducting oxide layer limits device performance. It was discovered that the electron blocking layer between the transparent conducting oxide and the bulk heterojunction is compromised following annealing. The electron acceptor material can diffuse into this layer, a location which does not benefit device performance. Additionally, the back contact deposition is important since the organic material can be damaged by the thermal evaporation of Aluminum, typically used for plastic solar cells. Depositing a thin thermal and

  6. Microsystems enabled photovoltaics: 14.9% efficient 14 {mu}m thick crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Campa, Jose L. [Sandia National Laboratories, M.S. 1080, 1515 Eubank Blvd. SE, Albuquerque, NM 87123 (United States); University of Texas at El Paso, Department of Electrical and Computer Engineering, 500 West University Avenue, El Paso, TX 79968 (United States); Okandan, Murat; Resnick, Paul J.; Clews, Peggy; Pluym, Tammy; Grubbs, Robert K.; Gupta, Vipin P.; Nielson, Gregory N. [Sandia National Laboratories, M.S. 1080, 1515 Eubank Blvd. SE, Albuquerque, NM 87123 (United States); Zubia, David [University of Texas at El Paso, Department of Electrical and Computer Engineering, 500 West University Avenue, El Paso, TX 79968 (United States)

    2011-02-15

    Crystalline silicon solar cells 10-15 times thinner than traditional commercial c-Si cells with 14.9% efficiency are presented with modeling, fabrication, and testing details. These cells are 14 {mu}m thick, 250 {mu}m wide, and have achieved 14.9% solar conversion efficiency under AM 1.5 spectrum. First, modeling results illustrate the importance of high-quality passivation to achieve high efficiency in thin silicon, back contacted solar cells. Then, the methodology used to fabricate these ultra thin devices by means of established microsystems processing technologies is presented. Finally, the optimization procedure to achieve high efficiency as well as the results of the experiments carried out with alumina and nitride layers as passivation coatings are discussed. (author)

  7. Plastic Schottky-barrier solar cells

    Science.gov (United States)

    Waldrop, J.R.; Cohen, M.J.

    1981-12-30

    A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

  8. Optoelectronics of solar cells

    CERN Document Server

    Smestad, Greg P

    2002-01-01

    With concerns about worldwide environmental security, global warming, and climate change due to emissions of carbon dioxide from the burning of fossil fuels, it is desirable to have a wide range of energy technologies in a nation's portfolio. Photovoltaics, or solar cells, are a viable option as a nonpolluting renewable energy source. This text is designed to be an overview of photovoltaic solar cells for those in the fields of optics and optical engineering, as well as those who are interested in energy policy, economics, and the requirements for efficient photo-to-electric energy conversion.

  9. Characterization of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Haerkoenen, J.; Tuominen, E.; Nybergh, K.; Ezer, Y.; Yli-Koski, M.; Sinkkonen, J. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Electrical and Communications Engineering

    1998-10-01

    Photovoltaic research in the Electron Physics Laboratory started in 1993, when laboratory joined the national TEKES/NEMO 2 research program. Since the beginning of the project, characterization as well as experimentally orientated development of the fabrication process of the solar cells were carried out parallery. The process development research started by the initiatives of the Finnish industry. At the moment a large amount of the laboratory personnel works on solar cell research and the financing comes mainly from external projects. The funding for the research has come from TEKES, Ministry of Education, Finnish Academy, GETA graduate school, special equipment grants of the university, and from the laboratory

  10. Improvement of silicon nanowire solar cells made by metal catalyzed electroless etching and nano imprint lithography

    Science.gov (United States)

    Chen, Junyi; Subramani, Thiyagu; Jevasuwan, Wipakorn; Fukata, Naoki

    2017-04-01

    Silicon nanowires were fabricated by metal catalyzed electroless etching (MCEE) and nano imprint lithography (NIL), then a shell p-type layer was grown by thermal chemical vapor deposition (CVD) techniques. To reduce back surface recombination and also to activate the dopant, we used two techniques, back surface field (BSF) treatment and rapid thermal annealing (RTA), to improve device performance. In this study, we investigated BSF and RTA treatments in silicon nanowire solar cells, and improved the device performance and efficiency from 4.1 to 7.4% (MCEE device) and from 1.1 to 6.6% (NIL device) after introducing BSF and RTA treatments. Moreover, to achieve better metal contact without sacrificing the reflectance after the shell formation, the selective-area etching method was investigated. Finally, after combining all processes, silicon nanowire solar cells fabricated via the MCEE process exhibited 8.7% efficiency.

  11. Measurement Back-Action in Quantum Point-Contact Charge Sensing

    Directory of Open Access Journals (Sweden)

    Bruno Küng

    2010-06-01

    Full Text Available Charge sensing with quantum point-contacts (QPCs is a technique widely used in semiconductor quantum-dot research. Understanding the physics of this measurement process, as well as finding ways of suppressing unwanted measurement back-action, are therefore both desirable. In this article, we present experimental studies targeting these two goals. Firstly, we measure the effect of a QPC on electron tunneling between two InAs quantum dots, and show that a model based on the QPC’s shot-noise can account for it. Secondly, we discuss the possibility of lowering the measurement current (and thus the back-action used for charge sensing by correlating the signals of two independent measurement channels. The performance of this method is tested in a typical experimental setup.

  12. Nanoimprinted polymer solar cell.

    Science.gov (United States)

    Yang, Yi; Mielczarek, Kamil; Aryal, Mukti; Zakhidov, Anvar; Hu, Walter

    2012-04-24

    Among the various organic photovoltaic devices, the conjugated polymer/fullerene approach has drawn the most research interest. The performance of these types of solar cells is greatly determined by the nanoscale morphology of the two components (donor/acceptor) and the molecular orientation/crystallinity in the photoactive layer. A vertically bicontinuous and interdigitized heterojunction between donor and acceptor has been regarded as one of the ideal structures to enable both efficient charge separation and transport. Synergistic control of polymer orientation in the nanostructured heterojunction is also critical to improve the performance of polymer solar cells. Nanoimprint lithography has emerged as a new approach to simultaneously control both the heterojunction morphology and polymer chains in organic photovoltaics. Currently, in the area of nanoimprinted polymer solar cells, much progress has been achieved in the fabrication of nanostructured morphology, control of molecular orientation/crystallinity, deposition of acceptor materials, patterned electrodes, understanding of structure-property correlations, and device performance. This review article summarizes the recent studies on nanoimprinted polymer solar cells and discusses the outstanding challenges and opportunities for future work.

  13. NASA Facts, Solar Cells.

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    The design and function of solar cells as a source of electrical power for unmanned space vehicles is described in this pamphlet written for high school physical science students. The pamphlet is one of the NASA Facts Science Series (each of which consists of four pages) and is designed to fit in the standard size three-ring notebook. Review…

  14. Mathematical Modeling of Contact Resistance in Silicon Photovoltaic Cells

    KAUST Repository

    Black, J. P.

    2013-10-22

    In screen-printed silicon-crystalline solar cells, the contact resistance of a thin interfacial glass layer between the silicon and the silver electrode plays a limiting role for electron transport. We analyze a simple model for electron transport across this layer, based on the driftdiffusion equations. We utilize the size of the current/Debye length to conduct asymptotic techniques to simplify the model; we solve the model numerically to find that the effective contact resistance may be a monotonic increasing, monotonic decreasing, or nonmonotonic function of the electron flux, depending on the values of the physical parameters. © 2013 Society for Industrial and Applied Mathematics.

  15. Degradation of CIGS solar cells

    NARCIS (Netherlands)

    Theelen, M.J.

    2015-01-01

    Thin film CIGS solar cells and individual layers within these solar cells have been tested in order to assess their long term stability. Alongside with the execution of standard tests, in which elevated temperatures and humidity levels are used, the solar cells have also been exposed to a combinatio

  16. Preparation of conjugated polymer-based composite thin film for application in solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yang-Yen, E-mail: yyyu@mail.mcut.edu.tw [Department of Materials Engineering, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Center for Thin Film Technologies and Applications, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Chien, Wen-Chen [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Ko, Yu-Hsin [Department of Materials Engineering, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Chen, Chih-Ping [Department of Materials Engineering, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan (China); Chang, Chao-Ching [Department of Chemical and Materials Engineering, Tamkang University, 151, Yingzhuan Rd., Tamsui Dist., New Taipei City 25137, Taiwan (China)

    2015-06-01

    This paper reports on the enhanced cell efficiency of structures and properties of regioregular poly(3-hexylthiophene) (P3HT)/multiwalled carbon nanotube (MWNT) hybrid materials. The prepared hybrid materials were characterized using ultraviolet–visible absorption spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Different concentrations of these MWNTs were suspended in polymer solutions and spin-cast onto indium tin oxide (ITO) glass. Solar cells with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) /P3HT:MWNTs/aluminum were then produced using evaporated aluminum as the back contact. The results showed that the ratio of P3HT to MWNTs considerably influenced the performance of the fabricated solar cells. The efficiency of the solar cells increased with the ratio of carbon nanotubes. Monochromatic incident photon-to-electron conversion efficiency analysis was performed and the results indicated that at the optimal P3HT/MWNTs ratio (= 1/1), the solar cells demonstrated a high-quality conversion of 2.16% with a fill factor of 42.22%, an open circuit voltage of 0.56 V, and a short circuit current of 9.12 mA/cm{sup 2}. - Highlights: • Solar cells ITO/PEDOT:PSS(DMSO)/P3HT:MWNT/Al were fabricated. • Optimal ratio of P3HT to MWNT was investigated. • Solar cell with 2.16% efficiency was obtained.

  17. Recent Developments of Flexible CdTe Solar Cells on Metallic Substrates: Issues and Prospects

    Directory of Open Access Journals (Sweden)

    M. M. Aliyu

    2012-01-01

    Full Text Available This study investigates the key issues in the fabrication of CdTe solar cells on metallic substrates, their trends, and characteristics as well as effects on solar cell performance. Previous research works are reviewed while the successes, potentials, and problems of such technology are highlighted. Flexible solar cells offer several advantages in terms of production, cost, and application over glass-based types. Of all the metals studied as substrates for CdTe solar cells, molybdenum appears the most favorable candidate, while close spaced sublimation (CSS, electrodeposition (ED, magnetic sputtering (MS, and high vacuum thermal evaporation (HVE have been found to be most common deposition technologies used for CdTe on metal foils. The advantages of these techniques include large grain size (CSS, ease of constituent control (ED, high material incorporation (MS, and low temperature process (MS, HVE, ED. These invert-structured thin film CdTe solar cells, like their superstrate counterparts, suffer from problems of poor ohmic contact at the back electrode. Thus similar strategies are applied to minimize this problem. Despite the challenges faced by flexible structures, efficiencies of up to 13.8% and 7.8% have been achieved in superstrate and substrate cell, respectively. Based on these analyses, new strategies have been proposed for obtaining cheaper, more efficient, and viable flexible CdTe solar cells of the future.

  18. Renewable Water: Direct Contact Membrane Distillation Coupled With Solar Ponds

    Science.gov (United States)

    Suarez, F. I.; Tyler, S. W.; Childress, A. E.

    2010-12-01

    The exponential population growth and the accelerated increase in the standard of living have increased significantly the global consumption of two precious resources: water and energy. These resources are intrinsically linked and are required to allow a high quality of human life. With sufficient energy, water may be harvested from aquifers, treated for potable reuse, or desalinated from brackish and seawater supplies. Even though the costs of desalination have declined significantly, traditional desalination systems still require large quantities of energy, typically from fossil fuels that will not allow these systems to produce water in a sustainable way. Recent advances in direct contact membrane distillation can take advantage of low-quality or renewable heat to desalinate brackish water, seawater or wastewater. Direct contact membrane distillation operates at low pressures and can use small temperature differences between the feed and permeate water to achieve a significant freshwater production. Therefore, a much broader selection of energy sources can be considered to drive thermal desalination. A promising method for providing renewable source of heat for direct contact membrane distillation is a solar pond, which is an artificially stratified water body that captures solar radiation and stores it as thermal energy at the bottom of the pond. In this work, a direct contact membrane distillation/solar pond coupled system is modeled and tested using a laboratory-scale system. Freshwater production rates on the order of 2 L day-1 per m2 of solar pond (1 L hr-1 per m2 of membrane area) can easily be achieved with minimal operating costs and under low pressures. While these rates are modest, they are six times larger than those produced by other solar pond-powered desalination systems - and they are likely to be increased if heat losses in the laboratory-scale system are reduced. Even more, this system operates at much lower costs than traditional desalination

  19. Radio-frequency magnetron triode sputtering of cadmium telluride and zinc telluride films and solar cells

    Science.gov (United States)

    Sanford, Adam Lee

    The n-CdS/p-CdTe solar cell has been researched for many years now. Research groups use a variety of processes to fabricate thin-film CdS/CdTe cells, including physical vapor deposition, chemical vapor deposition, and RF diode sputtering. One of the central areas of investigation concerning CdS/CdTe cells is the problem of a Schottky barrier at the back contact. Even cells fabricated with ohmic back contacts degrade into Schottky barriers as the devices are used. This severely degrades power generation. One possible solution is to use p+-ZnTe as an interlayer between CdTe and the back contact. ZnTe is easily doped with Cu to be p-type. However, even contacts with this ZnTe interlayer degrade over time, because Cu is highly mobile and diffuses away from the contact towards the CdS/CdTe junction. Another possibility is to dope ZnTe with N. It has been demonstrated using molecular beam epitaxy and RF diode sputtering. In this study, CdTe films are fabricated using a variation of RF diode sputtering called triode sputtering. This technique allows for control of ion bombardment to the substrate during deposition. Also, a higher plasma density near the target is achieved allowing depositions at lower pressures. These films are characterized structurally to show the effects of the various deposition parameters. N-doped ZnTe films are also fabricated using this technique. These films are characterized electrically to show the effects of the various deposition parameters. Also, the effects of post-deposition annealing are observed. It is found that annealing at the right temperature can increase the conductivity of the films by a factor of 3 or more. However, annealing at higher temperatures decreases the conductivity to as low as 12% of the initial conductivity. Finally, RF triode sputtered N-doped ZnTe films are used as an interlayer at the back contact of a CdS/CdTe solar cell. The effects of annealing the device before and after contact deposition are observed

  20. Thin film CdTe solar cells with an absorber layer thickness in micro- and sub-micrometer scale

    Science.gov (United States)

    Bai, Zhizhong; Yang, Jun; Wang, Deliang

    2011-10-01

    CdTe thin film solar cell with an absorber layer as thin as 0.5 μm was fabricated. An efficiency of 7.9% was obtained for a 1-μm-thick CdTe solar cell. An increased intensity of deep recombination states in the band gap, which was responsible for the reduced open-circuit voltage and fill factor for ultra-thin solar cells, was induced due to the not-well-developed polycrystalline CdTe microstructure and the CdS/CdTe heterojunction and the presence of Cu in the back contact. The experimental results presented in this study demonstrated that 1-μm-thick absorber layer is thick enough to fabricate CdTe solar cell with a decent efficiency.

  1. A pilot plant for solar-cell manufacture; Ligne pilote de fabrication de cellules solaires

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D.; Ziegler, Y.; Closset, A. [VHF - Technologies SA, Yverdon-les-Bains (Switzerland)

    2005-07-01

    A pilot plant for the manufacture of amorphous silicon solar cells on plastic film substrate was built allowing the annual production of 40 kW peak power. The production steps comprise: a) the continuous coating of n-i-p solar cells by VHF-PECVD with a capacity of 28.5 meters in 8.5 hours; b) transparent-conducting-oxide (TCO) top contact structuring using a continuous process; c) series connection step (scribing and Ag-paste) with a capacity of 28 meters in 6 hours; d) back and top contact sputtering with 3 parallel magnetrons; e) integration of a large-area vacuum laminator enabling the simultaneous lamination of 4 products of 4 Wp. In parallel with this project, a complete cost model was established enabling a more quantitative approach of the future technological and industrial strategy of the company. An increase of the capacity to 100 kWp has been planned for summer 2005.

  2. Systematic process development towards high performance transferred thin silicon solar cells based on epitaxially grown absorbers

    Science.gov (United States)

    Murcia Salazar, Clara Paola

    The value of thin crystalline silicon (c-Si) solar cells is the potential for higher performance compared to conventional wafer approaches. Thin silicon solar cells can outperform thick cells with the same material properties because the smaller active volume causes a reduced bulk recombination leading to higher voltages while efficient light trapping structures ensure all photons are absorbed. Efficiencies above 20+% can be achieved with less than 20um of c-Si with current silicon solar cell processing technologies. In a thin solar cell, factors that will lead to high efficiency include high minority carrier lifetime, low surface recombination, and good optical confinement. Independently optimizing surface optical and electrical properties in a thin solar cell can achieve this higher performance. In addition, re-utilizing a c-Si wafer with a process that allows optimization of both surfaces is a path to higher performance at lower cost. The challenge in the fabrication of this high performance concept is to separately analyze critical parameters through fabrication and transfer and establish the design rules for high performance. This work contributes to the design and systematic fabrication approach of a 20 mum thick epitaxial silicon solar cell. State-of-the-art thin absorbers of less than 30um have reported 655mV (on a textured front surface with antireflection coating), and efficiencies near 17%. We report near 640mV (on a planar front surface with antireflection coating) for 20 mum thick absorbers. It is found that previously reported efficiencies are tightly related to solar cell's active thickness. In the case of transferred solar cells, the thinnest epitaxial transferred cell reported is near 24 mum thick with an efficiency of 15.4% (transparent front handle, textured with ARC and metallic back reflector). Recently, a c-Si transferred solar cell of 43 mum has reported 19.1% efficiency (with a front texture and ARC with localized back contact and reflector

  3. Progress in amorphous silicon solar cells produced by reactive sputtering

    Science.gov (United States)

    Moustakas, T. D.

    The photovoltaic properties of reactively sputtered amorphous silicon are reviewed and it is shown that efficient PIN solar cells can be fabricated by the method of sputtering. The photovoltaic properties of the intrinsic films correlate with their structural and compositional inhomogeneities. Hydrogen incorporation and small levels of phosphorus and boron impurities also affect the photovoltaic properties through reduction of residual dangling bond related defects and modification of their occupation. The optical and transport properties of the doped P and N-films were found to depend sensitively on the amount of hydrogen and boron or phosphorus incorporation into the films as well as on their degree of crystallinity. Combination of the best intrinsic and doped films leads to PIN solar cell structures generating J(sc) of 13 mA/sq cm and V(oc) of between 0.85 to 0.95 volts. The efficiency of these devices, 5 to 6 percent, is limited by the low FF, typically about 50 percent. As a further test to the potential of this technology efficient tandem solar cell structures were fabricated, and device design concepts, such as the incorporation of optically reflective back contacts were tested.

  4. Characterization of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Haerkoenen, J.; Tuominen, E.; Nybergh, K.; Ezer, Y.; Yli-Koski, M.; Sinkkonen, J. [Helsinki Univ. of Technology (Finland). Dept. of Electrical and Communications Engineering

    1998-12-31

    Photovoltaic research began at the Electron Physics Laboratory of the Helsinki University of Tehnology in 1993, when the laboratory joined the national NEMO 2 research program. During the early stages of the photovoltaic research the main objective was to establish necessary measurement and characterisation routines, as well as to develop the fabrication process. The fabrication process development work has been supported by characterisation and theoretical modelling of the solar cells. Theoretical investigations have been concerned with systematic studies of solar cell parameters, such as diffusion lengths, surface recombination velocities and junction depths. The main result of the modelling and characterisation work is a method which is based on a Laplace transform of the so-called spatial collection efficiency function of the cell. The basic objective of the research has been to develop a fabrication process cheap enough to be suitable for commercial production

  5. Plasmonic silicon solar cells: impact of material quality and geometry

    NARCIS (Netherlands)

    Pahud, C.; Isabella, O.; Naqavi, A.; Haug, F.J.; Zeman, M.; Herzig, H.P.; Ballif, C.

    2013-01-01

    We study n-i-p amorphous silicon solar cells with light-scattering nanoparticles in the back reflector. In one configuration, the particles are fully embedded in the zinc oxide buffer layer; In a second configuration, the particles are placed between the buffer layer and the flat back electrode. We

  6. Contact Versus Noncontact Cell Electroporation

    Science.gov (United States)

    2009-05-28

    Mechanism Research of SKOV3 Cancer Cell Apoptosis Induced by Nanosecond Pulsed Electric Field ," 2008 30TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE...permeabilization in mammalian cells by nanosecond pulsed electric field (nsPEF)," BIOELECTROMAGNETICS, vol. 28, Dec. 2007, pp. 655-663. [6] R. Sundararajan...and K. Schoenbach, "Nanosecond pulsed electric field (nsPEF) effects on cells and tissues: Apoptosis induction and tumor growth inhibition," IEEE

  7. Junction studies on electrochemically fabricated p-n Cu(2)O homojunction solar cells for efficiency enhancement.

    Science.gov (United States)

    McShane, Colleen M; Choi, Kyoung-Shin

    2012-05-01

    p-n Cu(2)O homojunction solar cells were electrochemically fabricated by consecutively depositing an n-Cu(2)O layer on a p-Cu(2)O layer. In order to better understand the Fermi levels of the electrochemically grown polycrystalline p- and n-Cu(2)O layers and maximize the overall cell performance, the back and front contacts of the Cu(2)O homojunction cells were systematically changed and the I-V characteristics of the resulting cells were examined. The result shows that the intrinsic doping levels of the electrochemically prepared p-Cu(2)O and n-Cu(2)O layers are very low and they made almost Ohmic junctions with Cu metal with which previously studied p-Cu(2)O layers prepared by thermal oxidation of Cu foils are known to form Schottky junctions. The best cell performance (an η of 1.06%, a V(OC) of 0.621 V, an I(SC) of 4.07 mA cm(-2), and a fill factor (ff) of 42%) was obtained when the p-Cu(2)O layer was deposited on a commercially available ITO substrate as the back contact and a sputter deposited ITO layer was used as the front contact on the n-Cu(2)O layer. The unique features of the p-n Cu(2)O homojunction solar cell are discussed in comparison with other Cu(2)O-based heterojunction solar cells.

  8. Thin Film Solar Cells: Organic, Inorganic and Hybrid

    Science.gov (United States)

    Dankovich, John

    2004-01-01

    Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive

  9. Transparent contacts for stacked compound photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Tauke-Pedretti, Anna; Cederberg, Jeffrey; Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis

    2016-11-29

    A microsystems-enabled multi-junction photovoltaic (MEM-PV) cell includes a first photovoltaic cell having a first junction, the first photovoltaic cell including a first semiconductor material employed to form the first junction, the first semiconductor material having a first bandgap. The MEM-PV cell also includes a second photovoltaic cell comprising a second junction. The second photovoltaic cell comprises a second semiconductor material employed to form the second junction, the second semiconductor material having a second bandgap that is less than the first bandgap, the second photovoltaic cell further comprising a first contact layer disposed between the first junction of the first photovoltaic cell and the second junction of the second photovoltaic cell, the first contact layer composed of a third semiconductor material having a third bandgap, the third bandgap being greater than or equal to the first bandgap.

  10. High-flux solar furnace processing of silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S.; Pitts, J.R.; Landry, M.D.; Bingham, C.E.; Lewandowski, A.; Ciszek, T.F. [National Renewable Energy Lab., Golden, CO (United States)

    1994-12-31

    The authors used a 10-kW high-flux solar furnace (HFSF) to diffuse the front-surface n{sup +}-p junction and the back-surface p-p{sup +} junction of single-crystal silicon solar cells in one processing step. They found that all of the HFSF-processed cells have better conversion efficiencies than control cells of identical structures fabricated by conventional furnace diffusion methods. HFSF processing offers several advantages that may contribute to improved solar cell efficiency: (1) it provides a cold-wall process, which reduces contamination; (2) temperature versus time profiles can be precisely controlled; (3) wavelength, intensity, and spatial distribution of the incident solar flux can be controlled and changed rapidly; (4) a number of high-temperature processing steps can be performed simultaneously; and (5) combined quantum and thermal effects may benefit overall cell performance. The HFSF has also been successfully used to texture the surface of silicon wafers and to crystallize a-Si:H thin films on glass.

  11. EDITORIAL: Nanostructured solar cells Nanostructured solar cells

    Science.gov (United States)

    Greenham, Neil C.; Grätzel, Michael

    2008-10-01

    Conversion into electrical power of even a small fraction of the solar radiation incident on the Earth's surface has the potential to satisfy the world's energy demands without generating CO2 emissions. Current photovoltaic technology is not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be underestimated, a major bottleneck lies in the photovoltaic devices themselves. Improving efficiency is part of the solution, but diminishing returns in that area mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes. Solution-processible materials, e.g. organic molecules, conjugated polymers and semiconductor nanoparticles, offer new routes to the low-cost production of solar cells. The challenge here is that absorbing light in an organic material produces a coulombically bound exciton that requires dissociation at a donor-acceptor heterojunction. A thickness of at least 100 nm is required to absorb the incident light, but excitons only diffuse a few nanometres before decaying. The problem is therefore intrinsically at the nano-scale: we need composite devices with a large area of internal donor-acceptor interface, but where each carrier has a pathway to the respective electrode. Dye-sensitized and bulk heterojunction cells have nanostructures which approach this challenge in different ways, and leading research in this area is described in many of the articles in this special issue. This issue is not restricted to organic or dye-sensitized photovoltaics, since nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at

  12. Role of Copper in the Performance of CdS/CdTe Solar Cells (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Demtsu, S.; Albin, D.; Sites, J.

    2006-05-01

    The performance of CdS/CdTe solar cells made with evaporated Cu as a primary back contact was studied through current-voltage (JV) at different intensities, quantum efficiency (QE) under light and voltage bias, capacitance-voltage (CV), and drive-level capacitance profiling (DLCP) measurements. The results show that while modest amounts of Cu enhance cell performance, excessive amounts degrade device quality and reduce performance. The analysis is supported with numerical simulations to reproduce and explain some of the experimental results.

  13. Role of Copper in the Performance of CdS/CdTe Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Demtsu, S.; Albin, D.; Sites, J.

    2006-05-01

    The performance of CdS/CdTe solar cells made with evaporated Cu as a primary back contact was studied through current-voltage (JV) at different intensities, quantum efficiency (QE) under light and voltage bias, capacitance-voltage (CV), and drive-level capacitance profiling (DLCP) measurements. The results show that while modest amounts of Cu enhance cell performance, excessive amounts degrade device quality and reduce performance. The analysis is supported with numerical simulations to reproduce and explain some of the experimental results.

  14. Stability and Degradation of Organic and Polymer Solar Cells

    DEFF Research Database (Denmark)

    Organic photovoltaics (OPV) are a new generation of solar cells with the potential to offer very short energy pay back times, mechanical flexibility and significantly lower production costs compared to traditional crystalline photovoltaic systems. A weakness of OPV is their comparative instability...... during operation and this is a critical area of research towards the successful development and commercialization of these 3rd generation solar cells. Covering both small molecule and polymer solar cells, Stability and Degradation of Organic and Polymer Solar Cells summarizes the state of the art...

  15. Quantum Dot Solar Cells

    Science.gov (United States)

    Raffaelle, Ryne P.; Castro, Stephanie L.; Hepp, Aloysius; Bailey, Sheila G.

    2002-01-01

    We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

  16. Evolutionary process development towards next generation crystalline silicon solar cells : a semiconductor process toolbox application

    Science.gov (United States)

    John, J.; Prajapati, V.; Vermang, B.; Lorenz, A.; Allebe, C.; Rothschild, A.; Tous, L.; Uruena, A.; Baert, K.; Poortmans, J.

    2012-08-01

    Bulk crystalline Silicon solar cells are covering more than 85% of the world's roof top module installation in 2010. With a growth rate of over 30% in the last 10 years this technology remains the working horse of solar cell industry. The full Aluminum back-side field (Al BSF) technology has been developed in the 90's and provides a production learning curve on module price of constant 20% in average. The main reason for the decrease of module prices with increasing production capacity is due to the effect of up scaling industrial production. For further decreasing of the price per wattpeak silicon consumption has to be reduced and efficiency has to be improved. In this paper we describe a successive efficiency improving process development starting from the existing full Al BSF cell concept. We propose an evolutionary development includes all parts of the solar cell process: optical enhancement (texturing, polishing, anti-reflection coating), junction formation and contacting. Novel processes are benchmarked on industrial like baseline flows using high-efficiency cell concepts like i-PERC (Passivated Emitter and Rear Cell). While the full Al BSF crystalline silicon solar cell technology provides efficiencies of up to 18% (on cz-Si) in production, we are achieving up to 19.4% conversion efficiency for industrial fabricated, large area solar cells with copper based front side metallization and local Al BSF applying the semiconductor toolbox.

  17. Energy Conversion: Nano Solar Cell

    Science.gov (United States)

    Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad

    2009-09-01

    Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics can produce electricity at 20-30 c//kWhr with about 25% efficiency. Nanoparticles have a strong capacity to absorb light and generate more electrons for current as discovered in the recent work of organic and dye-sensitized cell. Using cheap preparation technique such as screen-printing and self-assembly growth, organic cells shows a strong potential for commercialization. Thin Films research group at National University Malaysia has been actively involved in these areas, and in this seminar, we will present a review works on nanomaterials for solar cells and particularly on hybrid organic solar cell based on ZnO nanorod arrays. The organic layer consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) and [6, 6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) was spin-coated on ZnO nanorod arrays. ZnO nanorod arrays were grown on FTO glass substrates which were pre-coated with ZnO nanoparticles using a low temperature chemical solution method. A gold electrode was used as the top contact. The device gave a short circuit current density of 2.49×10-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.

  18. SEMICONDUCTOR DEVICES: Optimization of grid design for solar cells

    Science.gov (United States)

    Wen, Liu; Yueqiang, Li; Jianjun, Chen; Yanling, Chen; Xiaodong, Wang; Fuhua, Yang

    2010-01-01

    By theoretical simulation of two grid patterns that are often used in concentrator solar cells, we give a detailed and comprehensive analysis of the influence of the metal grid dimension and various losses directly associated with it during optimization of grid design. Furthermore, we also perform the simulation under different concentrator factors, making the optimization of the front contact grid for solar cells complete.

  19. Silicon heterojunction solar cells

    CERN Document Server

    Fahrner, W R; Neitzert, H C

    2006-01-01

    The world of today must face up to two contradictory energy problems: on the one hand, there is the sharply growing consumer demand in countries such as China and India. On the other hand, natural resources are dwindling. Moreover, many of those countries which still possess substantial gas and oil supplies are politically unstable. As a result, renewable natural energy sources have received great attention. Among these, solar-cell technology is one of the most promising candidates. However, there still remains the problem of the manufacturing costs of such cells. Many attempts have been made

  20. Space solar cells - tradeoff analysis

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M.R. [ISRO Satellite Centre, Bangalore (India). Power Systems Group

    2003-05-15

    This paper summarizes the study that had the objective to tradeoff space solar cells and solar array designs to determine the best choice of solar cell and array technology that would be more beneficial in terms of mass, area and cost for different types of space missions. Space solar cells, which are commercially now available in the market and to be available in the near future, were considered for this trade study. Four solar array designs: rigid, flexible, thin film flexible and concentrator solar arrays were considered for assessment. Performance of the solar cells along with solar array designs were studied for two types of space missions:geo synchronous orbit (GEO) and low earth orbit (LEO) spacecraft. The Solar array designs assumed were to provide 15 kW power for 15 years mission life in GEO and 5 kW power for 5 years mission life in LEO altitudes. To perform tradeoff analysis a spread sheet model was developed that calculates the size, mass and estimates the cost of solar arrays based on different solar cell and array technologies for given set of mission requirements. Comparative performance metrics (W/kg, W/m{sup 2}, kg/m{sup 2}, and $/W) were calculated for all solar arrays studied and compared, at the solar array subsystem level and also at the spacecraft system level. The trade analysis results show that high-efficiency multijunction solar cells bring lot of cost advantages for both types of missions. The trade study also shows that thin film solar cells with moderate efficiency with ultra lightweight flexible array design may become competitive with well-established single crystalline solar cell technologies in the future. (author)

  1. Space solar cells. Tradeoff analysis

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M. Raja [Power Systems Group, Solar Panels Division, ISRO Satellite Centre, Bangalore 560017 (India)

    2003-05-15

    This paper summarizes the study that had the objective to tradeoff space solar cells and solar array designs to determine the best choice of solar cell and array technology that would be more beneficial in terms of mass, area and cost for different types of space missions. Space solar cells, which are commercially now available in the market and to be available in the near future, were considered for this trade study. Four solar array designs: rigid, flexible, thin film flexible and concentrator solar arrays were considered for assessment. Performance of the solar cells along with solar array designs were studied for two types of space missions: geo synchronous orbit (GEO) and low earth orbit (LEO) spacecraft. The Solar array designs assumed were to provide 15kW power for 15 years mission life in GEO and 5kW power for 5 years mission life in LEO altitudes. To perform tradeoff analysis a spread sheet model was developed that calculates the size, mass and estimates the cost of solar arrays based on different solar cell and array technologies for given set of mission requirements. Comparative performance metrics (W/kg, W/m{sup 2}, kg/m{sup 2}, and $/W) were calculated for all solar arrays studied and compared, at the solar array subsystem level and also at the spacecraft system level. The trade analysis results show that high-efficiency multijunction solar cells bring lot of cost advantages for both types of missions. The trade study also show that thin film solar cells with moderate efficiency with ultra lightweight flexible array design may become competitive with well-established single crystalline solar cell technologies in the future.

  2. Highly reflective rear surface passivation design for ultra-thin Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Vermang, Bart, E-mail: Bart.Vermang@angstrom.uu.se [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); ESAT-KU Leuven, University of Leuven, Leuven 3001 (Belgium); Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); Gunnarsson, Rickard; Pilch, Iris; Helmersson, Ulf [Plasma & Coatings Physics, University of Linköping, Linköping 58183 (Sweden); Kotipalli, Ratan; Henry, Frederic; Flandre, Denis [ICTEAM/IMNC, Université Catholique de Louvain, Louvain-la-Neuve 1348 (Belgium)

    2015-05-01

    Al{sub 2}O{sub 3} rear surface passivated ultra-thin Cu(In,Ga)Se{sub 2} (CIGS) solar cells with Mo nano-particles (NPs) as local rear contacts are developed to demonstrate their potential to improve optical confinement in ultra-thin CIGS solar cells. The CIGS absorber layer is 380 nm thick and the Mo NPs are deposited uniformly by an up-scalable technique and have typical diameters of 150 to 200 nm. The Al{sub 2}O{sub 3} layer passivates the CIGS rear surface between the Mo NPs, while the rear CIGS interface in contact with the Mo NP is passivated by [Ga]/([Ga] + [In]) (GGI) grading. It is shown that photon scattering due to the Mo NP contributes to an absolute increase in short circuit current density of 3.4 mA/cm{sup 2}; as compared to equivalent CIGS solar cells with a standard back contact. - Highlights: • Proof-of-principle ultra-thin CIGS solar cells have been fabricated. • The cells have Mo nano-particles (NPs) as local rear contacts. • An Al{sub 2}O{sub 3} film passivates the CIGS rear surface between these nano-particles. • [Ga]/([Ga] + [In]) grading is used to reduce Mo-NP/CIGS interface recombination.

  3. Applications of Laser Precisely Processing Technology in Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    According to the design method of laser resonator cavity, we optimized the primary parameters of resonator and utilized LD arrays symmetrically pumping manner to implementing output of the high-brightness laser in our laser cutter, then which was applied to precisely cutting the conductive film of CuInSe2 solar cells, the buried contact silicon solar cells' electrode groove, and perforating in wafer which is used to the emitter wrap through silicon solar cells. Laser processing precision was less than 40μm, the results have met solar cell's fabrication technology, and made finally the buried cells' conversion efficiency be improved from 18% to 21% .

  4. Light Coupling and Trapping in Ultrathin Cu(In,Ga)Se2 Solar Cells Using Dielectric Scattering Patterns.

    Science.gov (United States)

    van Lare, Claire; Yin, Guanchao; Polman, Albert; Schmid, Martina

    2015-10-27

    We experimentally demonstrate photocurrent enhancement in ultrathin Cu(In,Ga)Se2 (CIGSe) solar cells with absorber layers of 460 nm by nanoscale dielectric light scattering patterns printed by substrate conformal imprint lithography. We show that patterning the front side of the device with TiO2 nanoparticle arrays results in a small photocurrent enhancement in almost the entire 400-1200 nm spectral range due to enhanced light coupling into the cell. Three-dimensional finite-difference time-domain simulations are in good agreement with external quantum efficiency measurements. Patterning the Mo/CIGSe back interface using SiO2 nanoparticles leads to strongly enhanced light trapping, increasing the efficiency from 11.1% for a flat to 12.3% for a patterned cell. Simulations show that optimizing the array geometry could further improve light trapping. Including nanoparticles at the Mo/CIGSe interface leads to substantially reduced parasitic absorption in the Mo back contact. Parasitic absorption in the back contact can be further reduced by fabricating CIGSe cells on top of a SiO2-patterned In2O3:Sn (ITO) back contact. Simulations show that these semitransparent cells have similar spectrally averaged reflection and absorption in the CIGSe active layer as a Mo-based patterned cell, demonstrating that the absorption losses in the Mo can be partially turned into transmission through the semitransparent geometry.

  5. Photovoltaic properties of sintered CdS/CdTe solar cells doped with Cu

    Science.gov (United States)

    Park, J. W.; Ahn, B. T.; Im, H. B.; Kim, C. S.

    1992-11-01

    The effect of Cu doping before sintering on the photovoltaic properties of sintered CdS/CdTe solar cells were investigated by putting various amounts of CuCl2 either into the CdTe layer or into the back contact carbon layer. It was found that, as the amount of CuCl2 in the CdTe layers increased up to 25 ppm, the cell parameters of the sintered CdS/CdTe solar cells remained at about the same values, and then decreased sharply with further increase of CuCl2. The decreases in cell parameters are caused mainly by the increase in the resistivity of CdS and CdTe layer and the decrease in the optical transmission of CdS due to Cu doping from the CdTe.

  6. New Physical Deposition Approach for Low Cost Inorganic Hole Transport Layer in Normal Architecture of Durable Perovskite Solar Cells.

    Science.gov (United States)

    Nejand, Bahram Abdollahi; Ahmadi, Vahid; Shahverdi, Hamid Reza

    2015-10-07

    In this work we reported sputter deposited NiOx/Ni double layer as an HTM/contact couple in normal architecture of perovskite solar cell. A perovskite solar cell that is durable for more than 60 days was achieved, with increasing efficiency from 1.3% to 7.28% within 6 days. Moreover, low temperature direct deposition of NiOx layer on perovskite layer was introduced as a potential hole transport material for an efficient cost-effective solar cell applicable for various morphologies of perovskite layers, even for perovskite layers containing pinholes, which is a notable challenge in perovskite solar cells. The angular deposition of NiOx layers by dc reactive magnetron sputtering showed uniform and crack-free coverage of the perovskite layer with no negative impact on perovskite structure that is suitable for nickel back contact layer, surface shielding against moisture, and mechanical damages. Replacing the expensive complex materials in previous perovskite solar cells with low cost available materials introduces cost-effective scalable perovskite solar cells.

  7. Study of deep level defects of n+-CdS/p-CdTe solar cells

    Science.gov (United States)

    Kharangarh, Poonam Rani

    Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe solar cell performance, the effect of processing on defect states, and simple and effective characterization techniques must be investigated and identified. In this research the thin film n+-CdS/p-CdTe solar cells made with evaporated Cu as a primary back contact, are characterized by using the temperature dependence of the reverse bias diode current (J-V-T) to determine the energy levels of deep defects. The results of the J-V-T measurements on solar cells made at NJIT show that while modest amounts of Cu enhance cell performance, an excessive high temperature annealing step degrades device quality and reduces efficiency. This work addresses the error that can be introduced during defect energy level estimation if the temperature dependence of the carrier capture cross-section is neglected. Therefore, the location of traps is derived using a Shockley-Read-Hall recombination model with modified assumptions. A Cu-related deep level defect with activation energy of 0.57eV is observed for Cu evaporated back contact cells and an intrinsic defect with activation energy 0.89eV is found. Frequency dispersion in Capacitance-Voltage measurements confirms the presence of Cu-related deep level traps for cells with a Cu evaporated back contact, whereas no such defects

  8. Method for contact resistivity measurements on photovoltaic cells and cell adapted for such measurement

    Science.gov (United States)

    Burger, Dale R. (Inventor)

    1986-01-01

    A method is disclosed for scribing at least three grid contacts of a photovoltaic cell to electrically isolate them from the grid contact pattern used to collect solar current generated by the cell, and using the scribed segments for determining parameters of the cell by a combination of contact end resistance (CER) measurements using a minimum of three equally or unequally spaced lines, and transmission line modal (TLM) measurements using a minimum of four unequally spaced lines. TLM measurements may be used to determine sheet resistance under the contact, R.sub.sk, while CER measurements are used to determine contact resistivity, .rho..sub.c, from a nomograph of contact resistivity as a function of contact end resistance and sheet resistivity under the contact. In some cases, such as the case of silicon photovoltaic cells, sheet resistivity under the contact may be assumed to be equal to the known sheet resistance, R.sub.s, of the semiconductor material, thereby obviating the need for TLM measurements to determine R.sub.sk.

  9. Solar cell materials developing technologies

    CERN Document Server

    Conibeer, Gavin J

    2014-01-01

    This book presents a comparison of solar cell materials, including both new materials based on organics, nanostructures and novel inorganics and developments in more traditional photovoltaic materials. It surveys the materials and materials trends in the field including third generation solar cells (multiple energy level cells, thermal approaches and the modification of the solar spectrum) with an eye firmly on low costs, energy efficiency and the use of abundant non-toxic materials.

  10. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  11. Bifacial tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wojtczuk, Steven J.; Chiu, Philip T.; Zhang, Xuebing; Gagnon, Edward; Timmons, Michael

    2016-06-14

    A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.

  12. Microanalysis of Solar Cells

    Science.gov (United States)

    Kazmerski, Lawrence L.

    1980-11-01

    Applications of complementary surface analysis techniques (AES, SIMS, XPS) to solar cell device problems are discussed. Several examples of device interface and grain boundary problems are presented. Silicon, gallium arsenide and indium phosphide based devices are reviewed. Results of compositional and chemical analysis are correlated directly with EBIC measurements performed in-situ on identical sample areas. Those are, in turn, correlated with resulting photovoltaic device performance. The importance of microanalysis to the solution of critical device problems in the photovoltaics technology is emphasized.

  13. Review of the Potential of the Ni/Cu Plating Technique for Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Atteq ur Rehman

    2014-02-01

    Full Text Available Developing a better method for the metallization of silicon solar cells is integral part of realizing superior efficiency. Currently, contact realization using screen printing is the leading technology in the silicon based photovoltaic industry, as it is simple and fast. However, the problem with metallization of this kind is that it has a lower aspect ratio and higher contact resistance, which limits solar cell efficiency. The mounting cost of silver pastes and decreasing silicon wafer thicknesses encourages silicon solar cell manufacturers to develop fresh metallization techniques involving a lower quantity of silver usage and not relying pressing process of screen printing. In recent times nickel/copper (Ni/Cu based metal plating has emerged as a metallization method that may solve these issues. This paper offers a detailed review and understanding of a Ni/Cu based plating technique for silicon solar cells. The formation of a Ni seed layer by adopting various deposition techniques and a Cu conducting layer using a light induced plating (LIP process are appraised. Unlike screen-printed metallization, a step involving patterning is crucial for opening the masking layer. Consequently, experimental procedures involving patterning methods are also explicated. Lastly, the issues of adhesion, back ground plating, process complexity and reliability for industrial applications are also addressed.

  14. Space Solar Cell Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Measures, characterizes, and analyzes photovoltaic materials and devices. The primary focus is the measurement and characterization of solar cell response...

  15. Dye Sensitized Solar Cell, DSSC

    Directory of Open Access Journals (Sweden)

    Pongsatorn Amornpitoksuk

    2003-07-01

    Full Text Available A dye sensitized solar cell is a new type of solar cell. The operating system of this solar cell type is similar to plant’s photosynthesis process. The sensitizer is available for absorption light and transfer electrons to nanocrystalline metal oxide semiconductor. The ruthenium(II complexes with polypyridyl ligands are usually used as the sensitizers in solar cell. At the present time, the complex of [Ru(2,2',2'’-(COOH3- terpy(NCS3] is the most efficient sensitizer. The total photon to current conversion efficiency was approximately 10% at AM = 1.5.

  16. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  17. High Rate Laser Pitting Technique for Solar Cell Texturing

    Energy Technology Data Exchange (ETDEWEB)

    Hans J. Herfurth; Henrikki Pantsar

    2013-01-10

    High rate laser pitting technique for solar cell texturing Efficiency of crystalline silicon solar cells can be improved by creating a texture on the surface to increase optical absorption. Different techniques have been developed for texturing, with the current state-of-the-art (SOA) being wet chemical etching. The process has poor optical performance, produces surfaces that are difficult to passivate or contact and is relatively expensive due to the use of hazardous chemicals. This project shall develop an alternative process for texturing mc-Si using laser micromachining. It will have the following features compared to the current SOA texturing process: -Superior optical surfaces for reduced front-surface reflection and enhanced optical absorption in thin mc-Si substrates -Improved surface passivation -More easily integrated into advanced back-contact cell concepts -Reduced use of hazardous chemicals and waste treatment -Similar or lower cost The process is based on laser pitting. The objective is to develop and demonstrate a high rate laser pitting process which will exceed the rate of former laser texturing processes by a factor of ten. The laser and scanning technologies will be demonstrated on a laboratory scale, but will use inherently technologies that can easily be scaled to production rates. The drastic increase in process velocity is required for the process to be implemented as an in-line process in PV manufacturing. The project includes laser process development, development of advanced optical systems for beam manipulation and cell reflectivity and efficiency testing. An improvement of over 0.5% absolute in efficiency is anticipated after laser-based texturing. The surface textures will be characterized optically, and solar cells will be fabricated with the new laser texturing to ensure that the new process is compatible with high-efficiency cell processing. The result will be demonstration of a prototype process that is suitable for scale-up to a

  18. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  19. Enhancing Light-Trapping Properties of Amorphous Si Thin-Film Solar Cells Containing High-Reflective Silver Conductors Fabricated Using a Nonvacuum Process

    Directory of Open Access Journals (Sweden)

    Jun-Chin Liu

    2014-01-01

    Full Text Available We proposed a low-cost and highly reflective liquid organic sheet silver conductor using back contact reflectors in amorphous silicon (a-Si single junction superstrate configuration thin-film solar cells produced using a nonvacuum screen printing process. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (Jsc of sheet silver conductor cells was higher than 1.25 mA/cm2. Using external quantum efficiency measurements, the sheet silver conductor using back contact reflectors in cells was observed to effectively enhance the light-trapping ability in a long wavelength region (between 600 nm and 800 nm. Consequently, we achieved an optimal initial active area efficiency and module conversion efficiency of 9.02% and 6.55%, respectively, for the a-Si solar cells. The results indicated that the highly reflective sheet silver conductor back contact reflector layer prepared using a nonvacuum process is a suitable candidate for high-performance a-Si thin-film solar cells.

  20. An Introduction to Solar Cells

    Science.gov (United States)

    Feldman, Bernard J.

    2010-01-01

    Most likely, solar cells will play a significant role in this country's strategy to address the two interrelated issues of global warming and dependence on imported oil. The purpose of this paper is to present an explanation of how solar cells work at an introductory high school, college, or university physics course level. The treatment presented…

  1. CdTe薄膜太阳电池背接触的研究%A study of back contacts of CdTe thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    贺剑雄; 武莉莉; 王文武; 郑家贵; 李卫; 冯良桓; 蔡伟; 蔡亚平; 张静全; 黎兵; 雷智

    2007-01-01

    用近空间升华法制备了CdTe多晶薄膜,用硝酸-磷酸(NP)混合液对薄膜表面进行了腐蚀.经SEM观测,腐蚀后的CdTe薄膜晶界变宽,XRD测试发现,经NP腐蚀后,在CdTe薄膜表面生成了一层高电导的富Te层.在腐蚀后的CdTe薄膜上分别制备了Cu,Cu/ZnTe:Cu,ZnTe:Cu,ZnTe/ZnTe:Cu四种背接触层,比较了它们对太阳电池性能的影响.结果表明,用ZnTe/ZnTe:Cu复合层作为背接触层的效果较好,获得了面积为0.5 cm2,转换效率为13.38%的CdTe多晶薄膜太阳电池.

  2. Silicon-on-ceramic solar cell development. Solar cell development for the cell development task of the Low-Cost Solar Array Project. Quarterly report No. 1, February 15--June 30, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, P W; Grung, B L; Zook, J D

    1978-07-30

    The objective of this program is to investigate unique cell processing/design approaches to the successful fabrication of high-performance solar cells on silicon-on-ceramic (SOC) material. The work in the cell development area consists of two broad categories of activities: (1) the development of standard cell processing techniques, and (2) the investigation of novel device design approaches. The first area of activity has to do with the development of processing techniques for use with silicon dipped on ''slotted'' ceramic substrates. This embodiment allows us to make contact to the back surface of the silicon, thereby minimizing the front surface contact area. The second activity area is initially concerned with producing a ''stripe'' geometry cell on an unslotted ceramic substrate. The idea here is to expose the base layer for electrical contact on the top surface of the substrate and make up for the lost cell area by using an optical collector. Progress is reported.

  3. A New Technique to Produce Electricity Using Solar Cell in Aspect of Bangladesh: Dye-Sensitized Solar Cell (DSSC and It’s Prospect

    Directory of Open Access Journals (Sweden)

    M. F. Ali

    2014-09-01

    Full Text Available The Bangladesh is a developing country where electricity crisis is the most serious problem now-a-days. In order to meet electricity demand of our country we need to change the procedure of electricity production. For that we have to implement our renewable energy resources properly like solar cell. The dye sensitized solar cell (DSSCs is another new method to produce electricity which is more cost effective and also efficient comparing conventional silicon solar cell. When the visible light is absorbed by the thin film such as TiO2, an electron is injected by the excited sensitizer molecules into the conduction band of that thin film (TiO2. These electrons are then transported toward and collected by a back-contact electrode which travel in a big circle and create an electrical circuit which powers a device. In this paper we tried to describe the new DSSCs technology compared to conventional silicon solar cell according to the electricity demand of Bangladesh.

  4. Nanostructuring of Solar Cell Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    Solar energy is by far the most abundant renewable energy source available, but the levelized cost of solar energy is still not competitive with that of fossil fuels. Therefore there is a need to improve the power conversion effciency of solar cells without adding to the production cost. The main...... objective of this PhD thesis is to develop nanostructured silicon (Si) solar cells with higher power conversion efficiency using only scalable and cost-efficient production methods. The nanostructures, known as 'black silicon', are fabricated by single-step, maskless reactive ion etching and used as front...... and characterized for comparison. Power conversion eciency of 16.5% was obtained for this batch of RIE-textured Si solar cells. The eciency of the KOH-textured reference cell was 17.8%. Quantum Efficiency measurements and carrier loss analysis show that the lower eciency of the RIE-textured cells is primarily due...

  5. High Performance Perovskite Solar Cells.

    Science.gov (United States)

    Tong, Xin; Lin, Feng; Wu, Jiang; Wang, Zhiming M

    2016-05-01

    Perovskite solar cells fabricated from organometal halide light harvesters have captured significant attention due to their tremendously low device costs as well as unprecedented rapid progress on power conversion efficiency (PCE). A certified PCE of 20.1% was achieved in late 2014 following the first study of long-term stable all-solid-state perovskite solar cell with a PCE of 9.7% in 2012, showing their promising potential towards future cost-effective and high performance solar cells. Here, notable achievements of primary device configuration involving perovskite layer, hole-transporting materials (HTMs) and electron-transporting materials (ETMs) are reviewed. Numerous strategies for enhancing photovoltaic parameters of perovskite solar cells, including morphology and crystallization control of perovskite layer, HTMs design and ETMs modifications are discussed in detail. In addition, perovskite solar cells outside of HTMs and ETMs are mentioned as well, providing guidelines for further simplification of device processing and hence cost reduction.

  6. 3D-printed concentrator arrays for external light trapping on thin film solar cells

    NARCIS (Netherlands)

    van Dijk, Lourens; Marcus, E. A. Pepijn; Oostra, A. Jolt; Schropp, Ruud E. I.; Di Vece, Marcel

    2015-01-01

    After our recent demonstration of a 3D-printed external light trap on a small solar cell, we now consider its potential for large solar panels. An external light trap consists of a parabolic concentrator and a spacer that redirects the photons that are reflected by the solar cell back towards the so

  7. Upconversion in solar cells.

    Science.gov (United States)

    van Sark, Wilfried Gjhm; de Wild, Jessica; Rath, Jatin K; Meijerink, Andries; Schropp, Ruud Ei

    2013-02-15

    The possibility to tune chemical and physical properties in nanosized materials has a strong impact on a variety of technologies, including photovoltaics. One of the prominent research areas of nanomaterials for photovoltaics involves spectral conversion. Modification of the spectrum requires down- and/or upconversion or downshifting of the spectrum, meaning that the energy of photons is modified to either lower (down) or higher (up) energy. Nanostructures such as quantum dots, luminescent dye molecules, and lanthanide-doped glasses are capable of absorbing photons at a certain wavelength and emitting photons at a different (shorter or longer) wavelength. We will discuss upconversion by lanthanide compounds in various host materials and will further demonstrate upconversion to work for thin-film silicon solar cells.

  8. 0.35% Absolute Efficiency Gain of Bifacial N-type Si Solar cells by Industrial Metal Wrap Through Technology

    Energy Technology Data Exchange (ETDEWEB)

    Geerligs, L.J.; Guillevin, N.; Weeber, A.W.; Bultman, J.H.; Heurtault, B. [ECN Solar Energy, Petten (Netherlands); Zhao, Wenchao; Wang, Jianming; Shen, Yanlong; Wang, Ziqian; Chen, Yingle; Hu, Zhiyan; Li, Gaofei; Chen, Jianhui; Xiong, Jingfeng [Yingli Green Energy Holding Co., Ltd, 3399 North Chaoyang Avenue, Baoding (China)

    2012-06-15

    N-type Metal Wrap Through (n-MWT) is presented as an industrially promising back-contact technology to reach high performance of silicon solar cells and modules. It can combine benefits from both n-type base and MWT metallization. In this paper, the integration of the MWT technique with a commercial industrial bifacial n-type Si Solar cell (239 cm{sup 2}) process is described. After the integration, 0.35% absolute efficiency gain was achieved, and V{sub oc} gain and I{sub sc} gain up to 0.42% and 2.45%, respectively, were obtained, mainly attributed to reduced shadow loss and surface recombination. Based on calculations, the anticipation of further improvements for n-MWT solar cells, by taking better advantage of this integration, is also presented.

  9. Progress in polymer solar cell

    Institute of Scientific and Technical Information of China (English)

    LI LiGui; LU GuangHao; YANG XiaoNiu; ZHOU EnLe

    2007-01-01

    This review outlines current progresses in polymer solar cell. Compared to traditional silicon-based photovoltaic (PV) technology, the completely different principle of optoelectric response in the polymer cell results in a novel configuration of the device and more complicated photovoltaic generation process. The conception of bulk-heterojunction (BHJ) is introduced and its advantage in terms of morphology is addressed. The main aspects including the morphology of photoactive layer, which limit the efficiency and stability of polymer solar cell, are discussed in detail. The solutions to boosting up both the efficiency and stability (lifetime) of the polymer solar cell are highlighted at the end of this review.

  10. Dopant profile control of epitaxial emitter for silicon solar cells by low temperature epitaxy

    Science.gov (United States)

    Lai, Donny; Tan, Yew Heng; Gunawan, Oki; He, Lining; Seng Tan, Chuan

    2011-07-01

    We report an alternative approach to grow phosphorus-doped epitaxial silicon emitter by rapid thermal chemical vapor deposition at low temperature (T ≥ 700 °C). A power conversion efficiency (PCE) of (6.6 ± 0.3)% and a pseudo PCE of (10.2 ± 0.2)% has been achieved for the solar cell with epi-emitter grown at 700 °C, in the absence of surface texturization, antireflective coating, and back surface field enhancement, without considering front contact shading. Secondary ion mass spectroscopy revealed that lower temperature silicon epitaxy yields a more abrupt p-n junction, suggesting potential applications for radial p-n junction wire array solar cells.

  11. Recent progress in CdTe solar cell research at SCI

    Science.gov (United States)

    Sasala, R. A.; Powell, R. C.; Dorer, G. L.; Reiter, N.

    1997-02-01

    Research at Solar Cells Inc. is focused on developing processes which will lead to high volume and low cost manufacturing of solar cells and to increase the performance of our present technology. The process research has focused on developing vapor transport deposition of the semiconductors, eliminating wet chemistry steps while minimizing the chloride treatment time, forming a low-loss back contact using only dry processing, and an improved interconnection technique. The performance improvement work has focused on the increase of the photocurrent by a combination of more transparent glass substrates and a thinner CdS window layer deposited on an i-SnO2 buffer layer. SCI record 13.0% 1 cm2 devices have been fabricated using these techniques. Stability monitoring continues and shows minimal degradation for over 20,000 hours of continuous light soak at 0.8 sun illumination.

  12. Core-shell ITO/ZnO/CdS/CdTe nanowire solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Williams, B. L.; Phillips, L.; Major, J. D.; Durose, K. [Stephenson Institute for Renewable Energy, University of Liverpool, Chadwick Building, Peach St., Liverpool L69 7ZF (United Kingdom); Taylor, A. A.; Mendis, B. G.; Bowen, L. [G. J. Russell Microscopy Facility, University of Durham, South Road, Durham DH1 3LE (United Kingdom)

    2014-02-03

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was η = 2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (ϕ{sub B} = 0.52 eV) and low shunt resistances (R{sub SH} < 500 Ω·cm{sup 2})

  13. Results of the first 150 days of the NTS-1 solar cell experiments

    Science.gov (United States)

    Statler, R. L.

    1974-01-01

    Twelve solar cell experiments were on the Naval Research Laboratory NTS-1 satellite launched on 14 July 1974, into a 13,260 km circular orbit at an inclination of 125 deg. The experiment comprises: 2 ohm-cm n/p, lithium-diffused p/n, violet n/p, p(+) back surface field, and ultra-thin wrap around contact cells. The short-circuit current of the experiments ranged from 2 to 12 percent higher in space than under solar simulators. During the 5 year life of the satellite, the experiments will be exposed to radiation equivalent to 2 x 10 to the 15th power 1-MeV electron cm/2 and to nearly 5500 thermal cycles.

  14. Photon management in solar cells

    CERN Document Server

    Rau, Uwe; Gombert, Andreas

    2015-01-01

    Written by renowned experts in the field of photon management in solar cells, this one-stop reference gives an introduction to the physics of light management in solar cells, and discusses the different concepts and methods of applying photon management. The authors cover the physics, principles, concepts, technologies, and methods used, explaining how to increase the efficiency of solar cells by splitting or modifying the solar spectrum before they absorb the sunlight. In so doing, they present novel concepts and materials allowing for the cheaper, more flexible manufacture of solar cells and systems. For educational purposes, the authors have split the reasons for photon management into spatial and spectral light management. Bridging the gap between the photonics and the photovoltaics communities, this is an invaluable reference for materials scientists, physicists in industry, experimental physicists, lecturers in physics, Ph.D. students in physics and material sciences, engineers in power technology, appl...

  15. The intensity dependence of surface recombination in high concentration solar cells with charge induced passivation

    Science.gov (United States)

    Gray, J. L.; Schwartz, R. J.; Lundstrom, M. S.; Nasby, R. D.

    High intensity solar cells which are designed to minimize series resistance and shadowing losses, frequently employ an illuminated surface which is relatively far removed from the collecting junctions. This requires that the surface be well passivated to minimize surface recombination. One technique frequently employed to minimize surface recombination is to incorporate a fixed charge in the passivating oxide. This work shows that at sufficiently high intensities the surface recombination can increase dramatically. This results in a reduction in the high intensity collection efficiency. A comparison of the collection efficiency of interdigitated back contact cells and etched multiple vertical junction cells is given which shows that EMVJ cells are less sensitive to this effect than IBC cells.

  16. Novel Scheme of Amorphous/Crystalline Silicon Heterojunction Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    De Iuliis, S.; Geerligs, L.J. [ECN Solar Energy, Petten (Netherlands); Tucci, M.; Serenelli, L.; Salza, E. [ENEA Research Center Casaccia, Roma (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M. [University ' Sapienza' , Department of Electronic Engineering, Roma (Italy)

    2007-01-15

    In this paper we investigate in detail how the heterostructure concept can be implemented in an interdigitated back contact solar cell, in which both the emitters are formed on the back side of the c-Si wafer by amorphous/crystalline silicon heterostructure, and at the same time the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire process, held at temperature below 300C, is photolithography-free, using a metallic self-aligned mask to create the interdigitated pattern, and we show that the alignment is feasible. An open-circuit voltage of 687 mV has been measured on a p-type monocrystalline silicon wafer. The mask-assisted deposition process does not influence the uniformity of the deposited amorphous silicon layers. Photocurrent limits factor has been investigated with the aid of one-dimensional modeling and quantum efficiency measurements. On the other hand several technological aspects that limit the fill factor and the short circuit current density still need improvements.

  17. Dielectric Scattering Patterns for Efficient Light Trapping in Thin-Film Solar Cells.

    Science.gov (United States)

    van Lare, Claire; Lenzmann, Frank; Verschuuren, Marc A; Polman, Albert

    2015-08-12

    We demonstrate an effective light trapping geometry for thin-film solar cells that is composed of dielectric light scattering nanocavities at the interface between the metal back contact and the semiconductor absorber layer. The geometry is based on resonant Mie scattering. It avoids the Ohmic losses found in metallic (plasmonic) nanopatterns, and the dielectric scatterers are well compatible with nearly all types of thin-film solar cells, including cells produced using high temperature processes. The external quantum efficiency of thin-film a-Si:H solar cells grown on top of a nanopatterned Al-doped ZnO, made using soft imprint lithography, is strongly enhanced in the 550-800 nm spectral band by the dielectric nanoscatterers. Numerical simulations are in good agreement with experimental data and show that resonant light scattering from both the AZO nanostructures and the embedded Si nanostructures are important. The results are generic and can be applied on nearly all thin-film solar cells.

  18. Development of monocrystalline CdTe solar cells for terrestrial applications, especially for optical concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.; Fuessl, B.; Seipp, E.; Thiel, R.

    1981-01-01

    During the first phase of the contract most of the work was done in order to optimise the most important structural elements of the solar cells, which were produced on the base of crystalline CdTe. Two approaches in development of such cells were made: n-CdTe crystals were covered with a p-type heterolayer as a window for sunlight; ZnTe was evaporated as a p-type layer. p-CdTe crystals were covered with a n-type heterolayer as a window. Here, CdS evaporation layers and indium-tin-oxide (ITO) sputtered layers were applied. Within the first approach the realisation of ZnTe-layers simultaneously highly conductive and transparent was tried by using numerous dopants. Within the second approach, the development of p-CdTe/n-CdS solar cells, the resistances of the ohmic contacts on the back of the p-CdTe wafers were a major problem. We found some ways of preparing ohmic contacts of acceptable contact resistance, but an ideal problem solution is lacking still. We found a dependence of the contact resistance on the p-CdTe doping concentration. Solar cells made from p-CdTe crystals covered with n/sup +/-CdS attained an open circuit voltage of 655 mV and a short circuit current density of 13.8 mA/cm/sup 2/ in a 100 mW/cm/sup 2/ light. Assuming a sufficiently low series resistance we expect an efficiency of about 6 percent. Besides the n/sup +/-CdS layers n/sup +/-ITO-layers (indium-tin-oxide) were deposited on p-CdTe by sputtering. These cells exhibit a short circuit density a little higher but a lower open circuit voltage than the heterosolarcells with n/sup +/-CdS.

  19. Changes in CdS/CdTe Solar Cells Subjected to Elevated Temperature, Voltage and Illumination

    Science.gov (United States)

    Demtsu, Samuel; Nagle, Tim

    2003-10-01

    CdTe/CdS solar cells have been known to exhibit degradation in performance after being subjected to elevated temperature, voltage and illumination. These conditions are collectively referred to as "stress". We have studied and presented CdTe/CdS cell degradation under different stress conditions of devices from First Solar Inc., the University of South Florida and the University of Toledo. All cells were stressed in the light (close to 100 mW/cm2) for 56 days at elevated temperature of 900C at two different biases, short circuit (SC) and open circuit (OC). The stress condition surpasses the operation conditions expected in the field. To characterize the cells, we have measured current density as function of the applied voltage (JV), capacitance vs bias voltage (CV) and quantum efficiency (QE) measurements before and after exposure to stress. To investigate the spatial non-uniformity of photocurrent collection induced by stress we have done Light Beam-Induced Current (LBIC) measurement. The effect of the stress on the photovoltaic parameters short-circuit current (Jsc), open-circuit voltage (Voc), Fill-Factor (FF), and efficiency is presented and discussed. Carrier density as a function of the distance from the semiconductor junction is extracted from the C-V measurements. We have seen some variations between cells and degradation was not monotonic with stress time. The highly probable explanation for the degradation of the cells after the stress is that mobile copper ions diffuse out of the back contact towards the primary junction leaving a depletion of Cu in the back contact, which increases the contact barrier.

  20. Admittance spectroscopy of CdTe/CdS solar cells subjected to varied nitric-phosphoric etching conditions.

    OpenAIRE

    2007-01-01

    In this work we investigate the electric and structural properties of CdTe/CdS solar cells subjected to a nitric-phosphoric (NP) acid etching procedure, employed for the formation of a Te-rich layer before back contacting. The etching time is used as the only variable parameter in the study, while admittance spectroscopy is employed for the characterization of the cells' electric properties as well as for the analysis of the defect energy levels. Particular attention was also given to the cha...

  1. Cu-doped CdS and its application in CdTe thin film solar cell

    Directory of Open Access Journals (Sweden)

    Yi Deng

    2016-01-01

    Full Text Available Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the VCd− and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl2 annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  2. Cu-doped CdS and its application in CdTe thin film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi [School of Automation, Wuhan University of Technology, Wuhan, Hubei 430070 (China); College of Electronic and Information Engineering, Hankou University, Wuhan, Hubei 430212 (China); Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Deliang, E-mail: eedewang@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2016-01-15

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the V{sub Cd{sup −}} and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl{sub 2} annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  3. Cu-doped CdS and its application in CdTe thin film solar cell

    Science.gov (United States)

    Deng, Yi; Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao; Wang, Deliang

    2016-01-01

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the VCd- and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl2 annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  4. A comparative study on the performance of Kesterite based thin film solar cells using SCAPS simulation program

    Science.gov (United States)

    Simya, O. K.; Mahaboobbatcha, A.; Balachander, K.

    2015-06-01

    A comparative study of thin film solar cells based on CZTS, CZTSe, and CZTSSe (Copper Zinc Tin Sulphur Selenium) absorbers layers were simulated with Cadmium Sulphide (CdS) as buffer layer and Zinc Oxide (ZnO) as window layer using a solar cell capacitance simulator (SCAPS). The influences of series resistance, band to band recombination, defects and interfaces, thickness of (CZTS|CZTSe|CZTSSe) absorber layer, (CdS) buffer layer and transparent conductive oxide layer (ZnO) on the photovoltaic cell parameters were studied in detail. Improvements in efficiency were achieved by changing the back contact metal work function (BMWF) and choosing the flat band option in SCAPS software. Based on the best possible optimisation, an efficiency (η) of 12.03%, 13.16% and 15.77% were obtained for CZTS, CZTSe, and CZTSSe respectively. The performance of thin film photovoltaic devices (TFPV), for Mo back contact before optimisation and the SCAPS simulated values (flat band) after optimisation were described in detail to have in-depth understanding for better design of experiments (DOE) to obtain high efficiency solar cells.

  5. Black silicon solar cells with black bus-bar strings

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

    2016-01-01

    We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by maskless reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Four different methods to obtain blackened bus-bar strings were compared with respect to reflectance, and two of these methods (i.e., oxidized copper and etched solder) were used to fabricate functional allblack solar 9-cell panels. The black bus-bars (e.......g., by oxidized copper) have a reflectance below 3% in the entire visible wavelength range. The combination of black silicon cells and blackened bus-bars results in aesthetic, all-black panels based on conventional, front-contacted solar cells without compromising efficiency....

  6. 12% efficient CdTe/CdS thin film solar cells deposited by low-temperature close space sublimation

    Science.gov (United States)

    Schaffner, Judith; Motzko, Markus; Tueschen, Alexander; Swirschuk, Andreas; Schimper, Hermann-Josef; Klein, Andreas; Modes, Thomas; Zywitzki, Olaf; Jaegermann, Wolfram

    2011-09-01

    We report 12% efficient CdS/CdTe thin film solar cells prepared by low temperature close space sublimation (CSS). Both semiconductor films, CdS and CdTe, were deposited by high vacuum CSS in superstrate configuration on glass substrates with fluorine doped tin oxide (FTO) front contact. The CdTe deposition was carried out at a substrate temperature (Tsub) of ≤340 ∘C, which is much lower than that used in conventional processes (>500 ∘C). The CdTe films were treated with the usual CdCl2 activation process. Different optimal annealing times and temperatures were found for low-temperature cells (Tsub≤ 340 ∘C) compared to high-temperature cells (Tsub = 520 ∘C). The influence of the activation step on the morphology of high-temperature and low-temperature CdTe is determined by XRD, AFM, SEM top views, and SEM cross-sections. Grain growth, strong recrystallization, and a reduction of planar defects during the activation step are observed, especially for low-temperature CdTe. Further, the influence of CdS deposition parameters on the solar cell performance is investigated by using three different sets of parameters with different deposition rates and substrate temperatures for the CdS preparation. Efficiencies about 10.9% with a copper-free back contact and 12.0% with a copper-containing back contact were achieved using the low temperature CdTe process.

  7. Dust Removal from Solar Cells

    Science.gov (United States)

    Ashpis, David E. (Inventor)

    2015-01-01

    A solar panel cleaning device includes a solar panel having a plurality of photovoltaic cells arranged in rows and embedded in the solar panel with space between the rows. A transparent dielectric overlay is affixed to the solar panel. A plurality of electrode pairs each of which includes an upper and a lower electrode are arranged on opposite sides of the transparent dielectric and are affixed thereto. The electrodes may be transparent electrodes which may be arranged without concern for blocking sunlight to the solar panel. The solar panel may be a dielectric and its dielectric properties may be continuously and spatially variable. Alternatively the dielectric used may have dielectric segments which produce different electrical field and which affects the wind "generated."

  8. Fundamentals of thin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. [Univ. of California, Los Angeles, CA (United States)

    1995-08-01

    It is now widely recognized that thin solar cells can present certain advantages for performance and cost. This is particularly the case when light trapping in the semiconductor film is incorporated, as compensation for the diminished single path thickness of the solar cell. In a solar cell thinner than a minority carrier diffusion length, the current collection is of course very easy. More importantly the concentration of an equivalent number of carriers in a thinner volume results in a higher Free Energy, or open circuit voltage. This extra Free Energy may be regarded as due to the concentration factor, just as it would be for photons, electrons, or for any chemical species. The final advantage of a thin solar cell is in the diminished material usage, a factor of considerable importance when we consider the material cost of the high quality semiconductors which we hope to employ.

  9. Thin-Film Solar Cells with InP Absorber Layers Directly Grown on Nonepitaxial Metal Substrates

    KAUST Repository

    Zheng, Maxwell

    2015-08-25

    The design and performance of solar cells based on InP grown by the nonepitaxial thin-film vapor-liquid-solid (TF-VLS) growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and indium tin oxide transparent top electrode. An ex situ p-doping process for TF-VLS grown InP is introduced. Properties of the cells such as optoelectronic uniformity and electrical behavior of grain boundaries are examined. The power conversion efficiency of first generation cells reaches 12.1% under simulated 1 sun illumination with open-circuit voltage (VOC) of 692 mV, short-circuit current (JSC) of 26.9 mA cm-2, and fill factor (FF) of 65%. The FF of the cell is limited by the series resistances in the device, including the top contact, which can be mitigated in the future through device optimization. The highest measured VOC under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP. The design and performance of solar cells based on indium phosphide (InP) grown by the nonepitaxial thin-film vapor-liquid-solid growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and an indium tin oxide transparent top electrode. The highest measured open circuit voltage (VOC) under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP.

  10. Low cost silicon-on-ceramic photovoltaic solar cells

    Science.gov (United States)

    Koepke, B. G.; Heaps, J. D.; Grung, B. L.; Zook, J. D.; Sibold, J. D.; Leipold, M. H.

    1980-01-01

    A technique has been developed for coating low-cost mullite-based refractory substrates with thin layers of solar cell quality silicon. The technique involves first carbonizing one surface of the ceramic and then contacting it with molten silicon. The silicon wets the carbonized surface and, under the proper thermal conditions, solidifies as a large-grained sheet. Solar cells produced from this composite silicon-on-ceramic material have exhibited total area conversion efficiencies of ten percent.

  11. Thin film solar cell inflatable ultraviolet rigidizable deployment hinge

    Science.gov (United States)

    Simburger, Edward J. (Inventor); Matsumoto, James H. (Inventor); Giants, Thomas W. (Inventor); Garcia, III, Alec (Inventor); Perry, Alan R. (Inventor); Rawal, Suraj (Inventor); Marshall, Craig H. (Inventor); Lin, John K. H. (Inventor); Day, Jonathan Robert (Inventor); Kerslake, Thomas W. (Inventor)

    2010-01-01

    A flexible inflatable hinge includes curable resin for rigidly positioning panels of solar cells about the hinge in which wrap around contacts and flex circuits are disposed for routing power from the solar cells to the power bus further used for grounding the hinge. An indium tin oxide and magnesium fluoride coating is used to prevent static discharge while being transparent to ultraviolet light that cures the embedded resin after deployment for rigidizing the inflatable hinge.

  12. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  13. Modeling the PbI2 formation in perovskite solar cells using XRD/XPS patterns

    Science.gov (United States)

    Sohrabpoor, Hamed; Elyasi, Majid; Aldosari, Marouf; Gorji, Nima E.

    2016-09-01

    The impact of prolonged irradiation and air humidity on the stability of perovskite solar cells is modeled using X-ray diffraction and X-ray photoelectron spectroscopy patterns reported in the literature. Light or air-moisture causes the formation of a thin PbI2 or oxide defective layers (in nanoscale) at the interface of perovskite/hole-transport-layer or at the junction with metallic back contact. This thin layer blocks the carrier transport/passivation at the interfaces and cause degradation of device parameters. Variation in thickness of defective layers, changes the XRD and XPS peaks. This allows detection and estimation of the type, crystallinity and thickness of the defective layer. A simple model is developed here to extract the thickness of such thin defective layers formed in nanometer scale at the back region of several perovskite devices. Based on this information, corrected energy band diagram of every device before and after degradation/aging is drawn and discussed in order to obtain insight into the carrier transport and charge collection at the barrier region. In addition, graphene contacted perovskite devices are investigated showing that honey-comb network of graphene contact reduces the effect of aging leading to formation of a thinner defective layer at the perovskite surface compared to perovskite devices with conventional inorganic contacts i.e. Au, Al.

  14. Solution processed organic bulk heterojunction tandem solar