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1

Promising Thin Film Solar Cells - An Overview  

Science.gov (United States)

Several thin film solar cell materials have demonstrated greater than 10% conversion efficiency, including amorphous silicon, polycrystalline silicon, cadmium sulfide/copper sulfide, cadmium sulfide/copper indium diselenide, gallium arsenide (CLEFT), cadmium sulfide/cadmium telluride, and gallium arsenide/silicon. The generic category of thin film solar cells is examined to determine prerequisites for use of these materials for large quantities of competitive electrical energy production. The future extrapolated performance, low cost potential, and areas for further research are discussed.

Stone, Jack L.

1983-09-01

2

Advances in thin-film solar cells  

CERN Document Server

This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines

Dharmadasa, I M

2012-01-01

3

Thin-film cadmium telluride solar cells  

International Nuclear Information System (INIS)

Progress in the development of thin-film polycrystalline CdTe solar cells is reviewed. A wide variety of film preparation techniques is currently being used: Vacuum Evaporation, Chemical Vapor Deposition (CVD), Spray Pyrolysis, Screen Printing/Sintering, and Electrodeposition. These techniques differ considerably with regard to the quality of the films produced and the level of maturity of the technologies. Only methods producing all-thin-film solar cells are considered. Progress has been rapid and, in 1982, a 10% efficient thin-film solar cell was demonstrated. Work is now in progress at a number of different laboratories to produce a commercially viable solar cell. A critical comparison is made of the various approaches

4

Thin film solar cell technology in Germany  

International Nuclear Information System (INIS)

Within the scope of limited nonrenewable energy resources and the limited capacity of the ecosystem for greenhouse gases and nuclear waste, sustainability is one important target in the future. Different energy scenarios showed the huge potential for photovoltaics (PV) to solve this energy problem. Nevertheless, in the last decade, PV had an average growth rate of over 20% per year. In 2002, the solar industry delivered more than 500 MWp/year of photovoltaic generators [A. Jaeger-Waldau, A European Roadmap for PV R and D, E-MRS Spring Meeting, (2003)]. More than 85% of the current production involves crystalline silicon technologies. These technologies still have a high cost reduction potential, but this will be limited by the silicon feedstock. On the other hand the so-called second generation thin film solar cells based on a-Si, Cu(In,Ga)(Se,S2 (CIGS) or CdTe have material thicknesses of a few microns as a result of their direct band gap. Also, the possibility of circuit integration offers an additional cost reduction potential. Especially in Germany, there are a few companies who focus on thin film solar cells. Today, there are two manufacturers with production lines: the Phototronics (PST) division of RWE-Schott Solar with a-Si thin film technology and the former Antec Solar GmbH (now Antec Solar Energy GmbH) featuring the CdTe technology. A pilot line based on CIGS technology is run by Wuerth Solar GmbH. There is also a variety of research activity at other companies, namely, at Shell Solar, Sulfurcell Solartechnik GmbH, Solarion GmbH and the CIS-Solartechnik GmbH. We will give an overview on research activity on various thin film technologies, as well as different manufacturing and production processes in the companies mentioned above. (Author)

5

Light management in thin-film silicon solar cells:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Solar energy can fulfil mankinds energy needs and secure a more balanced distribution of primary sources of energy. Wafer-based and thin-film silicon solar cells dominate todays photovoltaic market because silicon is a non-toxic and abundant material and high conversion efficiencies are achieved with silicon-based solar cells. To stay competitive with bulk crystalline silicon and other thin-film solar cell technologies, thin-film silicon solar cells have to achieve a conversion efficie...

Isabella, O.

2013-01-01

6

Polycrystalline thin-film solar cells  

International Nuclear Information System (INIS)

A description of polycrystalline thin-film solar cells (PTFC) based on the historical development would contain the first observations by Becquerel in 1839, the research by Grondhal and Geiger on Cu20 almost one hundred years later and finally the modern story dating from 1954. In that year a single crystal Si cell and a polycrystalline cell, later recognized as a CdS/Cu2S heterojunction, both of 6% efficiency were reported. In this paper the first topic is a description of a generic solar cell; what are those materials and device features which are common to all photovoltaic systems? The special features of thin-film solar cells based on polycrystalline compound semiconductors are examined. The two materials under most active development are the II-VI compound CdTe and the I-III-VI2 chalcopyrite compound, CuInSe2, and in detail their development and prospects for the future are examined. There are some other materials which also form the basis of potential solar cells and these will be briefly reviewed. Finally, the prospects for tandem or multi-junction cells that incorporate polycrystalline semiconductors are discussed. 40 refs, 21 figs, 4 tabs

7

Electroluminescence of thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Electroluminescence (EL) and Dark-Lock-In-Thermography (DLIT) are commonly used methods to characterize crystalline silicon solar modules. We have applied these methods to analyze thin-film silicon-PV-mini-modules based on amorphous silicon (a-Si) and microcrystalline silicon ({mu}c-Si). DLIT shows the heat dissipation of the solar cell which originates mainly from the ohmic losses in the Transparent Conductive Oxide (TCO). Defects e.g. electrical short cuts of the cell (shunts) provide a large DLIT signal, due to the high temperature caused by the increased current. In contrast EL shows effects of the semiconductor material. Shunts caused by dust particles in the thin film appear as dark lateral spots since less luminescent recombination takes place. Furthermore EL allows the distinguishing between a-Si and {mu}c-Si. The different semiconductor band gaps lead to different emission spectra ({lambda}{sub {mu}}c-Si>{lambda}{sub a-Si}). Using adequate filters this behavior leads to the analysis of the individual diodes of tandem modules. In general EL and DLIT show a similar image of a systematic signal distribution. This effect results from the inhomogeneous voltage and current distribution across the cells in the semiconductor and TCO which is caused by the integrated series connection.

Moenkemoeller, Viola; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Niederkrueger, Matthias; Stiebig, Helmut [Malibu GmbH and Co. KG, Bielefeld (Germany)

2011-07-01

8

Materials availability for thin film solar cells  

Science.gov (United States)

Materials availability is one of the most important factors when we consider the mass-production of next generation photovoltaic devices. "In (indium)" is a vital element to produce high efficient thin film solar cells such as InP and CuIn(Ga)Se2 but its lifetime as a natural resource is suggested to be of order of 1015 years. The lifetime of a specific natural resource as an element to produce useful device substances is directly related with its abundance in the earth's crust, consumption rate and recycling rate (if recycling is economically meaningful). The chemical elements having long lifetime as a natural resource are those existing in the atmosphere such as N (nitrogen) and O (oxygen); the rich elements in the earth's crust such as Si, Ca, Sr and Ba; the mass-used metals such as Fe (iron), Al (aluminum) and Cu (copper) that reached the stage of large-scale recycling. We here propose a new paradigm of semiconductor material-science for the future generation thin film solar cells in which only abundant chemical elements are used. It is important to remark that these abundant chemical elements are normally not toxic and are fairly friendly to the environment. ?-FeSi2 is composed of two most abundant and nontoxic chemical elements. This material is one of the most promising device materials for future generation energy devices (solar cells and thermoelectric device that is most efficient at temperature range of 700-900 C). One should remind of the versatility of ?-FeSi2 that this material can be used not only as energy devices but also as photodetector, light emitting diode and/or laser diode at the wavelength of 1.5 ?m that can be monolithically integrated on Si substrates due to the relatively small lattice mismatch.

Makita, Yunosuke

1997-04-01

9

Thin-film solar cells. Past, present ... and future  

International Nuclear Information System (INIS)

This article traces the history of thin-film solar cells from the early 1950s, to the use of photovoltaic (PV) power supplies in space missions, and finally to the present where PV is now considered as a real option for terrestrial power production and rural electrification. The development of solar cell efficiencies is described, and the development of thin-film efficiencies is compared with that of crystalline silicon wafer-based cells. The market share of thin-film solar modules, and the impact of amorphous modules on the power market are considered. Details are given of early thin-film solar cells, four decades of cadmium-telluride solar cells (1962-2001), modern materials for thin-film solar cells, cells based on amorphous silicon, thin-layer and thin-film approaches based on crystalline silicon, the use of cadmium telluride, cells based on copper-indium-selenide (CIS) and related compounds, and the dye-sensitised cell. Theoretical and technological aspects of thin-film PV are examined, and the transfer of laboratory-scale production to industrial production is explored

10

Thin Film Solar Cells: Research in an Industrial Perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se2 and Cu2ZnS...

Edoff, Marika

2012-01-01

11

Broadband back grating design for thin film solar cells  

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.

Janjua, Bilal

2013-01-01

12

UV imprinting for thin film solar cell application  

International Nuclear Information System (INIS)

UV imprinting is an interesting, low cost technique to produce large area thin film solar cells incorporating nanometric textures. Here, we review and present new results confirming that replicas of the most common textures used in photovoltaics can be obtained by UV imprinting with an excellent fidelity. The use of these replicas as substrates for amorphous and micromorph thin film silicon solar cells is also shown, together with a comparison with devices obtained on the original textures

13

UV imprinting for thin film solar cell application  

Digital Repository Infrastructure Vision for European Research (DRIVER)

UV imprinting is an interesting, low cost technique to produce large area thin film solar cells incorporating nanometric textures. Here, we review and present new results confirming that replicas of the most common textures used in photovoltaics can be obtained by UV imprinting with an excellent fidelity. The use of these replicas as substrates for amorphous and micromorph thin film silicon solar cells is also shown, together with a comparison with devices obtained on the original textures.

Escarre, J.; Battaglia, C.; Soederstroem, K.; Pahud, C.; Biron, R.; Cubero, O.; Haug, F. -j; Ballif, C.

2012-01-01

14

Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se?/ZnS thin film solar cells.  

Science.gov (United States)

Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se? (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

2014-05-20

15

Indium tin oxide-silicon thin film solar cell  

International Nuclear Information System (INIS)

Heterojunction solar cells consisting of amorphous indium tin oxide (ITO) thin films on silicon films have been fabricated and studied. The results show that the devices give a photovoltaic effect and rectifying characteristics. One of the main characteristics of amorphous ITO thin films is better transparency (>85%) over the complete useful window of the solar spectrum. The polarity observed is found to be consistent with V/sub oc/ = 0.34 volt, I/sub sc/ = 22mA/cm/sup 2/ and fill factor = 0.48. An attempt has been made to understand the conduction mechanism of indium tin oxide - silicon heterojunction

16

Low cost thin film poly-silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of a project to design and develop a high density plasma based thin-film poly-silicon (TFPS) deposition system based on PQL proprietary advanced plasma technology to produce semiconductor quality TFPS for fabricating a TFPS solar cell. Details are given of the TFPS deposition system, the material development programme, solar cell structure, and cell efficiencies. The reproducibility of the deposition process and prospects for commercial exploitation are discussed.

NONE

2005-07-01

17

Testing and failure analysis of thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Elements of a systematic concept for test, characterization and analysis of thin film solar cells is discussed that is based on application and comparison of respective techniques in the world of micro- and nanoelectronic technologies, Starting with test and reliability issues, in depth electrical characterization like activation energy analysis from reverse dark currents, is presented. Analysis techniques that belong to the concept require electrically active devices and include all aspects of luminescence and stimulation. A key topic in electronic devices, Focused Ion Beam based Device or Circuit Edit, is also evaluated for application in thin film photovoltaics. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Boit, Christian [University of Technology, Berlin (Germany); PVcomB Competence Centre Thin-Film- and Nanotechnology for Photovoltaics, Berlin (Germany); Boostandoost, Mahyar; Glowacki, Arkadiusz [University of Technology, Berlin (Germany); Friedrich, Felice [PVcomB Competence Centre Thin-Film- and Nanotechnology for Photovoltaics, Berlin (Germany); University of Technology, Berlin (Germany)

2011-10-15

18

Thin-film crystalline silicon solar cells  

CERN Document Server

This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

Brendel, Rolf

2011-01-01

19

Buried contact multijunction thin film silicon solar cell  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1995-08-01

20

Thin-film silicon solar cells with integrated silver nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

Thin-film silicon solar cells need efficient light absorption to achieve high efficiencies. The standard light trapping approach consists of a randomly textured transparent substrate and a highly reflective back contact. In this case, light scattering at the rough TCO-silicon interface leads to a prolonged absorption path and consequently to an increased short circuit current. In this study, we will discuss a new approach based on silver nanoparticles to improve the light absorption in the thin-film silicon solar cells. Raman and SNOM measurements and theoretical investigations on systems with metallic nanoparticles indicate a strong increase of the electric field in their surrounding when they are irradiated by light. Moreover, nanoparticles with the proper diameter can enhance light scattering. In this study, we have investigated the influence of silver nanoparticles with different sizes on the optoelectronic properties of amorphous and microcrystalline silicon solar cells. The nanoparticles are located at the back contact of the thin-film solar cell deposited in a n-i-p layer sequence.

Moulin, E. [Research Center Juelich, Institute of Energy Research (Photovoltaics), D-52425 Juelich (Germany)], E-mail: e.moulin@fz-juelich.de; Sukmanowski, J. [Institute of Experimental Physics, Saarland University, P.O. Box 151150, D-66041 Saarbruecken (Germany); Schulte, M.; Gordijn, A. [Research Center Juelich, Institute of Energy Research (Photovoltaics), D-52425 Juelich (Germany); Royer, F.X. [Laboratoire de Physique des Milieux Denses (LPMD), Universite de Metz, 1 Bd Dominique Francois ARAGO, F-57078 Metz (France); Stiebig, H. [Research Center Juelich, Institute of Energy Research (Photovoltaics), D-52425 Juelich (Germany)

2008-08-30

 
 
 
 
21

Thin-film silicon solar cells with integrated silver nanoparticles  

International Nuclear Information System (INIS)

Thin-film silicon solar cells need efficient light absorption to achieve high efficiencies. The standard light trapping approach consists of a randomly textured transparent substrate and a highly reflective back contact. In this case, light scattering at the rough TCO-silicon interface leads to a prolonged absorption path and consequently to an increased short circuit current. In this study, we will discuss a new approach based on silver nanoparticles to improve the light absorption in the thin-film silicon solar cells. Raman and SNOM measurements and theoretical investigations on systems with metallic nanoparticles indicate a strong increase of the electric field in their surrounding when they are irradiated by light. Moreover, nanoparticles with the proper diameter can enhance light scattering. In this study, we have investigated the influence of silver nanoparticles with different sizes on the optoelectronic properties of amorphous and microcrystalline silicon solar cells. The nanoparticles are located at the back contact of the thin-film solar cell deposited in a n-i-p layer sequence

22

Nanowired Polymer Thin Film Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available The aspiration of the paper is to build up materials and processing techniques that will allow the production of low-cost multi-junction solar cells entirely by solution-processing or other low-cost techniques amenable to roll-to-roll (R2R fabrication such as lamination. Device modeling will help identify the best device structural design. Amalgamation of different types of materials (metals, oxides, semiconductors, polymers is one of the goals of this project.

Dr. K. Siddappa Naidu1 , Dr. D. Bhattacharya2 , Mr. Vijay Albert William3

2013-12-01

23

Laser annealing of thin film polycrystalline silicon solar cell  

Science.gov (United States)

Performances of thin film polycrystalline silicon solar cell grown on glass substrate, using solid phase crystallization of amorphous silicon can be limited by low dopant activation and high density of defects. Here, we investigate line shaped laser induced thermal annealing to passivate some of these defects in the sub-melt regime. Effect of laser power and scan speed on the open circuit voltage of the polysilicon solar cells is reported. The processing temperature was measured by thermal imaging camera. Enhancement of the open circuit voltage as high as 210% is achieved using this method. The results are discussed.

Chowdhury, A.; Bahouka, A.; Steffens, S.; Schneider, J.; Dore, J.; Mermet, F.; Slaoui, A.

2013-11-01

24

Thin film solar cell including a spatially modulated intrinsic layer  

Science.gov (United States)

One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.

Guha, Subhendu (Troy, MI); Yang, Chi-Chung (Troy, MI); Ovshinsky, Stanford R. (Bloomfield Hills, MI)

1989-03-28

25

Thin film solar cells from earth abundant materials growth and characterization of Cu2(ZnSn)(SSe)4 thin films and their solar cells  

CERN Document Server

The fundamental concept of the book is to explain how to make thin film solar cells from the abundant solar energy materials by low cost. The proper and optimized growth conditions are very essential while sandwiching thin films to make solar cell otherwise secondary phases play a role to undermine the working function of solar cells. The book illustrates growth and characterization of Cu2ZnSn(S1-xSex)4 thin film absorbers and their solar cells. The fabrication process of absorber layers by either vacuum or non-vacuum process is readily elaborated in the book, which helps for further developm

Kodigala, Subba Ramaiah

2013-01-01

26

Thin Film Solar Cells: Organic, Inorganic and Hybrid  

Science.gov (United States)

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 especially for space applications. Thin film photovoltaics have the potential to alleviate these problems and create a cheap and efficient way to harness the power of the sun.

Dankovich, John

2004-01-01

27

Development of CIGS2 thin film solar cells  

International Nuclear Information System (INIS)

tion of CuGa/In metallic precursors in diluted Ar:H2S(4%). Heterojunction partner CdS layers are deposited by chemical bath deposition. The regeneration sequence of ZnO/ZnO:Al targets was optimized for obtaining consistently good-quality, transparent and conducting ZnO/ZnO:Al bilayer by RF magnetron-sputter deposition. Excellent facilities at FSEC PV Materials Lab are one of its kinds and could serve as a nucleus of a small pilot plant for CIGSS thin film solar cell fabrication

28

???????????????? Optimization of Amorphous Silicon Thin Film Solar Cells Production Process  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????AZO???????Al???????????????????????????????????Minitab?????????????????????????????????????????????????Al???????????????????????????????????????????????AZO??????????Ar?????????????????????????????????????????????????????During the glass substrate amorphous silicon thin film solar cell production process, the laser scribe 2, sputtering AZO back reflected film, sputtering Al film, and laser scribe 3 etc. processes, have great effect on the maximum power (Pmax of the solar cell. In this paper, we use Minitab software to design factorial experiment and optimize the process parameters. By analyzing the experimental data, we get the conclusion that, between an acceptable range, the sputtering power of Al film has the greatest effect on the Pmax of the solar cell, which increases while the sputtering power increases?and the Pmax increases as the current of laser scribe 3, puttering power of Al films and flux of Ar increase. Otherwise, Pmax decreases as the current of laser scribe 2 increases. By using the factorial experiment, we get the optimum parameters of the process for the present production line.

???

2011-03-01

29

2D modelling of polycrystalline silicon thin film solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of grain boundary (GB properties on device parameters of polycrystalline silicon (poly-Si thin film solar cells is investigated by two-dimensional device simulation. A realistic poly-Si thin film model cell composed of antireflection layer, (n+-type emitter, thick p-type absorber, and (p+-type back surface field was created. The absorber consists of a low-defect crystalline Si grain with an adjacent highly defective grain boundary layer. The performances of a reference cell without GB, one with n-type and one with p-type GB, respectively, are compared. The doping concentration and defect density at the GB are varied. It is shown that the impact of the grain boundary on the poly-Si cell is twofold: a local potential barrier is created at the GB, and a part of the photogenerated current flows within the GB. Regarding the cell performance, a highly doped n-type GB is less critical in terms of the cells short circuit current than a highly doped p-type GB, but more detrimental in terms of the cells open circuit voltage and fill factor.

Leendertz Caspar

2013-07-01

30

Transmission electron microscopy for thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Thin-film amorphous and microcrystalline silicon are promising materials for photovoltaics as they have the potential to reduce the solar cell costs. In case of microcrystalline silicon the crystalline volume fraction is related to the efficiency factor of solar cells because it provides information about the microstructure of the material and the defect density. With Transmission Electron Microscopy of cross-sections it is possible to show the microstructure of the cells. However to determine the structure of the bulk it is necessary to analyse the diffraction of the electron beam. For the purpose of imaging diffraction patterns and displaying dark fields a new camera system has been installed in the Phillips CM200. With much higher sensitivity and a larger photoactive area it is possible to take images of the low-intensity diffraction and the dark field patterns.

Reininghaus, Nies; Schmidt, Vitalij; Hachmann, Wiebke; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Gruss, Stefan; Stiebig, Helmut [Malibu GmbH and Co. KG, Bielefeld (Germany)

2011-07-01

31

Transmission electron microscopy for thin film solar cells  

International Nuclear Information System (INIS)

Thin-film amorphous and microcrystalline silicon are promising materials for photovoltaics as they have the potential to reduce the solar cell costs. In case of microcrystalline silicon the crystalline volume fraction is related to the efficiency factor of solar cells because it provides information about the microstructure of the material and the defect density. With Transmission Electron Microscopy of cross-sections it is possible to show the microstructure of the cells. However to determine the structure of the bulk it is necessary to analyse the diffraction of the electron beam. For the purpose of imaging diffraction patterns and displaying dark fields a new camera system has been installed in the Phillips CM200. With much higher sensitivity and a larger photoactive area it is possible to take images of the low-intensity diffraction and the dark field patterns.

32

Enhanced quantum efficiency of amorphous silicon thin film solar cells with the inclusion of a rear-reflector thin film  

International Nuclear Information System (INIS)

We investigated the growth mechanism of amorphous silicon thin films by implementing hot-wire chemical vapor deposition and fabricated thin film solar cell devices. The fabricated cells showed efficiencies of 7.5 and 8.6% for the samples without and with the rear-reflector decomposed by sputtering, respectively. The rear-reflector enhances the quantum efficiency in the infrared spectral region from 550 to 750?nm. The more stable quantum efficiency of the sample with the inclusion of a rear-reflector than the sample without the rear-reflector due to the bias effect is related to the enhancement of the short circuit current

33

Sputter-Deposited AlTiO Thin Films for Semi-Transparent Silicon Thin Film Solar Cells  

Science.gov (United States)

This paper reports on sputter-deposited AlTiO (ATO) thin films and their effects on the performance of semi-transparent silicon thin film solar cells. The electrical resistivity and the transparency of the ATO films depend significantly on the flow ratio of oxygen to argon during the reactive sputtering process. With highly transparent ATO films, transmittances of over 80% were obtained by increasing this flow ratio. When the ATO films were used on silicon substrates, they exhibited an anti-reflection property, where the minimum reflectance at visible light wavelength was decreased to 1.2%. The introduction of ATO thin film layers into solar cells resulted in a 24% increase in transmittance at wavelengths of around 700 nm, due to the film's anti-reflection characteristic. In addition, the color of the cells changed from green to bright red as the ATO layers were adopted. These beneficial effects of the sputter-deposited ATO films suggest an effective pathway towards the semi-transparent silicon thin film solar cells for building-integrated photovoltaic system applications.

Lee, Seung-Yun; Bang, Ki Su; Lim, Jung Wook

2014-09-01

34

Flexible carbon nanotube/mono-crystalline Si thin-film solar cells  

Science.gov (United States)

Flexible heterojunction solar cells were fabricated from carbon nanotubes (CNTs) and mono-crystalline Si thin films at room temperature. The Si thin films with thickness less than 50 ?m are prepared by chemically etching Si wafer in a KOH solution. The initial efficiency of the thin-film solar cell varies from approximately 3% to 5%. After doping with a few drops of 1 M HNO3, the efficiency increases to 6% with a short-circuit current density of 16.8 mA/cm2 and a fill factor of 71.5%. The performance of the solar cells depends on the surface state and thickness of Si thin films, as well as the interface of CNT/Si. The flexible CNT/Si thin-film solar cells exhibit good stability in bending-recovery cycles.

Sun, Huanhuan; Wei, Jinquan; Jia, Yi; Cui, Xian; Wang, Kunlin; Wu, Dehai

2014-09-01

35

Flexible carbon nanotube/mono-crystalline Si thin-film solar cells  

Science.gov (United States)

Flexible heterojunction solar cells were fabricated from carbon nanotubes (CNTs) and mono-crystalline Si thin films at room temperature. The Si thin films with thickness less than 50?m are prepared by chemically etching Si wafer in a KOH solution. The initial efficiency of the thin-film solar cell varies from approximately 3% to 5%. After doping with a few drops of 1M HNO3, the efficiency increases to 6% with a short-circuit current density of 16.8mA/cm2 and a fill factor of 71.5%. The performance of the solar cells depends on the surface state and thickness of Si thin films, as well as the interface of CNT/Si. The flexible CNT/Si thin-film solar cells exhibit good stability in bending-recovery cycles. PMID:25258617

2014-01-01

36

Emitter epitaxy for crystalline silicon wafers and thin films: Solar cells and economical aspects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Epitaxial emitters grown by high temperature atmospheric pressure CVD can increase the spectral response of the solar cells at short wavelengths with optimised doping profiles. This paper presents the economical aspects, simulation and cell results of wafer and crystalline silicon thin-film solar cells with n-type epitaxial emitters. The economical potential of the emitter epitaxy is confirmed by cost calculations on system level and shows that using thin-film solar cells with epitaxial emitt...

Schmich, E.; Prigge, H.; Frie, T.; Reber, S.

2008-01-01

37

Utility of Thin-Film Solar Cells on Flexible Substrates for Space Power  

Science.gov (United States)

The thin-film solar cell program at NASA GRC is developing solar cell technologies for space applications which address two critical metrics: specific power (power per unit mass) and launch stowed volume. To be competitive for many space applications, an array using thin film solar cells must significantly increase specific power while reducing stowed volume when compared to the present baseline technology utilizing crystalline solar cells. The NASA GRC program is developing two approaches. Since the vast majority of the mass of a thin film solar cell is in the substrate, a thin film solar cell on a very lightweight flexible substrate (polymer or metal films) is being developed as the first approach. The second approach is the development of multijunction thin film solar cells. Total cell efficiency can be increased by stacking multiple cells having bandgaps tuned to convert the spectrum passing through the upper cells to the lower cells. Once developed, the two approaches will be merged to yield a multijunction, thin film solar cell on a very lightweight, flexible substrate. The ultimate utility of such solar cells in space require the development of monolithic interconnections, lightweight array structures, and ultra-lightweight support and deployment techniques.

Dickman, J. E.; Hepp, A. F.; Morel, D. L.; Ferekides, C. S.; Tuttle, J. R.; Hoffman, D. J.; Dhere, N. G.

2004-01-01

38

Plasmonic nanodot array optimization on organic thin film solar cells using anodic aluminum oxide templates  

Science.gov (United States)

The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.

Bae, Kyuyoung; Kim, Kyoungsik

2013-09-01

39

Charge carrier dynamics in thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

This work investigates the charge carrier dynamics in three different technological approaches within the class of thin film solar cells: radial heterojunctions, the dye solar cell, and microcrystalline CuInSe{sub 2}, focusing on charge transport and separation at the electrode, and the relaxation of photogenerated charge carriers due to recombination and energy dissipation to the phonon system. This work relies mostly on optical-pump terahertz-probe (OPTP) spectroscopy, followed by transient absorption (TA) and two-photon photoemission (2PPE). The charge separation in ZnO-electrode/In{sub 2}S{sub 3}-absorber core/shell nanorods, which represent a model system of a radial heterojunction, is analyzed by OPTP. It is concluded, that the dynamics in the absorber are determined by multiple trapping, which leads to a dispersive charge transport to the electrode that lasts over hundreds of picoseconds. The high trap density on the order of 10{sup 19}/cm{sup 3} is detrimental for the injection yield, which exhibits a decrease with increasing shell thickness. The heterogeneous electron transfer from a series of model dyes into ZnO proceeds on a time-scale of 200 fs. However, the photoconductivity builds up just on a 2-10 ps timescale, and 2PPE reveals that injected electrons are meanwhile localized spatially and energetically at the interface. It is concluded that the injection proceeds through adsorbate induced interface states. This is an important result because the back reaction from long lived interface states can be expected to be much faster than from bulk states. While the charge transport in stoichiometric CuInSe{sub 2} thin films is indicative of free charge carriers, CuInSe{sub 2} with a solar cell grade composition (Cu-poor) exhibits signs of carrier localization. This detrimental effect is attributed to a high density of charged defects and a high degree of compensation, which together create a spatially fluctuating potential that inhibits charge transport. On the other hand, the charge carrier lifetime in Cu-poor CIS is orders of magnitude higher as in stoichiometric CIS. This is explained by assuming that the CuIn antisite is the most effective recombination center.

Strothkaemper, Christian

2013-06-24

40

Photovoltaic solar cell from low-cost thin-film technology  

International Nuclear Information System (INIS)

One of the main hindrances of using solar energy for electrical power supply is the high initial cost. Thin-film technologies hold considerable promise for substantial cost reduction for photovoltaic solar cells. The paper reviews the present state of the most advanced thin-film technologies. Amorphous silicon (a-Si:H) solar cells have surmounted the barrier to mass production. Pilot manufacturing lines are under construction for CdTe thin-film module. Cu(In, Ga)Se2 has reached a record efficiency of 18.8 percent in the laboratory and pilot productions have been announced by various companies

 
 
 
 
41

Pulsed electrically detected magnetic resonance for thin film silicon and organic solar cells.  

Science.gov (United States)

In thin film solar cells based on non-crystalline thin film silicon or organic semiconductors structural disorder leads to localized states that induce device limiting charge recombination and trapping. Both processes frequently involve paramagnetic states and become spin-dependent. In the present perspectives article we report on advanced pulsed electrically detected magnetic resonance (pEDMR) experiments for the study of spin dependent transport processes in fully processed thin film solar cells. We reflect on recent advances in pEDMR spectroscopy and demonstrate its capabilities on two different state of the art thin film solar cell concepts based on microcrystalline silicon and organic MEH-PPV:PCBM blends, recently studied at HZB. Benefiting from the increased capabilities of novel pEDMR detection schemes we were able to ascertain spin-dependent transport processes and microscopically identify paramagnetic states and their role in the charge collection mechanism of solar cells. PMID:22941053

Schnegg, Alexander; Behrends, Jan; Fehr, Matthias; Lips, Klaus

2012-11-14

42

Characterization of ZnO:Ga transparent contact electrodes for microcrystalline silicon thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Gallium-doped zinc oxide (ZnO:Ga) thin films are of interest to the semiconductor industry as transparent conductive surfaces and as transparent contact electrode layers for applications such as microcrystalline silicon ({mu}c-Si) thin film solar cells. Physical vapor deposition (PVD) via sputtering is commonly used to produce thin films such as ZnO:Ga, but film quality and characteristics depend significantly on the PVD processing parameters. For use as contact electrode layers in {mu}c-Si thin film solar cells, this study investigates some of the important changes of ZnO:Ga thin films that result from varying DC magnetron PVD sputtering parameters, specifically the working power (500, 1200, and 1900 w), process gas (Ar, Ar/O{sub 2}=50/0.2 sccm) and working pressure (0.74 and 1.06 Pa). Process temperature is held at 200 C because thin film solar cells are damaged above 200 C. Adding O{sub 2} to the Ar carrier gas improved transmittance but the resistivity suffered. However, high-sputtering power solved the resistivity problem. Additionally, the effects of the produced ZnO:Ga material when applied as multi-layer front and back layer electrodes to {mu}c-Si thin film solar cells is evaluated in terms of open-circuit voltage ({delta}V{sub OC}), short-circuit current density ({delta}J{sub SC}), fill factor ({delta}FF) and efficiency ({delta}{eta}) of the cells. (author)

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); Liu, Chien-Chih [Department of Electrical Engineering, Nan Jeon Institute of Technology, Tainan County 737 (China); Lu, Chun-hsiung; Yeh, Chih-Hung [NexPower Technology Corporation, Taichung County 421 (China)

2010-03-15

43

Advances in thin-film solar cells for lightweight space photovoltaic power  

Science.gov (United States)

The present stature and current research directions of photovoltaic arrays as primary power systems for space are reviewed. There have recently been great advances in the technology of thin-film solar cells for terrestrial applications. In a thin-film solar cell the thickness of the active element is only a few microns; transfer of this technology to space arrays could result in ultralow-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe2) and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon:hydrogen and alloys. The best experimental efficiency on thin-film solar cells to date is 12 percent AMO for CuIn Se2. This efficiency is likely to be increased in the next few years. The radiation tolerance of thin-film materials is far greater than that of single-crystal materials. CuIn Se2 shows no degradation when exposed to 1 MeV electrons. Experimental evidence also suggests that most of all of the radiation damage on thin-films can be removed by a low temperature anneal. The possibility of thin-film multibandgap cascade solar cells is discussed, including the tradeoffs between monolithic and mechanically stacked cells. The best current efficiency for a cascade is 12.5 percent AMO for an amorphous silicon on CuInSe2 multibandgap combination. Higher efficiencies are expected in the future. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovolatic arrays may be a mission-enabling technology.

Landis, Geoffrey A.; Bailey, Sheila G.; Flood, Dennis J.

1989-01-01

44

Molybdenum Back-Contact Optimization for CIGS Thin Film Solar Cell  

Directory of Open Access Journals (Sweden)

Full Text Available Molybdenum (Mo thin films are most widely used as an ohmic back-contact in the copper indium diselenide (CIS and its alloy copper indium gallium diselenide (CIGS based thin film solar cell. Radio frequency (RF magnetron sputtering system used to deposit Mo thin films on soda lime glass substrate. The deposition was carried out using argon (Ar gas at different Ar controlled (working pressures (1 mTorr to 10 mTorr and at different RF powers (60 W to 100 W. The influence of both the working pressure and the RF power on the Mo thin films was studied by investigating its structural, morphological, electrical, and optical measurements. The results reveal that a stress-free, low-sheet-resistance (~1 ?/?cm2, and reflecting (~ 55 % Mo thin film was observed at 1 mTorr working pressure and 100 W RF power.

J.R. Ray

2011-01-01

45

Research status of silicon-based thin film solar cells in Nankai University  

Energy Technology Data Exchange (ETDEWEB)

This paper reviews the development of silicon-based thin films in Nankai University. It can be divided into the following research areas: (1) light arrangement for wide utilizing the solar energy: textural transparent conductive oxide (TCO) including p-type ZnO; (2) silicon-based thin film solar cells including amorphous silicon and microcrystalline silicon; (3) plasma diagnostic and simulation for effectively controlling deposition conditions; (4) one example explored on new concept of next generation solar cells: up-conversion for a-Si solar cells. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Zhao, Ying; Zhang, Xiaodan; Xue, Junming; Zhang, Jianjun; Hou, Guofu; Cai, Ning; Chen, Xinliang; Wei, Changchun; Sun, Jian; Zhang, Dekun; Ren, Huizhi; Xiong, Shaozhen; Geng, Xinhua [Inst. of Photo-electronics, Thin Film Devices and Technique of Nankai Univ., Key Lab. of Photo-electronics, Thin Film Devices and Technique of Tianjin, Key Lab. of Photo-electronic Information Science and Technology (Nankai University), Ministry of Education (China)

2009-07-01

46

Hydrogen passivation of polycrystalline Si thin film solar cells  

International Nuclear Information System (INIS)

Hydrogen passivation is a key process step in the fabrication of polycrystalline Si (poly-Si) thin film solar cells. In this work a parallel plate rf plasma setup was used for the hydrogen passivation treatment. The main topics that have been investigated are (i) the role of plasma parameters (like hydrogen pressure, electrode gap and plasma power), (ii) the dynamics of the hydrogen treatment and (iii) passivation of poly-Si with different material properties. Passivation was characterized by measuring the open-circuit voltage VOC of poly-Si reference samples. Optimum passivation conditions were found by measurements of the breakdown voltage Vbrk of the plasma for different pressures p and electrode gaps d. For each pressure, the best passivation was achieved at a gap d that corresponded to the minimum in Vbrk. Plasma simulations were carried out, which indicate that best VOC corresponds to a minimum in ion energy. VOC was not improved by a larger H flux. Investigations of the passivation dynamic showed that a plasma treatment in the lower temperature range (?400 C) is slow and takes several hours for the VOC to saturate. Fast passivation can be successfully achieved at elevated temperatures around 500 C to 600 C with a plateau time of 10 min. It was found that prolonged hydrogenation leads to a loss in VOC, which is less pronounced within the observed optimum temperature range (500 C-600 C). Electron beam evaporation has been investigated as an alternative method to fabricate poly-Si absorbers. The material properties have been tuned by alteration of substrate temperature Tdep=200-700 C and were characterized by Raman, ESR and VOC measurements. Largest grains were obtained after solid phase crystallization (SPC) of a-Si, deposited in the temperature range of 300 C. The defect concentration of Si dangling bonds was lowered by passivation by about one order of magnitude. The lowest dangling bond concentration of 2.5.1016 cm-3 after passivation was found for poly-Si with largest grains and coincides with best solar cell results, obtained after rapid thermal annealing and hydrogen passivation. Hydrogen passivation of poly-Si films was successfully achieved with a parallel plate rf H plasma treatment at elevated temperatures around 500 C to 600 C. Yet it seems that treatment induced defect generation causes a loss in VOC with prolonged passivation time and should be minimized. In order to achieve high open circuit voltages larger than 450 mV, in addition to hydrogen passivation, low recombination at the interfaces becomes more and more important. (orig.)

47

Analyzing periodic and random textured silicon thin film solar cells by Rigorous Coupled Wave Analysis.  

Science.gov (United States)

A simple and fast method was developed to determine the quantum efficiency and short circuit current of thin-film silicon solar cells prepared on periodically or randomly textured surfaces. The optics was studied for microcrystalline thin-film silicon solar cells with integrated periodic and random surface textures. Rigorous Coupled Wave Analysis (RCWA) was used to investigate the behaviour of the solar cells. The analysis of the periodic and random textured substrates allows for deriving optimal surface textures. Furthermore, light trapping in periodic and randomly textured substrates will be compared. PMID:25112301

Dewan, Rahul; Jovanov, Vladislav; Hamraz, Saeed; Knipp, Dietmar

2014-01-01

48

CdTe thin film solar cells: Interrelation of nucleation, structure, and performance  

International Nuclear Information System (INIS)

The performance of CdTe solar cells as prototype of thin film solar cells strongly depends on film morphology. The needs for high solar cell performance using thin film materials will be addressed covering nucleation and growth control of thin film materials. In order to understand the basic growth mechanisms and their impact on cell performance, we have systematically investigated the growth of CdTe thin films by Close Spaced Sublimation (CSS) using the integrated ultra-high vacuum system DAISY-SOL. CdTe thin films were deposited on TCO/CdS substrates (transparent conductive oxide) held at 270 deg. C to 560 deg. C . The properties of the films were determined before and after CdCl2 treatment using X-ray diffraction and electron microscopy. In addition, solar cells were prepared to find correlations between material properties and cell efficiency. At low sample temperature the films tend to form compact layers with preferred (111) orientation which is lost at elevated temperatures above 450 deg. C . For CdS layers without (0001) texture there is in addition a low temperature regime (350 deg. C ) with (111) texture loss. After activation treatment the (111) texture is lost for all deposited layers leading to strong recrystallisation of the grains. But the texture still depends on the previous growth history. The loss of (111) texture is evidently needed for higher performance. A clear correlation between cell efficiency and the texture of the CdTe film is observed

49

CdTe thin film solar cells: Interrelation of nucleation, structure, and performance  

Energy Technology Data Exchange (ETDEWEB)

The performance of CdTe solar cells as prototype of thin film solar cells strongly depends on film morphology. The needs for high solar cell performance using thin film materials will be addressed covering nucleation and growth control of thin film materials. In order to understand the basic growth mechanisms and their impact on cell performance, we have systematically investigated the growth of CdTe thin films by Close Spaced Sublimation (CSS) using the integrated ultra-high vacuum system DAISY-SOL. CdTe thin films were deposited on TCO/CdS substrates (transparent conductive oxide) held at 270 deg. C to 560 deg. C . The properties of the films were determined before and after CdCl{sub 2} treatment using X-ray diffraction and electron microscopy. In addition, solar cells were prepared to find correlations between material properties and cell efficiency. At low sample temperature the films tend to form compact layers with preferred (111) orientation which is lost at elevated temperatures above 450 deg. C . For CdS layers without (0001) texture there is in addition a low temperature regime (350 deg. C ) with (111) texture loss. After activation treatment the (111) texture is lost for all deposited layers leading to strong recrystallisation of the grains. But the texture still depends on the previous growth history. The loss of (111) texture is evidently needed for higher performance. A clear correlation between cell efficiency and the texture of the CdTe film is observed.

Luschitz, J.; Siepchen, B.; Schaffner, J.; Lakus-Wollny, K.; Haindl, G.; Klein, A. [TU Darmstadt, Institute of Materials Science, Surface Science Division, Petersenstrasse 23, 64287 Darmstadt (Germany); Jaegermann, W. [TU Darmstadt, Institute of Materials Science, Surface Science Division, Petersenstrasse 23, 64287 Darmstadt (Germany)], E-mail: jaegermann@surface.tu-darmstadt.de

2009-02-02

50

Enhanced optical absorption by Ag nanoparticles in a thin film Si solar cell  

International Nuclear Information System (INIS)

Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect band gap. In this paper, we investigate the suitability of surface plasmon resonance Ag nanoparticles for enhancing optical absorption in the thin film solar cell. For evaluating the transmittance capability of Ag nanoparticles and the conventional antireflection film, an enhanced transmittance factor is introduced. We find that under the solar spectrum AM1.5, the transmittance of Ag nanoparticles with radius over 160 nm is equivalent to that of conventional textured antireflection film, and its effect is better than that of the planar antireflection film. The influence of the surrounding medium is also discussed. (physics of gases, plasmas, and electric discharges)

51

GaAs thin film nanostructure arrays for III-V solar cell applications  

Science.gov (United States)

State of art III-V multi-junction solar cells have demonstrated a record high efficiency of 43.5%. However, these cells are only applicable to high concentration systems due to their high cost of substrates and epitaxial growth. We demonstrate thin film flexible nanostructure arrays for III-V solar cell applications. Such nanostructure arrays allow substrate recycling and much thinner epitaxial layer thus could significantly reduce the cost of traditional III-V solar cells. We fabricate the GaAs thin film nanostructure arrays by conformally growing GaAs thin film on nanostructured template followed by epitaxial lift-off. We demonstrate broadband optical absorption enhancement of a film of GaAs nanostructure arrays over a planar thin film with equal thickness. The absorption enhancement is about 300% at long wavelengths due to significant light trapping effect and about 30% at short wavelengths due to antireflection effect from tapered geometry. Optical simulation shows the physical mechanisms of the absorption enhancement. Using thin film nanostructure arrays, the III-V solar system cost could be greatly reduced, leading to low $/W and high kW/kg flexible solar systems.

Liang, Dong; Kang, Yangsen; Huo, Yijie; Wang, Ken Xinze; Gu, Anjia; Tan, Meiyueh; Yu, Zongfu; Li, Shuang; Jia, Jieyang; Bao, Xinyu; Wang, Shuang; Yao, Yan; Fan, Shanhui; Cui, Yi; Harris, James

2012-03-01

52

Understanding Light Harvesting in Radial Junction Amorphous Silicon Thin Film Solar Cells  

Science.gov (United States)

The radial junction (RJ) architecture has proven beneficial for the design of a new generation of high performance thin film photovoltaics. We herein carry out a comprehensive modeling of the light in-coupling, propagation and absorption profile within RJ thin film cells based on an accurate set of material properties extracted from spectroscopic ellipsometry measurements. This has enabled us to understand and evaluate the impact of varying several key parameters on the light harvesting in radially formed thin film solar cells. We found that the resonance mode absorption and antenna-like light in-coupling behavior in the RJ cell cavity can lead to a unique absorption distribution in the absorber that is very different from the situation expected in a planar thin film cell, and that has to be taken into account in the design of high performance RJ thin film solar cells. When compared to the experimental EQE response of real RJ solar cells, this modeling also provides an insightful and powerful tool to resolve the wavelength-dependent contributions arising from individual RJ units and/or from strong light trapping due to the presence of the RJ cell array. PMID:24619197

Yu, Linwei; Misra, Soumyadeep; Wang, Junzhuan; Qian, Shengyi; Foldyna, Martin; Xu, Jun; Shi, Yi; Johnson, Erik; Cabarrocas, Pere Roca i

2014-01-01

53

Understanding Light Harvesting in Radial Junction Amorphous Silicon Thin Film Solar Cells  

Science.gov (United States)

The radial junction (RJ) architecture has proven beneficial for the design of a new generation of high performance thin film photovoltaics. We herein carry out a comprehensive modeling of the light in-coupling, propagation and absorption profile within RJ thin film cells based on an accurate set of material properties extracted from spectroscopic ellipsometry measurements. This has enabled us to understand and evaluate the impact of varying several key parameters on the light harvesting in radially formed thin film solar cells. We found that the resonance mode absorption and antenna-like light in-coupling behavior in the RJ cell cavity can lead to a unique absorption distribution in the absorber that is very different from the situation expected in a planar thin film cell, and that has to be taken into account in the design of high performance RJ thin film solar cells. When compared to the experimental EQE response of real RJ solar cells, this modeling also provides an insightful and powerful tool to resolve the wavelength-dependent contributions arising from individual RJ units and/or from strong light trapping due to the presence of the RJ cell array.

Yu, Linwei; Misra, Soumyadeep; Wang, Junzhuan; Qian, Shengyi; Foldyna, Martin; Xu, Jun; Shi, Yi; Johnson, Erik; Cabarrocas, Pere Roca I.

2014-03-01

54

Spray-on Thin Film PV Solar Cells: Advances, Potentials and Challenges  

Directory of Open Access Journals (Sweden)

Full Text Available The capability to fabricate photovoltaic (PV solar cells on a large scale and at a competitive price is a milestone waiting to be achieved. Currently, such a fabrication method is lacking because the effective methods are either difficult to scale up or expensive due to the necessity for fabrication in a vacuum environment. Nevertheless, for a class of thin film solar cells, in which the solar cell materials can be processed in a solution, up scalable and vacuum-free fabrication techniques can be envisioned. In this context, all or some layers of polymer, dye-sensitized, quantum dot, and copper indium gallium selenide thin film solar cells illustrate some examples that may be processed in solution. The solution-processed materials may be transferred to the substrate by atomizing the solution and carrying the spray droplets to the substrate, a process that will form a thin film after evaporation of the solvent. Spray coating is performed at atmospheric pressure using low cost equipment with a roll-to-roll process capability, making it an attractive fabrication technique, provided that fairly uniform layers with high charge carrier separation and transport capability can be made. In this paper, the feasibility, the recent advances and challenges of fabricating spray-on thin film solar cells, the dynamics of spray and droplet impaction on the substrate, the photo-induced electron transfer in spray-on solar cells, the challenges on characterization and simulation, and the commercialization status of spray-on solar cells are discussed.

Morteza Eslamian

2014-01-01

55

Effects of phosphorous doping to poly (methylphenyl silane) and fabrication of thin film solar cells  

International Nuclear Information System (INIS)

Effects of phosphorus bromine (PBr3) doping to polysilane were investigated for spin-coating thin films. Phosphorus doped poly (methylphenyl silane) (PMPS) provided n-type semiconductor behavior, which was confirmed by Hall effect measurements. Desorption of phenyl and methyl groups in doped PMPS thin films was observed after annealing at 300 C from Raman scattering measurements and theoretical calculations. The band gap energy of PMPS was measured to be 3.2 eV. Decrease of photoluminescence intensity of PMPS was observed by phosphorus doping. Microstructures of the doped PMPS thin films were investigated by using X-ray diffraction, which indicated doped PMPS had an amorphous structure after annealing. A solar cell with PMPS(PBr3):poly[3-hexylthiophene] bulk-heterojunction structure was fabricated, and provided a photovoltaic behavior. Formation mechanism and carrier transport mechanism of the doped PMPS thin films were proposed.

56

Effects of phosphorous doping to poly (methylphenyl silane) and fabrication of thin film solar cells  

Science.gov (United States)

Effects of phosphorus bromine (PBr3) doping to polysilane were investigated for spin-coating thin films. Phosphorus doped poly (methylphenyl silane) (PMPS) provided n-type semiconductor behavior, which was confirmed by Hall effect measurements. Desorption of phenyl and methyl groups in doped PMPS thin films was observed after annealing at 300 C from Raman scattering measurements and theoretical calculations. The band gap energy of PMPS was measured to be 3.2 eV. Decrease of photoluminescence intensity of PMPS was observed by phosphorus doping. Microstructures of the doped PMPS thin films were investigated by using X-ray diffraction, which indicated doped PMPS had an amorphous structure after annealing. A solar cell with PMPS(PBr3):poly[3-hexylthiophene] bulk-heterojunction structure was fabricated, and provided a photovoltaic behavior. Formation mechanism and carrier transport mechanism of the doped PMPS thin films were proposed.

Nakagawa, Junya; Oku, Takeo; Suzuki, Atsushi; Akiyama, Tsuyoshi; Tokumitsu, Katsuhisa; Yamada, Masahiro; Nakamura, Mika

2013-04-01

57

Optical absorption losses in metal layers used in thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

We apply optical transmittance and reflectance spectroscopy, photothermal deflection spectroscopy (PDS) and laser calorimetry (LC) to evaluate optical absorption losses at rough interface between thin conductive oxide (TCO) and metal films used as backreflectors and electrical contacts in thin film solar cells. The paper proposes a simple method how to model the dielectric function of rough metal layers used in thin film solar cells. We show that the rough metal layer optically behaves as a semi-infinite layer with modified dielectric function calculated by the Landau-Lifshitz-Looyenga (LLL) model from the dielectric function of a smooth metal, the dielectric function of TCO and just one free parameter that needs to be found by fitting the total optical absorptance. This approach can be used to simplify the modelling of the optical properties of thin film solar cells. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Remes, Zdenek; Holovsky, Jakub; Purkrt, Adam; Izak, Tibor; Poruba, Ales; Vanecek, Milan [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnicka 10, 16253 Prague (Czech Republic); Dagkaldiran, Uemit [IEF5-Photovoltaik, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Yates, Heather M.; Evans, Philip; Sheel, David W. [Institute for Materials Research, University of Salford, Manchester, M5 4WT (United Kingdom)

2010-09-15

58

Material selection for thin-film solar cells using multiple attribute decision making approach  

International Nuclear Information System (INIS)

This paper presents a material selection approach for selecting absorbent layer material for thin-film solar cells (TFSCs) using multiple attribute decision making (MADM) approach. In this paper, different possible materials for absorbent layer and their properties like band gap, absorption coefficient, diffusion length, thermodynamic compatibility and recombination velocity is taken into consideration and MADM approach is applied to select the best material for thin-film solar cells. It is observed that Copper Indium Gallium Diselinide (CIGS) is the best material for the absorbent layer in thin-film solar cells out of all possible candidates. It was observed that the proposed result is in accordance with the experimental findings thus justifying the validity of the proposed study.

59

Progress in polycrystalline thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Photovoltaic devices based on several polycrystalline thin-film materials have reached near and above 10% sunlight-to-electricity conversion efficiencies. This paper examines the various polycrystalline thin-film PV materials including CuInSe/sub 2/ and CdTe in terms of their material properties, fabrication techniques, problems, and potentials.

Zweibel, K; Hermann, A; Mitchell, R

1983-07-01

60

Enhancing the driving field for plasmonic nanoparticles in thin-film solar cells.  

Science.gov (United States)

The scattering cross-section of a plasmonic nanoparticle is proportional to the intensity of the electric field that drives the plasmon resonance. In this work we determine the driving field pattern throughout a complete thin-film silicon solar cell. Our simulations reveal that by tuning of the thicknesses of silicon and transparent conductive oxide layers the driving field intensity experienced by an embedded plasmonic nanoparticle can be enhanced up to a factor of 14. This new insight opens the route towards more efficient plasmonic light trapping in thin-film solar cells. PMID:24978065

Santbergen, Rudi; Tan, Hairen; Zeman, Miro; Smets, Arno H M

2014-06-30

 
 
 
 
61

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 reflectance close to 100% is achieved over a broad wavelength region (7001300 nm). Based on this concept, a back reflector was designed for thin-film microcrystalline silicon solar cells, using n-doped am...

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

2009-01-01

62

Grain boundaries in Cu(In,Ga)(Se,S){sub 2} thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The paper reviews the current status of the research on grain boundaries in polycrystalline Cu(In,Ga)(S,Se){sub 2} alloys used as absorber materials for thin-film solar cells. We discuss the different concepts that are available to explain the relatively low electronic activity of grain boundaries in these materials. Numerical simulations that have been undergone so far to model the polycrystalline solar cells are briefly summarized. In addition, we give an overview on the experiments that have been conducted so far to elucidate the structural, defect-chemical, and electronic properties of grain boundaries in Cu(In,Ga)(S,Se){sub 2} thin-films. (orig.)

Rau, Uwe [Forschungszentrum Juelich, IEF5-Photovoltaik, Juelich (Germany); Taretto, Kurt [Universidad Nacional del Comahue, Dto. de Electrotecnia, Buenos Aires, Neuquen (Argentina); Siebentritt, Susanne [Universite du Luxembourg, Luxembourg (Luxembourg)

2009-07-15

63

Soft X-rays shedding light on thin-film solar cell surfaces and interfaces  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? S/Se gradient-driven chemical interaction at the CdS/CIG(S)Se interface. ? Depth-dependent band gap in chalcopyrites. ? Band alignment at the CdS/Cu{sub 2}ZnSnS{sub 4} solar cell heterojunction. ? Post-deposition treatment induces intermixing in the CdTe/CdS solar cell structure. -- Abstract: Thin-film solar cells based on compound semiconductors consist of a multilayer structure with various interfaces and contain a multitude of elements and impurities, etc. A rapid progress of these photovoltaic technologies can only be achieved by an insight-driven optimization/development. Hence it is crucial to characterize and understand the relationship between the chemical and electronic properties of these components. This paper reviews some examples of our recent work characterizing compound semiconductor thin films using laboratory- and synchrotron-based electron and soft X-ray spectroscopic characterization methods. It is demonstrated how these different analytical techniques are extraordinarily powerful to reveal the material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of the related electronic and chemical properties. As examples, the paper will discuss the electronic surface structure of chalcopyrite thin-film solar cell absorbers, the chemical structure of the CdS/chalcopyrite interface, present the band alignment at the CdS/kesterite interface, and report on how post-deposition treatments cause chemical interaction/interdiffusion processes in CdTe/CdS thin-film solar cell structures.

Br, M., E-mail: marcus.baer@helmholtz-berlin.de [Solar Energy Research, Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH (HZB), D-14109 Berlin (Germany); Institut fr Physik und Chemie, Brandenburgische Technische Universitt Cottbus, D-03046 Cottbus (Germany); Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Pookpanratana, S. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Weinhardt, L. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen (Germany); ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, D-76344 Eggenstein-Leopoldshafen (Germany); Wilks, R.G.; Schubert, B.A.; Marsen, B.; Unold, T. [Solar Energy Research, Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH (HZB), D-14109 Berlin (Germany); Blum, M.; Krause, S. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Zhang, Y. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Ranasinghe, A. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Ramanathan, K.; Repins, I.; Contreras, M.A. [National Renewable Energy Laboratory (NREL), Golden, CO 80401 (United States); Nishiwaki, S. [Institute for Energy Conversion (IEC), University of Delaware, Newark, DE 19716 (United States); and others

2013-10-15

64

Texture ZnO Thin-Films and their Application as Front Electrode in Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, three kinds of textured ZnO thin-films (the first kind has the textured structure with both columnar and polygon, the second posses pyramid-like textured structure only, and the third has the textured structure with both crater-like and pyramid-like, were prepared by three kinds of methods, and the application of these ZnO thin-films as a front electrode in solar cell was studied, respectively. In the first method with negative bias voltage and appropriate sputtering parameters, the textured structure with columnar and polygon on the surface of ZnO thin-film are both existence for the sample prepared by direct magnetron sputtering. Using as a front electrode in solar cell, the photoelectric conversion efficiency Eff of 7.00% was obtained. The second method is that by sputtering on the ZnO:Al self-supporting substrate, and the distribution of pyramid-like was gained. Moreover, the higher (8.25% photoelectric conversion efficiency of solar cell was got. The last method is that by acid-etching the as-deposited ZnO thin-film which possesses mainly both columnar and polygon structure, and the textured ZnO thin-film with both crater-like and pyramid-like structure was obtained, and the photoelectric conversion efficiency of solar cell is 7.10% when using it as front electrode. These results show that the textured ZnO thin-film prepared on self-supporting substrate is more suitable for using as a front electrode in amorphous silicon cells.

Yue-Hui Hu

2010-12-01

65

Properties of ITO-AZO bilayer thin films prepared by magnetron sputtering for applications in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

In this paper we study the electro-optical behavior and the application of indium-tin oxide (ITO) and aluminum-doped zinc oxide (AZO) bilayer thin films for silicon solar cells. ITO-AZO bilayer thin films were deposited on glass substrates using radio-frequency magnetron sputtering. The experimental results show that a decrease in the electrical resistivity of the ITO-AZO bilayer thin films has been achieved without significant degradation of optical properties. In the best case the resistivity of the bilayer films reached a minimum of 5.075 x 10{sup -4} {Omega} cm when the thickness of the AZO buffer layer was 12 nm. The ITO-AZO bilayer films were applied as the front electrodes of amorphous silicon solar cells and the short-circuit current density of the solar cells was considerably increased. (orig.)

Wang, Chao; Mao, Yanli [Henan University, Henan Key Laboratory of Photovoltaic Materials, School of Physics and Electronics, Kaifeng (China); Zeng, Xiangbo [Chinese Academy of Sciences, Key Laboratory of Semiconductor Materials, Beijing (China)

2013-01-15

66

Properties of ITO-AZO bilayer thin films prepared by magnetron sputtering for applications in thin-film silicon solar cells  

Science.gov (United States)

In this paper we study the electro-optical behavior and the application of indium-tin oxide (ITO) and aluminum-doped zinc oxide (AZO) bilayer thin films for silicon solar cells. ITO-AZO bilayer thin films were deposited on glass substrates using radio-frequency magnetron sputtering. The experimental results show that a decrease in the electrical resistivity of the ITO-AZO bilayer thin films has been achieved without significant degradation of optical properties. In the best case the resistivity of the bilayer films reached a minimum of 5.07510-4 ? cm when the thickness of the AZO buffer layer was 12 nm. The ITO-AZO bilayer films were applied as the front electrodes of amorphous silicon solar cells and the short-circuit current density of the solar cells was considerably increased.

Wang, Chao; Mao, Yanli; Zeng, Xiangbo

2013-01-01

67

Application of electrochemical deposition techniques to thin film solar cell processing  

Science.gov (United States)

During the last eight years the manufacturing volume of thin film modules has grown at a compounded annualized rate of over 90%. Today the share of thin film products in the global photovoltaics (PV) market is in the range of 10-15%. Considering the fact that wafer Si technologies have achieved impressive cost reductions during the last few years, any increase in thin film market share during the next decade will require these technologies to aggressively drive for cost reductions through device efficiency improvements and utilization of lower cost manufacturing techniques. Electrochemical deposition or electrodeposition is an attractive low cost approach for the formation of thin film coatings. Such coatings have already found large scale applications in circuit board fabrication and integrated circuit manufacturing. In these applications, the electroplated layers are mainly used as passive components that carry electrical current. Application of electrodeposition techniques to thin film solar cell fabrication involves formation of semiconductor absorber layers that actively participate in power generation. This requirement brings along certain challenges that need to be overcome. In this paper we will present a review of work carried out for the application of electrodeposition techniques to the fabrication of CdTe and CIGS based solar cells and modules.

Ba?ol, Blent M.

2011-09-01

68

?????????????????? Research Progress of Surface Plasmon Applied in Thin Film Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????In order to transfer light to electricity efficiently, thin film solar cells with the structure of supporting surface plasmons in metal particles are designed. Due to the surface plasmons can guide and localize lights, the physical thickness of solar photovoltaic absorbing layer can be decreased as well as the absorption in photovoltaic devices can be improved. This technology plays an important role in fabricating low-cost and high-efficiency thin film solar cells. In this review, the latest progress of the application of plasmonics in solar cells is researched, the mechanism of the intersection of plasmonics and photovoltaics is expounded, and an outlook on the future of solar cells based on these principles is offered.

???

2011-10-01

69

Disorder improves nanophotonic light trapping in thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500?nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500?nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures.

Paetzold, U. W., E-mail: u.paetzold@fz-juelich.de; Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Carius, R.; Rau, U. [IEK5Photovoltaik, Forschungszentrum Jlich GmbH, 52425 Jlich (Germany); Michaelis, D.; Waechter, C. [Fraunhofer Institut fr Angewandte Optik und Feinmechanik, Albert Einstein Str. 7, D-07745 Jena (Germany)

2014-03-31

70

Disorder improves nanophotonic light trapping in thin-film solar cells  

International Nuclear Information System (INIS)

We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500?nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500?nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures

71

Novel wide band gap materials for highly efficient thin film tandem solar cells  

Energy Technology Data Exchange (ETDEWEB)

Tandem solar cells (TSCs), which use two or more materials to absorb sunlight, have achieved power conversion efficiencies of >25% versus 11-20% for commercialized single junction solar cell modules. The key to widespread commercialization of TSCs is to develop the wide-band, top solar cell that is both cheap to fabricate and has a high open-circuit voltage (i.e. >1V). Previous work in TSCs has generally focused on using expensive processing techniques with slow growth rates resulting in costs that are two orders of magnitude too expensive to be used in conventional solar cell modules. The objective of the PLANT PV proposal was to investigate the feasibility of using Ag(In,Ga)Se2 (AIGS) as the wide-bandgap absorber in the top cell of a thin film tandem solar cell (TSC). Despite being studied by very few in the solar community, AIGS solar cells have achieved one of the highest open-circuit voltages within the chalcogenide material family with a Voc of 949mV when grown with an expensive processing technique (i.e. Molecular Beam Epitaxy). PLANT PVâ??s goal in Phase I of the DOE SBIR was to 1) develop the chemistry to grow AIGS thin films via solution processing techniques to reduce costs and 2) fabricate new device architectures with high open-circuit voltage to produce full tandem solar cells in Phase II. PLANT PV attempted to translate solution processing chemistries that were successful in producing >12% efficient Cu(In,Ga)Se2 solar cells by replacing copper compounds with silver. The main thrust of the research was to determine if it was possible to make high quality AIGS thin films using solution processing and to fully characterize the materials properties. PLANT PV developed several different types of silver compounds in an attempt to fabricate high quality thin films from solution. We found that silver compounds that were similar to the copper based system did not result in high quality thin films. PLANT PV was able to deposit AIGS thin films using a mixture of solution and physical vapor deposition processing, but these films lacked the p-type doping levels that are required to make decent solar cells. Over the course of the project PLANT PV was able to fabricate efficient CIGS solar cells (8.7%) but could not achieve equivalent performance using AIGS. During the nine-month grant PLANT PV set up a variety of thin film characterization tools (e.g. drive-level capacitance profiling) at the Molecular Foundry, a Department of Energy User Facility, that are now available to both industrial and academic researchers via the grant process. PLANT PV was also able to develop the back end processing of thin film solar cells at Lawrence Berkeley National Labs to achieve 8.7% efficient CIGS solar cells. This processing development will be applied to other types of thin film PV cells at the Lawrence Berkeley National Labs. While PLANT PV was able to study AIGS film growth and optoelectronic properties we concluded that AIGS produced using these methods would have a limited efficiency and would not be commercially feasible. PLANT PV did not apply for the Phase II of this grant.

Brian E. Hardin, Stephen T. Connor, Craig H. Peters

2012-06-11

72

Improving thin-film crystalline silicon solar cell efficiencies with photonic crystals.  

Science.gov (United States)

Most photovoltaic (solar) cells are made from crystalline silicon (c-Si), which has an indirect band gap. This gives rise to weak absorption of one-third of usable solar photons. Therefore, improved light trapping schemes are needed, particularly for c-Si thin film solar cells. Here, a photonic crystal-based light-trapping approach is analyzed and compared to previous approaches. For a solar cell made of a 2 mum thin film of c-Si and a 6 bilayer distributed Bragg reflector (DBR) in the back, power generation can be enhanced by a relative amount of 24.0% by adding a 1D grating, 26.3% by replacing the DBR with a six-period triangular photonic crystal made of air holes in silicon, 31.3% by a DBR plus 2D grating, and 26.5% by replacing it with an eight-period inverse opal photonic crystal. PMID:19550990

Bermel, Peter; Luo, Chiyan; Zeng, Lirong; Kimerling, Lionel C; Joannopoulos, John D

2007-12-10

73

Microcrystalline silicon for large area thin film solar cells  

International Nuclear Information System (INIS)

We present a comprehensive study of microcrystalline silicon (?c-Si:H) solar cells prepared by plasma-enhanced chemical vapour deposition (PECVD) at 13.56 MHz excitation frequency. In the first step the cell development was performed in a small area PECVD reactor showing the relationship between the deposition process parameters and the resulting solar cell performance. Focus was on the influence of deposition pressure, electrode distance and the application of a pulsed plasma on high rate deposition of solar cells. Subsequent up-scaling to a substrate area of 30x30 cm2 confirmed the suitability of the process for large area reactors. The influence of i-layer deposition parameters on solar cell performance was studied directly in p-i-n cells prepared on textured ZnO. Solar cell efficiencies up to 9% were achieved at deposition rates of 5-6 A/s for the i-layer using high plasma powers. Applied as bottom cell in a-Si:H/?c-Si:H tandem cells a stable cell efficiency of 11.2% could be obtained. The excellent homogeneity was proven by the realization of first modules with an aperture area of 689 cm2 and an active area initial efficiency of 10.3% (stable: 8.9%) using an established base technology for laser patterning and back contact sputtering at RWE Solar GmbH

74

Thin film solar cells using impure polycrystalline silicon  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Epitaxial solar cells have been studied with the view of using rather impure upgraded metallurgical grade (UMG)-Si as a substrate material. It is confirmed that transition elements have segregated during ingot growth and that impurities such as B, P, Al do not diffuse from substrate to epilayers, so that the latter have resistivity and electron diffusion length adequate to produce good solar cells. 10.3 % efficiency cells have been obtained. By spectral response measurements, interpreted thro...

Rodot, M.; Barbe, M.; Bouree, J. E.; Perraki, V.; Revel, G.; Kishore, R.; Pastol, J. L.; Mertens, R.; Caymax, M.; Eyckmans, M.

1987-01-01

75

Photon management in thin-film solar cells; Photon-Management in Duennschicht-Solarzellen  

Energy Technology Data Exchange (ETDEWEB)

In this thesis procedures were presented, which modify the propagation of the incident light in such a way that by this the efficiency of thin-film solar cells is increased. The strength of the presented numerical studies lies thereby in the rigorous solution of Maxwell's equations. Fundamental statements concerning the lay-out of an ideal texture could be made, which for present thin-film solar cells over the whole relevant spectral range both suppresses reflection losses and leads to an elongation of the effective path. Object of the thesis was also the design of a spectral- and angular-selective filter, which confines the acceptance angle of a solar cell with the aim of an improved absorption in the long-wave spectral region. Furthermore also tandem cells on the base of amorphous and microcrystalline silicon were studied.

Fahr, Stephan

2011-11-22

76

Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells  

Energy Technology Data Exchange (ETDEWEB)

This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

Chu, T.L. (University of South Florida, Tampa, FL (United States))

1992-04-01

77

Plasmonic light trapping in thin-film Si solar cells  

International Nuclear Information System (INIS)

Plasmonic nanostructures have been recently investigated as a possible way to improve absorption of light in solar cells. The strong interaction of small metal nanostructures with light allows control over the propagation of light at the nanoscale and thus the design of ultrathin solar cells in which light is trapped in the active layer and efficiently absorbed. In this paper we review some of our recent work in the field of plasmonics for improved solar cells. We have investigated two possible ways of integrating metal nanoparticles in a solar cell. First, a layer of Ag nanoparticles that improves the standard antireflection coating used for crystalline and amorphous silicon solar cells has been designed and fabricated. Second, regular and random arrays of metal nanostructures have been designed to couple light in waveguide modes of thin semiconductor layers. Using a large-scale, relative inexpensive nano-imprint technique, we have designed a back-contact light trapping surface for a-Si:H solar cells which show enhanced efficiency over standard randomly textured cells. (review article)

78

Microstructure Analysis and Properties of Anti-Reflection Thin Films for Spherical Silicon Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Structure and properties of anti-reflection thin films of spherical silicon solar cells were investigated and discussed. Conversion efficiencies of spherical Si solar cells coated with F-doped SnO2 anti-reflection films were improved by annealing. Optical absorption and fluorescence of the solar cells increased after annealing. Lattice constants of F-doped SnO2 anti-reflection layers, which were investigated by X-ray diffraction, decreased after annealing. A mechanism of atomic diffusion of F in SnO2 was discussed. The present work indicated a guideline for spherical silicon solar cells with higher efficiencies.

Masato Kanayama

2013-04-01

79

Thin film solar cell inflatable ultraviolet rigidizable deployment hinge  

Science.gov (United States)

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.

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

80

Transfer printing methods for flexible thin film solar cells: basic concepts and working principles.  

Science.gov (United States)

Fabricating thin film solar cells (TFSCs) on flexible substrates will not only broaden the applications of solar cells, but also potentially reduce the installation cost. However, a critical challenge for fabricating flexible TFSCs on flexible substrates is the incompatibility issues between the thermal, mechanical, and chemical properties of these substrates and the fabrication conditions. Transfer printing methods, which use conventional substrates for the fabrication and then deliver the TFSCs onto flexible substrates, play a key role to overcome these challenges. In this review, we discuss the basic concepts and working principles of four major transfer printing methods associated with (1) transfer by sacrificial layers, (2) transfer by porous Si layer, (3) transfer by controlled crack, and (4) transfer by water-assisted thin film delamination. We also discuss the challenges and opportunities for implementing these methods for practical solar cell manufacture. PMID:25184987

Lee, Chi Hwan; Kim, Dong Rip; Zheng, Xiaolin

2014-09-23

 
 
 
 
81

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate  

Science.gov (United States)

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

2006-05-30

82

Integration of solar sail and thin film solar cell using spectrum splitting technology for deep space exploration  

Science.gov (United States)

It is very important to lighten weight for deep space exploration. Thin film type spacecrafts like solar sails may be the good choice. Due to the favourable photoelectric effect in weak light and light weight, flexible thin film solar sell will also be considered as new generation energy. In order to integrate thin film solar cell into solar sail perfectly, the spectrum splitting technology using optical multilayer film is employed to divide the solar spectrum. The transmissivity of the designed optical film is calculated by a developed computer program. It shows that that the transmissivity is larger than 95% in the range 400-1000nm, and obviously decrease above 400 nm, and below 1000 nm. The result given in this work will provide a new way to realize a low area mass of the solar sail.

Feng, Yudong; Zuo, Huaping; Wang, Zhimin

83

Real time intelligent process control system for thin film solar cell manufacturing  

Energy Technology Data Exchange (ETDEWEB)

This project addresses the problem of lower solar conversion efficiency and waste in the typical solar cell manufacturing process. The work from the proposed development will lead toward developing a system which should be able to increase solar panel conversion efficiency by an additional 12-15% resulting in lower cost panels, increased solar technology adoption, reduced carbon emissions and reduced dependency on foreign oil. All solar cell manufacturing processes today suffer from manufacturing inefficiencies that currently lead to lower product quality and lower conversion efficiency, increased product cost and greater material and energy consumption. This results in slower solar energy adoption and extends the time solar cells will reach grid parity with traditional energy sources. The thin film solar panel manufacturers struggle on a daily basis with the problem of thin film thickness non-uniformity and other parameters variances over the deposited substrates, which significantly degrade their manufacturing yield and quality. Optical monitoring of the thin films during the process of the film deposition is widely perceived as a necessary step towards resolving the non-uniformity and non-homogeneity problem. In order to enable the development of an optical control system for solar cell manufacturing, a new type of low cost optical sensor is needed, able to acquire local information about the panel under deposition and measure its local characteristics, including the light scattering in very close proximity to the surface of the film. This information cannot be obtained by monitoring from outside the deposition chamber (as traditional monitoring systems do) due to the significant signal attenuation and loss of its scattering component before the reflected beam reaches the detector. In addition, it would be too costly to install traditional external in-situ monitoring systems to perform any real-time monitoring over large solar panels, since it would require significant equipment refurbishing needed for installation of multiple separate ellipsometric systems, and development of customized software to control all of them simultaneously. The proposed optical monitoring system comprises AccuStratas fiber optics sensors installed inside the thin film deposition equipment, a hardware module of different components (beyond the scope of this project) and our software program with iterative predicting capability able to control material bandgap and surface roughness as films are deposited. Our miniature fiber optics monitoring sensors are installed inside the vacuum chamber compartments in very close proximity where the independent layers are deposited (an option patented by us in 2003). The optical monitoring system measures two of the most important parameters of the photovoltaic thin films during deposition on a moving solar panel - material bandgap and surface roughness. In this program each sensor array consists of two fiber optics sensors monitoring two independent areas of the panel under deposition. Based on the monitored parameters and their change in time and from position to position on the panel, the system is able to provide to the equipment operator immediate information about the thin films as they are deposited. This DoE Supply Chain program is considered the first step towards the development of intelligent optical control system capable of dynamically adjusting the manufacturing process on-the-fly in order to achieve better performance. The proposed system will improve the thin film solar cell manufacturing by improving the quality of the individual solar cells and will allow for the manufacturing of more consistent and uniform products resulting in higher solar conversion efficiency and manufacturing yield. It will have a significant impact on the multibillion-dollar thin film solar market. We estimate that the financial impact of these improvements if adopted by only 10% of the industry ($7.7 Billion) would result in about $1.5 Billion in savings by 2015 (at the assumed 20% improvement). This can b

George Atanasoff

2010-10-29

84

Processing and modeling issues for thin-film solar cell devices. Final report  

Energy Technology Data Exchange (ETDEWEB)

During the third phase of the subcontract, IEC researchers have continued to provide the thin film PV community with greater depth of understanding and insight into a wide variety of issues including: the deposition and characterization of CuIn{sub 1-x}Ga{sub x}Se{sub 2}, a-Si, CdTe, CdS, and TCO thin films; the relationships between film and device properties; and the processing and analysis of thin film PV devices. This has been achieved through the systematic investigation of all aspects of film and device production and through the analysis and quantification of the reaction chemistries involved in thin film deposition. This methodology has led to controlled fabrications of 15% efficient CuIn{sub 1-x}Ga{sub x}Se{sub 2} solar cells over a wide range of Ga compositions, improved process control of the fabrication of 10% efficient a-Si solar cells, and reliable and generally applicable procedures for both contacting and doping films. Additional accomplishments are listed below.

Birkmire, R.W.; Phillips, J.E. [Univ. of Delaware, Newark, DE (United States). Institute of Energy Conversion

1997-11-01

85

Angular behavior of the absorption limit in thin film silicon solar cells  

CERN Document Server

We investigate the angular behavior of the upper bound of absorption provided by the guided modes in thin film solar cells. We show that the 4n^2 limit can be potentially exceeded in a wide angular and wavelength range using two-dimensional periodic thin film structures. Two models are used to estimate the absorption enhancement; in the first one, we apply the periodicity condition along the thickness of the thin film structure but in the second one, we consider imperfect confinement of the wave to the device. To extract the guided modes, we use an automatized procedure which is established in this work. Through examples, we show that from the optical point of view, thin film structures have a high potential to be improved by changing their shape. Also, we discuss the nature of different optical resonances which can be potentially used to enhance light trapping in the solar cell. We investigate the two different polarization directions for one-dimensional gratings and we show that the transverse magnetic pola...

Naqavi, Ali; Sderstrm, Karin; Battaglia, Corsin; Paeder, Vincent; Scharf, Toralf; Herzig, Hans Peter; Ballif, Christophe

2013-01-01

86

Development of a thin film solar cell interconnect for the PowerSphere concept  

International Nuclear Information System (INIS)

Progressive development of microsatellite technologies has resulted in increased demand for lightweight electrical power subsystems including solar arrays. The use of thin film photovoltaics has been recognized as a key solution to meet the power needs. The lightweight cells can generate sufficient power and still meet critical mass requirements. Commercially available solar cells produced on lightweight substrates are being studied as an option to fulfill the power needs. The commercially available solar cells are relatively inexpensive and have a high payoff potential. Commercially available thin film solar cells are primarily being produced for terrestrial applications. The need to convert the solar cell from a terrestrial to a space compatible application is the primary challenge. Solar cell contacts, grids and interconnects need to be designed to be atomic oxygen resistant and withstand rapid thermal cycling environments. A mechanically robust solar cell interconnect is also required in order to withstand handling during fabrication and survive during launch. The need to produce the solar cell interconnects has been identified as a primary goal of the PowerSphere program and is the topic of this paper. Details of the trade study leading to the final design involving the solar cell wrap around contact, flex blanket, welding process, and frame will be presented at the conference

87

Demonstration of enhanced absorption in thin film Si solar cells with periodic microhemisphere hole arrays  

Science.gov (United States)

This paper reports a study about how to enhance the performance of thin film Si solar cells. Periodic microhemisphere hole (PMHH) arrays with a period of 10 ?m and a depth of ~4 ?m were made on the glass wafers. We found that the PMHH arrays can trap light via testing the transmittance of glass with PMHH arrays. Comparing with the original cell, the thin film Si solar cell covered by this kind of PMHH arrays glass is different from the following two perspectives: the short-circuit current (Jsc) increased by 7.5% and the conversion efficiency (Eff) enhanced by 5.2%. The design based on light trapping scheme on the external of cell is feasible and worth promoting.

Huang, Kun; Wang, Qingkang; Yan, Xingmao; Hu, Kexiang; Yu, Mengyao; Shen, Xiangqian

2014-03-01

88

Advanced characterization techniques for thin film solar cells  

CERN Document Server

Written by scientists from leading institutes in Germany, USA and Spain who use these techniques as the core of their scientific work and who have a precise idea of what is relevant for photovoltaic devices, this text contains concise and comprehensive lecture-like chapters on specific research methods.They focus on emerging, specialized techniques that are new to the field of photovoltaics yet have a proven relevance. However, since new methods need to be judged according to their implications for photovoltaic devices, a clear introductory chapter describes the basic physics of thin-film

Rau, Uwe; Kirchartz, Thomas

2011-01-01

89

Thermal stability and environmental effects on CuGaSe 2 thin film solar cells  

Science.gov (United States)

CuGaSe 2 thin film absorbers were deposited on molybdenum coated glass substrates by open tube chemical vapour deposition (CVD) techniques. The absorber films have been characterized with X-ray diffraction, surface morphology, electrical and optical studies. Solar cell structures of the type Mo/CuGaSe 2/CdS/ZnO/Ni has been fabricated from the absorber thin films. Thin film absorbers as well as solar cells from them has been characterized with X-ray absorption spectroscopy in different environments and at various temperatures. XAS investigations have been performed due to their value in the study of the local structure of the heterogeneous compounds. X-ray absorption near edge structure of various components present in the system under various environments and at reaction temperatures has been determined. The thermal stability of the grown layers as well as the solar cell structures has been evaluated from the XAS studies. XAS data of the gas/solid reaction and the stability of the solid at different temperature ranges were monitored with the corresponding reaction rates. The stability of the cells in different environmental conditions, like in air and vacuum has been studied in detail. The influence of sodium-containing substrates on the properties of the developed films and the solar cell structures has been discussed.

Babu, S. M.; Meeder, A.; Fuertes Marron, D.; Schedel-Niedrig, T.; Havecker, M.; Knop-Gericke, A.; Lux-Steiner, M. Ch.

2005-02-01

90

Effect of Gaussian doping profile on the performance of a thin film polycrystalline solar cell  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A two-dimensional (2D) analytical model based on the Greens function method is applied to an n+-p thin film polycrystalline solar cell that allows us to calculate the conversion efficiency. This model considers the effective Gaussian doping profile in the p region in order to improve cell efficiency. The dependence of mobility and lifetime on grain doping is also investigated. This model is implemented through a simulation program in order to optimize conversion efficiency while varying th...

Ouali A.; Ben Amar M.; Samet H.; Kolsi S.

2012-01-01

91

Radiation resistance of thin-film solar cells for space photovoltaic power  

International Nuclear Information System (INIS)

Copper indium diselenide, cadmium telluride, and amorphous silicon alloy solar cells have achieved noteworthy performance and are currently being studied for space power applications. Cadmium sulfide cells had been the subject of much effort but are no longer considered for space applications. A review is presented of what is known about the radiation degradation of thin film solar cells in space. Experimental cadmium telluride and amorphous silicon alloy cells are reviewed. Damage mechanisms and radiation induced defect generation and passivation in the amorphous silicon alloy cell are discussed in detail due to the greater amount of experimental data available

92

Present Status and Future Prospects of Silicon Thin-Film Solar Cells  

Science.gov (United States)

In this report, an overview of the recent status of photovoltaic (PV) power generation is first presented from the viewpoint of reducing CO2 emission. Next, the Japanese roadmap for the research and development (R&D) of PV power generation and the progress in the development of various solar cells are explained. In addition, the present status and future prospects of amorphous silicon (a-Si) thin-film solar cells, which are expected to enter the stage of full-scale practical application in the near future, are described. For a-Si single-junction solar cells, the conversion efficiency of their large-area modules has now reached 6-8%, and their practical application to megawatt solar systems has started. Meanwhile, the focus of R&D has been shifting to a-Si and microcrystalline silicon (c-Si) tandem solar cells. Thus far, a-Si/c-Si tandem solar cell modules with conversion efficiency exceeding 13% have been reported. In addition, triple-junction solar cells, whose target year for practical application is 2025 or later, are introduced, as well as innovative thin-film full-spectrum solar cells, whose target year of realization is 2050.

Konagai, Makoto

2011-03-01

93

Light management through guided-mode resonances in thin-film silicon solar cells  

Science.gov (United States)

We theoretically explain and experimentally demonstrate light trapping in thin-film solar cells through guided-mode resonance (GMR) effects. Resonant field enhancement and propagation path elongation lead to enhanced solar absorption. We fabricate nanopatterned solar cells containing embedded 300-nm period, one-dimensional gratings. The grating pattern is fabricated on a glass substrate using laser interference lithography followed by a transparent conducting oxide coating as a top contact. A 320-nm thick p-i-n hydrogenated amorphous silicon solar cell is deposited over the patterned substrate followed by bottom contact deposition. We measure optical and electrical properties of the resonant solar cells. Compared to a planar reference solar cell, around 35% integrated absorption enhancement is observed over the 450 to 750-nm wavelength range. This light-management method results in enhanced short-circuit current density of 14.8 mA/cm2, which is a 40% improvement over planar solar cells. Our experimental demonstration proves the potential of simple and well-designed GMR features in thin-film solar cells.

Khaleque, Tanzina; Magnusson, Robert

2014-01-01

94

Superior light trapping in thin film silicon solar cells through nano imprint lithography  

Energy Technology Data Exchange (ETDEWEB)

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%.

Soppe, W.J.; Dorenkamper, M.S.; Schropp, R.E.I.; Pex, P.P.A.C.

2013-10-15

95

Cost-effective thin film solar cell processing on multicrystalline silicon  

Energy Technology Data Exchange (ETDEWEB)

Thin-film solar cells have been produced in a pilot-line making use of industrial techniques. Typical laboratory process steps such as P{sub 2}O{sub 5} solid-source diffusion, emitter etch-back, remote plasma hydrogenation, lithography, metal evaporation and lift-off, have been replaced by cost-effective techniques such as screenprinting or POCl{sub 3} diffusion, PECVD silicon nitride deposition, and screenprinting metallization and firing-through-nitride, respectively. The low-cost high-throughput techniques have been applied to epitaxial thin film solar cells with success. Efficiencies of 12% have been obtained on 20 {micro}m thin film solar cells made in epitaxial layers on highly doped multicrystalline silicon substrates without making use of optical path length enhancement. The hydrogenation induced by the firing-through-nitride process passivates the bulk of the epitaxial cell but not to the same extent as a remote plasma hydrogenation in the laboratory-scaled process.

Vermeulen, T.; Duerinckx, F.; Clercq, K. de; Szlufcik, J.; Poortmans, J.; Laermans, P.; Caymax, M.; Nijs, J.; Mertens, R. [IMEC, Heverlee (Belgium)

1997-12-31

96

Efficient organic solar cells using a high-quality crystalline thin film as a donor layer  

Energy Technology Data Exchange (ETDEWEB)

An efficient organic solar cell is fabricated by the weak-epitaxy-growth method and the achieved power conversion efficiency is over 3%. A Single-crystal-like thin film improves the carrier mobility and reduces the electron-hole recombination. Deposition of a zinc phthalocyanine (ZnPc):C60 mixed layer at 100 C results in a better interpenetrating interface and the device performance is improved further. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Yu, Bo; Huang, Lizhen [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun (China); Graduate School of Chinese, Academy of Sciences, Beijing (China); Wang, Haibo; Yan, Donghang [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun (China)

2010-03-05

97

Low-temperature processed meso-superstructured to thin-film perovskite solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have reduced the processing temperature of the bulk absorber layer in CH3NH3PbI3-xClx perovskite solar cells from 500 to <150 C and achieved power conversion efficiencies up to 12.3%. Remarkably, we find that devices with planar thin-film architecture, where the ambipolar perovskite transports both holes and electrons, convert the absorbed photons into collected charge with close to 100% efficiency. 2013 The Royal Society of Chemistry.

Ball, Jm; Lee, Mm; Hey, A.; Snaith, Hj

2013-01-01

98

Scope of VHF plasma deposition for thin-film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The world-wide attempts in obtaining thin-film crystalline silicon are reviewed. Based on literature published so far, it appears that high-temperature manufacturing steps seem to be unavoidable for obtaining high conversion efficiencies of crystalline silicon based solar cells. High process temperatures are in contradiction for the use of low-cost substrates like e.g. glass or aluminium. Such substrates, however, are essential for obtaining low module manufacturing costs. The very high frequ...

Keppner, Herbert; Kroll, U.; Torres, Pedro; Meier, Johannes; Fischer, Diego; Goetz, M.; Tscharner, R.; Shah, Arvind

2008-01-01

99

The analysis of CdS thin film at the processes of manufacturing CdS/CdTe solar cells  

Science.gov (United States)

In sequence, the deposited CdS thin film had undergone physical and optical changes by the processes of manufacturing CdS/CdTe solar cells. CdS thin film was manufactured by the Chemical Bath Deposition (CBD) method. The aqueous solution was based on ammonia solution. The temperature of bath system was 75 C and deposition time was 50 min. The thickness of deposited CdS thin film was about 200 nm. The substrate was the glass coated with SnO 2:F thin film. The following process was the deposition of CdTe thin film by the Closed-Space-Sublimation (CSS) method. The final process was the CdCl 2 heat treatment at N 2+O 2 atmosphere, and the contrast experiment progressed for CdCl 2-CdS thin film after CSS process at N 2 atmosphere. The phase transition of CdS thin film, stress relaxation and optical band gap narrowing were developed by each process. And so, the formation of cadmium oxide was detected after the CdCl 2 heat treatment. It influenced to increase the optical band gap of CdS thin film. The variation in the structure properties, optical properties and residual stresses of CdS thin film was analyzed by X-ray diffractometer (XRD), Raman spectroscopy and ultraviolet (UV)-visible (VIS) spectroscopy.

Chun, S.; Jung, Y.; Kim, J.; Kim, D.

2011-07-01

100

Positron annihilation study on CuInSe2 solar cell thin films  

International Nuclear Information System (INIS)

Positron annihilation spectroscopy has been used to investigate CuInSe2 solar cell thin films. The films were grown on Mo-coated soda lime glass substrates by the electrochemical deposition processing technique. As-grown samples are found to contain large concentration of vacancy defects. The selenium (Se) atmosphere and sulfur (S) atmosphere annealing of as-grown samples at 800 K can dramatically reduce the number of vacancy defects and the film becomes crystalline. In addition, a defect layer of about 50 nm thickness was observed at the surface of the CuInSe2 thin film. This layer results from the electrochemical deposition method, but the defect concentration in the defect layer can be greatly reduced by annealing in selenium atmosphere. The Doppler broadening line shape parameter correlation plot provided evidence that the positron trapping defect states where in three samples. - Highlights: ? As-grown CuInSe2 thin films contain large concentration of defects. ? A defect layer of about 50 nm exists in the CuInSe2 thin film surface. ? The defect concentration in the defect layer can be greatly reduced.

 
 
 
 
101

Electrical conductivity of chlorophyll with poly thiophene thin film as a bulk heterojunction solar cell  

International Nuclear Information System (INIS)

Full text: In this work, electrical conductivity of the combinations mixture with different ratio of Poly thiophene (PT) and Chlorophyll (CHLO) thin film as a bulk heterojunction solar cell was studied. Spin coating technique was used to deposit the combination of PT and CHLO thin film on the Aurum (Au) layer which acts as a substrate. The optical characterization of thin film was measured using UV-Visible Spectrophotometer and four point probes were used to determine the film electrical properties in the dark and under the light. From the optical absorption study, the combination mixture between PT and CHLO altered the energy band gap of the thin film. The increasing of the mixture ratio of both solutions decreased the electrical conductivity in the dark and also under light. Under the light, the electrical conductivity of combine mixture shows the increasing with the increased of light intensity. The lowest mixture ratio shows the highest electrical conductivity 1.389 S/m under dark and increased with the increasing of the light intensity. (author)

102

Rapid composition analysis of compound semiconductor thin film solar cell by laser induced breakdown spectroscopy  

Science.gov (United States)

The characteristics of laser-induced breakdown spectroscopy (LIBS) such as short measurement time and no sample preparation provide clear advantages over other analytical techniques for rapid elemental analysis at manufacturing sites where the composition of products need to be determined in real-time for process monitoring or quality control. Thin film solar cells based on CuIn1-xGaxSe2 (CIGS), polycrystalline compound semiconductor material, have unique advantages of high efficiency (>20%), long-term stability, and low manufacturing cost over other types of solar cell. The electrical and optical properties of the thin CIGS films are closely related to the concentration ratios among its major constituent elements Cu, In, Ga and Se such as Ga/(Ga + In) and Cu/(Ga + In), and thus an accurate measurement of the composition of CIGS thin films has been an issue among CIGS solar cell researchers, requiring a fast and reliable technique for composition analysis. This paper presents the results of nanosecond (ns) and femtosecond (fs) laser based LIBS analysis of thin CIGS films. The critical issues for LIBS analysis of CIGS thin films such are discussed in comparison with ns- and fs-LIBS measurement results. The calibration of LIBS signal intensity ratios with respect to reference concentration data is carried out and the results of optimal line selection for LIBS analysis, depth profiling capability, and reproducibility are discussed.

Lee, S. H.; Kim, C. K.; In, J. H.; Jeong, S. H.

2014-03-01

103

Accurate modeling of light trapping in thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to assess the accuracy of the simplifying assumption of total retransmission of light inside the escape or loss cone which is made in many models of optical confinement in thin-film silicon solar cells. A closed form expression is derived for the absorption enhancement factor as a function of the refractive index in the low-absorption limit for a thin-film cell with a flat front surface and a lambertian back reflector. Numerical calculations are carried out to investigate similar systems with antireflection coatings, and the investigation of cells with a textured front surface is achieved using a modified version of the existing ray-tracing computer simulation program TEXTURE.

Abouelsaood, A.A. [Cairo Univ. (Egypt). Physics and Mathematics Dept.; Ghannam, M.Y. [Kuwait Univ. (Kuwait); Poortmans, J.; Mertens, R.P. [IMEC, Leuven (Belgium)

1997-12-31

104

Impurity-doped ZnO Thin Films Prepared by Physical Deposition Methods Appropriate for Transparent Electrode Applications in Thin-film Solar Cells  

International Nuclear Information System (INIS)

This paper describes the development of transparent conducting impurity-doped ZnO thin films that would be appropriate for applications as transparent electrodes in thin-film solar cells. Transparent conducting Al-, B- and Ga-doped ZnO (AZO, BZO and GZO) thin films were prepared in a thickness range from 500 to 2000 nm on glass substrates at 200C using various physical deposition methods: BZO films with vacuum arc plasma evaporation, AZO and GZO films with different types of magnetron sputtering depositions (MSDs) and all films with pulsed laser deposition (PLD). The suitability and stability of the electrical properties and, in addition, the suitability of the light scattering characteristics and surface texture formation were investigated in the prepared thin films. In particular, the suitability and stability evaluation was focused on the use of AZO, BZO and GZO thin films prepared by doping each impurity at an appropriate content to attain the lowest resistivity. The higher Hall mobility obtained in impurity-doped ZnO thin films with a resistivity on the order of 10?4 ?cm was related more to the content, i.e., the obtained carrier concentration, rather than the kind of impurity doped into the films. The stability of resistivity of the BZO thin films in long-term moisture-resistance tests (in air at 85% relative humidity and 85C) was found to be lower than that of the AZO and GZO thin films. The surface texture formation was carried out by wet-che formation was carried out by wet-chemical etching (in a 0.1% HCl solution at 25C) conducted either before or after being heat-treated either with rapid thermal annealing (RTA) or without RTA. The suitability of the light scattering characteristics and the surface texture formation obtainable by wet-chemical etching (for use in transparent electrode applications) was considerably dependent on the deposition method used as well as whether the wet-chemical etching was conducted with or without RTA. A significant improvement of both transmittance and haze value at wavelengths up to about 1200 nm in the near-infrared region was attained in surface-textured AZO films that were prepared by r.f. power superimposed d.c. MSD as well as etched after being heat treated with RTA at 500C for 5 min in air. The obtained suitability and stability in impurity-doped ZnO thin films were related more to the content rather than the kind of impurity doped into the films as well as to the deposition method used.

105

Thin-film silicon solar cell development on imprint-textured glass substrates  

International Nuclear Information System (INIS)

Highlights: ? Microcrystalline thin-film silicon solar cells fabricated on textured glass. ? Replication of light trapping textures with a UV-nanoimprint process. ? Excellent replication precision with soft polymer mold. ? Thin TCO front contacts (60 nm) for enhanced incoupling of incident light. ? Impact of high series resistance of front contacts avoided by reduced cell width. -- Abstract: In this work, we report on the fabrication of microcrystalline thin-film silicon solar cells on textured glass substrates. The development of transparent and conductive front contacts for these solar cells is presented. State-of-the-art random textures for light-trapping were replicated into a glass-like resist on glass substrates with an imprint process. We applied an industrial relevant soft polymer mold that gives excellent replication accuracy. The necessity of applying thin front contacts for enhanced incoupling of the incident light is shown. An increased series resistance of these thin front contacts caused a decrease of the fill factor of the solar cells. One way to surpass this decrease in fill factor by reducing the solar cell width is demonstrated. In addition, the light-trapping and the light-incoupling for solar cells deposited on three different types of random textures were compared

106

3D photonic crystal intermediate reflector for micromorph thin-film tandem solar cell  

Energy Technology Data Exchange (ETDEWEB)

The concept of 3D photonic intermediate reflectors for micromorph silicon tandem solar cells has been investigated. In thin-film silicon tandem solar cells consisting of amorphous and microcrystalline silicon with two junctions of a-Si/{mu}c-Si, efficiency enhancements can be achieved by increasing the current density in the a-Si top cell. It is one goal to provide an optimized current matching at high current densities. For an ideal photon-management between top and bottom cell, a spectrally selective intermediate reflective layer (IRL) is necessary, which is less dependent of the angle of incidence than state-of-the-art thickness dependent massive interlayers. The design, preparation and characterization of a 3D photonic thin-film filter device for this purpose has been pursued straight forward in simulation and experimental realization. The inverted opal is capable of providing a suitable optical band stop with high reflectance and the necessary long wavelength transmittance as well and provides further options for improved light trapping. We have determined numerically the relative efficiency enhancement of an a-Si/{mu}c-Si tandem solar cell using a conductive 3D-photonic crystal. We have further fabricated such structures by ZnO-replication of polymeric opals using chemical vapour deposition and atomic layer deposition techniques and present the results of their characterization. Thin film photonic IRL have been prepared at the rear side of a-Si solar cells. Completed with a back contact, this is the first step to integrate this novel technology into an a-Si/{mu}c-Si tandem solar cell process. The spectral response of the cell is presented and compared with reference cells. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Uepping, Johannes; Miclea, Paul T.; Wehrspohn, Ralf B. [Institute of Physics, Martin-Luther-University of Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Germany); Rockstuhl, Carsten; Lederer, Falk [Institute of Condensed Matter Theory and Solid States Optics, Friedrich Schiller University Jena, 07743 Jena (Germany); Peters, Marius [Freiburg Centre for Material Research, University of Freiburg, 79104 Freiburg (Germany); Steidl, Lorenz; Zentel, Rudolf [Dept. of Chemistry, Pharmacy and Earth Science, Johannes Gutenberg University of Mainz, Duesbergweg 10-14 (Germany); Lee, Seung-Mo; Knez, Mato [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Lambertz, Andreas; Carius, Reinhard [Institute of Energy Research, IEF-5 Photovoltaics, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Bielawny, Andreas

2008-12-15

107

Broadband enhancement in thin-film amorphous silicon solar cells enabled by nucleated silver nanoparticles.  

Science.gov (United States)

Recently plasmonic effects have gained tremendous interest in solar cell research because they are deemed to be able to dramatically boost the efficiency of thin-film solar cells. However, despite of the intensive efforts, the desired broadband enhancement, which is critical for real device performance improvement, has yet been achieved with simple fabrication and integration methods appreciated by the solar industry. We propose in this paper a novel idea of using nucleated silver nanoparticles to effectively scatter light in a broadband wavelength range to realize pronounced absorption enhancement in the silicon absorbing layer. Since it does not require critical patterning, experimentally these tailored nanoparticles were achieved by the simple, low-cost and upscalable wet chemical synthesis method and integrated before the back contact layer of the amorphous silicon thin-film solar cells. The solar cells incorporated with 200 nm nucleated silver nanoparticles at 10% coverage density clearly demonstrate a broadband absorption enhancement and significant superior performance including a 14.3% enhancement in the short-circuit photocurrent density and a 23% enhancement in the energy conversion efficiency, compared with the randomly textured reference cells without nanoparticles. Among the measured plasmonic solar cells the highest efficiency achieved was 8.1%. The significant enhancement is mainly attributed to the broadband light scattering arising from the integration of the tailored nucleated silver nanoparticles. PMID:22300399

Chen, Xi; Jia, Baohua; Saha, Jhantu K; Cai, Boyuan; Stokes, Nicholas; Qiao, Qi; Wang, Yongqian; Shi, Zhengrong; Gu, Min

2012-05-01

108

Advanced APCVD-processes for high-temperature grown crystalline silicon thin film solar cells.  

Science.gov (United States)

Crystalline silicon thin film (cSiTF) solar cells based on the epitaxial wafer-equivalent (EpiWE) concept combine advantages of wafer-based and thin film silicon solar cells. In this paper two processes beyond the standard process sequence for cSiTF cell fabrication are described. The first provides an alternative to wet chemical saw damage removal by chemical vapor etching (CVE) with hydrogen chloride in-situ prior to epitaxial deposition. This application decreases the number of process and handling steps. Solar cells fabricated with different etching processes achieved efficiencies up to 14.7%. 1300 degrees C etching temperature led to better cell results than 1200 degrees C. The second investigated process aims for an improvement of cell efficiency by implementation of a reflecting interlayer between substrate and active solar cell. Some characteristics of epitaxial lateral overgrowth (ELO) of a patterned silicon dioxide film in a lab-type reactor constructed at Fraunhofer ISE are described and first solar cell results are presented. PMID:22097550

Driessen, Marion; Merkel, Benjamin; Reber, Stefan

2011-09-01

109

Plasmonic core-shell nanoparticle-based thin film solar cells  

Science.gov (United States)

The enhanced optical absorption in solar cells using nanoscale structure and novel physical effect has received a lot of attention in recent years. One of the promising methods is to utilize the noble metal nanoparticles with plasmonic effect for increasing the light absorption, consequently the conversion efficiency of photovoltaic devices. While the bare metal nanoparticles may suffer from the energy loss introduced by themselves due to the recombination of electro-hole pairs. Here, we propose to apply the plasmonic metal-dielectric core-shell nano-particles to improve the optical absorption efficiency of thin film solar cells. It is expected that the metal core could increase the optical absorption of thin film solar cells due to the filed enhancement effect of localized surface plasmon (LSP), and meanwhile the dielectric shell could avoid the metal core to become a new recombination center of the light-induced excitons. Further, varying the refractive index of the dielectric shell could adjust the enhancement region of LSP in a large range to cover the whole wavelength range of solar cells. Simulations are carried out by means of the finite element method in a three-dimensional model. The results show that the absorption enhancement up to 110% could be obtained when the active layer of thin film organic solar cells is 30nm thick. Then, some initial experiments have been done. The Au-citrate core-shell nanoparticles synthesized by the sodium citrate reduction method are deposited on the solar cells. And the obvious photocurrent enhancement has been observed.

Liu, Fang; Qu, Di; Xu, Qi; Xie, Wanlu; Huang, Yidong

2011-09-01

110

Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing  

Science.gov (United States)

A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD) of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

Gabriel, Onno; Kirner, Simon; Klick, Michael; Stannowski, Bernd; Schlatmann, Rutger

2014-02-01

111

Hole-conductor-free perovskite organic lead iodide heterojunction thin-film solar cells: High efficiency and junction property  

Science.gov (United States)

Efficient hole-conductor-free organic lead iodide thin film solar cells have been fabricated with a sequential deposition method, and a highest efficiency of 10.49% has been achieved. Meanwhile, the ideal current-voltage model for a single heterojunction solar cell is applied to clarify the junction property of the cell. The model confirms that the TiO2/CH3NH3PbI3/Au cell is a typical heterojunction cell and the intrinsic parameters of the cell are comparable to that of the high-efficiency thin-film solar cells.

Shi, Jiangjian; Dong, Juan; Lv, Songtao; Xu, Yuzhuan; Zhu, Lifeng; Xiao, Junyan; Xu, Xin; Wu, Huijue; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

2014-02-01

112

Sustainability of photovoltaics. The case for thin-film solar cells  

International Nuclear Information System (INIS)

To ensure photovoltaics become a major sustainable player in a competitive power-generation market, they must provide abundant, affordable electricity, with environmental impacts drastically lower than those from conventional power generation. The recent reduction in the cost of 2nd generation thin-film PV is remarkable, meeting the production milestone of $1 per watt in the fourth quarter of 2008. This achievement holds great promise for the future. However, the questions remaining are whether the expense of PV modules can be lowered further, and if there are resource- and environmental-impact constraints to growth. I examine the potential of thin-films in a prospective life-cycle analysis, focusing on direct costs, resource availability, and environmental impacts. These three aspects are closely related; developing thinner solar cells and recycling spent modules will become increasingly important in resolving cost, resource, and environmental constraints to large scales of sustainable growth. (author)

113

Electron beam evaporation deposition of cadmium sulphide and cadmium telluride thin films: Solar cell applications  

International Nuclear Information System (INIS)

Cadmium sulphide (CdS) and cadmium telluride (CdTe) thin films are deposited by electron beam evaporation. Atomic force microscopy (AFM) reveals that the root mean square (RMS) roughness values of the CdS films increase as substrate temperature increases. The optical band gap values of CdS films increase slightly with the increase in the substrate temperature, in a range of 2.422.48 eV. The result of Hall effect measurement suggests that the carrier concentration decreases as the substrate temperature increases, making the resistivity of the CdS films increase. CdTe films annealed at 300C show that their lowest transmittances are due to their largest packing densities. The electrical characteristics of CdS/CdTe thin film solar cells are investigated in dark conditions and under illumination. Typical rectifying and photovoltaic properties are obtained. (interdisciplinary physics and related areas of science and technology)

114

Precise selective scribing of thin-film solar cells by a picosecond laser  

Science.gov (United States)

In this paper, precise scribing of thin-film solar cells (CIGS/Mo/Glass) via a picosecond laser is investigated. A parametric study is carried out for P1 and P2 scribing to study the effects of laser fluence and overlap ratio on scribing quality and ablation depth. Three ablation regimes are observed for P1 scribing in different laser fluence ranges, due to the involvement of different ablation mechanisms. The optimum scribing conditions are determined for both P1 and P2 scribing, and the potential processing speed is significantly increased. The heat accumulation effect at different repetition rates is studied to extrapolate the results from low to high repetition rates. A two-temperature model-based model is developed to simulate the scribing process for multiple thin films, providing decent prediction of the slot depth for both P1 and P2 scribing.

Zhao, Xin; Cao, Yunfeng; Nian, Qiong; Shin, Yung C.; Cheng, Gary

2014-08-01

115

Characterization of chemical bath deposited buffer layers for thin film solar cell applications  

Energy Technology Data Exchange (ETDEWEB)

Cadmium sulfide (CdS), indium sulfide (In{sub 2}S{sub 3}) and zinc sulfide (ZnS) thin films have been deposited by chemical bath deposition (CBD) for buffer layer applications in Cu-chalcopyrite-based thin film solar cells. Films were characterized by scanning electron microscopy (SEM), UV-Vis transmission, X-ray photoelectron spectroscopy (XPS), grazing-incidence X-ray diffraction (GIXRD), and spectroscopic ellipsometry. Results indicate CdS can be deposited with low oxygen content and high light transmission over 245-1700 nm. CBD-ZnS and CBD-InS both exhibit 5-10% less light transmission than CdS in the same thickness range. In terms of light transmission and degree of impurities CdS appears to be a better buffer material than CBD-ZnS or CBD-InS. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Dwyer, D.; Efstathiadis, H.; Haldar, P. [College of Nanoscale Science and Engineering, University at Albany - State University of New York, 257 Fuller Rd., Albany, NY 12203 (United States); Sun, R. [Angstrom Sun Technologies Inc., 33 Nagog Park, Acton, MA 01720 (United States)

2010-10-15

116

CIGS2 Thin-Film Solar Cells on Flexible Foils for Space Power  

Science.gov (United States)

CuIn(1-x)Ga(x)S2 (CIGS2) thin-film solar cells are of interest for space power applications because of the near optimum bandgap for AM0 solar radiation in space. CIGS2 thin film solar cells on flexible stainless steel (SS) may be able to increase the specific power by an order of magnitude from the current level of 65 Wkg(sup -1). CIGS solar cells are superior to the conventional silicon and gallium arsenide solar cells in the space radiation environment. This paper presents research efforts for the development of CIGS2 thin-film solar cells on 127 micrometers and 20 micrometers thick, bright-annealed flexible SS foil for space power. A large-area, dual-chamber, inline thin film deposition system has been fabricated. The system is expected to provide thickness uniformity of plus or minus 2% over the central 5" width and plus or minus 3% over the central 6" width. During the next phase, facilities for processing larger cells will be acquired for selenization and sulfurization of metallic precursors and for heterojunction CdS layer deposition both on large area. Small area CIGS2 thin film solar cells are being prepared routinely. Cu-rich Cu-Ga/In layers were sputter-deposited on unheated Mo-coated SS foils from CuGa (22%) and In targets. Well-adherent, large-grain Cu-rich CIGS2 films were obtained by sulfurization in a Ar: H2S 1:0.04 mixture and argon flow rate of 650 sccm, at the maximum temperature of 475 C for 60 minutes with intermediate 30 minutes annealing step at 120 C. Samples were annealed at 500 C for 10 minutes without H2S gas flow. The intermediate 30 minutes annealing step at 120 C was changed to 135 C. p-type CIGS2 thin films were obtained by etching the Cu-rich layer segregated at the surface using dilute KCN solution. Solar cells were completed by deposition of CdS heterojunction partner layer by chemical bath deposition, transparent-conducting ZnO/ZnO: Al window bilayer by RF sputtering, and vacuum deposition of Ni/Al contact fingers through metal mask. PV parameters of a CIGS2 solar cell on 127 micrometers thick SS flexible foil measured under AM 0 conditions at NASA GRC were: V(sub oc) = 802.9 mV, J(sub sc) = 25.07 mA per square centimeters, FF = 60.06%, and efficiency 0 = 8.84%. For this cell, AM 1.5 PV parameters measured at NREL were: V(sub oc) = 788 mV, J(sub sc) = 19.78 mA per square centimeter, FF = 59.44%, efficiency 0 = 9.26%. Quantum efficiency curve showed a sharp QE cutoff equivalent to CIGS2 bandgap of approximately 1.50 eV, fairly close to the optimum value for efficient AM0 PV conversion in the space.

Dhere, Neelkanth G.; Ghongadi, Shantinath R.; Pandit, Mandar B.; Jahagirdar, Anant H.; Scheiman, David

2002-01-01

117

Epitaxially grown crystalline silicon thin-film solar cells reaching 16.5% efficiency with basic cell process  

Energy Technology Data Exchange (ETDEWEB)

We report about the current performance of crystalline silicon thin-film (cSiTF) solar cells that are a very attractive alternative to conventional wafer-based silicon solar cells if sufficiently high cell efficiencies are achieved at acceptable cost of production. Applying a standard cell process (diffused POCl{sub 3} emitter, front contacts by photolithography, no surface texture) to thin-films deposited with a lab-type reactor, specifically designed for high-throughput photovoltaic applications, on highly-doped Cz substrates we routinely obtain efficiencies above 16%. On 1 {Omega} cm FZ material substrates we reach efficiencies up to 18.0%, which is among the highest thin-film efficiencies ever reported. Additionally, a comparison to microelectronic-grade epitaxially grown cSiTF material underlines the excellent electrical quality of the epitaxial layers deposited.

Rosenits, Philipp, E-mail: philipp.rosenits@ise.fraunhofer.de; Kopp, Fabian; Reber, Stefan

2011-03-01

118

Absorption Enhancement of Thin-film Solar Cell with Rectangular Ag Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available Solar power has gained a great deal of attention as a clean energy source with the potential to replace fossil fuel. Researchers have focused in increasing the efficiency of thin film solar cells. In this study, rectangular Ag nanoparticles were placed on the silicon layer of a silicon solar cell. The absorption enhancement of the silicon was systematically investigated via the Finite Difference Time Domain Method (FDTD. The improvement in silicon absorption of the solar cell because of the addition of Ag nanoparticles was studied by calculating the enhancement factor by using the Lumerical FDTD solutions simulation package. The results demonstrated that the light absorption was significantly improved because of the localized surface plasmon resonance of the Ag nanoparticles. The structure with rectangular Ag nanoparticles obtained the most efficient absorption enhancement compared with the sphere and cylinder Ag nanoparticles. The effects of nanoparticle parameters on the absorption enhancement were also thoroughly analyzed. The optimal absorption enhancement was achieved by adjusting the parameters of nanoparticles. The structure may be used to develop highly efficient thin film solar cells.

Zongheng Yuan

2014-01-01

119

Electrodeposition of antimony selenide thin films and application in semiconductor sensitized solar cells.  

Science.gov (United States)

Sb2Se3 thin films are proposed as an alternative light harvester for semiconductor sensitized solar cells. An innovative electrodeposition route, based on aqueous alkaline electrolytes, is presented to obtain amorphous Sb2Se3. The amorphous to crystalline phase transition takes place during a soft thermal annealing in Ar atmosphere. The potential of the Sb2Se3 electrodeposited thin films in semiconductor sensitized solar cells is evaluated by preparing TiO2/Sb2Se3/CuSCN planar heterojunction solar cells. The resulting devices generate electricity from the visible and NIR photons, exhibiting the external quantum efficiency onset close to 1050 nm. Although planar architecture is not optimized in terms of charge carrier collection, photocurrent as high as 18 mA/cm(2), under simulated (AM1.5G) solar light, is achieved. Furthermore, the effect of the Sb2Se3 thickness and microstructural properties on the photocurrent is analyzed, suggesting the hole transport is the main limiting mechanism. The present findings provide significant insights to design efficient semiconductor sensitized solar cells based on advanced architectures (e.g., nanostructured and tandem), opening wide possibilities for progresses in this emerging photovoltaics technology. PMID:24437500

Ngo, T Tuyen; Chavhan, Sudam; Kosta, Ivet; Miguel, Oscar; Grande, Hans-Jurgen; Tena-Zaera, Ramn

2014-02-26

120

Mode coupling by plasmonic surface scatterers in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate effective mode coupling by light scattering from periodic Ag nanoparticle arrays printed onto a completed thin-film a-Si:H solar cell. Current-voltage measurements show a photocurrent enhancement of 10% compared to a flat reference cell with a standard antireflection coating. External quantum efficiency measurements for the nanopatterned cells show clear infrared photocurrent enhancement peaks, corresponding to coupling to discrete waveguide modes in the a-Si:H layer. The data are in good agreement with three-dimensional finite element simulations, which are used to further optimize the design. We show that broadband photocurrent enhancement can be obtained over the 450-750 nm spectral range.

Van Lare, M.; Polman, A. [Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, Amsterdam 1098 XG (Netherlands); Lenzmann, F. [Energy research Center of the Netherlands ECN, P. O. Box 1, 1755 ZG Petten (Netherlands); Verschuuren, M.A. [Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven (Netherlands)

2012-11-27

 
 
 
 
121

Synthesis of Cu2ZnSnS4 thin films by a precursor solution paste for thin film solar cell applications.  

Science.gov (United States)

Cu2ZnSnS4 (CZTS) is a very promising semiconductor material when used for the absorber layer of thin film solar cells because it consists of only abundant and inexpensive elements. In addition, a low-cost solution process is applicable to the preparation of CZTS absorber films, which reduces the cost when this film is used for the production of thin film solar cells. To fabricate solution-processed CZTS thin film using an easily scalable and relatively safe method, we suggest a precursor solution paste coating method with a two-step heating process (oxidation and sulfurization). The synthesized CZTS film was observed to be composed of grains of a size of ~300 nm, showing an overall densely packed morphology with some pores and voids. A solar cell device with this film as an absorber layer showed the highest efficiency of 3.02% with an open circuit voltage of 556 mV, a short current density of 13.5 mA/cm(2), and a fill factor of 40.3%. We also noted the existence of Cd moieties and an inhomogeneous Zn distribution in the CZTS film, which may have been triggered by the presence of pores and voids in the CZTS film. PMID:23611655

Cho, Jin Woo; Ismail, Agus; Park, Se Jin; Kim, Woong; Yoon, Sungho; Min, Byoung Koun

2013-05-22

122

Fabrication of solution processed 3D nanostructured CuInGaS? thin film solar cells.  

Science.gov (United States)

In this study we demonstrate the fabrication of CuInGaS? (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ?1.3 ?m. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ?6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions. PMID:24569126

Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

2014-03-28

123

Effects of RF power and pressure on performance of HF-PECVD silicon thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

High-frequency plasma-enhanced chemical vapor deposition (HF-PECVD) is a widely applicable method of deposition over a large area at a high rate for fabricating silicon thin-film solar cells. This investigation presents the properties of hydrogenated amorphous silicon (a-Si:H) films and the preparation of highly-efficient p-i-n solar cells using an RF (27.1 MHz) excitation frequency. The influence of the power (10-40 W) and pressure (20-50 Pa) used during the deposition of absorber layers in p-i-n solar cells on the properties and mechanism of growth of the a-Si:H thin films and the solar cells is studied. The a-Si:H thin films prepared under various deposition conditions have widely varying deposition rates, optical-electronic properties and microstructures. When the deposition parameters were optimized, amorphous silicon-based thin-film silicon solar cells with efficiency of 7.6% were fabricated by HF-PECVD. These results are very encouraging for the future fabrication of highly-efficient thin-film solar cells by HF-PECVD.

Lien, Shui-Yang, E-mail: syl@mdu.edu.t [Department of Materials Science and Engineering, MingDao University, ChungHua 52345, Taiwan (China); Wang, Chao-Chun [Department of Materials Science and Engineering, Nation Chung Hsing University, Taichung 402, Taiwan (China); Shen, Chau-Te; Ou, Yu-Chih; Cho, Yun-Shao; Weng, Ko-Wei; Chao, Ching-Hsun; Chen, Chia-Fu; Wuu, Dong-Sing [Department of Materials Science and Engineering, MingDao University, ChungHua 52345, Taiwan (China)

2010-10-01

124

Analysis of thin-film silicon solar cells with white paint back reflectors  

Energy Technology Data Exchange (ETDEWEB)

In this work, we investigate the concept of transparent conductive oxide (TCO)/white paint (WP) back reflectors as an alternative to the conventional textured metal-based reflectors in thin-film silicon solar cells. The optical characterisation results show that WP back reflectors exhibit good reflectivity and excellent light scattering properties which can lead to enhanced light confinement within the thin absorber layers of the cell. To confirm this, ZnO:Al/WP reflectors with WP films of different pigment volume concentration and thickness are tested in thin-film amorphous silicon solar cells. The external quantum efficiency measurements indicate that by employing ZnO:Al/WP reflectors, good solar cell performance can be achieved, which is comparable to the performance of the cell with the conventional TCO/Ag reflector. Finally, optical simulations are employed to study the potential for further improvements in cell performance as a result of the optimisation of TCO/WP reflectors. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Lipovsek, Benjamin; Krc, Janez; Topic, Marko [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, 1000 Ljubljana (Slovenia); Isabella, Olindo; Zeman, Miro [Delft University of Technology - Electrical Energy Conversion Unit/DIMES, P.O. Box 5053, 2600 GB Delft (Netherlands)

2010-04-15

125

A study of ZnO:B films for thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer ZnO:B films with different thicknesses were prepared with LPCVD technique. Black-Right-Pointing-Pointer The thicker ZnO:B back electrodes lead to higher FF but slightly lower J{sub sc.} Black-Right-Pointing-Pointer Back polyvinyl butyral (PVB) foils improves the utilization of incident light in solar cells. Black-Right-Pointing-Pointer The thicker ZnO:B front electrode films result in high J{sub sc} but lower FF. - Abstract: Boron doped zinc oxide (ZnO:B) films with different thicknesses were prepared with low pressure chemical vapor deposition (LPCVD) technique and implemented in thin film silicon solar cells as front and back electrodes. It is found that thick back ZnO:B film electrode in thin film silicon solar cells leads to a high fill factors (FF), which is attributed to an improvement of the electrical properties of the thick ZnO:B films, and in the meanwhile a slightly low short circuit currents (J{sub sc}) due to a high light absorption in the thick back ZnO:B films. Differently, the thicker front ZnO:B film electrodes result in a high J{sub sc} but a low FF of solar cells compared to the thinner ones. The low FF of the solar cells may be caused by the local shunt originated from the pinholes or by the cracks (zones of non-dense material) formed in particular in microcrystalline silicon materials deposited on rough front ZnO:B films. As to the high J{sub sc}, it is expected to be due to a good light trapping effect inside solar cells grown on rough front ZnO:B films. Moreover, the application of high reflective polyvinyl butyral (PVB) foils effectively enhances the utilization of incident light in solar cells. By optimizing deposition process of the ZnO:B films, high efficiencies of 8.8% and 10% for single junction thin film amorphous silicon solar cells (a-Si:H, intrinsic layer thickness < 200 nm) and amorphous/microcrystalline silicon tandem solar cells (a-Si:H/{mu}c-Si:H, intrinsic amorphous silicon layer thickness < 220 nm), respectively, are achieved.

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

2012-10-15

126

A study of ZnO:B films for thin film silicon solar cells  

International Nuclear Information System (INIS)

Highlights: ? ZnO:B films with different thicknesses were prepared with LPCVD technique. ? The thicker ZnO:B back electrodes lead to higher FF but slightly lower Jsc. ? Back polyvinyl butyral (PVB) foils improves the utilization of incident light in solar cells. ? The thicker ZnO:B front electrode films result in high Jsc but lower FF. - Abstract: Boron doped zinc oxide (ZnO:B) films with different thicknesses were prepared with low pressure chemical vapor deposition (LPCVD) technique and implemented in thin film silicon solar cells as front and back electrodes. It is found that thick back ZnO:B film electrode in thin film silicon solar cells leads to a high fill factors (FF), which is attributed to an improvement of the electrical properties of the thick ZnO:B films, and in the meanwhile a slightly low short circuit currents (Jsc) due to a high light absorption in the thick back ZnO:B films. Differently, the thicker front ZnO:B film electrodes result in a high Jsc but a low FF of solar cells compared to the thinner ones. The low FF of the solar cells may be caused by the local shunt originated from the pinholes or by the cracks (zones of non-dense material) formed in particular in microcrystalline silicon materials deposited on rough front ZnO:B films. As to the high Jsc, it is expected to be due to a good light trapping effect inside solar cells grown on rough front ZnO:B films. Moreover, the application of high reflective polyvinyl butyral (PVB) foils effectively enhances the utilization of incident light in solar cells. By optimizing deposition process of the ZnO:B films, high efficiencies of 8.8% and 10% for single junction thin film amorphous silicon solar cells (a-Si:H, intrinsic layer thickness < 200 nm) and amorphous/microcrystalline silicon tandem solar cells (a-Si:H/?c-Si:H, intrinsic amorphous silicon layer thickness < 220 nm), respectively, are achieved.

127

Physical vapor deposition of CdTe thin films at low temperature for solar cell applications  

International Nuclear Information System (INIS)

Cadmium telluride is successfully utilized as an absorber material for thin film solar cells. Industrial production makes use of high substrate temperatures for the deposition of CdTe absorber layers. However, in order to exploit flexible substrates and to simplify the manufacturing process, lower deposition temperatures are beneficial. Based on the phase diagram of CdTe, predictions on the stoichiometry of CdTe thin films grown at low substrate temperatures are made in this work. These predictions were verified experimentally using additional sources of Cd and Te during the deposition of the CdTe thin films at different substrate temperatures. The deposited layers were analyzed with energy-dispersive X-ray spectroscopy. In case of CdTe layers which were deposited at substrate temperatures lower than 200 C without usage of additional sources we found a non-stoichiometric growth of the CdTe layers. The application of the additional sources leads to a stoichiometric growth for substrate temperatures down to 100 C which is a significant reduction of the substrate temperature during deposition.

128

Defect annealing processes for polycrystalline silicon thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? Defect annealing processes were applied to polycrystalline silicon thin films. ? Conventional rapid thermal annealing was compared to novel annealing processes using a laser system and a zone-melting recrystallization setup. ? The open circuit voltages could be enhanced from below 170 mV up to 482 mV. ? Increase in Sun's-V{sub OC} values with decrease in FWHM of the TO Raman phonon of crystalline silicon. ? Solar cells were fabricated for IV-measurements: Best solar cell efficiency of 6.7%. -- Abstract: A variety of defect healing methods was analyzed for optimization of polycrystalline silicon (poly-Si) thin-film solar cells on glass. The films were fabricated by solid phase crystallization of amorphous silicon deposited either by plasma enhanced chemical vapor deposition (PECVD) or by electron-beam evaporation (EBE). Three different rapid thermal processing (RTP) set-ups were compared: A conventional rapid thermal annealing oven, a dual wavelength laser annealing system and a movable two sided halogen lamp oven. The two latter processes utilize focused energy input for reducing the thermal load introduced into the glass substrates and thus lead to less deformation and impurity diffusion. Analysis of the structural and electrical properties of the poly-Si thin films was performed by Suns-V{sub OC} measurements and Raman spectroscopy. 1 cm{sup 2} cells were prepared for a selection of samples and characterized by IV-measurements. The poly-Si material quality could be extremely enhanced, resulting in increase of the open circuit voltages from about 100 mV (EBE) and 170 mV (PECVD) in the untreated case up to 480 mV after processing.

Steffens, S., E-mail: simon.steffens@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Berlin (Germany); Becker, C. [Helmholtz-Zentrum Berlin, Berlin (Germany); Zollondz, J.-H., E-mail: hzollondz@masdarpv.com [CSG Solar AG, Thalheim (Germany); Chowdhury, A.; Slaoui, A. [LInstitut dlectronique du Solide et des Systmes, Strasbourg (France); Lindekugel, S. [Fraunhofer-Institut fr Solare Energiesysteme, Freiburg (Germany); Schubert, U.; Evans, R. [Suntech R and D Australia Pty Ltd, Sydney (Australia); Rech, B. [Helmholtz-Zentrum Berlin, Berlin (Germany)

2013-05-15

129

Defect annealing processes for polycrystalline silicon thin-film solar cells  

International Nuclear Information System (INIS)

Highlights: ? Defect annealing processes were applied to polycrystalline silicon thin films. ? Conventional rapid thermal annealing was compared to novel annealing processes using a laser system and a zone-melting recrystallization setup. ? The open circuit voltages could be enhanced from below 170 mV up to 482 mV. ? Increase in Sun's-VOC values with decrease in FWHM of the TO Raman phonon of crystalline silicon. ? Solar cells were fabricated for IV-measurements: Best solar cell efficiency of 6.7%. -- Abstract: A variety of defect healing methods was analyzed for optimization of polycrystalline silicon (poly-Si) thin-film solar cells on glass. The films were fabricated by solid phase crystallization of amorphous silicon deposited either by plasma enhanced chemical vapor deposition (PECVD) or by electron-beam evaporation (EBE). Three different rapid thermal processing (RTP) set-ups were compared: A conventional rapid thermal annealing oven, a dual wavelength laser annealing system and a movable two sided halogen lamp oven. The two latter processes utilize focused energy input for reducing the thermal load introduced into the glass substrates and thus lead to less deformation and impurity diffusion. Analysis of the structural and electrical properties of the poly-Si thin films was performed by Suns-VOC measurements and Raman spectroscopy. 1 cm2 cells were prepared for a selection of samples and characterized by IV-measurements. The poly-Si material quality could be extremely enhanced, resulting in increase of the open circuit voltages from about 100 mV (EBE) and 170 mV (PECVD) in the untreated case up to 480 mV after processing

130

Light trapping with plasmonic back contacts in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Trapping light in silicon solar cells is essential as it allows an increase in the absorption of incident sunlight in optically thin silicon absorber layers. This way, the costs of the solar cells can be reduced by lowering the material consumption and decreasing the physical constraints on the material quality. In this work, plasmonic light trapping with Ag back contacts in thin-film silicon solar cells is studied. Solar cell prototypes with plasmonic back contacts are presented along with optical simulations of these devices and general design considerations of plasmonic back contacts. Based on three-dimensional electromagnetic simulations, the conceptual design of plasmonic nanostructures on Ag back contacts in thin-film silicon solar cells is studied in this work. Optimizations of the nanostructures regarding their ability to scatter incident light at low optical losses into large angles in the silicon absorber layers of the thin-film silicon solar cells are presented. Geometrical parameters as well as the embedding dielectric layer stack of the nanostructures on Ag layers are varied. Periodic as well as isolated hemispherical Ag nanostructures of dimensions above 200 nm are found to scatter incident light at high efficiencies and low optical losses. Hence, these nanostructures are of interest for light trapping in solar cells. In contrast, small Ag nanostructures of dimension below 100 nm are found to induce optical losses. At the surface of randomly textured Ag back contacts small Ag nanostructures exist which induce optical losses. In this work, the relevance of these localized plasmon induced optical losses as well as optical losses caused by propagating plasmons are investigated with regard to the reflectance of the textured back contacts. In state-of-the-art solar cells, the plasmon-induced optical losses are shifted out of the relevant wavelength range by incorporating a ZnO:Al interlayer of low refractive index at the back contact. The additional but small potential for increasing the reflection at the back contact with dielectric interlayers of even lower refractive index, such as SiO{sub 2} and air, is demonstrated. The light-trapping effect of two types of plasmonic back contacts, which make use of large and efficiently scattering Ag nanostructures, is studied in thin-film silicon solar cell prototypes. The first type of plasmonic back contact applies non-ordered Ag nanostructures. The preparation, characterization and three-dimensional electromagnetic simulations of these back contacts with various distributions of non-ordered Ag nanostructures are presented. Measured reflectance spectra of the Ag back contacts with non-ordered nanostructures are correlated with reflectance spectra derived from three-dimensional electromagnetic simulations of isolated nanostructures on Ag back contacts. A microcrystalline silicon solar cell fabricated on one type of plasmonic Ag back contact with non-ordered Ag nanostructures shows a significantly enhanced plasmonic light trapping when compared with a flat solar cell. The second type of plasmonic back contact applies periodic arrangements of plasmonic Ag nanostructures in a square lattice at the surface of the Ag back contact. It is called a plasmonic reflection grating back contact. A particular advantage of this device is the control of the scattering angles via the diffraction orders of the grating while taking advantage of the efficient plasmon-induced light scattering at the Ag nanostructures. The plasmonic reflection grating back contacts are prepared with a nanoimprint process. The prototype microcrystalline silicon solar cells exhibit a very good light-trapping effect. Even in comparison with solar cells with a state-of-the-art random texture for light trapping, an enhanced light-trapping effect is demonstrated for a solar sell with a plasmonic reflection grating of optimized period. Based on electromagnetic simulations, the light-trapping effect is explained from the intuitive perspective of geometrical optics as well as from the perspective of leaky waveguides.

Paetzold, Ulrich Wilhelm

2013-02-08

131

Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures  

Science.gov (United States)

In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent.

Hilali, Mohamed M.; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S. V.

2012-10-01

132

Absorbing photonic crystals for mono-crystalline silicon thin film solar cells  

Science.gov (United States)

In this paper, we present the integration of an absorbing photonic crystal within a monocrystalline silicon thin film solar cell stack. Optical simulations performed on a complete solar cell revealed that patterning the epitaxial monocrystalline silicon active layer as a 1D and 2D photonic crystal enabled to increase its integrated absorption by 38%rel and 50%rel in the whole 300-1100 nm range, compared to a similar but unpatterned stack. In order to fabricate such promising cells, a specific fabrication process based on holographic lithography, inductively coupled plasma etching and reactive ion etching has been developed and implemented to obtain such photonic crystal patterned solar cells. Optical measurements performed on the patterned stacks highlight the significant absorption enhancement, as expected by simulation. A more advanced structuration combining a front and a rear 1D binary photonic patterning with different periods is designed, enabling a 60%abs larger absorption in silicon.

Meng, Xianqin; Depauw, Valerie; Gomard, Guillaume; El Daif, Ounsi; Trompoukis, Christos; Drouard, Emmanuel; Jamois, Ccile; Fave, Alain; Dross, Frederic; Gordon, Ivan; Seassal, Christian

2012-06-01

133

Back contact buffer layer for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

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.

Compaan, Alvin D.; Plotnikov, Victor V.

2014-09-09

134

Laser-Induced Indium-Diffusion into Cadmium Sulfide Thin Film for Solar Cell Applications  

International Nuclear Information System (INIS)

Laser-induced diffusion is employed to dope indium (In) into sputtering-deposited cadmium sulfide (CdS) thin films. The increased optical band gap energy from 2.52 to 2.60 eV with maintenance of high optical transmittance about 60 nm in the 200-nm-thick films, the enhanced mobility over 42.5 cm2/Vs, and the decreased resistivity to 1.42 10?3 ?cm are successfully obtained to be advantageous for a window layer in solar cells

135

Properties of the new absorber antimony tin sulphide thin films for solar cell applications  

International Nuclear Information System (INIS)

The new absorber layer antimony tin sulphide thin film was deposited by physical vapor deposition (PVD) using two source simultaneous deposition techniques for solar cell applications. The structural properties were measured by using XRD techniques. The quantum efficiency was measured by photoconductivity spectrometer shows the photo-activeness of the material. The thickness, band gap, refractive index and transmittance were calculated by using ellipsometry techniques. The transmittance of the material was above the visible range which decreases with the increase in wavelength. The material has n-type conductivity measured with hot probe technique. (author)

136

Resonant and nonresonant plasmonic nanoparticle enhancement for thin-film silicon solar cells.  

Science.gov (United States)

This paper investigates the influence of resonant and nonresonant plasmonic nanostructures, such as arrays of silver and aluminum nanoparticles in the forward scattering configuration, on the optical absorption in a thin-film amorphous silicon solar cell. It is demonstrated that nonresonant coupling of the incident sunlight with aluminum nanoparticles results in higher optical absorption in the photoactive region than resonant coupling with silver nanoparticle arrays. In addition, aluminum nanoparticles are shown to maintain a net positive enhancement of the optical absorption in amorphous silicon, as compared to a negative effect by silver nanoparticles, when the nanoparticles are oxidized. PMID:20463389

Akimov, Yu A; Koh, W S

2010-06-11

137

Resonant and nonresonant plasmonic nanoparticle enhancement for thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

This paper investigates the influence of resonant and nonresonant plasmonic nanostructures, such as arrays of silver and aluminum nanoparticles in the forward scattering configuration, on the optical absorption in a thin-film amorphous silicon solar cell. It is demonstrated that nonresonant coupling of the incident sunlight with aluminum nanoparticles results in higher optical absorption in the photoactive region than resonant coupling with silver nanoparticle arrays. In addition, aluminum nanoparticles are shown to maintain a net positive enhancement of the optical absorption in amorphous silicon, as compared to a negative effect by silver nanoparticles, when the nanoparticles are oxidized.

Akimov, Yu A; Koh, W S, E-mail: kohws@ihpc.a-star.edu.sg [Advanced Photonics and Plasmonics Team, Computational Electronics and Photonics Programme, Institute of High Performance Computing, 1 Fusionopolis Way, 16-16 Connexis, 138632 (Singapore)

2010-06-11

138

Resonant and nonresonant plasmonic nanoparticle enhancement for thin-film silicon solar cells  

International Nuclear Information System (INIS)

This paper investigates the influence of resonant and nonresonant plasmonic nanostructures, such as arrays of silver and aluminum nanoparticles in the forward scattering configuration, on the optical absorption in a thin-film amorphous silicon solar cell. It is demonstrated that nonresonant coupling of the incident sunlight with aluminum nanoparticles results in higher optical absorption in the photoactive region than resonant coupling with silver nanoparticle arrays. In addition, aluminum nanoparticles are shown to maintain a net positive enhancement of the optical absorption in amorphous silicon, as compared to a negative effect by silver nanoparticles, when the nanoparticles are oxidized.

139

Effects of defects in semiconductors on reproducibility and performance of thin-film photovoltaic solar cells  

International Nuclear Information System (INIS)

Thin-film solar cells based on GaAs/AlxGa(1?x)As showing open circuit voltages of (11001170) mV and fill factors of (0.800.87) have been exposed to external electrical stresses, and currentvoltage characteristics were monitored in order to study the effects of defects present in the device structure. It has been found that peculiar kinks, sudden jumps and various deformations occur in currentvoltage curves which could be caused when the Fermi level moves position at the device interface. These changes occur when there is a group of defect levels and the Fermi level is forced to move across these levels. The reproducibility and performance of solar cells heavily depend on the properties of these defect structures, and external forces such as electrical stresses, illumination and temperature variations cause changes in the measured currentvoltage characteristics. The observed variations during this work together with examples from the literature are presented and discussed in this paper. It is concluded that the control of these defects present in device structures is crucial in developing stable, durable and high-efficiency thin-film solar cells

140

Thin film polycrystalline silicon: Promise and problems in displays and solar cells  

Energy Technology Data Exchange (ETDEWEB)

Thin film polycrystalline Si (poly-Si) with its carrier mobilities, potentially good stability, low intragrain defect density, compatibility with silicon processing, and ease of doping activation is an interesting material for {open_quotes}macroelectronics{close_quotes} applications such as TFTs for displays and solar cells. The poly-Si films needed for these applications can be ultra-thin-in the 500{Angstrom} to 1000{Angstrom} thickness range for flat panel display TFTs and in the 4{mu}m to 10{mu}m thickness range for solar cells. Because the films needed for these microelectronics applications can be so thin, an effective approach to producing the films is that of crystallizing a-Si precursor material. Unlike cast materials, poly-Si films made this way can be produced using low temperature processing. Unlike deposited poly-Si films, these crystallized poly-Si films can have grain widths that are much larger than the film thickness and almost atomically smooth surfaces. This thin film poly-Si crystallized from a-Si precursor films, and its promise and problems for TFTs and solar cells, is the focus of this discussion.

Fonash, S.J. [Pennsylvania State Univ., University Park, PA (United States)

1995-08-01

 
 
 
 
141

Effects of film growth modes on light trapping in silicon thin film solar cells  

Science.gov (United States)

In this work, the impact of two different growth modes on the efficiency of an amorphous thin film solar cell comprising randomly textured interfaces is investigated. The two modes are the commonly used conformal growth which assumes identical textured interfaces and the isotropic growth, in which deposited material grows in the direction of the local surface normal. In the latter, the texture's morphology can change significantly. The rivalling impact of these two growth modes on the solar cell absorption is not yet fully understood. Here, we show that the efficiency of a solar cell crucially depends on the growth mode. In different size regimes, they may outperform each other with regard to efficiency by almost 15%. The insights gained by this study will guide experimentalists in the future in selecting the optimised growth mode.

Wiesendanger, S.; Bischoff, T.; Jovanov, V.; Knipp, D.; Burger, S.; Lederer, F.; Rockstuhl, C.

2014-06-01

142

Periodic anti-ring back reflectors for hydrogenated amorphous silicon thin-film solar cells.  

Science.gov (United States)

Large and periodic anti-ring arrays are fabricated by using a monolayer of polymer/nanosphere hybrid technique and applied as back reflectors in substrate-type hydrogenated amorphous silicon (a-Si:H) thin-film solar cells. The structure of each anti-ring comprises a nanodome centered inside a nanohole. The excitation of Bloch wave surface plasmon polaritons is observed in the Ag-coated anti-ring arrays. The nanodomes of the anti-ring arrays turn out to enhance large-angle light scattering and increase the effective optical path in the solar cell. The resulting efficiency of an ultrathin a-Si:H (thickness: 150 nm) solar cell is enhanced by 39% compared to that with a flat back reflector and by 13% compared to that with a nanohole back reflector. PMID:24978075

Chen, Po-Yuan; Hsiao, Hui-Hsin; Ho, Chung-I; Ho, Chi-Chih; Lee, Wei-Li; Chang, Hung-Chun; Lee, Si-Chen; Chen, Jian-Zhang; Cheng, I-Chun

2014-06-30

143

Towards numerical simulation of nonhomogeneous thin-film silicon solar cells  

Science.gov (United States)

We have developed an algorithm for the numerical simulation of the electrical and optical properties of a thin-film silicon solar cell. The intrinsic layer in the p-i-n solar cell is nonhomogeneous in the thickness direction. This nonhomogeneity is to be engineered via variations in the composition of the amorphous silicon. A layer of a transparent conducting oxide is welded to the p layer and the n layer is backed by a periodically corrugated metallic back reflector. The nonhomogeneous intrinsic layer may trap the incident light better than a homogeneous layer and increase the generation rate of electron-hole pairs. The periodically corrugated metallic back reflector can excite surface plasmon-polariton waves as well as waveguide modes. The generation rate of electron-hole pairs is computed using the rigorous coupledwave approach and the drift-diffusion model is used for the computation of the current density-voltage characteristics of the solar cell.

Anderson, Tom H.; Faryad, Muhammad; Mackay, Tom G.; Lakhtakia, Akhlesh

2014-03-01

144

Band alignment measurements at heterojunction interfaces in layered thin film solar cells & thermoelectrics  

Science.gov (United States)

Public awareness of the increasing energy crisis and the related serious environmental concerns has led to a significantly growing demand for alternative clean and renewable energy resources. Thin film are widely applied in multiple renewable energy devices owing to the reduced amount of raw materials and increase flexibility of choosing from low-cost candidates, which translates directly into reduced capital cost. This is a key driving force to make renewable technology competitive in the energy market. This thesis is focused on the measurement of energy level alignments at interfaces of thin film structures for renewable energy applications. There are two primary foci: II -VI semiconductor ZnSe/ZnTe thin film solar cells and Bi2Te3/Sb2Te3 thin film structures for thermoelectric applications. In both cases, the electronic structure and energy band alignment at interfaces usually controls the carrier transport behavior and determines the quality of the device. High-resolution photoemission spectroscopy (lab-based XPS & synchrotron-based UPS) was used to investigate the chemical and electronic properties of epitaxial Bi2Te3 and Sb2Te3 thin films, in order to validate the anticipated band alignment at interfaces in Bi 2Te3/Sb2Te3 superlattices as one favoring electron-transmission. A simple, thorough two-step treatment of a chemical etching in dilute hydrochloric acid solution and a subsequent annealing at 150C under ultra-high vacuum environment is established to remove the surface oxides completely. It is an essential step to ensure the measurements on electronic states are acquired on stoichimetric, oxide-free clean surface of Bi 2Te3 and Sb2Te3 films. The direct measurement of valence band offsets (VBO) at a real Sb 2Te3/Bi2Te3 interface is designed based on the Kraut model; a special stacking film structure is prepared intentionally: sufficiently thin Sb2Te3 film on top of Bi2Te 3 that photoelectrons from both of them are collected simultaneously. From a combination of core levels and valence band ultraviolet photoemission spectra of the bulk materials as well as the heterojunction (Sb2Te 3/Bi2Te3), the VBO at p-type Sb2Te 3 and n-type Bi2Te3 is determined as 0.04 +/- 0.10 eV. Such a small energy offset is within the same magnitude of the thermal energy of kT, at room temperature. The motivation for the II-VI ZnTe-based thin film solar cell derives from the need to identify and overcome performance-limiting properties related to the processing of film deposition using close space sublimation (CSS). Chemical and electronic properties of the CSS grown ZnTe/ZnSe films were studied in x-ray diffraction, scanning electron microscopy and photoemission spectroscopy. Specifically, Se oxide was observed on the ZnSe surface, the removal of this oxide generated apparent offsets in the valence band and hence the alignment at the heterojunction energy diagram. Processing steps to mitigate oxidation yielded the best cells. Film structure was studied on the dependence of growth time; physical film damage is found during the initial stages when depositing ZnTe on a grown ZnSe film. Preliminary studies of films grown by evaporation and their characterizations are presented at last. In this thesis, a better understanding of the electronic structure at interfaces is built in two different thin film devices, and the resulting band energy diagram of the corresponding devices offered effective feedback in materials and device.The problem of energy equilibrium in the human body has received a great deal.

Fang, Fang

145

Thin-film GaAs epitaxial lift-off solar cells for space applications  

Energy Technology Data Exchange (ETDEWEB)

In the present work the space compatibility of thin-film GaAs solar cells is studied. These cells are separated from their GaAs substrate by the epitaxial lift-off (ELO) technique and mounted behind a CMG cover glass which at the same time serves as a stable carrier for the thin film cells. In the present initial stage of development these cells have an average efficiency of about 15.4% under AM0 illumination due to not yet optimized grid contacts and anti-reflection coatings. Inspection after irradiation by 1 MeV electrons, thermal vacuum and thermal cycling experiments reveal that degradation of the cells is largely due to delamination and micro-cracking. Based on these results, glass dehydration and adhesive degassing procedures are implemented in the ELO cell processing. As a consequence, even in this premature phase, newly produced cells show a radiation hardness comparable to or better than that of commercially available GaAs cells on Ge substrates and are virtually unaffected by severe thermal cycling. (Author)

Schermer, J.J.; Mulder, P.; Bauhuis, G.J.; Larsen, P.K. [Radboud University, Nijmegen (Netherlands). Institute for Molecules and Materials; Oomen, G.; Bongers, E. [Dutch Space B.V., Leiden (Netherlands)

2005-11-15

146

Plasmonic and photonic designs for light trapping in thin film solar cells  

Science.gov (United States)

Thin film solar cells are promising to realize cheap solar energy. Compared to conventional wafer cells, they can reduce the use of semiconductor material by 90%. The efficiency of thin film solar cells, however, is limited due to insufficient light absorption. Sufficient light absorption at the bandgap of semiconductor requires a light path more than 10x the thickness of the semiconductor. Advanced designs for light trapping are necessary for solar cells to absorb sufficient light within a limited volume of semiconductor. The goal is to convert the incident light into a trapped mode in the semiconductor layer. In this dissertation, a critical review of currently used methods for light trapping in solar cells is presented. The disadvantage of each design is pointed out including insufficient enhancement, undesired optical loss and undesired loss in carrier transport. The focus of the dissertation is light trapping by plasmonic and photonic structures in thin film Si solar cells. The performance of light trapping by plasmonic structures is dependent on the efficiency of photon radiation from plasmonic structures. The theory of antenna radiation is used to study the radiation by plasmonic structures. In order to achieve efficient photon radiation at a plasmonic resonance, a proper distribution of surface charges is necessary. The planar fishnet structure is proposed as a substitution for plasmonic particles. Large particles are required in order to resonate at the bandgap of semiconductor material. Hence, the resulting overall thickness of solar cells with large particles is large. Instead, the resonance of fishnet structure can be tuned without affecting the overall cell thickness. Numerical simulation shows that the enhancement of light absorption in the active layer is over 10x compared to the same cell without fishnet. Photons radiated from the resonating fishnet structure travel in multiple directions within the semiconductor layer. There is enhanced field localization due to interference. The short circuit current was enhanced by 13.29%. Photonic structures such as nanodomes and gratings are studied. Compared to existing designs, photonic structures studied in this dissertation exhibited further improvements in light absorption and carrier transport. The nanodome geometry was combined with conductive charge collectors in order to perform simultaneous enhancement in optics and carrier transport. Despite the increased volume of semiconductor material, the collection length for carriers is less than the diffusion length for minority carriers. The nanodome geometry can be used in the back end and the front end of solar cells. A blazed grating structure made of transparent conductive oxide serves as the back passivation layer while enhancing light absorption. The surface area of the absorber is increased by only 15%, indicating a limited increase in surface recombination. The resulting short circuit current is enhanced by over 20%. The designs presented in the dissertation have demonstrated enhancement in Si thin film solar cells. The enhancement is achieved without hurting carrier transport in solar cells. As a result, the enhancement in light absorption can efficiently convert to the enhancement in cell efficiency. The fabrication of the proposed designs in this dissertation involves expensive process such as electron beam lithography. Future work is focused on optical designs that are feasible for cheap fabrication process. The designs studied in this dissertation can serve as prototype designs for future work.

Ji, Liming

147

Crystalline silicon for thin film solar cells. Final report; Kristallines Silizium fuer Duennschichtsolarzellen. Schlussbericht  

Energy Technology Data Exchange (ETDEWEB)

Thin film solar cells based on silicon are of great interest for cost-effective conversion of solar energy into electric power. In order to reach this goal, intensive research is still necessary, pointing, e.g., to a further enhancement of the conversion efficiency, an improvement of stability and a reduction of the production time. Aim of the project work was the achievement of knowledge on microcrystalline silicon and its application in thin film solar cells by means of a broad research and development program. Material research focused on growth processes of the microcrystalline material, the incorporation and stability of hydrogen, the electronic transport and defects. In particular the transition from amorphous to microcrystalline material which is obtained for the present deposition methods by minor variations of the deposition parameters as well as the enhancement of the deposition rate were intensively studies. Another focus of research aimed toward the development and improvement of zinc oxide films which are of central importance for this type of solar cells for the application as transparent contacts. A comprehensive understanding was achieved. The films were incorporated in thin film solar cells and with conversion efficiencies >8% for single cells (at relatively high deposition rate) and 10% (stable) for tandem cells with amorphous silicon, top values were achieved by international standards. The project achievements serve as a base for a further development of this type of solar cell and for the transfer of this technology to industry. (orig.) [German] Duennschichtsolarzellen auf der Basis von Silizium sind von grossem Interesse fuer eine kostenguenstige Umwandlung von Sonnenenergie in elektrischen Strom. Um dieses Ziel zu erreichen, ist jedoch noch intensive Forschung, u.a. zur weiteren Steigerung des Wirkungsgrades, zur Verbesserung der Stabilitaet und zur Verkuerzung des Produktionsprozesses erforderlich. Ziel der Projektarbeiten war, durch ein breit angelegtes Forschungs- und Entwicklungsprogramm Kenntnisse ueber mikrokristallines Silizium und dessen Einsatzmoeglichkeit in Duennschichtsolarzellen zu gewinnen. Im Rahmen der Materialforschungzustanden Wachstumsprozesse von mirkrokristallinem Material, der Einbau und die Stabilitaet von Wasserstoff, der elektronische Transport und Defekte im Vordergrund. Insbesondere der Uebergang amorph-mikrokristallin, der bei den vorliegenden Depositionsmethoden durch geringfuegige Veraenderungen der Depositionsparameter erreicht werden kann, sowie eine Erhoehung der Depositionsrate wurden intensiv untersucht. Weiterhin wurden an der Entwicklung und Optimierung von Zinkoxidschichten gearbeitet, die fuer diesen Typ von Solarzellen als transparente Kontaktschichten von zentraler Bedeutung sind. Ein umfassendes Verstaendnis wurde erzielt. Die Schichten wurden in Duennschichtsolarzellen eingebaut und mit Wirkungsgraden >8% fuer Einzelzellen (bei relativ hohen Depositionsraten) und 10% (stabil) fuer Tandemsolarzellen mit amorphem Silizium wurden Spitzenwerte (im internationalen Vergleich) erreicht. Die Projektergebnisse dienen als Basis fuer die Weiterentwicklung dieses Solarzellentyps und fuer einen Transfer der Technologie in die Industrie. (orig.)

Wagner, H.

2001-07-01

148

CdTe thin-film solar cells with cobalt-phthalocyanine back contacts  

Science.gov (United States)

We have fabricated CdTe thin-film solar cells using cobalt-phthalocyanine (CoPC) and Au as Cu-free back contacts on F-doped SnO2-coated soda lime glass substrates. The CdTe solar cells using CoPC/Au back contacts showed 80-120 mV improvements on open circuit voltage (VOC) as compared to the cells using Au-only back contacts. The best small area cell using CoPC/Au back contacts has demonstrated an efficiency of 14.3% with an open circuit voltage of 815 mV, a short circuit current of 24.3 mA/cm2, and a fill factor of 72.3% under AM1.5 illumination. Accelerated life testing performed at 200 C and open circuit biasing revealed degradations, partially caused by the presence of oxygen and/or moisture.

Paudel, Naba R.; Yan, Yanfa

2014-04-01

149

Effect of Gaussian doping profile on the performance of a thin film polycrystalline solar cell  

Directory of Open Access Journals (Sweden)

Full Text Available A two-dimensional (2D analytical model based on the Greens function method is applied to an n+-p thin film polycrystalline solar cell that allows us to calculate the conversion efficiency. This model considers the effective Gaussian doping profile in the p region in order to improve cell efficiency. The dependence of mobility and lifetime on grain doping is also investigated. This model is implemented through a simulation program in order to optimize conversion efficiency while varying thickness and doping profile in the base region of the cell. Compared with n+-p standard structure, our proposed structure shows a 43% improvement in conversion efficiency for a polycrystalline solar cell.

Ouali A.

2012-06-01

150

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

Science.gov (United States)

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.

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

1989-01-01

151

ZnO transparent conductive oxide for thin film silicon solar cells  

Science.gov (United States)

There is general agreement that the future production of electric energy has to be renewable and sustainable in the long term. Photovoltaic (PV) is booming with more than 7GW produced in 2008 and will therefore play an important role in the future electricity supply mix. Currently, crystalline silicon (c-Si) dominates the market with a share of about 90%. Reducing the cost per watt peak and energy pay back time of PV was the major concern of the last decade and remains the main challenge today. For that, thin film silicon solar cells has a strong potential because it allies the strength of c-Si (i.e. durability, abundancy, non toxicity) together with reduced material usage, lower temperature processes and monolithic interconnection. One of the technological key points is the transparent conductive oxide (TCO) used for front contact, barrier layer or intermediate reflector. In this paper, we report on the versatility of ZnO grown by low pressure chemical vapor deposition (ZnO LP-CVD) and its application in thin film silicon solar cells. In particular, we focus on the transparency, the morphology of the textured surface and its effects on the light in-coupling for micromorph tandem cells in both the substrate (n-i-p) and superstrate (p-i-n) configurations. The stabilized efficiencies achieved in Neuchtel are 11.2% and 9.8% for p-i-n (without ARC) and n-i-p (plastic substrate), respectively.

Sderstrm, T.; Domin, D.; Feltrin, A.; Despeisse, M.; Meillaud, F.; Bugnon, G.; Boccard, M.; Cuony, P.; Haug, F.-J.; Fa, S.; Nicolay, S.; Ballif, C.

2010-03-01

152

Microcrystalline silicon carbide alloys prepared with HWCVD as highly transparent and conductive window layers for thin film solar cells  

International Nuclear Information System (INIS)

Crystalline silicon carbide alloys have a very high potential as transparent conductive window layers in thin-film solar cells provided they can be prepared in thin-film form and at compatible deposition temperatures. The low-temperature deposition of such material in microcrystalline form (?c-Si:C:H) was realized by use of monomethylsilane precursor gas diluted in hydrogen with the Hot-Wire Chemical Vapor Deposition process. A wide range of deposition parameters has been investigated and the structural, electronic and optical properties of the ?c-SiC:H thin films have been studied. The material, which is strongly n-type from unintentional doping, has been used as window layer in n-side illuminated microcrystalline silicon solar cells. High short-circuit current densities are obtained due to the high transparency of the material resulting in a maximum solar cell conversion efficiency of 9.2%.

153

Plasmonic enhancement of thin-film solar cells using gold-black coatings  

Energy Technology Data Exchange (ETDEWEB)

Coatings of conducting gold-black nano-structures on commercial thin-film amorphous-silicon solar cells enhance the short-circuit current by 20% over a broad spectrum from 400 to 800 nm wavelength. The efficiency, i.e. the ratio of the maximum electrical output power to the incident solar power, is found to increase 7% for initial un-optimized coatings. Metal blacks are produced cheaply and quickly in a low-vacuum process requiring no lithographic patterning. The inherently broad particle-size distribution is responsible for the broad spectrum enhancement in comparison to what has been reported for mono-disperse lithographically deposited or self-assembled metal nano-particles. Photoemission electron microscopy reveals the spatial-spectral distribution of hot-spots for plasmon resonances, where scattering of normally-incident solar flux into the plane increases the effective optical path in the thin film to enhance light harvesting. Efficiency enhancement is correlated with percent coverage and particle size distribution, which are determined from histogram and wavelet analysis of scanning electron microscopy images. Electrodynamic simulations reveal how the gold-black particles scatter the radiation and locally enhance the field strength.

Fredricksen, Christopher J.; Panjwani, D. R.; Arnold, J. P.; Figueiredo, P. N.; Rezaie, F. K.; Colwell, J. E.; Baillie, K.; Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.; Peale, Robert E.

2011-08-11

154

Effect of CdCl{sub 2} annealing treatment on CdS thin films and CdTe/CdS thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

In order to study the effect of CdCl{sub 2} annealing treatment on thin CdS films and CdTe/CdS thin film solar cells, a comparative study was carried out on three types of CdTe/CdS solar cells, which had different kinds of CdS window layer: as-deposited CdS, air-annealed CdS without CdCl{sub 2} pre-coating, and CdCl{sub 2}-annealed CdS. When annealed in air the CdS film was partially oxidated to CdO and CdSO{sub 4}. These oxides increased the series resistance of the CdTe solar cell and led to the lowest fill factor. The presence of CdCl{sub 2} on the surface of a CdS thin film during heat treatment in air protected it from oxidation and promoted the recrystallization of the CdS film, resulting in large and closely packed grains with a grain size of {proportional_to} 50 -150 nm. CdTe/CdS solar cell with such a kind of CdS window layer showed the largest short circuit current and highest conversion efficiency of 12.4%. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bai, Zhizhong; Wan, Lei; Hou, Zerong; Wang, Deliang [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2011-02-15

155

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

Directory of Open Access Journals (Sweden)

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.

Boccard Mathieu

2014-07-01

156

A fast deposition-crystallization procedure for highly efficient lead iodide perovskite thin-film solar cells.  

Science.gov (United States)

Thin-film photovoltaics based on alkylammonium lead iodide perovskite light absorbers have recently emerged as a promising low-cost solar energy harvesting technology. To date, the perovskite layer in these efficient solar cells has generally been fabricated by either vapor deposition or a two-step sequential deposition process. We report that flat, uniform thin films of this material can be deposited by a one-step, solvent-induced, fast crystallization method involving spin-coating of a DMF solution of CH3NH3PbI3 followed immediately by exposure to chlorobenzene to induce crystallization. Analysis of the devices and films revealed that the perovskite films consist of large crystalline grains with sizes up to microns. Planar heterojunction solar cells constructed with these solution-processed thin films yielded an average power conversion efficiency of 13.90.7% and a steady state efficiency of 13% under standard AM 1.5 conditions. PMID:25047967

Xiao, Manda; Huang, Fuzhi; Huang, Wenchao; Dkhissi, Yasmina; Zhu, Ye; Etheridge, Joanne; Gray-Weale, Angus; Bach, Udo; Cheng, Yi-Bing; Spiccia, Leone

2014-09-01

157

Admittance spectroscopy of Cu2ZnSnS4 based thin film solar cells  

Science.gov (United States)

In this report, we propose an AC response equivalent circuit model to describe the admittance measurements of Cu2ZnSnS4 thin film solar cell grown by sulphurization of stacked metallic precursors. This circuit describes the contact resistances, the back contact, and the heterojunction with two trap levels. The study of the back contact resistance allowed the estimation of a back contact barrier of 246 meV. The analysis of the trap series with varying temperature revealed defect activation energies of 45 meV and 113 meV. The solar cell's electrical parameters were obtained from the J-V curve: conversion efficiency, 1.21%; fill factor, 50%; open circuit voltage, 360 mV; and short circuit current density, 6.8 mA/cm2.

Fernandes, P. A.; Sartori, A. F.; Salom, P. M. P.; Malaquias, J.; da Cunha, A. F.; Graa, M. P. F.; Gonzlez, J. C.

2012-06-01

158

Laser crystallization induced multicrystalline silicon thin film solar cells on glass : European High-EF Project  

International Nuclear Information System (INIS)

The European project HIGH-EF is aimed at developing a unique process for silicon thin films based solar cells on glass substrate. To provide high solar cells efficiency (? 12 percent), a combination of laser crystallization of a seed layer and an additional solid phase epitaxy of a thicker layer is realized. In a first step, the crystallization of the seed layer is obtained by scanning a focused in-line laser beam obtained by a specific optical lens system. In a second step, epitaxial growth of a large grains active silicon layer is achieved by solid phase epitaxy. Process optimization is supported by numerical simulations of both melting and crystallization process of the seed layer as well as epitaxial solid phase crystallization

159

A non-resonant dielectric metamaterial for enhancement of thin-film solar cells  

CERN Document Server

Recently, we have suggested dielectric metamaterial composed as an array of submicron dielectric spheres located on top of an amorphous thin-film solar cell. We have theoretically shown that this metamaterial can decrease the reflection and simultaneously can suppress the transmission through the photovoltaic layer because it transforms the incident plane wave into a set of focused light beams. This theoretical concept has been strongly developed and experimentally confirmed in the present paper. Here we consider the metamaterial for oblique angle illumination, redesign the solar cell and present a detailed experimental study of the whole structure. In contrast to our precedent theoretical study we show that our omnidirectional light-trapping structure may operate better than the optimized flat coating obtained by plasma-enhanced chemical vapor deposition.

Omelyanovich, Mikhail; Simovski, Constantin

2014-01-01

160

Enhancing light trapping properties of thin film solar cells by plasmonic effect of silver nanoparticles.  

Science.gov (United States)

The preparation of thin film silicon solar cells containing Ag nanoparticles is reported in this article. Ag nanoparticles were deposited on fluorine doped tin oxide coated glass substrates by the evaporation and condensation method. a-Si:H solar cells were deposited on these substrates by cluster type plasma enhanced chemical vapor deposition. We discuss the double textured surface effect with respect to both the surface morphology of the substrate and the plasmonic effect of the Ag nanoparticles. Ag nanoparticles of various sizes from 10 to 100 nm were deposited. The haze values of the Ag embedded samples increased with increasing particle size whereas the optical transmittance decreased at the same conditions. The solar cell with the 30 nm size Ag nanoparticles showed a short circuit current density of 12.97 mA/cm2, which is 0.53 mA/cm2 higher than that of the reference solar cell without Ag nanoparticles, and the highest quantum efficiency for wavelengths from 550 to 800 nm. When 30 nm size nanoparticles were employed, the conversion efficiency of the solar cell was increased from 6.195% to 6.696%. This study reports the application of the scattering effect of Ag nanoparticles for the improvement of the conversion efficiency of amorphous silicon solar cells. PMID:24266153

Jung, Junhee; Ha, Kyungyeon; Cho, Jaehyun; Ahn, Shihyun; Park, Hyeongsik; Hussain, Shahzada Qamar; Choi, Mansoo; Yi, Junsin

2013-12-01

 
 
 
 
161

Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture  

Science.gov (United States)

Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structure (LLTS) as a means of improving the light-harvesting capacity and performance of cells, achieving a 13.07% initial efficiency and greatly improved current output of a-Si:H single-junction solar cell based on this architecture. Given the unique transparency characteristics of thin-film solar cells, this proposed architecture has great potential for integration into the windows of buildings, microelectronics and other applications requiring transparent components. PMID:25145774

Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

2014-01-01

162

Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture  

Science.gov (United States)

Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structure (LLTS) as a means of improving the light-harvesting capacity and performance of cells, achieving a 13.07% initial efficiency and greatly improved current output of a-Si:H single-junction solar cell based on this architecture. Given the unique transparency characteristics of thin-film solar cells, this proposed architecture has great potential for integration into the windows of buildings, microelectronics and other applications requiring transparent components.

Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

2014-08-01

163

Cu(In,GaSe2 thin films processed by co-evaporation and their application into solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available Polycrystalline Cu(In,GaSe2 (CIGS solar cells are attractive because low cost techniques can be used to obtain high efficiency thin film photovoltaic devices. Several research groups around the world have developed CIGS/CdS solar cells with efficiencies larger than 15% [1] using evaporation, making it an attractive and reliable technique for thin film deposition. Our PVD system is provided with MBE-type Knudsen cells to deposit CIGS thin films on glass/Molibdenum (Mo substrates. The deposition conditions for each metal source have been established by doing a deposition profile of temperature data vs. growth rate by co-evaporation to obtain CIGS thin film for solar cells. Characterization of the co-evaporated CIGS thin films was performed by X-ray diffraction (X-RD, scanning electron microscopy (SEM and energy dispersive x-ray spectroscopy (EDS techniques. Good quality polycrystalline films were obtained as shown by X-RD patterns. SEM micrographs show films having a very uniform appearance with large grain sizes (1 m. Photoluminescence (PL studies on CIGS samples with different Ga and Cu concentrations (Ga/Ga+In = 0.25 and 0.34 and (Cu/In+Ga = 0.83, 0.88 and 0.94 have been performed. The EDS results have shown that is possible to control very precisely the CIGS thin film composition using these Knudsen cells. Film thicknesses of 3-4 m, were measured with an Ambios profilemeter XP 100 stylus type. A conversion efficiency of 10.9 % has been achieved for solar cells made from the co-evaporated absorbers.

J. Sastr\\u00E9-Hern\\u00E1ndez

2011-01-01

164

Cu(In,Ga)Se2 thin films processed by co-evaporation and their application into solar cells  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in english Polycrystalline Cu(In,Ga)Se2 (CIGS) solar cells are attractive because low cost techniques can be used to obtain high efficiency thin film photovoltaic devices. Several research groups around the world have developed CIGS/CdS solar cells with efficiencies larger than 15% [1] using evaporation, makin [...] g it an attractive and reliable technique for thin film deposition. Our PVD system is provided with MBE-type Knudsen cells to deposit CIGS thin films on glass/Molibdenum (Mo) substrates. The deposition conditions for each metal source have been established by doing a deposition profile of temperature data vs. growth rate by co-evaporation to obtain CIGS thin film for solar cells. Characterization of the co-evaporated CIGS thin films was performed by X-ray diffraction (X-RD), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) techniques. Good quality polycrystalline films were obtained as shown by X-RD patterns. SEM micrographs show films having a very uniform appearance with large grain sizes (~1 m). Photoluminescence (PL) studies on CIGS samples with different Ga and Cu concentrations (Ga/Ga+In) = 0.25 and 0.34 and (Cu/In+Ga) = 0.83, 0.88 and 0.94) have been performed. The EDS results have shown that is possible to control very precisely the CIGS thin film composition using these Knudsen cells. Film thicknesses of ~3-4 m, were measured with an Ambios profilemeter XP 100 stylus type. A conversion efficiency of 10.9 % has been achieved for solar cells made from the co-evaporated absorbers.

J., Sastr-Hernndez; M.E., Calixto; M., Tufio-Velzquez; G., Contreras-Puente; A., Morales-Acevedo; G., Casados-Cruz; M.A., Hernndez-Prez; M.L., Albor-Aguilera; R., Mendoza-Prez.

2011-10-11

165

Titanium oxide thin film improving efficiency in polymer/fullerene solar cells  

Energy Technology Data Exchange (ETDEWEB)

Full text. Polymer/fullerene based solar cells are of great interest in polymer-based photovoltaic due to low cost fabrication in large areas and on flexible substrates, and roll-to-roll manufacturing. Standard power conversion efficiencies of about 5 - 8% are reported in such organic photovoltaic cells (OPVC) but in order to improve device performance new materials and device architectures are needed. Our OPVC thin films consists of blend of P3HT-PCBM (1:1 by weight) and are spin-coated over indium tin oxide (ITO)-glass substrate covered with poly(3,4-ethylenedioxylenethiophene) polystyrene sulfonic acid (PEDOT:PSS) forming the hole electrode. The collector electrode is a lower-work-function metal, which is in our case Al. Many papers reported the use of lithium fluoride (LiF) layer for a better ohmic contact, but this insulating layer can also reduce the electron collection efficiency if its thickness is above few nanometers. From current-voltage curves in dark and under illumination we show an improvement in the fill factor (FF) and better quality of an OPVC when LiF layer is replaced by titanium oxide (TiO) thin film. The final device is annealed to 150 deg C well below the crystallization temperature for TiO{sub 2} (anatase), resulting in an amorphous phase of this oxide but keeping good conductive quality.

Feu, W.H.M.; Martins, R.F.; Krambrock, K.; Cury, L.A.; Guimaraes, P.S.S. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Fisica; Reis, G.A.; Franchello, F.; Dias, I.F.L. [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica

2011-07-01

166

Determination of optical and mechanical properties of Nb2O5 thin films for solar cells application  

Science.gov (United States)

In this paper investigation results of niobium pentoxide thin films deposited by microwave assisted reactive magnetron sputtering process were described. Surface of prepared coatings was examined with the aid of atomic force microscope (AFM) operating in the contact-mode and in ultra high vacuum conditions. The surface of thin films was homogenous, crack free and exhibit low root mean square (RMS) roughness of about 0.34 nm. X-ray photoelectron spectroscopy (XPS) studies were performed to determine the chemical states of the niobium at the surface of thin films. Contact angle and surface free energy were additionally investigated to examine the surface properties of the deposited coatings. Optical properties of the Nb2O5 thin films showed, that prepared coatings were well transparent from 350 nm to longer wavelength range. Based on transmission and reflection measurements the values of refractive index and extinction coefficient were determined. The antireflective coating based on Nb2O5 thin films for solar cells application was proposed. The hardness and Young's modulus measurements were performed by the nanoindentation technique. These investigations revealed that the hardness of the deposited coatings was ca., 7 GPa. Also scratch tests were applied, which have shown that the Nb2O5 thin films were scratch resistant.

Mazur, M.; Szyma?ska, M.; Kaczmarek, D.; Kalisz, M.; Wojcieszak, D.; Domaradzki, J.; Placido, F.

2014-05-01

167

Recent Progress in CuInS2 Thin-Film Solar Cell Research at NASA Glenn  

Science.gov (United States)

The National Aeronautics and Space Administration (NASA) is interested in developing low-cost highly efficient solar cells on light-weight flexible substrates, which will ultimately lower the mass-specific power (W/kg) of the cell allowing extra payload for missions in space as well as cost reduction. In addition, thin film cells are anticipated to have greater resistance to radiation damage in space, prolonging their lifetime. The flexibility of the substrate has the added benefit of enabling roll-to-roll processing. The first major thin film solar cell was the "CdS solar cell" - a heterojunction between p-type CuxS and n-type CdS. The research on CdS cells started in the late 1950s and the efficiency in the laboratory was up to about 10 % in the 1980s. Today, three different thin film materials are leading the field. They include amorphous Si, CdTe, and Cu(In,Ga)Se2 (CIGS). The best thin film solar cell efficiency of 19.2 % was recently set by CIGS on glass. Typical module efficiencies, however, remain below 15 %.

Jin, M. H.-C.; Banger, K. K.; Kelly, C. V.; Scofield, J. H.; McNatt, J. S.; Dickman, J. E.; Hepp, A. F.

2005-01-01

168

The use of porous silicon layers in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

In the quest for lowering the manufacturing cost of silicon solar cells, imec has been working successfully on two crystalline Si 'thin-film' cell concepts. In a first concept, a 20 {mu}m-thin Si solar cell is epitaxially grown on top of a porous Si-based Bragg-type reflector which is electrochemically etched in a low-cost UMG Si substrate. Large area solar cells with efficiencies of 15.2% have been made, using (semi-)industrial processing tools. This clearly demonstrates that this cell concept has almost reached the stage of industrial application. In a second, longer-term approach, a 1-5 {mu}m-thin, stand-alone mono-crystalline film is created based on the controlled annealing of an ordered macroporous silicon layer (the 'Epi-free' process). With this very thin Si layer, a simple proof-of-concept solar cell has been made exhibiting an efficiency of 4%. By optimizing the cell process in terms of light trapping and passivation, efficiencies over 15% can be expected from this technology. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Hoeymissen, Jan van; Depauw, Valerie; Kuzma-Filipek, Izabela; Nieuwenhuysen, Kris van; Payo, Maria Recaman; Qiu, Yu; Gordon, Ivan; Poortmans, Jef [Solar Cell Technology Group, Imec, Leuven (Belgium)

2011-06-15

169

Electrodeposition of wide band gap InGaxSyOz thin films for solar cell applications  

International Nuclear Information System (INIS)

Indium-Gallium-sulfide-oxide thin films were deposited onto F-doped SnO2-coated glass by electrochemical deposition from an aqueous bath. The films were deposited at three different ratios of gallium to indium in the precursor bath; namely [Ga/In] = 2/8, 5/5 and 8/2. The impact of the gallium content on the composition, optical transmission, structure, photosensitivity, electrical resistivity and morphology of the deposited films was investigated. The films deposited at [Ga/In] = 5/5 and 8/2 had an energy gap as high as 3.5 eV. The X-ray diffraction spectrum of the film deposited at [Ga/In] = 2/8 contained weak peaks of indium metal, but the In peaks were absent in the spectra of the films deposited at [Ga/In] = 5/5 and 8/2. The photosensitivity of the film was observed by means of photoelectrochemical measurements, which confirmed that all the films showed n-type conduction. Finally, the film has been used as a buffer layer to fabricate a SnS-based thin film solar cell.

170

Three dimensionally structured interdigitated back contact thin film heterojunction solar cells  

Science.gov (United States)

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.

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

2011-04-01

171

Electrical Properties of Al, Ag, Cu, Ti and SS Thin Film for Electrode of Solar Cell  

International Nuclear Information System (INIS)

The Al, Ag, Cu, Ti and SS materials were deposited on the surface of glass substrate using plasma DC sputtering technique. The deposition process was done with the following plasma parameters : deposition time, gas pressure and substrate temperature with the aim to obtain a good conductance of thin films. Variation of substrate deposition time was 1 - 15 minutes, gas pressure was 5x10-2 - 7x10-2 torr and of temperature was 100 - 300 oC. The resistance measurement has been done by four points probes and the conductivity was calculated using mathematic formulation. It was obtained that the minimum resistance in the order of R = 0.07 ?, was found at Ag materials and this was obtained at the following plasma parameters : deposition time 15 minutes, gas pressure 6x10-2 torr and temperature 300 oC, while, the resistance of : Cu, Al, Ti and SS materials were R = 0.13 ?, R = 450 ?, R = 633 ?, R = 911 ? respectively, It could be concluded that the Ag thin film has a minimum resistance, high conductivity compared to the other materials Al, Cu, Ti and SS. Ag is therefore the suitable material for applying as electrode of solar cell. (author)

172

A study of the applicability of ZnO thin-films as anti-reflection coating on Cu2ZnSnS4 thin-films solar cell  

Science.gov (United States)

Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu2ZnSnS4 (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF2. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

Ray, Abhijit; Patel, Malkeshkumar; Tripathi, Brijesh; Kumar, Manoj

2012-06-01

173

Study of thin-film silicon solar cells at irradiances above ten thousand suns  

International Nuclear Information System (INIS)

We used a tightly focused Gaussian beam of a HeNe laser to study accelerated light-induced degradation (Staebler-Wronski effect) and high photocarrier generation rates in amorphous and microcrystalline silicon thin-film solar cells, at up to13 MW/m2 irradiance. For the experiments, the spot radius was varied from a minimum of 8.6 ?m in the focus to around 1 mm away from the focus. According to COMSOL'' (registered) simulations, even at these high power densities heat diffusion into a glass substrate aided by spreading conduction via the Ag back-contact restricts the temperature rise to less than 14 K. Short-circuit current can be measured directly over a range of irradiances, and the J-V characteristic may be estimated by taking into account shunting by the inactive part of the cell.

174

Perovskite solar cells based on nanocolumnar plasma-deposited ZnO thin films.  

Science.gov (United States)

ZnO thin films having a nanocolumnar microstructure are grown by plasma-enhanced chemical vapor deposition at 423 K on pre-treated fluorine-doped tin oxide (FTO) substrates. The films consist of c-axis-oriented wurtzite ZnO nanocolumns with well-defined microstructure and crystallinity. By sensitizing CH3NH3PbI3 on these photoanodes a power conversion of 4.8% is obtained for solid-state solar cells. Poly(triarylamine) is found to be less effective when used as the hole-transport material, compared to 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), while the higher annealing temperature of the perovskite leads to a better infiltration in the nanocolumnar structure and an enhancement of the cell efficiency. PMID:24643984

Ramos, F Javier; Lpez-Santos, Maria C; Guilln, Elena; Nazeeruddin, Mohammad Khaja; Grtzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

2014-04-14

175

Thin film solar energy collector  

Science.gov (United States)

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Aykan, Kamran (Monmouth Beach, NJ); Farrauto, Robert J. (Westfield, NJ); Jefferson, Clinton F. (Millburn, NJ); Lanam, Richard D. (Westfield, NJ)

1983-11-22

176

A nanoparticle ink printing process for all printed thin film copper-indium-selenide (CIS) solar cells  

Science.gov (United States)

Copper indium selenide (CIS) or its derivatives (such as gallium doped CIS and sulfur substituted CIS) are considered the best optical absorber material used in polycrystalline thin film photovoltaic solar cells due to their favorable electrical and optical properties, and long term stability. To develop a low cost yet high throughput thin film deposition process with both composition and film uniformity control, precursor ink has been formulated using nanoparticle metal oxide of copper and indium in an organic solvent system dissolved with selenium or sulfur. Smooth thin film of precursor oxide mixture has been demonstrated by wet printing process. Upon heat treatment of the precursor thin film under atmosphere of selenium and/or sulfur, copper-indium selenide and/or sulfide (CIS) was formed. Several approaches of nanoparticle ink coating processes have been investigated through spin-coating, screen-printing and contact printing. For using glass substrate, contact printing demonstrated superior uniformity and composition control. By using a post-thermal treatment process on the nanoparticle-coated film, good morphology thin film with composition control was achieved. Both the chemical composition and physical morphology has been investigated using ICP-OES and XRD measurements. Based on molybdenum glass substrate, all-printed solar cells have been demonstrated.

Li, X. Charles; Soltesz, Istvan; Wu, Mindy; Ziobro, Frank; Amidon, Roger; Kiss, Zoltan

2008-08-01

177

Single source precursors for fabrication of I-III-VI2 thin-film solar cells via spray CVD  

International Nuclear Information System (INIS)

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors can be used in either a hot, or cold-wall spray chemical vapour deposition reactor, for depositing CuInS2, CuGaS2 and CuGaInS2 at reduced temperatures (400-450 sign C), which display good electrical and optical properties suitable for photovoltaic devices. X-ray diffraction studies, energy dispersive spectroscopy and scanning electron microscopy confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures

178

Ternary Precursors for Depositing I-III-VI2 Thin Films for Solar Cells via Spray CVD  

Science.gov (United States)

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors (SSP's) can be used in either a hot or cold-wall spray chemical vapour deposition (CVD) reactor, for depositing CuInS2, CuGaS2, and CuGaInS2 at reduced temperatures (400 to 450 C), which display good electrical and optical properties suitable for photovoltaic (PV) devices. X-ray diffraction studies, energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures.

Banger, K. K.; Hollingsworth, J. A.; Jin, M. H.-C.; Harris, J. D.; Duraj, S. A.; Smith, M.; Scheiman, D.; Bohannan, E. W.; Switzer, J. A.; Buhro, W. E.

2002-01-01

179

Fabrication of Cu2ZnSnS4 Thin-Film Solar Cell Prepared by Pulsed Laser Deposition  

Science.gov (United States)

A thin-film solar cell based on a Cu2ZnSnS4 (CZTS) absorber layer deposited by pulsed laser deposition has been fabricated with an Al:ZnO (n-type) window layer and a CdS buffer layer. Some peaks attributed to (112), (200), (220), and (312) planes of CZTS appeared in an X-ray diffraction pattern of a thin film. The composition of the film was Sn-rich and the band gap energy was approximately 1.5 eV. A CZTS film annealed at 500 C in an atmosphere of N2 had optical characteristics suitable for use in an absorber layer of a thin-film solar cell and was used for a solar cell. The CZTS thin-film solar cell with an active area of 0.092 cm2 showed an open-circuit voltage of 546 mV, a short-circuit current of 6.78 mA/cm2, a fill factor of 0.48, and a conversion efficiency of 1.74%.

Moriya, Katsuhiko; Tanaka, Kunihiko; Uchiki, Hisao

2007-09-01

180

Silicontetrachloride based microcrystalline silicon for application in thin film silicon solar cells  

International Nuclear Information System (INIS)

The replacement of the process gas silane by silicontetrachloride for the deposition of microcrystalline silicon thin films is explored. The films were prepared by plasma enhanced chemical vapor deposition from mixtures of silicontetrachloride and hydrogen. Deposition conditions similar as employed for efficient silane-based microcrystalline silicon solar cells of high deposition rate were applied. Structural and electronic properties of the films are studied by infrared optical absorption and Raman spectroscopies and conductivity measurements. Increasing the flow ratio of silicontetrachloride to hydrogen, the transition from the crystalline to the amorphous state is found to occur in a similar range of flow ratio as in silane-based material. The lowest porosity is observed for a crystalline fraction near 80%. Porosity, void-related microstructure and chlorine content are found to decrease with increasing substrate temperature. For boron doped material deposited at a substrate temperature of 250 deg. C, conductivity values exceeding 50 (? cm)-1 were achieved. This latter material was incorporated as p-layer into microcrystalline pin silicon solar cells. Solar cell efficiencies similar as for solar cells with a silane-based p-layer were obtained

 
 
 
 
181

Application of plasmonic silver island films in thin-film silicon solar cells  

International Nuclear Information System (INIS)

Silver nanoparticles can be used as light scattering elements for enhancing solar cell energy conversion efficiencies. The objective of our work is to gain more insight into the optical properties of silver nanoparticle films and their effect on the performance of solar cells. We use a common self-assembly technique to fabricate a range of silver island films on transparent substrates and measure their reflectance and transmittance for visible and near infrared light. We demonstrate that it is possible to represent silver island films by an effective medium with the same optical properties. The observed strong dependence on illumination side of the reflectance and absorptance, attributed to driving field effects, is reproduced very well. Thin-film silicon solar cells with embedded silver island films were fabricated and it was found that their performance is reduced due to parasitic absorption of light in the silver island film. Simulations of these solar cells, where the silver island film is represented as an effective medium layer, show a similar trend. This highlights the importance of minimizing parasitic absorption

182

Thin film CIGS solar cells with a novel low cost process - Final report  

Energy Technology Data Exchange (ETDEWEB)

Novel manufacturing routes for efficient and low-cost Cu(In,Ga)Se{sub 2} (called CIGS) thin film solar cells are explored and patented. CIGS has proven its suitability for highly efficient and extremely stable solar cells. The low-cost methods allow impurity free material synthesis, fast large-area deposition, high material utilization and a very short energy payback time with drastically lower manufacturing costs. Two non-vacuum, solution-based approaches are investigated to deposit thin layers of CIGS. The first approach considers incorporation of copper into indium gallium selenide precursor layers by ion-exchange from aqueous or organic solutions. Organic solutions provide faster copper incorporation and do not corrode the metal back contact. Solar cells processed from selenized precursor films exhibit efficiencies of up to 4.1%. The second approach with paste coating of inorganic salt solution results in a solar cell efficiency of 4% (record 6.7%), where further improvements are hindered by the presence of the residual carbon layer. Using alternative organic binders, pre-deposited selenium layers, non-binder recipes helps to avoid the carbon layer although the obtained layers are inhomogeneous and contain impurity phases. A patent for the ion-exchange approach is pending, and the obtained research results on the paste coating approach will be scrutinized during new European FP7 project 'NOVA-CIGS'. (authors)

Tiwari, A. N.; Romanyuk, Y.

2010-01-15

183

Natural evolution inspired design of light trapping structure in thin film organic solar cells  

Science.gov (United States)

Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

2013-09-01

184

Organic solar cells based on liquid crystalline and polycrystalline thin films  

Science.gov (United States)

This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors. Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements. In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7% under broadband illumination (350--900 nm) with a peak external quantum efficiency of 58% have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using the equivalent circuit model used for inorganic pn-junction solar cells. Dependences of equivalent-circuit parameters on light intensity are further investigated using a modified equivalent circuit model, and their effects on the overall photovoltaic performance are discussed.

Yoo, Seunghyup

185

Development of copper sulfide/cadmium sulfide thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Unencapsulated thin-film solar cells of the Cu/sub 2/S/CdS type have been aged in controlled flowing-gas ambients to characterize changes in their photovoltaic properties. Severe degradation occurring in wet O/sub 2/ ambients at room temperature probably accounts for the large short-circuit current losses reported earlier. Limited loss (<15% of initial values) in J/sub sc/ occurs at RT in dry oxygen. No loss can be attributed to moisture in Ar or N/sub 2/ ambients for exposure times greater than approx. 2 hrs. Direct measurements of optical absorption in the front Cu/sub 2/S layer would be facilitated by an integral CdS/Cu/sub 2/S detector on the back surface. Several techniques for making such a detector were successfully demonstrated.

Szedon, J.R.; Biter, W.J.; Dickey, H.C.

1982-03-01

186

Spin Coated Plasmonic Nanoparticle Interfaces for Photocurrent Enhancement in Thin Film Si Solar Cells  

CERN Document Server

Nanoparticle (NP) arrays of noble metals strongly absorb light in the visible to infrared wavelengths through resonant interactions between the incident electromagnetic field and the metal's free electron plasma. Such plasmonic interfaces enhance light absorption and photocurrent in solar cells. We report a cost effective and scalable room temperature/pressure spin-coating route to fabricate broadband plasmonic interfaces consisting of silver NPs. The NP interface yields photocurrent enhancement (PE) in thin film silicon devices by up to 200% which is significantly greater than previously reported values. For coatings produced from Ag nanoink containing particles with average diameter of 40 nm, an optimal NP surface coverage of 7% was observed. Scanning electron microscopy of interface morphologies revealed that for low surface coverage, particles are well-separated, resulting in broadband PE. At higher surface coverage, formation of particle strings and clusters caused red-shifting of the PE peak and a narro...

Israelowitz, Miriam; Cong, Tao; Sureshkumar, Radhakrishna

2013-01-01

187

Studying nanostructured nipple arrays of moth eye facets helps to design better thin film solar cells  

International Nuclear Information System (INIS)

Nipples on the surface of moth eye facets exhibit almost perfect broadband anti-reflection properties. We have studied the facet surface micro-protuberances, known as corneal nipples, of the chestnut leafminer moth Cameraria ohridella by atomic force microscopy, and simulated the optics of the nipple arrays by three-dimensional electromagnetic simulation. The influence of the dimensions and shapes of the nipples on the optics was studied. In particular, the shape of the nipples has a major influence on the anti-reflection properties. Furthermore, we transferred the structure of the almost perfect broadband anti-reflection coatings to amorphous silicon thin film solar cells. The coating that imitates the moth-eye array allows for an increase of the short circuit current and conversion efficiency of more than 40%.

188

Absorbance enhancement of thin film solar cells with front double dielectric and back metallic grating  

Science.gov (United States)

We present finite difference time domain (FDTD) and rigorous coupled-wave analysis (RCWA) simulations to analyze the optical absorption enhancement of thin film solar cells (TFSCs) employing front double dielectric and back plasmonic grating structures. Simulation results show that the combination of a subwavelength aperture and a double nano-structured dielectric grating with back triangle metallic grating results in an enhancement in total optical absorption. The absorption of the planar structure is enhanced thanks to an increase of the optical path length of the red and near-infrared photons, causing a proportional enhancement of the absorption in this spectral range. 90.85% Average harvesting (on TE and TM) can be achieved by the optimized structure in the spectrum range from 300 to 1100 nm. The designed SC has high integrated absorption and is weakly dependent on incident angle, which should be useful for application in film photovoltaics, photodetectors and infrared imaging.

Zheng, Gaige; Zhang, Wei; Xu, Linhua; Chen, Yunyun; Liu, Yuzhu

2014-11-01

189

Transparent sculptured titania films for enhanced light absorption in thin-film Si solar cells  

International Nuclear Information System (INIS)

This study presents a description of the enhancement of light absorption in thin-film silicon (Si) solar cells by using sculptured titania (TiO2) films. We used an electron-beam evaporation system with a glancing angle deposition (GLAD) method to deposit porous TiO2 films on fluorine-doped SnO2 (FTO) substrates. The GLAD TiO2/FTO films were used as conductive electrodes in hydrogenated microcrystalline silicon (?c-Si:H) solar cells. Transmission electron microscopy revealed that the GLAD TiO2 films are composed of sculptured nano-pillars on an FTO surface, and this nanostructure provides a synergistic route for light scattering enhancement. The GLAD TiO2/FTO exhibited a 68% improvement of optical haze (at ? = 600 nm). The ?c-Si:H solar cells consisting of the GLAD-nanostructured TiO2 resulted in a 5% improvement of short-circuit current (Jsc) and yielded a cell efficiency of 6.6%.

190

Transparent sculptured titania films for enhanced light absorption in thin-film Si solar cells  

Energy Technology Data Exchange (ETDEWEB)

This study presents a description of the enhancement of light absorption in thin-film silicon (Si) solar cells by using sculptured titania (TiO{sub 2}) films. We used an electron-beam evaporation system with a glancing angle deposition (GLAD) method to deposit porous TiO{sub 2} films on fluorine-doped SnO{sub 2} (FTO) substrates. The GLAD TiO{sub 2}/FTO films were used as conductive electrodes in hydrogenated microcrystalline silicon ({mu}c-Si:H) solar cells. Transmission electron microscopy revealed that the GLAD TiO{sub 2} films are composed of sculptured nano-pillars on an FTO surface, and this nanostructure provides a synergistic route for light scattering enhancement. The GLAD TiO{sub 2}/FTO exhibited a 68% improvement of optical haze (at {lambda} = 600 nm). The {mu}c-Si:H solar cells consisting of the GLAD-nanostructured TiO{sub 2} resulted in a 5% improvement of short-circuit current (J{sub sc}) and yielded a cell efficiency of 6.6%.

Hung, Kai-Hsiang, E-mail: khhung@itri.org.tw [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chiou, Guan-Di; Wong, Ming-Show [Department of Materials Science and Engineering, National Dong Hwa University, Hualien, Taiwan (China); Wang, Yu-Chih [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chung, I-Shan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

2011-12-30

191

Overview and Challenges of Thin Film Solar Electric Technologies  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we report on the significant progress made worldwide by thin-film solar cells, namely, amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). Thin-film photovoltaic (PV) technology status is also discussed in detail. In addition, R&D and technology challenges in all three areas are elucidated. The worldwide estimated projection for thin-film PV technology production capacity announcements are estimated at more than 5000 MW by 2010.

Ullal, H. S.

2008-12-01

192

Microcrystalline silicon absorber layers prepared at high deposition rates for thin-film tandem solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available We have investigated high deposition rate processes for the fabrication of thin-film silicon tandem solar cells. Microcrystalline silicon absorber layers were prepared under high pressure depletion conditions at an excitation frequency of 81.36 MHz. The deposition rate was varied in the range of 0.2 nm/s to 3.2 nm/s by varying the deposition pressure and deposition power for given electrode spacings. The silane-to-hydrogen process gas mixture was adjusted in each case to prepare optimum phase mixture material. The performance of these tandem solar cells was investigated by external quantum efficiency and current-voltage measurements under AM1.5 illumination before and after 1000 h of light degradation. Up to deposition rates of 0.8 nm/s for the microcrystalline silicon absorber layer high quality tandem solar cells with an initial efficiency of 10.9% were obtained (9.9% stabilized efficiency after 1000 h of light degradation.

Michard S.

2013-12-01

193

Photo-induced electron transfer processes in thin-film solar cells.  

Science.gov (United States)

Power conversion efficiency of single heterojuntion and bulk heterojunction thin-film solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. Furthermore, a numerical model was developed to predict current-voltage characteristics of solar cells on the basis of photo-induced electron transfer processes. As an application of this modeling, the power conversion efficiency was analyzed for the donor/acceptor (CuPc/C60) heterojunction under various conditions. In this way, the maximum power conversion efficiency, under 1 sun AM 1.5 solar illumination, was estimated to be 6.1% for the optimum single heterojunction structure. As for the bulk heterojunction structure, a vertical lattice (alternating donor/acceptor lamellae perpendicular to a substrate) structure was proposed and the maximum power conversion efficiency was estimated to be 10.8%. It was concluded that the power conversion efficiency of the vertical lattice bulk heterojunction cell could be increased up to ca. 15% by the improvement of the hole mobility of the donor film. PMID:25084587

Isoda, Satoru

2011-06-01

194

Optimization of film morphology for the performance of organic thin film solar cells  

Science.gov (United States)

The power conversion efficiency of organic thin film solar cells must be improved before they can become commercially competitive alternatives to silicon-based photovoltaics. Exciton diffusion and charge carrier migration in organic films are strongly influenced by film morphology, which can be controlled by the substrate temperature during film growth. Zinc-phthalocyaninelbuckminsterfullerene bilayer film devices are fabricated with substrate temperatures between 25C and 224C and their solar cell performance is investigated here. The device open-circuit voltage, efficiency, and fill factor all exhibit peaks when films are grown at temperatures between 160C and 180C, which is likely a result of both the increase in shunt resistance and reduction in undesirable back diode effects which occur between l00C and 180C. The device performance can also be attributed to changes in the film crystallite size, roughness, and abundance of pinholes, as well as the occurrence of crystalline phase transitions which occur in both zinc-phthalocyanine and buckminsterfullerene between 150C and 200C. The unusually high open-circuit voltage (1.2 V), low short-circuit current density (0.03 mA/cm2), and low device efficiency (0.04%) reported here are reminiscent of single layer phthalocyanine-based Schottky solar cells, which suggests that pinholes in bilayer film devices can effectively lead to the formation of Schottky diodes.

Muckley, Eric S.

195

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

196

Electron Backscatter Diffraction: An Important Tool for Analyses of Structure-Property Relationships in Thin-Film Solar Cells  

Science.gov (United States)

The present work gives an overview of the application of electron backscatter diffraction (EBSD) in the field of thin-film solar cells, which consist of stacks of polycrystalline layers on various rigid or flexible substrates. EBSD provides access to grain-size and local-orientation distributions, film textures, and grain-boundary types. By evaluation of the EBSD patterns within individual grains of the polycrystalline solar cell layers, microstrain distributions also can be obtained. These microstructural properties are of considerable interest for research and development of thin-film solar cells. Moreover, EBSD may be performed three-dimensionally, by alternating slicing of cross sections in a focused ion-beam machine and EBSD acquisition. To relate the microstructural properties to the electrical properties of individual layers as well as to the device performances of corresponding solar cells, EBSD can be combined with electron-beam-induced current and cathodoluminescence measurements and with various scanning-probe microscopy methods such as Kelvin-probe force, scanning spreading resistance, or scanning capacitance microscopy on identical specimen positions. Together with standard device characterization of thin-film solar cells, these scanning microscopy measurements provide the means for extensive analysis of structure-property relationships in solar-cell stacks with polycrystalline layers.

Abou-Ras, D.; Kavalakkatt, J.; Nichterwitz, M.; Schfer, N.; Harndt, S.; Wilkinson, A. J.; Tsyrulin, K.; Schulz, H.; Bauer, F.

2013-09-01

197

Thin film solar cell and its production method; Hakumaku taiyo denchi oyobi gai hakumaku taiyo denchi no seizo hoho  

Energy Technology Data Exchange (ETDEWEB)

This invention provides a thin film solar cell which contains no cadmium, having a hetero-junction with high conversion efficiency by forming a transparent and highly resistive sulfur-containing zinc-mixed compound semiconductor film grown chemically from the solution at the interface between the first multicomponent compound semiconductor film and the second metal oxide semiconductor film. The sulfur-containing zinc-mixed compound is prepared in the following way: Zinc ammine complex is formed by dissolving the zinc acetate in a complex formation agent such as ammonium hydroxide. In the solution, sulfur-containing compound such as thiourea or thioacetamide. The first semiconductor thin film, or the light absorption layer is contacted with the solution to deposit the sulfur-containing zinc-mixed compound semiconductor thin film on the semiconductor thin film. The thin film is then annealed for a few minutes or dozens of minutes. By the annealing, the film is dried and converts zinc hydroxide contained in the film to zinc oxide. At the same time, it is formed by the process in which the surface modification of the first semiconductor film is accelerated by sulfur. 4 figs.

Kushiya, K.; Arai, T.

1996-12-13

198

Electronic grain boundary properties in polycrystalline Cu(In,Ga)Se2 semiconductors for thin film solar cells  

International Nuclear Information System (INIS)

Solar cells based on polycrystalline Cu(In,Ga)Se2 (CIGSe) thin film absorbers reach the highest energy conversion efficiency among all thin film solar cells. The record efficiency is at least partly attributed to benign electronic properties of grain boundaries (GBs) in the CIGSe layers. However, despite a high amount of research on this phenomenon the underlying physics is not sufficiently understood. This thesis presents an elaborate study on the electronic properties of GBs in CIGSe thin films. Kelvin probe force microscopy (KPFM) was employed to investigate the electronic properties of GBs in dependence of the Ga-content. Five CIGSe thin lms with various Ga-contents were grown by means of similar three stage co-evaporation processes. Both as grown as well as chemically treated (KCN etched) thin films were analyzed. The chemical treatment was employed to remove surface oxides. No difference in electronic GB properties was found with or without the chemical treatment. Therefore, we conclude that a moderate surface oxidation does not alter the electronic properties of GBs. In general, one can observe significant variations of electronic potential barriers at GBs. Under consideration of the averaging effect of the work function signal of nanoscale potential distributions in KPFM measurements which was quantified in the course of this thesis both positive and negative potential barriers in a range between ?-350 mV and ?+450 mV were detected. Additionally, variations in the defect densities at GBs between ?3.1 x 1011 cm-2 and ?2.1 x 1012 cm-2 were found. However, no correlation between the electronic properties of GBs and the Ga-content of CIGSe thin films was discovered. Consequently, one cannot explain the drop in device efficiency observed for CIGSe thin film solar cells with a high Ga-content by a change of the electronic properties of GBs. Combined KPFM and electron backscatter diffraction measurements were employed for the first time on CIGSe thin films to gather complementary information about both the structural and electronic properties of individual GBs. With the help of this information it was possible to investigate the interrelationship between the symmetry and the electronic potential barrier of GBs. We could reveal that highly symmetric ?3 GBs have a lower probability to possess a charged potential barrier than lower symmetric non-?3 GBs. The assumption of a general symmetry-dependence of the electronic properties of GBs in CIGSe, i.e. a correlation between the particular symmetry of a GB and its potential barrier that is also valid for GBs with symmetries lower than ?3, could help to explain the large variations of potential barriers observed at GBs in polycrystalline CIGSe thin films.

199

Surface and interface characterization of thin-film silicon solar cell structures  

Energy Technology Data Exchange (ETDEWEB)

The properties of Si thin films for solar cells, the interaction with different substrates and the influence of dopants are examined with synchrotron based x-ray spectroscopy - primarily X-ray emission spectroscopy (XES) and hard X-ray photoelectron spectroscopy (HAXPES). The films are studied as-deposited (i.e., amorphous, a-Si) and after conversion into polycrystalline (poly-Si) employing solid phase crystallization (SPC). Si L{sub 2,3} XES spectra of thin-film Si samples can be described by a superposition of a-Si and monocrystalline Si-wafer (c-Si) reference spectra. According to a quantification based on that superposition principle, none of the investigated samples are completely crystallized - a measurable a-Si component always remains (5-20 %) regardless of deposition and treatment conditions. Based on additional results from electron back scattering diffraction different models are developed which may explain this finding. According to these models, the remnant a-Si component can be attributed to amorphous/disordered material at the grain boundaries. Using one of these models, the thickness of this grain-surrounding material s could be approximated to be (1.5 {+-} 0.5) nm. Further investigations of the SPC process reveal a faster crystallization for boron-doped samples, and a slower crystallization for phosphorous-doped samples, when compared to the crystallization of undoped a Si:H thin films. The peculiarities of B K XES spectra (and observed changes upon SPC) indicate that boron could act as a nucleation center promoting crystallization. Si L{sub 2,3} XES spectra of a-Si:H and P-doped poly-Si exhibit spectral features above the valence band maximum at 100 eV that could be attributed to a-Si defect states and n{sup +}-dopant states, respectively. The SPC crystallization velocity of Si thin films on ZnO:Al/glass is found to be faster than that on SiNx/glass substrate. Multiple indications for oxidization at the poly-Si/ZnO:Al interface are found based on our Si L{sub 2,3} XES analysis. Spatially resolved x-ray photoelectron spectroscopy data support this and even suggest the formation of sub-oxides or zinc silicate as an interface species. The electronic structure of the buried a-SiO{sub x}:H(B)/ZnO:Al and {mu}c-Si:H(B)/ZnO:Al interfaces are unraveled with ''depth resolved'' hard x-ray photoelectron spectroscopy. A surface band bending limited to the very surface of the silicon layers is found. The valence band maxima for the Si cover layers and the ZnO:Al TCO are determined and interface induced band bending for both interfaces are derived. At the a-SiO{sub x}:H(B)/ZnO:Al interface a tunnel barrier of (0.22 {+-} 0.31) eV and at {mu}c-Si:H(B)/ZnO:Al interface a tunnel barrier of (-0.08 {+-} 0.31) eV is determined. This explains a previously empirically found solar cell efficiency increase produced by introducing a {mu}c-Si:H(B) buffer layer between an a-Si p-i-n cell and the ZnO:Al/glass substrate.

Gerlach, Dominic

2013-02-21

200

Band gap engineering of hydrogenated amorphous carbon thin films for solar cell application  

Science.gov (United States)

In this work, self bias variation, nitrogen introduction and oxygen plasma (OP) treatment approaches have been used for tailoring the band gap of hydrogenated amorphous carbon (a-C:H) thin films. The band gap of a-C:H and modified a- C:H films is varied in the range from 1.25 eV to 3.45 eV, which is found to be nearly equal to the full solar spectrum (1 eV- 3.5 eV). Hence, such a-C:H and modified a-C:H films are found to be potential candidate for the development of full spectrum solar cells. Besides this, computer aided simulation with considering variable band gap a-C:H and modified a- C:H films as window layer for amorphous silicon p-i-n solar cells is also performed by AFORS-HET software and maximum efficiency as ~14 % is realized. Since a-C:H is hard material, hence a-C:H and modified a-C:H films as window layer may avoid the use of additional hard and protective coating particularly in n-i-p configuration.

Dwivedi, Neeraj; Kumar, Sushil; Dayal, Saurabh; Rauthan, C. M. S.; Panwar, O. S.; Malik, Hitendra K.

2012-10-01

 
 
 
 
201

Modelling of two-and four-terminal thin-film silicon tandem solar cells  

International Nuclear Information System (INIS)

We have performed semi-empirical modelling of amorphous silicon/microcrystalline silicon thin-film solar cells in tandem optical configuration, under series (two-terminal) and independent (four-terminal) electrical connection. The four-terminal connection relaxes the constraint of current matching between the cells. Computer simulations indicate an increase in maximum initial efficiency from 10.0% (two-terminal) to 10.8% (four-terminal). Following degradation of the amorphous silicon top-cell the figures are 8.5% and 9.8% respectively, with an optimum top-cell absorber layer thickness in four-terminal connection of 150 nm. Changes in solar spectral quality have been simulated by applying weighted spectra, and improvements in efficiency favouring four-terminal connection occur under red- and blue-rich conditions. However, these typically convey only a small fraction of the total annual insolation, and gains of 5% or less in annual electrical output are predicted. Possible increased optical and electrical losses due to additional contact layers in four-terminal connection are not taken into account.

202

Effect of carrier injection stress in thin film solar cells by impedance spectroscopy.  

Science.gov (United States)

In amorphous silicon solar cells, degradation is directly related to V(oc), FF and cell performance. The dependence of the stability of thin film amorphous silicon solar cells is studied in terms of the volume fraction of B2H6 in the p-layer. When the volume fraction of B2H6 is increased by an order of magnitude, the doping-induced defects tend to increase quite rapidly. Low-doped p-type a-SiO(x) layers had better initial properties but rapidly degraded. Heavily doped p-type a-SiO(x) layers had lower initial properties but displayed better stability. The improvement in stability is explained in conjunction with the capacitance and resistance values of impedance spectroscopy. When the B2H6 gas flow rate is increased, the cell is degraded showing a capacitance decay decrease from 51.75% to less than 18.18%. In addition, the increase in the resistance decreased from 90.90% to 11.73%. PMID:22849108

Park, Seungman; Lee, Sunhwa; Park, Jinjoo; Kim, Youngkuk; Yoon, Kichan; Shin, Chonghoon; Baek, Seungsin; Lee, Youn-Jung; Yi, Junsin

2012-04-01

203

Dye sensitized solar cells based on nanowire sculptured thin film titanium dioxide photoanodes  

Science.gov (United States)

Energy harvested from the sun using photovoltaics (PVs) is a renewable resource in high demand. Photovoltaics convert photons into electron-hole pairs which are then separated and used for electrical power. 75 TW of energy arrives from the sun every year onto US soil. Harvesting it all would provide enough energy to power the entire world for more than five years. It is this abundance of energy that makes PVs an attractive alternative to fossil fuels. PVs currently produce 0.15% of the energy consumed in the US. Production needs to grow as the worldwide demand for energy is projected to almost double by 2050. Fundamental and device based PV research have made steady efficiency gains in silicon based devices and thin film devices have started to become commercially viable. However, less expensive devices with suitable efficiency have not been fully developed. Dye sensitized solar cells (DSSCs) are one such device which has been optimized using standard components. However, device efficiency has not increased significantly since DSSCs were first conceived in 1991. Interestingly, none of the standard components are optimized, but act in a synergistic way in the most efficient devices. This research, along with other parallel research, attempts to optimize a single component of DSSCs with the goal of combining efforts to produce a device with increased efficiency. This research attempts to optimize the TiO2 photoanode used in DSSCs in terms of electron collection, dye coverage, light harvesting, and novel electrolyte infiltration by replacing the standard colloidal structure with nanowires deposited using physical vapor deposition at an oblique angle to form sculptured thin films. The results are quantified through standard photovoltaic testing, electrochemical impedance spectroscopy, UV-Vis-NIR spectroscopy, and general materials characterization techniques. The nanowire photoanodes are engineered during deposition using reactive evaporation, substrate heating, substrate positioning/movement, and co-deposition. The influence of substrate roughness, source material, and post deposition processing in device performance is also quantified. The novel nanowire sculptured thin film photoanodes are shown to have the ability to advantageously modulate dye coverage, electron lifetime, light scattering, and pore spacing more than the standard colloidal photoanode. Device performance using standard dye and electrolyte is shown to be closely matched to that of colloidal based devices constructed as control samples. Along with optimized dye and electrolytes these nanowire based photoanodes should be considered for the research and development of a fully optimized DSSC which would operate more efficiently than the current state of the art.

Pursel, Sean M.

204

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 transition in electricity production. At the present time PV module production is dominated by the crystalline wafer technology. Thin film silicon technology is an alternative solar energy technol...

Franken, R. H. -j

2006-01-01

205

Correlation of grain structure and electrical properties of Cu(In,Ga)Se{sub 2} thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Electron back scatter diffraction (EBSD) and electron beam-induced current (EBIC) in a scanning electron microscope are powerful tools to investigate the structural and electrical properties of polished cross sections of Cu(In,Ga)Se{sub 2} thin-film solar cells. Electron beam induced current measurements allow for the analysis of the charge carrier transport with a high spatial resolution and the extraction of the minority charge carrier diffusion length. In combination with EBSD, it was possible to gain information about the influence of grain boundaries on the current collection of Cu(In,Ga)Se{sub 2} thin-film solar cells. At several positions, reduced EBIC signals correlate with the positions of grain boundaries, as located by means of EBSD. These grain boundaries are identified as regions of enhanced recombination. Solar cells with various chemical compositions of the Cu(In,Ga)Se{sub 2} absorbers were studied.

Nichterwitz, Melanie; Abou-Ras, Daniel; Bundesmann, Juergen; Scheer, Roland; Schock, Hans-Werner [Hahn-Meitner-Institut, Berlin (Germany)

2008-07-01

206

Thin film cell development workshop report  

Science.gov (United States)

The Thin Film Development Workshop provided an opportunity for those interested in space applications of thin film cells to debate several topics. The unique characteristics of thin film cells as well as a number of other issues were covered during the discussions. The potential of thin film cells, key research and development issues, manufacturing issues, radiation damage, substrates, and space qualification of thin film cells were discussed.

Woodyard, James R.

1991-01-01

207

Effect of substrate position in i-ZnO thin-film formation to Cu(In,Ga)Se2 solar cell  

International Nuclear Information System (INIS)

Intrinsic ZnO (i-ZnO) thin films were prepared by rf magnetron sputtering of nondoped ZnO targets in Ar gas under various substrate positions and they were applied to solar cells. We have characterized i-ZnO thin films and investigated the solar cell performance. The resistivity and the full width at half maximum (FWHM) in the x-ray diffraction peak were changed, depending on the substrate position. The performance of solar cells was correspondent to the change of the resistivity and the FWHM of the i-ZnO thin films

208

Thin-film silicon solar cells applying optically decoupled back reflectors  

International Nuclear Information System (INIS)

Thin-film silicon solar cells often apply a metal back reflector (BR) separated from the silicon layers by a thin rear dielectric of thickness around 80 nm or a white paint combined with a thick rear dielectric of several micrometers. In this work, we investigate the optical performance of microcrystalline silicon (?c-Si:H) solar cells applying BRs of various topographies. In contrast to a standard 80 nm-ZnO/Ag BR design, for which the BR nearly strictly follows the texture of the underlying ?c-Si:H layers, placing the Ag BR far from the ?c-Si:H layers allows for a variation of the BR topography. Irrespective of the investigated BR topographies and also for a conventional white paint BR, long distances (of several micrometers) between the BR and the ?c-Si:H layers are found to be detrimental for the light trapping. Optical simulations based on both rigorous and scalar scattering theory have been performed to understand the impact of the diverse BR designs on the optical cell performance

209

Morphological studies of microcrystalline silicon for thin-film solar cells by raman spectroscopy and TEM  

Energy Technology Data Exchange (ETDEWEB)

Thin-film amorphous and microcrystalline silicon are promising materials for photovoltaics as they have the potential to reduce the solar cell costs. In case of microcrystalline silicon the crystalline volume fraction is an important issue for the quality of solar cells as it is related to the microstructure of the material and the defect density. Using an AKT PECVD system optimized for amorphous silicon layer deposition we deposited microcrystalline silicon diodes on 1300 mm x 1100 mm glass-TCO superstrates under variation of deposition time, RF power, silane concentration and distance of the electrodes. Focusing on the crystalline fraction and especially its lateral homogeneity over the 1.4 m{sup 2} area we analyzed the intrinsic layer by Raman spectroscopy on different positions. Two excitation wavelength (473 nm and 633 nm) are used in ordner to get depth dependent information of the crystallinity. TEM observations of cross-section of chosen samples confirmed the spectroscopy given results. Based on the lateral information achieved the process was optimized, and a correlation between crystalline volume fraction and local cell efficiency is discussed.

Schmidt, Vitalij; Hachmann, Wiebke; Sacher, Marc; Heinzmann, Ulrich [University of Bielefeld (Germany); Janzen, Daniel; Gruss, Stefan; Stiebig, Helmut [Malibu GmbH and Co. KG, Bielefeld (Germany)

2010-07-01

210

Electro deposition of cuprous oxide for thin film solar cell applications  

Science.gov (United States)

p and n type copper oxide semiconductor layers were fabricated by electrochemistry using new approaches for photovoltaic applications. Thin films were electroplated by cathodic polarization on a copper foil or indium tin oxide (ITO) substrates. The optimum deposition conditions (composition, pH and temperature of the electrolyte and applied potential) of the layers as thin films have been identified; in particular the conditions that allow getting the n-type layers have been well identified for the first time. The configuration of a photo - electrochemical cell was used to characterize the spectral response of the layers. It was shown that the p type layers exhibit a photocurrent in the cathode potential region and n layers exhibit photo current in the anode potential region. Measurements of electrical resistivity of electro chemically deposited layers of p and n type Cu2O, showed that the resistivity of p-type Cu2O varies from 3.2 x 105 to 2.0 x 108 Ocm. These values depend the electrodepositing conditions such as the pH of the solution, the deposition potential and temperature. The influence of several plating parameters of the p type layers of Cu2O, such as applied potential, pH and temperature of the bath on the chemical composition, degree of crystallinity, grain size and orientation parameters of the sample was systematically studied using X-ray diffraction and scanning electron microscopy. Depending of the electro-deposition potential, two different surface morphologies with various preferential crystal orientations were obtained for the temperatures of the electro-deposition of 30 C and pH 9. For the same temperature, the layers of p type Cu2O of highly crystalline p type are obtained at pH 12, indicating that the crystallinity depends on the pH of the bath. Also, it has been shown that the morphology of Cu2O layers was changed by varying the potential and the duration of deposition, as well as the temperature of the solution. The conditions for the electro-deposition of Cu2O n-type were identified consistently for the first time. The electro-deposition electrolyte is based 0.01M acetate copper and 0.1 M sodium acetate: it has a pH between 6.3 and 4, a potential of from 0 to -0.25 V vs. Ag / AgCl and a temperature of 60oC. The optimum annealing temperature of the n-type Cu2O layers is between 120-150oC for the annealing time of 30 to 120 minutes. Resistivity of the n-type films varies between 5 x 103 and 5 x 104 at pH 4 to pH 6.4. We have shown for the first time that bubbling nitrogen gas in the electroplating cell improves significantly the spectral response of the electro-deposited n-type thin film. A two steps electro-deposition process was implemented to make the p-n homojunction cuprous oxide. Indium tin oxide (ITO) was used as a transparent conductive oxide substrate. A p-Cu2O was electrodeposited on ITO. After heat treatment a thin film layer of n-Cu 2O was electrodeposited on top of previous layer. The performance of a p-n homojunction photovoltaic solar cell of Cu2O was determined. The short-circuit current and the open circuit voltage were respectively determined to be as 0.35 volts and 235 muA/cm2. The fill factor (FF) and conversion efficiency of light into electricity were respectively measured to be 0.305 and 0.082%.

Shahrestani, Seyed Mohammad

211

The investigation of optimal Silicon/Silicon(1-x)Germanium(x) thin-film solar cells with quantitative analysis  

Science.gov (United States)

Thin-film solar cells are emerging from the research laboratory to become commercially available devices for low cost electrical power generation applications. Silicon which is a cheap, abundant and non-toxic elemental semiconductor is an attractive candidate for these solar cells. Advanced modeling and simulation of Si thin-film solar cells has been performed to make this technology more cost effective without compromising the performance and efficiency. In this study, we focus on the design and optimization of Si/Si1-xGex heterostructures, and microcrystalline and nanocrystalline Si thin-film solar cells. Layer by layer optimization of these structures was performed by using advanced bandgap engineering followed by numerical analysis for their structural, electrical and optical characterizations. Special care has been introduced for the selection of material layers which can help to improve the light absorption properties of these structures for harvesting the solar spectrum. Various strategies such as the optimization of the doping concentrations, Ge contents in Si1-xGex buffer layer, incorporation of the absorber layers and surface texturing have been in used to improve overall conversion efficiencies of the solar cells. To be more specific, the observed improvement in the conversion efficiency of these solar cells has been calculated by tailoring the thickness of the buffer, absorber, and emitter layers. In brief, an approach relying on the phenomena of improved absorption of the buffer and absorber layer which leads to a corresponding gain in the open circuit voltage and short circuit current is explored. For numerical analysis, a PC1D simulator is employed that uses finite element analysis technique for solving semiconductor transport equations. A comparative study of the Si/Si1-xGex and Ge/Si1-xGex is also performed. We found that due to the higher lattice mismatch of Ge to Si, thin-film solar cells based on Si/Si1-xGex heterostructures performed much better. It has been found that microc-Si and nc-Si pin structures have strong dependence on their grain sizes and crystallinity to enhance the light absorption capability of these solar cells. Our results show that silicon based thin-film solar cells exhibit high level of performance making them very competitive for the next generation of low cost photovoltaic technology.

Ehsan, Md Amimul

212

Inverted polymer solar cells with sol-gel derived cesium-doped zinc oxide thin film as a buffer layer  

Science.gov (United States)

An inverted structure of polymer solar cells based on Poly(3-hexylthiophene)(P3HT):[6-6] Phenyl-(6) butyric acid methyl ester (PCBM) with thin films of sol-gel derived Cesium doped ZnO (Cs:ZnO) was developed as an efficient cathode buffer layer. Doped and undoped thin films were deposited using a less studied method, doctor blade, which was compatible with Roll-2-Roll printing method. By comparing the effect of Cs:ZnO thin films with various dopant ratio on the performance of inverted polymer solar cells, 0.5% Cs doped ZnO was found as the most effective doping level among the selected doping ratios. Using 30 nm thickness of 0.5% Csn:ZnO thin film as an electron transport layer led to the average efficiency which was significantly higher than (9%) that of similar devices employing the same thickness of undoped ZnO film. Results showed that the devices fabricated with 1% and 2% cesium doped ZnO yielded lower power conversion efficiency, which could be due to the lower FF. Also, the influence of dopant incorporation on the optical transmittance and electrical conductivity of ZnO films was investigated.

Ahmadi, Mehdi; Mirabbaszadeh, Kavoos; Salari, Saeid; Fatehy, Hamed

2014-09-01

213

Fabrication of Cu2ZnSnS4 thin film solar cell using single step electrodeposition method  

DEFF Research Database (Denmark)

Cu2ZnSnS4 (CZTS) thin films were deposited onto Mo-coated and tin-doped indium oxide (ITO) coated glass substrates by using single step electrodeposition technique followed by annealing in N2 + H2S atmosphere. Subsequently, they were applied to the fabrication of thin film solar cells. Upon annealing, the amorphous nature of as-deposited precursor film changes into polycrystalline kesterite crystal structure with uniform and densely packed surface morphology. Energy dispersive X-ray spectroscopy (EDS) study reveals that the deposited thin films are nearly stoichiometric. Optical absorption study shows the band gap energy of as-deposited CZTS thin films is 2.7 eV whereas, after annealing, it is found to be 1.53 eV. The solar cell fabricated with CZTS absorber layer, showed the best conversion efficiency (?) 1.21% for 0.44 cm2 with open-circuit voltage (Voc) = 315 mV, short-circuit current density (J sc) = 12.27 mA/cm2 and fill factor (FF) = 0.31. 2012 The Japan Society of Applied Physics.

Pawar, Sambhaji M.; Bae, Dowon

2012-01-01

214

Fabrication of Cu2ZnSnS4 Thin Film Solar Cell Using Single Step Electrodeposition Method  

Science.gov (United States)

Cu2ZnSnS4 (CZTS) thin films were deposited onto Mo-coated and tin-doped indium oxide (ITO) coated glass substrates by using single step electrodeposition technique followed by annealing in N2 + H2S atmosphere. Subsequently, they were applied to the fabrication of thin film solar cells. Upon annealing, the amorphous nature of as-deposited precursor film changes into polycrystalline kesterite crystal structure with uniform and densely packed surface morphology. Energy dispersive X-ray spectroscopy (EDS) study reveals that the deposited thin films are nearly stoichiometric. Optical absorption study shows the band gap energy of as-deposited CZTS thin films is 2.7 eV whereas, after annealing, it is found to be 1.53 eV. The solar cell fabricated with CZTS absorber layer, showed the best conversion efficiency (?) 1.21% for 0.44 cm2 with open-circuit voltage (Voc) = 315 mV, short-circuit current density (Jsc) = 12.27 mA/cm2 and fill factor (FF) = 0.31.

Pawar, Sambhaji M.; Pawar, Bharati S.; Gurav, Kishor V.; Bae, Do Won; Kwon, Se Han; Kolekar, Sanjay S.; Hyeok Kim, Jin

2012-10-01

215

Preparation of CulnS2 Thin Films on the Glass Substrate by DC Sputtering for Solar Cell Component  

International Nuclear Information System (INIS)

The CuInS2 alloys were deposited on glass substrate using plasma DC sputtering technique. A CuInS2 alloy target was made from Cu, In, Se powder with impurity of 99.998%. The deposition process was done with the following process parameter variations: deposition time and substrate temperature were the range of 15 to 45 min and 150 to 300 ?, the gas pressure was kept at 1.4x10-1 Torr. The purpose of the research is to obtain the solar cell component of CuInS2 thin films. The electrical and optical properties measurement has been done by four-point probe and UV-Vis. Crystal structure was analyzed using X-ray diffraction (XRD). The result shows that minimum resistance of CuInS2 thin films is 35.7 k? and optical transmittance is 14.7 %. The crystal structure of CuInS2 is oriented at (112) plane and by Touc-plot method was obtained that the band gap energy of thin films is 1.45 eV. It could be concluded that the CuInS2 thin film can be used as a solar cell component. (author)

216

Design, fabrication and optical characterization of photonic crystal assisted thin film monocrystalline-silicon solar cells.  

Science.gov (United States)

In this paper, we present the integration of an absorbing photonic crystal within a monocrystalline silicon thin film photovoltaic stack fabricated without epitaxy. Finite difference time domain optical simulations are performed in order to design one- and two-dimensional photonic crystals to assist crystalline silicon solar cells. The simulations show that the 1D and 2D patterned solar cell stacks would have an increased integrated absorption in the crystalline silicon layer would increase of respectively 38% and 50%, when compared to a similar but unpatterned stack, in the whole wavelength range between 300 nm and 1100 nm. In order to fabricate such patterned stacks, we developed an effective set of processes based on laser holographic lithography, reactive ion etching and inductively coupled plasma etching. Optical measurements performed on the patterned stacks highlight the significant absorption increase achieved in the whole wavelength range of interest, as expected by simulation. Moreover, we show that with this design, the angle of incidence has almost no influence on the absorption for angles as high as around 60. PMID:22828615

Meng, Xianqin; Depauw, Valrie; Gomard, Guillaume; El Daif, Ounsi; Trompoukis, Christos; Drouard, Emmanuel; Jamois, Ccile; Fave, Alain; Dross, Frdric; Gordon, Ivan; Seassal, Christian

2012-07-01

217

Synthesis of FeS2 Nano Crystals for ink based thin film solar cells  

Science.gov (United States)

With a band gap of 0.95 eV and high absorption coefficient (?10^5 cm-1), FeS2 is ideal for use as a p-type hetero-junction partner in a solar cell. Although pyrite is abundant in nature, getting the right phase for thin films is difficult due to the various phases of iron sulfides. We propose an ink based process for attaining the pyrite phase. Our experimental process involves use of low cost non-toxic chemicals for synthesis. The process involves reacting iron (II) chloride, 1, 2-hexadecanediol with 70% Oleylamine at 100 C for 1 hour followed by introduction of sulfur and reacting for 2 hours at 220 C. The reaction provides perfect nano crystals dispersed in a carbon based solution which is later subjected to centrifugation to separate the crystals. After multiple cleaning cycles, the crystals were dispersed in chloroform for uniform suspension. SEM image the film formed by drop casting followed by argon-annealing revealed that the nano-crystals were hexagonal with sizes ranging from 100-500nm with perfect symmetry. EDAX analysis showed the iron to sulfur atomic percentage ratio 1:1. The argon annealed film was then sulfurized using an organic sulfur source at 400 C, which gave a desired pyrite cubic phase. We will present the growth process and the efficiency data for this ink based FeS2 solar cell.

Dhakal, Tara; Ganta, Lakshmi; Westgate, Charles

2012-02-01

218

Diode laser crystallization processes of Si thin-film solar cells on glass  

Science.gov (United States)

The crystallization of Si thin-film on glass using continuous-wave diode laser is performed. The effect of various processing parameters including laser power density and scanning speed is investigated in respect to microstructure and crystallographic orientation. Optimal laser power as per scanning speed is required in order to completely melt the entire Si film. When scan speed of 15-100 cm/min is used, large linear grains are formed along the laser scan direction. Laser scan speed over 100 cm/min forms relatively smaller grains that are titled away from the scan direction. Two diode model fitting of Suns-Voc results have shown that solar cells crystallized with scan speed over 100 cm/min are limited by grain boundary recombination (n = 2). EBSD micrograph shows that the most dominant misorientation angle is 60. Also, there were regions containing high density of twin boundaries up to ~1.2 10-8/cm2. SiOx capping layer is found to be effective for reducing the required laser power density, as well as changing preferred orientation of the film from ? 110 ? to ? 100 ? in surface normal direction. Cracks are always formed during the crystallization process and found to be reducing solar cell performance significantly.

Yun, Jae Sung; Ahn, Cha Ho; Jung, Miga; Huang, Jialiang; Kim, Kyung Hun; Varlamov, Sergey; Green, Martin A.

2014-07-01

219

Diode laser crystallization processes of Si thin-film solar cells on glass  

Directory of Open Access Journals (Sweden)

Full Text Available The crystallization of Si thin-film on glass using continuous-wave diode laser is performed. The effect of various processing parameters including laser power density and scanning speed is investigated in respect to microstructure and crystallographic orientation. Optimal laser power as per scanning speed is required in order to completely melt the entire Si film. When scan speed of 15100 cm/min is used, large linear grains are formed along the laser scan direction. Laser scan speed over 100 cm/min forms relatively smaller grains that are titled away from the scan direction. Two diode model fitting of Suns-Voc results have shown that solar cells crystallized with scan speed over 100 cm/min are limited by grain boundary recombination (n = 2. EBSD micrograph shows that the most dominant misorientation angle is 60. Also, there were regions containing high density of twin boundaries up to ~1.2 10-8/cm2. SiOx capping layer is found to be effective for reducing the required laser power density, as well as changing preferred orientation of the film from ? 110 ? to ? 100 ? in surface normal direction. Cracks are always formed during the crystallization process and found to be reducing solar cell performance significantly.

Yun Jae Sung

2014-07-01

220

The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.  

Science.gov (United States)

The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization. PMID:25363298

Gerlach, D; Wimmer, M; Wilks, R G; Flix, R; Kronast, F; Ruske, F; Br, M

2014-12-21

 
 
 
 
221

Low temperature (< 100 deg. C) fabrication of thin film silicon solar cells by HWCVD  

International Nuclear Information System (INIS)

Amorphous silicon films have been made by HWCVD at a very low substrate temperature of ? 100 deg. C (in a dynamic substrate heating mode) without artificial substrate cooling, through a substantial increase of the filament-substrate distance (? 80 mm) and using one straight tantalum filament. The material is made at a reasonable deposition rate of 0.11 nm/s. Optimized films made this way have device quality, as confirmed by the photosensitivity of > 105. Furthermore, they possess a low structural disorder, manifested by the small ?/2 value (half width at half maximum) of the transverse optic (TO) Si-Si vibration peak (at 480 cm-1) in the Raman spectrum of ? 30.4 cm-1, which translates into a bond angle variation of only ? 6.4 deg. The evidence gathered from the studies on the structure of the HWCVD grown film by three different techniques, Raman spectroscopy, spectroscopic ellipsometry and transmission electron microscopy, indicate that we have been able to make a photosensitive material with a structural disorder that is smaller than that expected at such a low deposition temperature. Tested in a p-i-n solar cell on Asahi SnO2:F coated glass (without ZnO at the back reflector), this i-layer gave an efficiency of 3.4%. To our knowledge, this is the first report of a HWCVD thin film silicon solar cell made at such a low temperature

222

Defect engineering in solar cell manufacturing and thin film solar cell development  

Energy Technology Data Exchange (ETDEWEB)

During the last few years many defect engineering concepts were successfully applied to fabricate high efficiency silicon solar cells on low-cost substrates. Some of the research advances are described.

Sopori, B.L. [National Renewable Energy Lab., Golden, CO (United States)

1995-08-01

223

Preparation of thin films, with base to precursor materials of type Cu-In-Se elaborated by electrodeposition for the solar cells elaboration  

International Nuclear Information System (INIS)

Thin films of chalcogenide compounds are promising because they have excellent optoelectronic characteristics to be applied in solar cells. In particular, CuInSe2 and Cd Te thin films have shown high solar to electrical conversion efficiency. However, this efficiency is limited by the method of preparation, in this case, physical vapor deposition techniques are used. In order to increase the area of deposition t is necessary to use chemical methods, for example, electrodeposition technique. In this paper, the preparation of Cu-In-Se precursors thin films by electrochemical method is reported. These precursors were used to build solar cells with 7.9 % of efficiency. (Author)

224

Fabrication of CdS/CdTe-Based Thin Film Solar Cells Using an Electrochemical Technique  

Directory of Open Access Journals (Sweden)

Full Text Available Thin film solar cells based on cadmium telluride (CdTe are complex devices which have great potential for achieving high conversion efficiencies. Lack of understanding in materials issues and device physics slows down the rapid progress of these devices. This paper combines relevant results from the literature with new results from a research programme based on electro-plated CdS and CdTe. A wide range of analytical techniques was used to investigate the materials and device structures. It has been experimentally found that n-, i- and p-type CdTe can be grown easily by electroplating. These material layers consist of nano- and micro-rod type or columnar type grains, growing normal to the substrate. Stoichiometric materials exhibit the highest crystallinity and resistivity, and layers grown closer to these conditions show n ? p or p ? n conversion upon heat treatment. The general trend of CdCl2 treatment is to gradually change the CdTe materials n-type electrical property towards i-type or p-type conduction. This work also identifies a rapid structural transition of CdTe layer at 385 5 C and a slow structural transition at higher temperatures when annealed or grown at high temperature. The second transition occurs after 430 C and requires more work to understand this gradual transition. This work also identifies the existence of two different solar cell configurations for CdS/CdTe which creates a complex situation. Finally, the paper presents the way forward with next generation CdTe-based solar cells utilising low-cost materials in their columnar nature in graded bandgap structures. These devices could absorb UV, visible and IR radiation from the solar spectrum and combine impact ionisation and impurity photovoltaic (PV effect as well as making use of IR photons from the surroundings when fully optimised.

I. M. Dharmadasa

2014-06-01

225

Antimony sulphide thin film as an absorber in chemically deposited solar cells  

International Nuclear Information System (INIS)

Antimony sulfide thin films (thickness, 500 nm) were deposited on chemically deposited CdS thin films (100 nm) obtained on 3 mm glass substrates coated with a transparent conductive coating of SnO2:F (TEC-15 with 15 ? sheet resistance). Two different chemical formulations were used for depositing antimony sulfide films. These contained (i) antimony trichloride dissolved in acetone and sodium thiosulfate, and (ii) potassium antimony tartrate, triethanolamine, ammonia, thioacetamide and small concentrations of silicotungstic acid. The films were heated at 250 deg. C in nitrogen. The cell structure was completed by depositing a 200 nm p-type PbS thin film. Graphite paint applied on the PbS thin film and a subsequent layer of silver paint served as the p-side contact. The cell structure: SnO2:F/CdS/Sb2S3 (i or ii)/PbS showed open circuit voltage (Voc) of 640 mV and short circuit current density (Jsc) above 1 mA cm-2 under 1 kW m-2 tungsten-halogen radiation. Four cells, each of 1.7 cm2 area, were series-connected to give Voc of 1.6 V and a short circuit current of 4.1 mA under sunlight (1060 W m-2)

226

Antimony sulphide thin film as an absorber in chemically deposited solar cells  

Energy Technology Data Exchange (ETDEWEB)

Antimony sulfide thin films (thickness, 500 nm) were deposited on chemically deposited CdS thin films (100 nm) obtained on 3 mm glass substrates coated with a transparent conductive coating of SnO{sub 2}:F (TEC-15 with 15 {omega} sheet resistance). Two different chemical formulations were used for depositing antimony sulfide films. These contained (i) antimony trichloride dissolved in acetone and sodium thiosulfate, and (ii) potassium antimony tartrate, triethanolamine, ammonia, thioacetamide and small concentrations of silicotungstic acid. The films were heated at 250 deg. C in nitrogen. The cell structure was completed by depositing a 200 nm p-type PbS thin film. Graphite paint applied on the PbS thin film and a subsequent layer of silver paint served as the p-side contact. The cell structure: SnO{sub 2}:F/CdS/Sb{sub 2}S{sub 3} (i or ii)/PbS showed open circuit voltage (V{sub oc}) of 640 mV and short circuit current density (J{sub sc}) above 1 mA cm{sup -2} under 1 kW m{sup -2} tungsten-halogen radiation. Four cells, each of 1.7 cm{sup 2} area, were series-connected to give V{sub oc} of 1.6 V and a short circuit current of 4.1 mA under sunlight (1060 W m{sup -2})

Messina, Sarah; Nair, M T S; Nair, P K [Department of Solar Energy Materials, Centro de Investigacion en EnergIa, Universidad Nacional Autonoma de Mexico, Temixco, Morelos-62580 (Mexico)

2008-05-07

227

Antimony sulphide thin film as an absorber in chemically deposited solar cells  

Science.gov (United States)

Antimony sulfide thin films (thickness, 500 nm) were deposited on chemically deposited CdS thin films (100 nm) obtained on 3 mm glass substrates coated with a transparent conductive coating of SnO2:F (TEC-15 with 15 ? sheet resistance). Two different chemical formulations were used for depositing antimony sulfide films. These contained (i) antimony trichloride dissolved in acetone and sodium thiosulfate, and (ii) potassium antimony tartrate, triethanolamine, ammonia, thioacetamide and small concentrations of silicotungstic acid. The films were heated at 250 C in nitrogen. The cell structure was completed by depositing a 200 nm p-type PbS thin film. Graphite paint applied on the PbS thin film and a subsequent layer of silver paint served as the p-side contact. The cell structure: SnO2:F/CdS/Sb2S3 (i or ii)/PbS showed open circuit voltage (Voc) of 640 mV and short circuit current density (Jsc) above 1 mA cm-2 under 1 kW m-2 tungsten-halogen radiation. Four cells, each of 1.7 cm2 area, were series-connected to give Voc of 1.6 V and a short circuit current of 4.1 mA under sunlight (1060 W m-2).

Messina, Sarah; Nair, M. T. S.; Nair, P. K.

2008-05-01

228

Studies of compositional dependent CZTS thin film solar cells by pulsed laser deposition technique: An attempt to improve the efficiency  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Synthesis of CZTS thin films by PLD. Black-Right-Pointing-Pointer Effect of stoichiometry, its deviation on the physical properties. Black-Right-Pointing-Pointer Improvement in conversion efficiency using CZTS absorber layer. - Abstract: The performance of CZTS thin films deposited by using pulsed laser deposition technique is investigated as a function of target composition. The chemical composition ratio a = Cu/(Zn + Sn) of the target material has been varied from 0.8 to 1.2 in step of 0.1 by keeping Zn/Sn constant. The effect of the chemical composition in the precursor thin films on the structural, morphological, chemical and optical properties of the CZTS thin films has been investigated. X-ray diffraction and X-ray photoelectron spectroscopy studies showed that the annealed CZTS thin films are of a single kesterite crystal structure without any other secondary phases. The direct band gap energy of the CZTS thin films is found to decrease from 1.72-1.53 eV with increase of 'a'. The estimated band-gap energy from the quantum efficiency measurements is about 1.54 eV. The solar cell fabricated with Glass/Mo/CZTS/CdS/ZnO:Al/Al structure grown using [a = Cu/(Zn + Sn) = 1.1] showed the best conversion efficiency of 4.13% with V{sub oc} = 700 mV, J{sub sc} = 10.01 mA/cm{sup 2} and FF = 0.59.

Moholkar, A.V., E-mail: avmoholkar@yahoo.co.in [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Shinde, S.S. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Agawane, G.L.; Jo, S.H. [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500 757 (Korea, Republic of); Rajpure, K.Y. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Patil, P.S. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Bhosale, C.H. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Kim, J.H., E-mail: jinhyeok@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500 757 (Korea, Republic of)

2012-12-15

229

Investigation of Cu2ZnSnS4-Based Thin Film Solar Cells Using Abundant Materials  

Science.gov (United States)

Aiming to develop the solar cells free from both environmental contaminants and rare metals, thin film solar cells were produced by using Cu2ZnSnS4 (CZTS) as an absorber. CZTS thin films could be successfully formed by the vapor phase sulfurization of precursors prepared by the electron-beam evaporation on the soda-lime glass substrates. The atomic ratio of Cu/(Zn+Sn) was varied from nearly 0.5 to 1.2 to investigate the influence of the composition on the surface morphology and the optical properties. In order to optimize the sulfurization condition, we varied the sulfurization temperature from 510C to 550C. As the results, the value of the conversion efficiency of 4.53% was obtained for the cell of which CZTS absorber sulfurized at 520C.

Kobayashi, Takeshi; Jimbo, Kazuo; Tsuchida, Kazuyuki; Shinoda, Shunsuke; Oyanagi, Taisuke; Katagiri, Hironori

2005-01-01

230

New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells  

Science.gov (United States)

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350?nm800?nm, the conversion efficiency of solar cells can be further enhanced.

Wang, DongLin; Su, Gang

2014-01-01

231

Fabrication and photovoltaic characteristics of Cu{sub 2}O/TiO{sub 2} thin film heterojunction solar cell  

Energy Technology Data Exchange (ETDEWEB)

A p-Cu{sub 2}O/n-TiO{sub 2} thin film heterojunction solar cell has been fabricated by electrodeposition of Cu{sub 2}O on radio-frequency sputtered n-TiO{sub 2} thin film. The heterojunction solar cell was characterized by X-ray diffraction, scanning electron microscopy and UV spectroscopy. Capacitance-voltage (C-V) and current-voltage measurements were performed. The values of barrier height and carrier concentration were estimated from the reverse bias C-V. The transport mechanism is related to space charge limited current and a trapped charge limited current having slope values of 1.95 and 3.5. Impedance measurement showed that electrical resistance decreases when the voltage is increased. The energy band diagram shows that the main-band discontinuity forms in the valence band. The ideality factor, barrier height and series resistance, fill factor and efficiency were also measured. The heterojunction solar cell exhibits a maximum fill factor and a power conversion efficiency of about 0.35 and 0.15% respectively. - Highlights: Black-Right-Pointing-Pointer p-Cu{sub 2}O/n-TiO{sub 2} thin film heterojunction was fabricated. Black-Right-Pointing-Pointer Conduction and valance band discontinuities were measured. Black-Right-Pointing-Pointer The maximum efficiency of solar cell was measured to be 0.15%. Black-Right-Pointing-Pointer The defects, band discontinuity and large mismatch caused low efficiency.

Hussain, Sajad [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China); Department of Physics, GC University, Faisalabad (Pakistan); Cao, Chuanbao, E-mail: cbcao@bit.edu.cn [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China); Usman, Zahid; Chen, Zhuo; Nabi, Ghulam; Khan, Waheed S.; Ali, Zulfiqar; Butt, Faheem K.; Mahmood, Tariq [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China)

2012-11-01

232

New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells.  

Science.gov (United States)

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350?nm-800?nm, the conversion efficiency of solar cells can be further enhanced. PMID:25418477

Wang, DongLin; Su, Gang

2014-01-01

233

New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells  

CERN Document Server

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350nm-800nm, the conversion efficiency of solar cells can be further enhanced.

Wang, DongLin

2014-01-01

234

Fabrication and photovoltaic characteristics of Cu2O/TiO2 thin film heterojunction solar cell  

International Nuclear Information System (INIS)

A p-Cu2O/n-TiO2 thin film heterojunction solar cell has been fabricated by electrodeposition of Cu2O on radio-frequency sputtered n-TiO2 thin film. The heterojunction solar cell was characterized by X-ray diffraction, scanning electron microscopy and UV spectroscopy. Capacitancevoltage (CV) and currentvoltage measurements were performed. The values of barrier height and carrier concentration were estimated from the reverse bias CV. The transport mechanism is related to space charge limited current and a trapped charge limited current having slope values of 1.95 and 3.5. Impedance measurement showed that electrical resistance decreases when the voltage is increased. The energy band diagram shows that the main-band discontinuity forms in the valence band. The ideality factor, barrier height and series resistance, fill factor and efficiency were also measured. The heterojunction solar cell exhibits a maximum fill factor and a power conversion efficiency of about 0.35 and 0.15% respectively. - Highlights: ? p-Cu2O/n-TiO2 thin film heterojunction was fabricated. ? Conduction and valance band discontinuities were measured. ? The maximum efficiency of solar cell was measured to be 0.15%. ? The defects, band discontinuity and large mismatch caused low efficiency.

235

Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures  

International Nuclear Information System (INIS)

In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent. (paper)

236

Influence of optical properties of ZnO thin-films deposited by spray pyrolysis and RF magnetron sputtering on the output performance of silicon solar cell  

International Nuclear Information System (INIS)

ZnO thin-films were deposited by spray pyrolysis and RF magnetron sputtering techniques. The optical reflection of these thin-films is measured using UV-Vis spectrophotometer. The measured optical reflection data is used in PC-1D simulation software to study the output performance of commercial silicon wafer-based solar cell. As far as optical performance is concerned it could be demonstrated that the sprayed ZnO thin-film under laboratory conditions show equivalent performance compared to sputtered ZnO thin-film. The influence of optical properties of 65 nm thick zinc oxide thin-films deposited by vacuum and non-vacuum techniques on quantum efficiency and IV characteristics of commercial silicon-wafer based solar cell is studied and reported here.

237

Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells; January 28, 2010 -- January 31, 2011  

Energy Technology Data Exchange (ETDEWEB)

Final subcontract report for PV Incubator project 'Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells.' The goal of this program was to produce tandem Si cells using photonic bandgap enhancement technology developed at ISU and Lightwave Power that would have an NREL-verified efficiency of 7.5% on 0.25 cm{sup 2} area tandem junction cell on plastic substrates. This goal was met and exceeded within the timeframe and budget of the program. On smaller area cells, the efficiency was even higher, {approx}9.5% (not verified by NREL). Appropriate polymers were developed to fabricate photonic and plasmonic devices on stainless steel, Kapton and PEN substrates. A novel photonic-plasmon structure was developed which shows a promise of improving light absorption in thin film cells, a better light absorption than by any other scheme.

Slafer, D.; Dalal, V.

2012-03-01

238

Characterization of Cu(In,Ga)S{sub 2}-thin film solar cells with varied gallium concentration  

Energy Technology Data Exchange (ETDEWEB)

During the last decades interest in thin film solar cells based on chalcopyrite semiconductors (e.g. Cu(In,Ga)(S,Se){sub 2}) has steadily increased. Particularly, chalcopyrite compounds exclusively based on sulfides are of interest because of their low cost potential as compared to selenium-containing devices. In this contribution we present recent investigations of Cu(In,Ga)S{sub 2} thin film solar cells with varied gallium incorporation in the absorber layer. Doping the absorber with gallium has twofold meaning: moderate gallium concentrations lower the increase of the efficiency by decreasing the band gap energy while high concentrations result in a decrease of the open circuit voltage. We investigate the effects of Ga-doping by admittance spectroscopy and capacity-voltage measurements. These methods were chosen to get information about the local doping concentration and activation energies of the traps.

Malek, Stephanie; Neerken, Janet; Knipper, Martin; Riedel, Ingo; Parisi, Juergen [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg (Germany); Merdes, Saoussen; Mainz, Roland [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany)

2009-07-01

239

High-Temperature Degradation Mechanism of Cu(In,Ga)Se2-Based Thin Film Solar Cells  

Science.gov (United States)

The degradation mechanism of Cu(In,Ga)Se2 (CIGS) thin film solar cells under high-temperatures conditions has been investigated. CIGS thin film solar cells were heated at temperatures ranging from 100 to 450 C in a vacuum for 30 min. It was found that the CIGS devices with chemical bath deposited (CBD)-CdS and CBD-ZnS(O,OH) buffer layers were stable below 320 and 350 C, respectively. These results suggest that CIGS devices possess high heat-resistance enough for practical usage. Secondary ion mass spectrometer (SIMS) and electron beam induced current (EBIC) analyses revealed that the main cause for the degradation of CIGS devices at high temperatures is attributable to a shift of the space charge region (SCR) toward the Mo back contact due to excess diffusion of Cd into CIGS absorber layer.

Kijima, Shunsuke; Nakada, Tokio

2008-07-01

240

A blazed grating for light trapping in a-Si thin-film solar cells  

International Nuclear Information System (INIS)

A blazed grating has been studied to improve light absorption in thin-film solar cells (TFSCs). The grating is a periodic arrangement of wedges made of aluminum zinc oxide (AZO) that also serves as the back spacer. The absorber layer of the photovoltaic (PV) device can be made of inorganic or organic semiconductor material. Here we study hydrogenated amorphous silicon (a-Si:H) and nano-crystalline Si (nc-Si). Full wave, finite element simulations were performed to optimize the design for the highest short circuit current (Jsc). The Jsc of the optimized 1D grating design was 16.05 mA cm?2 for TE polarization and 15.18 mA cm?2 for TM polarization, with an effective a-Si:H layer thickness of only 277 nm. As compared to a planar cell with the same volume of a-Si:H, the enhancement of Jsc by the 1D grating design was 27.6% for TE polarization and 20.7% for TM polarization. We extended this design to a 2D grating structure that was less sensitive to polarization as compared to the 1D grating design. With an equivalent a-Si:H layer thickness of 322 nm, the optimized design yielded a Jsc of 17.16 mA cm?2. The blazed grating surface can be fabricated using the glancing angle deposition method. (paper)

 
 
 
 
241

Deposition and characterization of (Zn,Mg)O buffer layers on CIGSSe thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

(Zn, Mg)O buffer layers on Cu(In,Ga)(S,Se){sub 2}(CIGSSe) thin film solar cells are promising alternatives to CdS buffer layers by featuring comparable efficiencies, better environmental compatibility and the possibility to implement the deposition process into a vacuum processing line. The (Zn,Mg)O buffer layers are deposited by radio frequency magnetron co-sputtering from two separate ZnO and MgO ceramic sputter targets to control the Mg-content and therefore the band gap of the buffer layer. In our experimental setup the sputter preparation chamber is connected with a UHV analysis system which allows in-situ characterization with X-ray photoelectron spectroscopy (XPS). The interface between the absorber and the buffer layer is believed to have a major influence on the cell efficiency and is thus of particular interest in this work. This interface has been investigated during layer deposition by sequentially interrupting the sputter process and performing XPS scans. We observed island growth of (Zn,Mg)O on CIGSSe and a strong oxidation of the absorber surface induced by the deposit. In order to complement the chemical and electronic information with structural data, energy dispersive X-ray analysis, X-ray diffraction, and scanning electron microscopy have been applied.

Hussmann, Benjamin; Erfurth, Felix; Schoell, Achim [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Niesen, Thomas; Palm, Joerg [Avancis GmbH, Muenchen (Germany); Grimm, Alexander [Hahn-Meitner-Institut Berlin (Germany); Umbach, Eberhard [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Forschungszentrum Karlsruhe (Germany)

2008-07-01

242

Efficiency of thin-films silicon solar cells with a photonic pattern  

Science.gov (United States)

We present a theoretical study of amorphous and crystalline thin-film solar cells with a periodic pattern on a sub-micron scale realized in the silicon layer and filled with silicon dioxide right below a properly designed antireflection coating. The study and optimization of the PV structure as a function of all the photonic crystals parameters allows to identify the different roles of the periodic pattern and of the etching depth in determining an increase of the absorption. From one side, the photonic crystal acts as an impendence matching layer, thus minimizing reflection of incident light over a particularly wide range of frequencies. Moreover a strong absorption enhancement is observed when the incident light is coupled into the quasi guided modes of the photonic slab. We compare the efficiency of this structure to that of PV cells characterized by the sole antireflection coating. We found a substantial increase of the short-circuit current when the parameters are properly optimized, demonstrating the advantage of a wavelength-scale, photonic-crystal based approach.

Zanotto, S.; Liscidini, M.; Andreani, L. C.

2010-05-01

243

Simulation approach for studying the performances of original superstrate CIGS thin films solar cells  

International Nuclear Information System (INIS)

In this work, we report on the performances of superstrate Cu(In,Ga)Se2 (CIGS) thin film solar cells with an alternative SLG/SnO2:F/CIGS/In2Se3/Zn structure using AMPS-1D (Analysis of Microelectronic and Photonic structures) device simulator. An inverted surface layer, n-type CIGS layer, is inserted between the In2Se3 buffer and CIGS absorber layers and the SnO2:F layer is just a transparent conducting oxide (TCO). The simulation has been carried out by lighting through SnO2:F. The obtained results show that the existence of so-called 'ordered defect compound' (ODC) layer in such a structure is the critical factor responsible for the optimization of the performances. Photovoltaic parameters were determined using the current density-voltage (J-V) curve. An optimal absorber and ODC layer thickness has been estimated, that improve significantly the devices efficiency exceeding 15% AM1.5 G. The variation of carrier density in In2Se3 layer has an influence on the superstrate CIGS cells performances. Moreover, the quantum efficiency (Q.E.) characteristics display a maximum value of about 80% in the visible range.

244

Ion beam treatment of functional layers in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

In silicon thin-film solar cells, transparent conductive layers have to fulfill the following requirements: high conductivity as effective contact, high transparency to transmit the light into the cell, and a textured surface which provides light scattering. Magnetron sputtered and wet-chemically textured aluminum doped zinc oxide (ZnO:Al) films are widely used as the transparent conductor. The technological goal of this dissertation is to develop an alternative to the wet etching process for light trapping in the thin silicon absorber layers through modification of the glass/ZnO:Al or ZnO:Al/Si interfaces by ion beam treatment. The study focuses on the textured growth of ZnO:Al films on ion beam pretreated glass substrates, and the preparation and application of textured glass for light trapping. The technological aspects such as the etch rates of the glass substrate and ZnO:Al films with different ion beam configurations were studied. The experimental etch rates are compared with simulated and theoretically predicted values. With regard to the ion beam treatment of glass substrate, the influence of the ion pretreated glass on the growth of ZnO:Al films was investigated. The ZnO:Al films grown on ion beam pretreated glass substrates exhibit self-textured morphology with surface roughness of 40 nm while remaining highly conductive. Silicon thin-film solar cells prepared on the as-grown rough ZnO:Al films show that this front contact can provide excellent light trapping effect. The highest initial efficiencies for amorphous single junction solar cells on as-grown rough ZnO:Al films was 9.4%. The as-grown rough morphology was attributed to large conical ZnO:Al grains initiated from the ion pretreated glass surface. It was found that the roughness of the as-grown rough ZnO:Al film is proportional to the number of O dangling bonds created by ion beam treatment on the glass substrate. A growth model was proposed to explain the growth mechanism of ZnO:Al films on Zn- and O-polar ZnO single crystals, as well as on untreated and ion beam treated glass substrates. With regard to the ion beam treatment of ZnO:Al films, the influence of the ion treatment on the surface morphology, HCl etching, silicon growth, and additional ZnO:Al growth was investigated. Ion beam etching has a smoothening effect on the textured ZnO:Al films. Using sputtered and wet chemically etched ZnO:Al as ion beam etching mask, textured glass with features similar to the ZnO:Al films were obtained. Textured glass with a wide range of morphologies was prepared by varying the etching mask and the ion beam treatment conditions. Finally, as-grown textured ZnO:Al films prepared on ion beam treated textured glass, which exhibit 'double textured' features, were produced and applied in solar cells. The ion beam treatment enabled the preparation of light scattering surfaces by textured glass and as-grown rough ZnO:Al films without the need of wet etching between TCO preparation and absorber deposition. Further, new 'double textured' surface structures could be created by the combination of both techniques. Solar cells with efficiency of 11.9% proved the applicability as-grown textured ZnO:Al for light trapping. The growth studies provided deeper insights and a new understanding of ZnO structure formation and will govern optimization of ZnO:Al film properties.

Zhang, Wendi

2013-10-01

245

Optimal structure of light trapping in thin-film solar cells: dielectric nanoparticles or multilayer antireflection coatings?  

Science.gov (United States)

Recent research has found an alternative way to enhance light trapping of thin-film solar cells by using dielectric nanoparticles deposited on the cell surface. To improve the performance of light trapping, a systematic study on the influence of dielectric nanoparticles on enhancement efficiency is performed in this paper. We prove that the optimal dielectric nanoparticles are substantially equivalent to the multilayer antireflection coatings (ARCs) with a "low-high-low" dielectric constant profile. Moreover, it is demonstrated that the use of a simple two-layer SiO2/SiC ARC can reach 34.15% enhancement, which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC, and TiO2 nanoparticles. That means the optimal multilayer ARCs structure is obviously superior to the optimal dielectric nanoparticles structure, and the deposition of a simple two-layer SiO2/SiC structure on top of a thin-film silicon solar cell can significantly enhance photoelectron generation and hence, result in superior performance of thin-film solar cells. PMID:25320932

Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

2014-08-10

246

Small molecular weight organic thin-film photodetectors and solar cells  

Science.gov (United States)

In this review, we discuss the physics underlying the operation of single and multiple heterojunction, vacuum-deposited organic solar cells based on small molecular weight thin films. For single heterojunction cells, we find that the need for direct contact between the deposited electrode and the active organics leads to quenching of excitons. An improved device architecture, the double heterojunction, is shown to confine excitons within the active layers, allowing substantially higher internal efficiencies to be achieved. A full optical and electrical analysis of the double heterostructure architecture leads to optimal cell design as a function of the optical properties and exciton diffusion lengths of the photoactive materials. Combining the double heterostructure with novel light trapping schemes, devices with external efficiencies approaching their internal efficiency are obtained. When applied to an organic photovoltaic cell with a power conversion efficiency of 1.0%0.1% under 1 sun AM1.5 illumination, devices with external power conversion efficiencies of 2.4%0.3% are reported. In addition, we show that by using materials with extended exciton diffusion lengths LD, highly efficient double heterojunction photovoltaic cells are obtained, even in the absence of a light trapping geometry. Using C60 as an acceptor material, double heterostructure external power conversion efficiencies of 3.6%0.4% under 1 sun AM1.5 illumination are obtained. Stacking of single heterojunction devices leads to thin film multiple heterojunction photovoltaic and photodetector structures. Thin bilayer photovoltaic cells can be stacked with ultrathin (5 ), discontinuous Ag layers between adjacent cells serving as efficient recombination sites for electrons and holes generated in the neighboring cells. Such stacked cells have open circuit voltages that are n times the open circuit voltage of a single cell, where n is the number of cells in the stack. In optimized structures, the short circuit photocurrent remains approximately constant upon stacking thin cells, leading to higher achievable power conversion efficiencies, as confirmed by modelling optical interference effects and exciton migration. A 2.5%0.3% power efficiency under 100 mW/cm2 AM1.5 illumination conditions is obtained by stacking two 1% efficient devices. Alternatively, when the contact layers between the stacked cells are eliminated, a multilayer structure consisting of alternating films of donor and acceptor-type materials is obtained. Since the thicknesses of the individual layers (5 ) can be substantially smaller than the exciton diffusion length, nearly 100% of the photogenerated excitons are dissociated, and the resulting free charges are detected. In addition, the ultrathin organic layers facilitate electron and hole transport through the multilayer stack by tunneling. When these devices are operated as photodetectors under applied fields >106 V/cm, the carrier collection efficiency reaches 80%, leading to external quantum efficiencies of 75%1% across the visible spectrum in cells containing the thinnest layers. We find that due to the fast carrier tunneling process, the temporal response of these multilayer detectors is a direct measure of exciton dynamics. Response times of 72050 ps are achieved, leading to a 3 dB bandwidth of 43030 MHz. A summary of representative results obtained for both polymer and small molecule photovoltaic cells and photodetectors is included in this review. Prospects for further improvements in organic solar cells and photodetectors are considered.

Peumans, Peter; Yakimov, Aharon; Forrest, Stephen R.

2003-04-01

247

Characterization of Thin Films for Polymer Solar Cells : Stability and Response to Concentrated Light  

DEFF Research Database (Denmark)

The field of polymer solar cells has undergone an extensive development in recent years after the invention of semiconducting polymers in 1991. Efficiencies have gradually increased to above 10 %, and high throughput processing methods such as roll-to-roll coating allow for production of thousands of solar cells with low embedded time, material, and energy consumption as compared to silicon solar cells. Consequently, different demonstration products of small mobile gadgets based on polymer solar cells have been produced, which are fully competitive with conventional energy technologies, illustrating the maturity of the technology. However, a limiting factor in terms of full commercialization is the stability of polymer solar cells. While is has been estimated that 10 years lifetime is needed, existing technologies only provide stabilities up to 1 year. Degradation of polymer solar cell is a multi facetted process where oxygen and water diffusion from the atmosphere, morphology evolution, and photo-bleaching of the polymer are some of the dominant processes. Encapsulation by foils consisting of multi-layer polymer stacks is a conventional way to reduce the diffusion into the solar cell, by which the life time of the cell is highly increased. An alternative approach is to increase the photo stability of the cell components, and especially the light absorbing conjugated polymer has been subject to extensive attention. The photo stability of conjugated polymers varies by orders of magnitude from type to type depending on the chemical structure of the material and consequently, the lifetime is highly influenced by the polymer stability. Photochemical degradation of polymers, i.e. degradation of thin films of polymer in the ambient under light exposure, is a technique normally applied to evaluate polymer stabilities. Hereby, an extensive list of stabilities of different materials has been established providing an understanding of the stability of the individual building blocks of polymer. While being a highly practical tool, no rigorous reports on the photochemical degradation as a technique exist where the technique is validated and different pit-falls identified. Consequently, a rigorous study on the validation and maturing of this technique was performed during this PhD work (Chapter 2). Furthermore, as research gradually increases the lifetime of polymers to months or years, stability evaluations at standard degradation conditions become impractical. Accelerated degradation has been performed with heat and different gases by which the timeframe of stability evaluations have been reduced by up to a factor of 20. However, light, which appears at the most intuitive acceleration condition to conjugated polymers, has until this PhD work not been applied as an acceleration condition to polymer degradation. Light can be concentrated up to thousand of solar intensities by optical components, which has the potential to significantly accelerate polymer degradation. Concentration of light was one of the main topics during this PhD, where the construction and development of light concentrators, both by sun light as well as artificial light, was given extensive attention. This resulted in three different light concentrators, a lens based solar concentrator, a mirror based solar concentrator, and an artificial light concentrator for indoor use (Chapter 3). With these concentration setups, acceleration factors of up to 1200 were obtained for degradation of typical conjugated polymers thus significantly reducing the timeframe of stability evaluations. The potential of this approach is that stability evaluation can become a routine characterization techniquefor novel conjugated polymers, when these are applied to polymer solar cells and their efficiencies are reported. By making the polymer stability practically accessible, development of polymer stability can become significantly more transparent and focused (Chapter 4). A direct alternative application of concentrated light is the application to polymer solar cells. Stabilities of polyme

Tromholt, Thomas

2012-01-01

248

Perovskite-based hybrid solar cells exceeding 10% efficiency with high reproducibility using a thin film sandwich approach.  

Science.gov (United States)

Organometal halide perovskites have tremendous potential as light absorbers for photovoltaic applications. In this work we demonstrate hybrid solar cells based on the mixed perovskite CH3 NH3 PbI2 Cl in a thin film sandwich structure, with unprecedented reproducibility and generating efficiencies up to 10.8%. The successfulness of our approach is corroborated by the experimental electronic structure determination of this perovskite. PMID:24338932

Conings, Bert; Baeten, Linny; De Dobbelaere, Christopher; D'Haen, Jan; Manca, Jean; Boyen, Hans-Gerd

2014-04-01

249

Micromorph thin-film silicon solar cells with transparent high-mobility hydrogenated indium oxide front electrodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the performance of hydrogenated indium oxide as a transparent front electrode for micromorph thin-film silicon solar cells on glass. Light trapping is achieved by replicating the morphology of state-of-the-art zinc oxide electrodes, known for their outstanding light trapping properties, via ultraviolet nanoimprint lithography. As a result of the high electron mobility and excellent near-infrared transparency of hydrogenated indium oxide, the short-circuit current density of the...

Battaglia, Corsin; Erni, Lukas; Boccard, Mathieu; Barraud, Loris; Escarre?, Jordi; So?derstro?m, Karin; Bugnon, Gre?gory; Billet, Adrian; Ding, Laura; Despeisse, Matthieu; Haug, Franz-josef; Wolf, Stefaan; Ballif, Christophe

2011-01-01

250

Cu2ZnSnS4 Thin Film Solar Cells Utilizing Sulfurization of Metallic Precursor Prepared by Simultaneous Sputtering of Metal Targets  

Science.gov (United States)

Cu2ZnSnS4 (CZTS) thin films were prepared by simultaneous sputtering of metallic targets and sulfurizing a metallic precursor under elemental sulfur atmosphere in a sealed tube. Subsequently, they were applied to the fabrication of thin film solar cells. The precursors with desired compositional ratio and thickness were obtained by controlling the area ratio of sputtering targets and also sputtering parameters. We have succeeded in obtaining high-quality polycrystalline CZTS thin films by sulfurization under a sulfur vapor pressure higher than atmospheric pressure. A CZTS-based solar cell with 3.7% conversion efficiency was obtained from CZTS films sulfurized at 590 C for 7 min.

Momose, Noritaka; Than Htay, Myo; Yudasaka, Takuto; Igarashi, Shigeo; Seki, Takuro; Iwano, Shota; Hashimoto, Yoshio; Ito, Kentaro

2011-01-01

251

Double-layer indium doped zinc oxide for silicon thin-film solar cell prepared by ultrasonic spray pyrolysis  

International Nuclear Information System (INIS)

Indium doped zinc oxide (ZnO:In) thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO:In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.8210?3 ?cm and particle grains. The double-layers structure is designed to fabricate the ZnO:In thin film with low resistivity (2.5810?3 ?cm) and good surface morphology. It is found that the surface morphology of the double-layer ZnO:In film strongly depends on the substrate-layer, and the second-layer plays a large part in the resistivity of the double-layer ZnO:In thin film. Both total and direct transmittances of the double-layer ZnO:In film are above 80% in the visible light region. Single junction a-Si:H solar cell based on the double-layer ZnO:In as front electrode is also investigated. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

252

Multi-frequency EDMR applied to microcrystalline thin-film silicon solar cells  

Science.gov (United States)

Pulsed multi-frequency electrically detected magnetic resonance (EDMR) at X-, Q- and W-Band (9.7, 34, and 94 GHz) was applied to investigate paramagnetic centers in microcrystalline silicon thin-film solar cells under illumination. The EDMR spectra are decomposed into resonances of conduction band tail states (e states) and phosphorus donor states (P states) from the amorphous layer and localized states near the conduction band (CE states) in the microcrystalline layer. The e resonance has a symmetric profile at all three frequencies, whereas the CE resonance reveals an asymmetry especially at W-band. This is suggested to be due to a size distribution of Si crystallites in the microcrystalline material. A gain in spectral resolution for the e and CE resonances at high fields and frequencies demonstrates the advantages of high-field EDMR for investigating devices of disordered Si. The microwave frequency independence of the EDMR spectra indicates that a spin-dependent process independent of thermal spin-polarization is responsible for the EDMR signals observed at X-, Q- and W-band.

Meier, Christoph; Behrends, Jan; Teutloff, Christian; Astakhov, Oleksandr; Schnegg, Alexander; Lips, Klaus; Bittl, Robert

2013-09-01

253

Processing and modeling issues for thin-film solar cell devices: Annual subcontract report, January 16, 1995 -- January 15, 1996  

Energy Technology Data Exchange (ETDEWEB)

The overall mission of the Institute of Energy Conversion is the development of thin film photovoltaic cells, modules, and related manufacturing technology and the education of students and professionals in photovoltaic technology. The objectives of this four-year NREL subcontract are to advance the state of the art and the acceptance of thin film PV modules in the areas of improved technology for thin film deposition, device fabrication, and material and device characterization and modeling, relating to solar cells based on CuInSe{sub 2} and its alloys, on a-Si and its alloys, and on CdTe. In the area of CuInSe{sub 2} and its alloys, EEC researchers have produced CuIn{sub 1-x}GaxSe{sub 2} films by selenization of elemental and alloyed films with H{sub 2}Se and Se vapor and by a wide variety of process variations employing co-evaporation of the elements. Careful design, execution and analysis of these experiments has led to an improved understanding of the reaction chemistry involved, including estimations of the reaction rate constants. Investigation of device fabrication has also included studies of the processing of the Mo, US and ZnO deposition parameters and their influence on device properties. An indication of the success of these procedures was the fabrication of a 15% efficiency CuIn{sub 1-x}GaxSe{sub 2} solar cell.

Birkmire, R W; Phillips, J E; Buchanan, W A; Eser, E; Hegedus, S S; McCandless, B E; Meyers, P V; Shafarman, W N [Univ. of Delaware, Newark, DE (United States)

1996-08-01

254

Photovoltaic performance improvement of dye-sensitized solar cells based on tantalum-doped TiO2 thin films  

International Nuclear Information System (INIS)

Dye-sensitized solar cells based on a tantalum (Ta)-doped TiO2 thin film prepared by the hydrothermal method show a photovoltaic efficiency of 8.18%, which is higher than that of the undoped TiO2 thin film (7.40%). The Mott-Schottky plot indicates that the Ta-doped TiO2 photoanode shifts the flat band potential positively and increases the electron density. The positive shift of the flat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2. Furthermore, the increased electron density caused by the Ta-doped TiO2 improves the fill factor of the solar cell. The increased electron density accelerates the transfer rate of electrons in the Ta-doped TiO2 thin films by comparison to undoped films, which is confirmed by intensity-modulated photocurrent spectroscopy measurements.

255

Characterization of Optic Properties ZnO:Al Thin Film on Glass Substrate for Solar Cell Window  

International Nuclear Information System (INIS)

It has been characterized a ZnO:Al thin film growth using sputtering technique for solar cell window. The aims of this research is to get a ZnO:Al thin film that can be used as a TCO (Transparent Conducting Oxide) on amorphous silicon solar cell. To get an optimum properties, deposition process has been done for various parameters, such as composition/concentration of Al, substrate temperature, gas pressure and deposition time. Based on experiments result, it is found that the optimum result was achieved at temperature 450 oC, gas pressure 6 x 10 -2 torr and time 1.5 hours. From optical properties (transmittance) measurements using UV-vis, it was found that the optimum results was achieved at temperature 450 oC. At this conditions, wave length (500 - 800) nm, the transmittance was (50 - 82) %, at pressure 6 x 10 -2 torr the transmittance was (50 - 80) % and at deposition time 1.5 hours was (49 - 81) %. For ZnO thin film, was at wave length (500 - 800) nm, the transmittance was (78 - 80) %. From micro structure analysis using SEM, it was found that the thickness layer of ZnO was 1.5 ?m and 1.3 ?m for ZnO: Al. While from surface morphology it was found that for ZnO thin layer the grains was distributed homogeneously, while for ZnO: Al the grains was distributed unhomogeneously. (author)

256

Combined model of non-conformal layer growth for accurate optical simulation of thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

In thin-film silicon solar cells textured interfaces are introduced, leading to improved antireflection and light trapping capabilities of the devices. Thin-layers are deposited on surface-textured substrates or superstrates and the texture is translated to internal interfaces. For accurate optical modelling of the thin-film silicon solar cells it is important to define and include the morphology of textured interfaces as realistic as possible. In this paper we present a model of thin-layer growth on textured surfaces which combines two growth principles: conformal and isotropic one. With the model we can predict the morphology of subsequent internal interfaces in thin-film silicon solar cells based on the known morphology of the substrate or superstrate. Calibration of the model for different materials grown under certain conditions is done on various cross-sectional scanning electron microscopy images of realistic devices. Advantages over existing growth modelling approaches are demonstrated - one of them is the ability of the model to predict and omit the textures with high possibility of defective regions formation inside the Si absorber layers. The developed model of layer growth is used in rigorous 3-D optical simulations employing the COMSOL simulator. A sinusoidal texture of the substrate is optimised for the case of a micromorph silicon solar cell. More than a 50 % increase in short-circuit current density of the bottom cell with respect to the flat case is predicted, considering the defect-free absorber layers. The developed approach enables accurate prediction and powerful design of current-matched top and bottom cell.

Sever, M.; Lipovsek, B.; Krc, J.; Campa, A.; Topic, M. [University of Ljubljana, Faculty of Electrical Engineering Trzaska cesta 25, Ljubljana 1000 (Slovenia); Sanchez Plaza, G. [Technical University of Valencia, Valencia Nanophotonics Technology Center (NTC) Valencia 46022 (Spain); Haug, F.J. [Ecole Polytechnique Federale de Lausanne EPFL, Institute of Microengineering IMT, Photovoltaics and Thin-Film Electronics Laboratory, Neuchatel 2000 (Switzerland); Duchamp, M. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons Institute for Microstructure Research, Research Centre Juelich, Juelich D-52425 (Germany); Soppe, W. [ECN-Solliance, High Tech Campus 5, Eindhoven 5656 AE (Netherlands)

2013-12-15

257

Copper oxide thin film and nanowire as a barrier in ZnO dye-sensitized solar cells  

International Nuclear Information System (INIS)

The ZnO dye-sensitized solar cells (DSSCs) with different photoelectrodes were studied on the effect of CuO layer as a barrier layer toward power conversion characteristics. The structures of DSSCs based on ZnO as a photoelectrode, Eosin-Y as a dye sensitizer, iodine/iodide solution as an electrolyte and Pt/FTO as a counterelectrode. CuO powder, nanowire prepared by oxidation reaction of copper powder and CuO thin film prepared by evaporation copper thin film, were used as a layer on the top of ZnO layer to form blocking layer. The photocurrent, photovoltage and power conversion efficiency characteristics for DSSCs were measured under illumination of simulated sunlight obtained from a solar simulator with the radiant power of 100 mW/cm2. It was found that ZnO DSSCs with CuO thin film exhibited highest current density of 5.10 mA/cm2 and highest power conversion efficiency of 0.92% than those of CuO powder and nanowire. The enhancement of the power conversion efficiency can be explained in terms of the retardation of the interfacial recombination dynamics of CuO blocking layer.

258

Doped and multi-compound ZnO-based transparent conducting oxides for silicon thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[eng] The objective of the present work is to provide a better understanding of magnetron sputtered transparent conducting oxides based on ZnO in order to use them as electrodes in thin film silicon solar cells at the Grup d'Energia Solar of the Universitat de Barcelona. This thesis presents the properties of magnetron sputtered aluminium and gallium doped ZnO as well as the properties of multi-compound materials deposited by the co-sputtering of zinc oxide and indium tin oxide. The applicati...

Carreras Segui?, Paz

2013-01-01

259

Thin films in photothermal solar energy conversion  

Energy Technology Data Exchange (ETDEWEB)

Thin films play an important part in photothermal solar energy conversion. They intercept, redirect and concentrate the incident solar radiation and convert it into useful heat. The cost of materials and their processing makes thin films the most cost-effective solution, since most optical interactions occur within 1 ..mu..m of the front surface. However, the large surface-to-volume ratio of thin films facilitates degradation processes that limit the service life. Durability at elevated temperatures is essential and sets solar thin film technology aside from conventional applications. Spectrally selective coatings are discussed in detail, with emphasis on single-film converters, absorber-reflector tandems, dark mirrors and heat mirrors. A discussion of reflecting films and glazings concludes the review.

Seraphin, B.O.

1982-04-30

260

Electronic grain boundary properties in polycrystalline Cu(In,Ga)Se{sub 2} semiconductors for thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Solar cells based on polycrystalline Cu(In,Ga)Se{sub 2} (CIGSe) thin film absorbers reach the highest energy conversion efficiency among all thin film solar cells. The record efficiency is at least partly attributed to benign electronic properties of grain boundaries (GBs) in the CIGSe layers. However, despite a high amount of research on this phenomenon the underlying physics is not sufficiently understood. This thesis presents an elaborate study on the electronic properties of GBs in CIGSe thin films. Kelvin probe force microscopy (KPFM) was employed to investigate the electronic properties of GBs in dependence of the Ga-content. Five CIGSe thin lms with various Ga-contents were grown by means of similar three stage co-evaporation processes. Both as grown as well as chemically treated (KCN etched) thin films were analyzed. The chemical treatment was employed to remove surface oxides. No difference in electronic GB properties was found with or without the chemical treatment. Therefore, we conclude that a moderate surface oxidation does not alter the electronic properties of GBs. In general, one can observe significant variations of electronic potential barriers at GBs. Under consideration of the averaging effect of the work function signal of nanoscale potential distributions in KPFM measurements which was quantified in the course of this thesis both positive and negative potential barriers in a range between ?-350 mV and ?+450 mV were detected. Additionally, variations in the defect densities at GBs between ?3.1 x 10{sup 11} cm{sup -2} and ?2.1 x 10{sup 12} cm{sup -2} were found. However, no correlation between the electronic properties of GBs and the Ga-content of CIGSe thin films was discovered. Consequently, one cannot explain the drop in device efficiency observed for CIGSe thin film solar cells with a high Ga-content by a change of the electronic properties of GBs. Combined KPFM and electron backscatter diffraction measurements were employed for the first time on CIGSe thin films to gather complementary information about both the structural and electronic properties of individual GBs. With the help of this information it was possible to investigate the interrelationship between the symmetry and the electronic potential barrier of GBs. We could reveal that highly symmetric ?3 GBs have a lower probability to possess a charged potential barrier than lower symmetric non-?3 GBs. The assumption of a general symmetry-dependence of the electronic properties of GBs in CIGSe, i.e. a correlation between the particular symmetry of a GB and its potential barrier that is also valid for GBs with symmetries lower than ?3, could help to explain the large variations of potential barriers observed at GBs in polycrystalline CIGSe thin films.

Baier, Robert

2012-06-25

 
 
 
 
261

Thin-Film Silicon Solar Cells with Integrated Metal Nanoparticles and Metal Nanostructures for an Enhanced Light Absorption - Impedance Measurements and Simulations of Thin-Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Photovoltaic technology offers the possibility of environmentally friendly production of electricity based on an almost infinite source of energy, the sun. Today most commercially available solar cells are made of crystalline or polycrystalline silicon. Such solar cells can achieve efficiencies of up to 24.7 % for unconcentrated light. However, their disadvantages are the high material cost and the high energy consumption during production...

2009-01-01

262

Characterization of deep defects in CdS/CdTe thin film solar cells using deep level transient spectroscopy  

International Nuclear Information System (INIS)

The presence of deep defects in CdS/CdTe thin film solar cells strongly affects the electrical properties and as a result the performance of the cells. Therefore, it is desirable to understand the role of these defect states. This paper describes the detection of electron traps in CdS/CdTe thin film solar cells using deep level transient spectroscopy. Two series of samples with a different activation step (activation in air vs. activation in vacuum) are compared. Electrical injection DLTS uses an electrical pulse to inject electrons in the CdTe. This way a new electron trap could be characterized at 0.44 eV below conduction band in the air activated cells. Optical DLTS uses an optical laser pulse (?=635 nm) to create minority carriers. In this case minority traps are found in both kinds of samples. In the air activated cells two closely spaced defects are detected (0.44 and 0.42 eV below conduction band) with concentrations of a few percent of the background concentration. In the vacuum activated cells a broad band is detected. However, not fully characterized, it is located at approximately 0.4 eV below conduction band. Using the DLTS results, simulations were performed to explain the forward J-V-characteristics of the solar cells. These simulations are in close agreement with the experimental results if the concentrations of the deep traps are taken sufficiently high

263

Synthesis of NaYF{sub 4}: Yb, Er nanocrystals and its application in silicon thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Up-converting material, which can be efficiently excited by near infrared light and emit strong visible light through a process termed 'up-conversion fluorescence', has shown a great potential for application in solar cells. In this paper, sodium yttrium fluoride (NaYF{sub 4}) up-converting nanocrystals doped with lanthanide ions (Yb{sup 3+} and Er{sup 3+}) using different disodium ethylenediaminetetraacetate (EDTA) concentrations have been synthesized using hydrothermal method. Up-converting nanocrystal with hexagonal phase has shown strong up-conversion fluorescence under 980nm laser excitation compared with cubic phase. In order to realize the application of this kind of up-converting nanocrystals into amorphous silicon thin film solar cells, an up-convertor made by solidified mixture of above nanocrystal powder and polydimethylsiloxane (PDMS). The up-convertor attached on the rear side of p-i-n type amorphous silicon thin film solar cells enhanced the short circuit current density under the AM1.5 illumination and thus improved the conversion efficiency of solar cells (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Zhang, X.D. [Nankai Univ., Tianjin (China). Inst. of Photo-electronic Thin Film Devices and Technology, Key Lab. of Photo-electronic Thin Film Devices and Technology; State Key Lab of Silicon Materials, Zhejiang University, Hangzhou (China); Jin, X.; Wang, D.F.; Xiong, S.Z.; Geng, X.H.; Zhao, Y. [Nankai Univ., Tianjin (China). Inst. of Photo-electronic Thin Film Devices and Technology, Key Lab. of Photo-electronic Thin Film Devices and Technology

2010-04-15

264

Impacts of electron irradiation on the optical and electrical properties of CIGS thin films and solar cells  

International Nuclear Information System (INIS)

Full text : A thin film solar cell composed of polycrystalline Cu(In,Ga)Se2 (CIGS) is essentially light-weight and shows high conversion efficiency and excellent radiation tolerance. These characteristics lead to CIGS solar cells very attractive for space applications. However, only a few irradiation studies have been carried out on CIGS thin films and entire solar cell structure, resulting in limited knowledge on the mechanisms responsible for the irradiation-induced damage. In addition, the cell performance is known to change due to the damp heat and/or light soaking effects. Accordingly, understanding the degradation mechanisms of CIGS, ZnO, a buffer, Mo, and even glass components is necessary for not only space use but also commercial use. In this presentation, electron irradiation effects will be discussed for CIGS solar cells and each layer that composed the CIGS solar cell structure such as CIGS, CdS, undoped ZnO, and Ga- or Al-doped ZnO films. Electron irradiation experiments were carried out using the DYNAMITRON electron accelerator. The electron energy was fixed at 2 MeV and the fluence was varied between 1 * 1013 and 1 * 1018 cm-2. All the irradiated CIGS films exhibited common PL peaks originating from donor to acceptor transitions. PL peak intensity due to Cu-related point defects, which did not affect solar cell performance significantly, increased in CIGS thin films with increasing electron irradiation. Converth increasing electron irradiation. Conversely, transmittance spectra of all the irradiated ZnO and ZnO:Al films did not change by the electron irradiation up to 6 * 1017 cm-2. The normalized performance parameters of the irradiated CIGS solar cell such as Voc, Jsc, and ? are shown in article as a function of irradiation fluence. ? tended to decrease in comparison with Voc and Jsc for large irradiation fluence. Shunt resistance and series resistance of the CIGS solar cells degraded even though the resistivity of each layer did not change after electron irradiation. The result indicates that CdS/CIGS interface or another heterojunction tended to degrade easily in comparison with each bulk of solar cell composed of semiconductors

265

Metal-induced growth of microcrystalline silicon thin films for solar cells  

Science.gov (United States)

The research focused on the process study for deposition of device quality polycrystalline silicon (poly-Si) thin films and solar cell fabrication by using a novel technique, metal-induced growth (MIG). Cobalt (Co) is introduced in the studies as a seed layer metal for the first time, while nickel (Ni) was another candidate. To grow the poly-Si, Co or Ni seed-layers were deposited on the foreign substrates by thermal evaporation with a few nm to 50 nm thickness. Substrates were transferred into the sputtering system for Si sputtering at elevated temperature from 525C to 625C. The Co or Ni reacted with sputtered Si to form metal disilicides which have very small lattice mismatch with Si (0.4% lattice mismatch for NiSi2 and Si, 1.2% lattice mismatch for CoSi2 and Si). The crystalline metal disilicides provide nucleation sites for poly-Si growth. With metal-induced growth, the relatively large-grain poly-Si films can be produced at relatively low temperatures on the various foreign substrates. Compared with Ni induced Si films, Co induced poly-Si has longer minority lifetime of 0.46 mus as deposited and 1.3 mus after annealing. A two-step sputtering method used for film deposition showed superiority over single step sputtering by achieving Si films with larger grain size (over 1 mum) and less contamination. A double seed layer (5nm Co/50nm Ni) method was developed to produce the Si film with less Ni diffusion into Si. Metal-induced Si films were deposited on flexible thin tungsten substrates for solar cell fabrication. The good back Ohmic contact (metal disilicide) was formed naturally when the Si film was deposited. In this work, the solar cells were fabricated successfully by using metal-induced grown poly-Si. With the fabricated Schottky and P/N junction solar cells, the metal-induced growth processing parameters were studied. It was found that low-pressure sputtering, oxygen control during film growth, post-annealing and Si film hydrogenation are important to produce high quality poly-Si with fewer defects. The Schottky solar cell with optimized processing parameters showed the Jsc and Voc of 12 mA/cm2 and 0.2 V, respectively. By passivating the MIG muc-Si surface with hydrogenated nanocrystalline Si (nc-Si:H), the Voc was improved to 0.31 V. In addition, the current transport mechanism in Schottky and P/N junction devices were studied for different film growth conditions. The results showed that two-step sputtering, oxygen control and hydrogenation improved the quality of the Si film and devices.

Ji, Chunhai

266

Sulfur-doped nickel oxide thin film as an alternative to Pt for dye-sensitized solar cell counter electrodes  

Energy Technology Data Exchange (ETDEWEB)

A low-cost, sulfur-doped NiO (S-NiO) thin film is electrodeposited on fluorine-doped SnO{sub 2} substrate and studied in an iodide-based redox system. High electrochemical activity is present because of a large catalytic surface area and a low charge transfer resistance. A dye- sensitized solar cell with a low-loaded S-NiO counter electrode achieves a power conversion efficiency of 5.04%, close to that of a cell with a conventional platinized electrode. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Guai, Guan Hong [Center for Advanced Bionanosystems and School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore); Leiw, Ming Yian [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Ng, Chee Mang [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore); Li, Chang Ming [Center for Advanced Bionanosystems and School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); Institute for Clean Energy and Advanced Materials, Southwest University, Chongqing 400715 (China)

2012-03-15

267

Impact of contamination on hydrogenated amorphous silicon thin films and solar cells  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with atmospheric contamination and cross-contamination of boron (single-chamber process) of the intrinsic absorber layer (i-layer) of p-i-n thin film solar cells based on hydrogenated amorphous silicon. The atmospheric contaminations were introduced by means of intentional leaks. Hereby, the focus is on the influence of contamination species (oxygen and nitrogen), quantity of contamination (leak flow), source of contamination (leaks at chamber wall or in the process gas pipe), and plasma power on the properties of solar cells. Thereby, the minimum requirements for the purity of vacuum and process gas as well as leak conditions of the recipient and gas pipe system have been determined. Additionally, deposition regimes were developed, where the incorporation of impurities is significantly suppressed. For standard processes critical levels of nitrogen and oxygen contamination are determined to be {proportional_to} 4 x 10{sup 18} cm{sup -3} and {proportional_to} 2 x 10{sup 19} cm{sup -3}, respectively, for a leak situated at the chamber wall. Above these concentrations the solar cell efficiency deteriorates. In literature, incorporation of oxygen and nitrogen in doping configuration is assumed to be the reason for the cell deterioration. This assumption is supported by additional material studies of contaminated absorber layers done in this work. The difference in critical concentration is due to the higher doping efficiency of nitrogen compared to that for oxygen. Nevertheless, applying an air leak the critical concentrations of O and N are reached almost simultaneously since the incorporation probability of oxygen is about one order of magnitude higher compared to that for nitrogen. Applying a leak in the process gas pipe the critical oxygen contamination level increases to {proportional_to} 2 x 10{sup 20} cm{sup -3} whereas the critical nitrogen level remains unchanged compared to a chamber wall leak. Applying a deposition regime with a very high flow of process gases for oxygen the higher critical contamination level is found as well for a chamber wall leak. Possible reasons for the dependence of the critical oxygen contamination on the deposition regime and the oxygen source may be the following. Before entering the plasma zone the oxygen can react with hydrogen atoms, silane (very high reaction probability), or silane radicals. Mainly, three reaction products may result, namely SiO{sub 2}-clusters, siloxane (SiH{sub 3}-O-SiH{sub 3}), and OH / H{sub 2}O molecules. The SiO{sub 2} is assumed to drop to the bottom of the reactor or to be pumped out. If oxygen is incorporated from siloxane, it is assumed to be electrically inactive. In contrast, oxygen incorporated from hydrogen-oxygen molecules leads to oxygen incorporation in an electrically active configuration. For a source gas pipe leak, the density of silane in the gas pipe is high compared to that for the chamber wall leak. For the chamber wall leak the hydrogen density is assumed to be much higher compared to that for the process gas pipe leak. Thus, the critical oxygen concentration is suggested to increases due to the resulting higher siloxane to OH / H{sub 2}O ratio for the gas pipe leak compared to that in the vicinity of the chamber wall leak. The different critical levels for different deposition regimes can be explained by their oxygen incorporation velocity. The lifetime of the OH / H{sub 2}O molecules is assumed to be shorter, compared to that for the siloxane. As a consequence this might lead to the fact, that oxygen form these molecules is incorporated in one regime (fast incorporation), and in another regime it is not incorporated (slow incorporation). For nitrogen the same critical contamination levels are observed which is attributed to the lack of reactivity of silane and nitrogen. The observed critical impurity concentrations do not change after light-soaking experiments of the solar cells. A further aspect of this thesis is to improve the single-chamber process for the fabrication of amorphous hydrogenated silicon thin-film solar c

Woerdenweber, Jan

2011-09-26

268

Highly transparent and conductive indium tin oxide thin films for solar cells grown by reactive thermal evaporation at low temperature  

Science.gov (United States)

Transparent conductive tin-doped indium oxide (In2O3:Sn, ITO) thin films with various Sn-doping concentrations have been prepared using the low cost reactive thermal evaporation (RTE) technique at a low growth temperature of ~160 C. The structural characteristics, optical and electrical properties of the ITO thin films were investigated. These polycrystalline ITO films exhibited preferential orientation along (222) plane and possessed low resistivities ranging from 3.51 to 5.71 10-4 ? cm. The decreased mobility was attributed to the scattering by ionized and neutral impurities at high doping concentrations. The optimized ITO thin film deposited with 6.0 wt% Sn-doping concentration exhibited a high average transparency of 87 % in the wavelength range of 380-900 nm and a low resistivity of 3.74 10-4 ? cm with a high Hall mobility of 47 cm2 V-1s-1. A hydrogenated amorphous silicon and silicon-germanium (a-Si:H/a-SiGe:H) double-junction solar cell fabricated with the RTE-grown ITO electrodes presented a conversion efficiency of 10.51 %.

Du, Jian; Chen, Xin-liang; Liu, Cai-chi; Ni, Jian; Hou, Guo-fu; Zhao, Ying; Zhang, Xiao-dan

2014-04-01

269

A comparative study of solution-processed low- and high-band-gap chalcopyrite thin-film solar cells  

Science.gov (United States)

Low-cost and printable chalcopyrite thin-film solar cells were fabricated by a precursor solution-based coating method with a multi-step heat-treatment process (oxidation, sulfurization, and selenization). The high-band-gap (1.57 eV) Cu(InxGa1-x)S2 (CIGS) solar cell showed a high open-circuit voltage of 787 mV, whereas the low-band-gap (1.12 eV) Cu(InxGa1-x)(S1-ySey)2 (CIGSSe) cell exhibited a high short-circuit current density of 32.6 mA cm-2. The energy conversion efficiencies were 8.28% for CIGS and 8.81% for CIGSSe under standard irradiation conditions. Despite similar efficiencies, the two samples showed notable differences in grain size, surface morphology, and interfacial properties. Low-temperature transport and admittance characteristics of the samples clearly revealed how their structural differences influenced their photovoltaic and electrical properties. Such analyses provide insight into the enhanced solar cell performance of the solution-processed chalcopyrite thin films.

Park, Se Jin; Cho, Yunae; Moon, Sung Hwan; Kim, Ji Eun; Lee, Doh-Kwon; Gwak, Jihye; Kim, Jihyun; Kim, Dong-Wook; Koun Min, Byoung

2014-04-01

270

ZnO thin films fabricated by chemical bath deposition, used as buffer layer in organic solar cells  

International Nuclear Information System (INIS)

ZnO thin films synthetized by chemical bath deposition are used as buffer layer between the anode and the organic electron donor in organic solar cells. Films deposited from zinc nitrate solutions are annealed in room air at 300 deg. C for half an hour. The X-ray diffraction and microanalysis studies show that ZnO polycrystalline thin films are obtained. The solar cells used are based on the couple copper phthalocyanine as electron donor and (N,N-diheptyl-3,4,9,10-perylenetetracarboxylicdiimide-PTCDI-C7) as electron acceptor. It is shown that the presence of the ZnO buffer layer improves the energy conversion efficiency of the cells. Such improvement could be attributed to a better energy level alignment at the anode/electron donor interface. The anode roughness induced by the ZnO buffer layer can also transform the planar interface organic electron donor/electron acceptor into roughen topography. This increases the interface area, where carrier separation takes place, which improves solar cells performances.

271

Enhancement of Conversion Efficiency of Cu2ZnSnS4 Thin Film Solar Cells by Improvement of Sulfurization Conditions  

Science.gov (United States)

To enhance the conversion efficiency of Cu2ZnSnS4 (CZTS) thin film solar cells prepared by the sulfurization method, we investigated the formation process of the CZTS thin film. The holding temperature of the sulfurization was 580 C. This study showed that the spreading resistance (SR) of the CZTS layer strongly depends on the holding time of the sulfurization. At the intermediate holding time (?30 min), the SR of the CZTS layer came to a minimum, and the efficiency of the CZTS solar cell came to a maximum. A 7.6% efficiency CZTS solar cell without a high-resistance buffer layer and an antireflection coating was fabricated.

Fukano, Tatsuo; Tajima, Shin; Ito, Tadayoshi

2013-06-01

272

Dipolar and Quadrupolar Modes of SiO2/Au Nanoshell Enhanced Light Trapping in Thin Film Solar Cells  

International Nuclear Information System (INIS)

Dipolar and quadrupolar resonance wavelengths of SiO2/Au nanoshell surface plasmons are designed at 560 nm to enhance the light trapping in thin film solar cells. In order to quantitatively describe the light trapping effect, the forward-scattering efficiency (FSE) and the light trapping efficiency (LTE) are proposed by considering the light scattering direction of SiO2/Au nanoshells. Based on the Mie theory, the FSE and the LTE are calculated for SiO2/Au nanoshells of different dimensions, and the contributions of the dipolar and quadrupolar modes to the light trapping effect are analyzed in detail. When the surface coverage of nanoshells is 5%, the LTEs are 21.7% and 46.9% for SiO2/Au nanoshells with sizes of (31 nm, 69 nm) and (53 nm, 141 nm), respectively. The results indicate that the SiO2/Au nanoshell whose quadrupolar mode peak is designed to the strongest solar energy flux density of the solar spectrum facilitates the further enhancement of light harvesting in thin film solar cells. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

273

Light coupling into the Whispering Gallery Modes of a fiber array thin film solar cell for fixed partial Sun tracking  

Science.gov (United States)

We propose the use of whispering gallery mode coupling in a novel configuration based on implementing a thin film cell on the backside of an array of parallel fibers. We performed numerical calculations using the parameters of a thin film organic cell which demonstrate that light coupling becomes more effective as the angle for the incident light relative to the fiber array normal increases up to an optimal angle close to 55?deg. At this angle the power conversion efficiency of the fiber array solar cell we propose becomes 30% times larger than the one from an equivalent planar cell configuration. We demonstrate that the micro fiber array solar cell we propose may perform an effective partial tracking of the sun movement for over 100?degrees without any mechanical help. In addition, in the event that such fiber array cell would be installed with the adequate orientation on a vertical faade, an optimal photon-to-charge conversion would be reached for sunlight incident at 55?deg with respect to the horizon line, very close to the yearly average position for the sun at Latitude of 40?deg. PMID:24825320

Mariano, Marina; Rodriguez, Francisco J.; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

2014-01-01

274

Simulation of nanostructure-based and ultra-thin film solar cell devices beyond the classical picture  

CERN Document Server

In this paper, an optoelectronic device simulation framework valid for arbitrary spatial variation of electronic potentials and optical modes, and for transport regimes ranging from ballistic to diffusive, is used to study non-local photon absorption, photocurrent generation and carrier extraction in ultra-thin film and nanostructure-based solar cell devices at the radiative limit. Among the effects that are revealed by the microscopic approach and which are inaccessible to macroscopic models is the impact of structure, doping or bias induced nanoscale potential variations on the local photogeneration rate and the photocarrier transport regime.

Aeberhard, Urs

2014-01-01

275

Ion-beam and plasma etching of a conical-pores photonic crystal for thin-film solar cell  

Science.gov (United States)

Conical holes bored in the active layer of a thin-film silicon solar cell by ion-beam lithography (IBL) show increase of effective optical absorption in the underlying silicon active layer. The optical properties are numerically simulated by the 3D finite-difference time-domain method (3D-FDTD), showing wideband increase of the UV, visible, and IR quantum efficiency. An experimental fabrication procedure is developed using IBL for high wide- area repeatability. A further optimization on the cone shapes is performed in order to make fabrication feasible with plasma etching techniques.

Gervinskas, Gediminas; Rosa, Lorenzo; Juodkazis, Saulius

2013-12-01

276

Structural and optical properties of silver doped TiO2 thin films for solar cell applications  

Science.gov (United States)

Electron collection efficiency and hence the device performance of a dye sensitized solar cell can be increased by localized surface plasmons (LSP) produced by the thin films of 2% silver doped TiO2 photo electrode. These films of silver doped TiO2 on glass substrates are prepared by pulsed laser deposition (PLD) method and have a lowest grain size of 8-31 nm. XRD, AFM and raman studies are made to characterize the surface at various annealing temperatures and annealing time durations. The lowest grain size of 8 nm of these films developed.

Murty, V. V. S.; Dashore, Vinay

2014-09-01

277

Comparison between periodic and stochastic parabolic light trapping structures for thin-film microcrystalline Silicon solar cells.  

Science.gov (United States)

Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a scattering structure, characterized by an atomic force microscope. This structure is used for light trapping in thin-film microcrystalline silicon solar cells. Very good agreement is found in a first comparison between simulation and experimental results. The geometrical parameters of the stochastic structure are varied and it is found that the light trapping mainly depends on the aspect ratio (length/height). Furthermore, the maximum possible light trapping with this kind of stochastic structure geometry is investigated. In a second step, the stochastic structure is analysed and typical geometrical features are extracted, which are then arranged in a periodic structure. Investigating the light trapping properties of the periodic structure, we find that it performs very similar to the stochastic structure, in agreement with reports in literature. From the obtained results we conclude that a potential advantage of periodic structures for PV applications will very likely not be found in the absorption enhancement in the solar cell material. However, uniformity and higher definition in production of these structures can lead to potential improvements concerning electrical characteristics and parasitic absorption, e.g. in a back reflector. PMID:23388775

Peters, M; Battaglia, C; Forberich, K; Blsi, B; Sahraei, N; Aberle, A G

2012-12-31

278

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

Science.gov (United States)

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.

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

2013-08-01

279

Plasmonic back contacts with non-ordered Ag nanostructures for light trapping in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

In this work, we investigate the light trapping of thin-film silicon solar cells which apply plasmonic Ag back contacts with non-ordered Ag nanostructures. The preparation, characterization and three-dimensional electromagnetic simulations of these back contacts with various distributions of non-ordered Ag nanostructures are presented. The measured reflectance spectra of the Ag back contacts with non-ordered nanostructures in air are well reproduced in reflectance spectra derived from the three-dimensional electromagnetic simulations of isolated nanostructures on Ag back contacts. The lightmatter interaction of these nanostructures is given by localized surface plasmons and, thus, the measured diffuse reflectance of the back contacts is attributed to plasmon-induced light scattering. A significant plasmonic light-trapping effect in n-i-p substrate-type ?c-Si:H thin-film solar cell prototypes which apply a Ag back contact with non-ordered nanostructures is identified when compared with flat reference solar cells.

Paetzold, Ulrich W., E-mail: u.paetzold@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Meier, Matthias, E-mail: ma.meier@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Moulin, Etienne, E-mail: e.moulin@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Smirnov, Vladimir, E-mail: v.smirnov@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Pieters, Bart E., E-mail: b.pieters@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Rau, Uwe, E-mail: u.rau@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany); Carius, Reinhard, E-mail: r.carius@fz-juelich.de [IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich (Germany)

2013-05-15

280

Enhanced performance of flexible nanocrystalline silicon thin-film solar cells using seed layers with high hydrogen dilution.  

Science.gov (United States)

Flexible hydrogenated nanocrystalline (nc-Si:H) thin-film solar cells were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD), and the effect of highly crystalline intrinsic Si seed layers at the initial growth stage of i nc-Si:H absorbers on their structural and electrical properties and on the performance of solar cells was investigated. The crystallization of i nc-Si:H absorbers was significantly enforced by the introduction of highly crystalline seed layers, resulting in the reduction of defect-dense a-Si:H grain boundary and incubation layer thickness. The open circuit voltage of the nc-Si:H solar cells with the seed layers was improved by the decrease of charged defect density in the defect-rich amorphous region. PMID:24266159

Lee, Ji-Eun; Kim, Donghwan; Yoon, Kyung Hoon; Cho, Jun-Sik

2013-12-01

 
 
 
 
281

Segregation of Te at the back contact in electrochemically deposited CdTe thin film solar cells  

Science.gov (United States)

One significant problem associated with thin film CdTe solar cells is the reverse biased Schottky barrier at the back contact (CdTe/metal interface), caused by the high electron affinity of p-CdTe, along with the non-availability of metals with adequate work functions. This Schottky barrier increases contact resistance, thereby reducing cell performance. In order to eliminate this barrier, attempts to create a tunnelling contact are being made by etching the CdTe surface, to form a Te rich degenerate semiconductor surface. The Te rich surface layer usually contains increased conductivity and is p +-type. Electrochemically deposited CdTe thin films are naturally Te-rich, but significantly, in this work, we report the segregated concentration of Te at the back contact resulting from the controlled addition of Te to the deposition electrolyte. This segregation of Te is notable as it minimises the use of acidic etchants to create a Te rich surface. Raman and XRD spectra confirm Te segregation at the surface of the CdTe, which one would expect to produce a good ohmic back contact. Effectively, high-quality layers and cells can be obtained from this process, which can be scaled up to an industrial level, inline and without the use of etching baths or external CdCl 2 treatment. Photocurrent spectroscopy was undertaken on CdTe thin film solar cells to investigate their interfacial and structural properties, both of which play a crucial role in determining photovoltaic performance. High chopping frequencies were employed in order to obtain reliable incident photon to current conversion efficiency (IPCE) data, in the cases where surface recombination was rapid. The absorption edge at the low energy end of the IPCE spectrum corresponds to an interfacial bandgap of 1.45 eV, which in turn corresponds to interdiffusion of about 10% of S into CdTe, according to bowing equations found in literature.

Samantilleke, A. P.; Cerqueira, M. F.; Mari, B.

2011-04-01

282

Silicon-Light: a European FP7 Project Aiming at High Efficiency Thin Film Silicon Solar Cells on Foil  

DEFF Research Database (Denmark)

Silicon-Light is a European FP7 project, which started January 1st, 2010 and aims at development of low cost, high-efficiency thin film silicon solar cells on foil. Three main routes are explored to achieve these goals: a) advanced light trapping by implementing nanotexturization through UV Nano Imprinting Lithography (UV-NIL); b) growth of crack-free silicon absorber layers on highly textured substrates; c) development of new TCOs which should combine the best properties of presently available materials like ITO and AZO. The paper presents the midterm status of the project results, showing model calculations of ideal nanotextures for light trapping in thin film silicon solar cells; the fabrication of masters and the replication and roll-to-roll fabrication of these nanotextures. Further, results on ITO variants with improved work function are presented. Finally, the status of cell fabrication on foils with nanotexture is shown. Microcrystalline and amorphous silicon single junction cells with stable efficiencies with more than 8 % have been made, paving the way towards a-Si/ c-Si tandem cells with more than 11% efficiency.

Soppe, W.; Haug, F.-J.

2011-01-01

283

Investigation on improvements of TCO processing on cadmium telluride thin film solar cells  

Science.gov (United States)

Cadmium Stannate (Cd2SnO4) is a high performance TCO (transparent conducting oxide) that has been used in the fabrication of leading performance thin film CdTe solar cells. Several studies in this work were done to enhance the technical knowledgebase and industry processing of the Cd2SnO4: mechanical film properties, tantalum doping, pulsed-DC compared to RF plasma deposition, and modeling of the sputter system in Fluent and Comsol. Mechanical properties, determined from nanoindentation measurements, are valuable for flexible substrate design and topcoats. It was found films annealed in oxygen rather than nitrogen increases elastic modulus by 16% and hardness by 32%, but film electrical and optical properties were degraded. Tantalum was also investigated as an n-type dopant in Cd2SnO 4 with the goal of removing the lab-standard CdS plate anneal, which is impractical for industrial manufacturing. Various doping levels, deposition temperatures, and post-anneals were done on sputtered films. Quantification of film quality is done using three properties: electrical, optical, and crystalline. These properties are measured with x-ray diffraction, Hall effect, spectrophotometer, and a profilometer to measure thickness and surface roughness. While 1-10% Ta is not an effective dopant, a significant discovery is approximate film properties can be achieved with a 550C undoped Cd2SnO 4 deposition with a standard anneal compared to the standard 20C film with CdS anneal. This film may be competitive in industry as an improvement for the current ITO (SnO4:F). Pulsed DC plasma sputtering was investigated to enhance Cd2SnO 4 film properties and is known to deposit faster than with RF for certain materials. It was found PDC improves film qualities at deposition temperatures of 300C and above, compared to standard RF Cd2SnO4 films. Even without any anneal, the 530C PDC deposition has good properties compared to the RF 550C. While conductivity is not as high with PDC, the mobility of the film is outstanding. With added CdS anneals, deposition temperatures 300C and above give improvements to the standard RF film. Deposition rates of these PDC films is increases 6-21% over RF at corresponding temperatures. The sputter deposition was also modeled in Fluent (gas and surface reactions) and Comsol (plasma) in order to approximate deposition rates under various conditions and optimize chamber properties. The result is there is a solid base for a comprehensive model for the sputter deposition.

Sledz, Dana

284

Synthesis and characterization of Zn(O,OH)S and AgInS{sub 2} layers to be used in thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

In this paper AgInS{sub 2} and Zn(O,OH)S thin films were synthesized and characterized. AgInS{sub 2} layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS{sub 2} thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS{sub 2} films presented p-type conductivity, a high absorption coefficient (greater than 10{sup 4} cm{sup -1}) and energy band-gap E{sub g} of about 1.95 eV, Zn(O,OH),S thin films presented E{sub g} of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS{sub 2} layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

Vallejo, W., E-mail: wavallejol@unal.edu.co [Departamento de Quimica, Universidad Nacional de Colombia, Cra 30 No 45-03, Bogota (Colombia); Arredondo, C.A.; Gordillo, G. [Departamento de Fisica, Universidad Nacional de Colombia, Cra 30 No 45-03, Bogota (Colombia)

2010-11-01

285

Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells  

International Nuclear Information System (INIS)

In this paper AgInS2 and Zn(O,OH)S thin films were synthesized and characterized. AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS2 thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS2 films presented p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and energy band-gap Eg of about 1.95 eV, Zn(O,OH),S thin films presented Eg of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS2 layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

286

Thin-film monocrystalline-silicon solar cells made by a seed layer approach on glass-ceramic substrates  

Energy Technology Data Exchange (ETDEWEB)

Solar modules made from thin-film crystalline-silicon layers of high quality on glass substrates could lower the price of photovoltaic electricity substantially. One way to create crystalline-silicon thin films on non-silicon substrates is to use the so-called ''seed layer approach'', in which a thin crystalline-silicon seed layer is first created, followed by epitaxial thickening of this seed layer. In this paper, we present the first solar cell results obtained on 10-{mu}m-thick monocrystalline-silicon (mono-Si) layers obtained by a seed layer approach on transparent glass-ceramic substrates. The seed layers were made using implant-induced separation and anodic bonding. These layers were then epitaxially thickened by thermal CVD. Simple solar cell structures without integrated light trapping features showed efficiencies of up to 7.5%. Compared to polycrystalline-silicon layers made by aluminum-induced crystallization of amorphous silicon and thermal CVD, the mono-Si layers have a much higher bulk diffusion lifetime. (author)

Gordon, I.; Beaucarne, G.; Poortmans, J. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Vallon, S. [Corning European Technology Center, 7bis avenue de Valvins, 77210 Avon (France); Mayolet, A. [Corning Incorporated, SP-FR02-12, Corning, NY 14831 (United States)

2010-02-15

287

Analysis of radiation resistance of InGaP/GaAs dual-junction thin-film space solar cell  

International Nuclear Information System (INIS)

Thin-film III-V multi-junction solar cells can realize the advantages of being high-efficiency and light-weight, as such these cells meets the requirement for higher specific power and lower stowage volume solar panels. Here we report the development results of an InGaP/GaAs thin-film dual-junction (TF2J) solar cell. In this paper, we study the radiation resistance of the TF2J cells with efficiency of 20-23% under AM0.1 sun at 25degC. The cells were subjected to proton irradiation with an energy range of 100keV-10MeV. The results were compared with the radiation resistance of a conventional InGaP/GaAs/Ge triple-junction (3J) cell. In the proton energy range of 200-400keV, radiation resistance of the TF2J cell is superior to that of the 3J cell. Particularly, the 1sc of the TF2J cell is significantly higher than that of the 3J cell after exposure to 380keV protons, which results in higher remaining factor of Pmax for the TF2J cell. In additions, Voc of the cells after the irradiations are almost equivalent, even though the TF2J cell is a dual-junction structure. The higher 1sc of the TF2J cell after irradiation is due to higher radiation resistance of the GaAs subcell according to the comparison of the spectral response. (author)

288

Optical properties of Cd1-xZnxS thin films for CuInGaSe2 solar cell application  

International Nuclear Information System (INIS)

The photovoltaic Cd1-xZnxS thin films, fabricated by chemical bath deposition, were successfully used as n-type buffer layer in CuInGaSe2 (CIGS) solar cells. Comprehensive optical properties of the Cd1-xZnxS thin films were measured and modeled by spectroscopic ellipsometry (SE), which is proven to be an excellent and non-destructive technique to determine optical properties of thin films. The optical band gap of Cd1-xZnxS thin films can be tuned from 2.43 eV to 3.25 eV by controlling the Zn content (x) and deposition conditions. The wider-band-gap Cd1-xZnxS film was found to be favorable to improve the quantum efficiency in the wavelength range of 450-550 nm, resulting in an increase of short-circuits current for solar cells. From the characterization of quantum efficiency (QE) and current-voltage curve (J-V) of CIGS cells, the Cd1-xZnxS films (x = 0.32, 0.45) were demonstrated to significantly enhance the photovoltaic performance of CIGS solar cell. The highest efficiency (10.5%) of CIGS solar cell was obtained using a dense and homogenous Cd0.68Zn0.32S thin film as the buffer layer.

289

Polycrystalline thin-film, cadmium-telluride solar cells fabricated by electrodeposition cells. Final subcontract report, March 20, 1992--April 27, 1995  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project was to develop improved processes for the fabrication of CdTe/CdS polycrystalline thin film solar cells. The technique we used for the formation of CdTe, electrodeposition, was a non-vacuum, low-cost technique that is attractive for economic, large-scale production. Annealing effects and electrical properties are discussed.

Trefny, J.U.; Mao, D.; Kim, D. [and others

1995-10-01

290

Preparation routes based on magnetron sputtering for tungsten disulfide (WS2) films for thin-film solar cells  

International Nuclear Information System (INIS)

The semiconductor tungsten disulfide (WS2) exhibits van der Waals bonding, crystallizes in a layer-type structure and is of interest as an absorber layer for thin-film solar cells. In this review article different preparation routes for WS2 thin films, based on magnetron sputtering, are reviewed. Films prepared by direct magnetron sputtering, though exhibiting quite a good structural quality, are not or only poorly photoactive. This can be attributed to the generation of recombination centers, especially sulfur vacancies, during the ion bombardment of the films, due to the low defect-formation energy of tungsten disulfide, an intrinsic property of transition metal dichalcogenides. A promising preparation route, which leads to photoactive WS2 films, is a two-step process, where, in a first step, a sulfur-rich, X-ray amorphous tungsten sulfide is deposited at low substrate temperatures onto a thin metal film (Ni, Co). This film sandwich is after wards annealed in an ampoule in a sulfur atmosphere or in flowing gas with a sufficient H2S partial pressure. From in-situ transmission electron microscopy and energy-dispersive X-ray diffraction, it was found that the WS2 film crystallization with a pronounced (001) texture is closely related to the formation of the liquid (eutectic) metal-sulfur phase. Based on these in-situ investigations the growth of the 2-dimensional WS2 nanosheets from an amorphous WS3+x precursor can be described as an amorphous solid-liquid-crystalline solid process (SLS), somewhat similar to the well-known vapor-liquid-solid (VLS) process for the growth of whiskers or nanorods and nanotubes. Research opportunities, to overcome current limitations for a broad use of WS2 (and MoS2) as thin-film solar cell absorbers are given. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

291

Development of a hybrid sputtering/evaporation process for Cu(In,Ga)Se{sub 2} thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

In this paper we report a new method for Cu(In,Ga)Se{sub 2} deposition for solar cell application. Differently from the common co-evaporation process, an alterative approach for thin film Cu(In,Ga)Se{sub 2} has been tested: the sputtering deposition of metal elements combined with the selenium evaporation. We have studied the relationships between the growth parameters of our hybrid sputtering/evaporation method and the chemical-physical properties of the CIGS films. The cells are completed with a CdS buffer layer deposited by chemical bath deposition and ZnO + ITO deposited by RF sputtering. Test solar cells of 0.5 cm{sup 2} have shown an efficiency of 10% and 2.5% on glass and stainless steel substrate respectively. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Acciarri, M.; Binetti, S.; Le Donne, A.; Lorenzi, B.; Caccamo, L.; Miglio, L. [Dipartimento di Scienza dei Materiali e Solar Energy Research Center MIB-SOLAR, Universita di Milano Bicocca, Milan (Italy); Moneta, R.; Marchionna, S.; Meschia, M. [Voltasolar s.r.l, Turate (Italy)

2011-08-15

292

Development of thin film amorphous silicon oxide/microcrystalline silicon double-junction solar cells and their temperature dependence  

Energy Technology Data Exchange (ETDEWEB)

We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (V{sub oc}), which are attractive for the use in high temperature environment. All p, i and n layers were deposited on transparent conductive oxide (TCO) coated glass substrate by a 60 MHz-very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. The p-i-n-p-i-n double-junction solar cells were fabricated by varying the CO{sub 2} and H{sub 2} flow rate of i top layer in order to obtain the wide bandgap with good quality material, which deposited near the phase boundary between a-SiO:H and hydrogenated microcrystalline silicon oxide ({mu}c-SiO:H), where the high V{sub oc} can be expected. The typical a-SiO:H/{mu}c-Si:H solar cell showed the highest initial cell efficiency of 10.5%. The temperature coefficient (TC) of solar cells indicated that the values of TC for conversion efficiency ({eta}) of the double-junction solar cells were inversely proportional to the initial V{sub oc}, which corresponds to the bandgap of the top cells. The TC for {eta} of typical a-SiO:H/{mu}c-Si:H was -0.32%/ C, lower than the value of conventional a-Si:H/{mu}c-Si:H solar cell. Both the a-SiO:H/{mu}c-Si:H solar cell and the conventional solar cell showed the same light induced degradation ratio of about 20%. We concluded that the solar cells using wide bandgap a-SiO:H film in the top cells are promising for the use in high temperature regions. (author)

Sriprapha, K.; Piromjit, C.; Limmanee, A.; Sritharathikhun, J. [Institute of Solar Energy Technology Development (SOLARTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

2011-01-15

293

Multilayer nanoparticle arrays for broad spectrum absorption enhancement in thin film solar cells  

CERN Document Server

In this paper, we present a theoretical study on the absorption efficiency enhancement of a thin film amorphous Silicon (a-Si) photovoltaic cell over a broad spectrum of wavelengths using multiple nanoparticle arrays. The light absorption efficiency is enhanced in the lower wavelengths by a nanoparticle array on the surface and in the higher wavelengths by another nanoparticle array embedded in the active region. The efficiency at intermediate wavelengths is enhanced by the constructive interference of plasmon coupled light. We optimize this design by tuning the radius of particles in both arrays, the period of the array and the distance between the two arrays. The optimization results in 61.44% increase in total quantum efficiency for a 500 nm thick a-Si substrate.

Krishnan, Aravind; Krishna, Siva Rama; Khan, Mohammed Zafar Ali

2013-01-01

294

Sputtered ITO for application in thin-film silicon solar cells: Relationship between structural and electrical properties  

Science.gov (United States)

Indium tin oxide (ITO) thin films for application in thin-film silicon solar cells with superior electrical and optical properties (resistivity ranging from 1.4 to 8.4 10-4 ? cm; transparency of >80%) have been investigated. ITO layers were deposited by radio-frequency (RF) magnetron sputtering process at different argon gas pressures and substrate temperatures ranging from room temperature to 280 C. The main goal was to identify the relationship between structural and electrical properties. Generally, ITO layers were rather smooth with granular topography; electro-optically superior layers exhibited substantially different surface morphology of large, well-organized domain formations. Hall mobility of remarkably high value of 49 cm2/V s (resistivity of 2.6 10-4 ? cm) was achieved for the ITO layers, which were deposited at surprisingly low temperature of 125 C. ITO process has been successfully applied, even at room temperature, to fabricate front contacts for microcrystalline silicon solar cells, exhibiting excellent performance on both rigid and flexible substrates.

Hotovy, J.; Hpkes, J.; Bttler, W.; Marins, E.; Spiess, L.; Kups, T.; Smirnov, V.; Hotovy, I.; Kov?, J.

2013-03-01

295

Electrochemical deposition of quaternary Cu2ZnSnS4 thin films as potential solar cell material  

Science.gov (United States)

Quaternary compound semiconductor Cu2ZnSnS4 (CZTS), which appears to be a promising candidate for the absorber of a thin film type solar cell, was grown on polycrystalline Ag substrates by electrochemical epitaxial method. The elements were deposited in the following sequence: S/Sn/S/Cu/S/Zn/S/Cu , the order being one cycle of SnS, one cycle of ZnS and two cycles of CuS. Morphology of the deposit has been characterized by field emission scanning electron microscopy (FE-SEM) with an energy dispersive X-ray (EDX) analyzer. X-ray diffraction (XRD) studies showed a (112) preferred orientation for the deposit. X-ray photoelectron spectroscopy (XPS) of the deposit indicated an approximate ratio 2:1:1:4 of Cu, Zn, Sn, and S, the expected stoichiometry for the deposit, and similar results have been obtained from EDX data. Near IR absorption measurements of the deposit at room temperature indicated a direct band gap of 1.5 eV, and open-circuit potential (OCP) studies indicated a good p-type property, both of which were suitable for fabricating a thin film solar cell.

Zhang, Xin; Shi, Xuezhao; Ye, Weichun; Ma, Chuanli; Wang, Chunming

2009-02-01

296

Enhanced Conversion Efficiencies of Cu2ZnSnS4-Based Thin Film Solar Cells by Using Preferential Etching Technique  

Science.gov (United States)

Cu2ZnSnS4 (CZTS) thin film solar cells have been fabricated by co-sputtering technique using three targets of Cu, SnS, and ZnS. CZTS-based thin film solar cells over 6.7% efficiency were obtained for the first time by soaking the CZTS layer on the Mo coated soda-lime glass substrate in deionized water (DIW) after forming the CZTS layer. It was found that DIW-soaking had the effect of preferential etching, which eliminated selectively metal oxide particles in the CZTS layer, by electron probe X-ray micro analysis.

Katagiri, Hironori; Jimbo, Kazuo; Yamada, Satoru; Kamimura, Tsuyoshi; Shwe Maw, Win; Fukano, Tatsuo; Ito, Tadashi; Motohiro, Tomoyoshi

2008-04-01

297

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

Science.gov (United States)

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. PMID:24882468

Patel, Malkeshkumar; Ray, Abhijit

2014-07-01

298

Silicon-Light: a European project aiming at high efficiency thin film silicon solar cells on foil  

Science.gov (United States)

In the European project Silicon-Light we developed concepts and technologies to increase conversion efficiencies of thin film silicon solar cells on foil. Main focus was put on improved light management, using NIL for creating light scattering textures, improved TCOs using sputtering, and improved silicon absorber material made by PECVD. On foil we achieved initial cell efficiencies of 11% and on rigid substrates stable efficiencies of 11.6% were achieved. Finally, the project demonstrated the industrial scale feasibility of the developed technologies and materials. Cost of ownership calculations showed that implementation of these technologies on large scale would enable the production of these high efficiency solar modules at manufacturing cost of 0.65 /Wp with encapsulation costs (0.20 /Wp) being the dominant costs. Life cycle analysis showed that large scale production of modules based on the technologies developed in Silicon-Light would have an energy payback time of 0.85 years in Central European countries.

Soppe, W.; Krc, J.; Leitner, K.; Haug, F.-J.; Duchamp, M.; Sanchez Plaza, G.; Wang, Q.-K.

2014-07-01

299

Numerical Analysis of Efficiency Enhancement in Plasmonic Thin-Film Solar Cells by Using the SILVACO TCAD Simulator  

International Nuclear Information System (INIS)

A physical model for simulating plasmonic solar cells (SCs) using the SILVACO TCAD simulator is established and the effects of some factors on the efficiency enhancement of the amorphous silicon thin film SCs are simulated. Through this simulation, it is demonstrated that our method can successfully simulate the optical and electrical properties of plasmonic solar cells without the overestimation of the characteristics and without the neglect of parameter change in the device operation process. It is shown that not only the size and kind of metal nanoparticles but also other factors, such as the surrounding medium, the distance from the bottom of particles to the device surface, and the light incident angle, play important roles in the optical and electrical properties of plasmonic SCs. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

300

Ultra-Lightweight Hybrid Thin-Film Solar Cells: A Survey of Enabling Technologies for Space Power Applications  

Science.gov (United States)

The development of hybrid inorganic/organic thin-film solar cells on flexible, lightweight, space-qualified, durable substrates provides an attractive solution for fabricating solar arrays with high mass specific power (W/kg). Next generation thin-film technologies may well involve a revolutionary change in materials to organic-based devices. The high-volume, low-cost fabrication potential of organic cells will allow for square miles of solar cell production at one-tenth the cost of conventional inorganic materials. Plastic solar cells take a minimum of storage space and can be inflated or unrolled for deployment. We will explore a cross-section of in-house and sponsored research efforts that aim to provide new hybrid technologies that include both inorganic and polymer materials as active and substrate materials. Research at University of Texas at Arlington focuses on the fabrication and use of poly(isothianaphthene-3,6-diyl) in solar cells. We describe efforts at Norfolk State University to design, synthesize and characterize block copolymers. A collaborative team between EIC Laboratories, Inc. and the University of Florida is investigating multijunction polymer solar cells to more effectively utilize solar radiation. The National Aeronautics and Space Administration (NASA)/Ohio Aerospace Institute (OAI) group has undertaken a thermal analysis of potential metallized substrates as well as production of nanoparticles of CuInS2 and CuInSe2 in good yield at moderate temperatures via decomposition of single-source precursors. Finally, preliminary work at the Rochester Institute of Technology (R.I.T.) to assess the impact on performance of solar cells of temperature and carbon nanotubes is reported. Technologies that must be developed to enable ultra-lightweight solar arrays include: monolithic interconnects, lightweight array structures, and new ultra-light support and deployment mechanisms. For NASA applications, any solar cell or array technology must not only meet weight and AMO efficiency goals, but also must be durable enough to survive launch conditions and space environments.

Hepp, Aloysius F.; McNatt, Jeremiah S.; Bailey, Sheila G.; Dickman, John E.; Raffaelle, Ryne P.; Landi, Brian J.; Anctil, Annick; DiLeo, Roberta; Jin, Michael H.-C.; Lee, Chung-Young; Friske, Theresa J.; Sun, Sam-S.; Zhang, Cheng; Choi, S.; Ledbetter, Abram; Seo, Kang; Bonner, Carl E.; Banger, Kulbinder K.; Castro, Stephanie L.; Rauh, David

2007-01-01

 
 
 
 
301

Development of natively textured surface hydrogenated Ga-doped ZnO-TCO thin films for solar cells via magnetron sputtering  

International Nuclear Information System (INIS)

Highlights: ? Natively textured surface hydrogenated gallium-doped zinc oxide (HGZO) thin films have been deposited via magnetron sputtering on glass substrates. ? The directly deposited HGZO thin films present rough crater-type surface morphology. ? Typical HGZO thin film exhibits a high electron mobility of 41.3 cm2/V s and a relative low sheet resistance of ?7.0 ?. ? These HGZO thin films have high optical transmittances in the visible and near infrared region (?3801100 nm). ? A gradient H2 growth method for fabricating HGZO thin films has been proposed in magnetron sputtering process. - Abstract: The main purposes are to obtain high quality transparent conductive oxide (TCO) based on zinc oxide (ZnO) thin films with high optical transparency in the visible and near infrared spectral range, high electrical conductivity and good light-scattering capability to enhance the path of the light inside the Si-based thin film solar cells. Natively textured surface hydrogenated gallium-doped ZnO (HGZO) thin films have been deposited via pulsed direct current (DC) magnetron sputtering on glass substrates at a substrate temperature of 553 K. These natively textured HGZO thin films exhibit high optical transmittance (over 80%) in the visible and near infrared region (? = 3801100 nm) and excellent electrical properties. The optimized HGZO thin film with crater-type textured surface obtained at the hydrogen flow rate of ?2.0 sccm exhibits a high electron mobility of 41.3 cm2/V s and a relatively low sheet resistance of ?7.0 ?. The influences of hydrogen flow rates on the surface morphology, electrical and optical properties of HGZO thin films were investigated in detail. In addition, we put forward a method of gradient H2 growth technique for fabricating HGZO thin films so as to obtain rough surface structure with good light-scattering capability and high electrical conductivity. Crater-like surface feature size and optical transmittance can be improved through gradient H2 growth technique.

302

Development of natively textured surface hydrogenated Ga-doped ZnO-TCO thin films for solar cells via magnetron sputtering  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Natively textured surface hydrogenated gallium-doped zinc oxide (HGZO) thin films have been deposited via magnetron sputtering on glass substrates. Black-Right-Pointing-Pointer The directly deposited HGZO thin films present rough crater-type surface morphology. Black-Right-Pointing-Pointer Typical HGZO thin film exhibits a high electron mobility of 41.3 cm{sup 2}/V s and a relative low sheet resistance of {approx}7.0 {Omega}. Black-Right-Pointing-Pointer These HGZO thin films have high optical transmittances in the visible and near infrared region ({approx}380-1100 nm). Black-Right-Pointing-Pointer A gradient H{sub 2} growth method for fabricating HGZO thin films has been proposed in magnetron sputtering process. - Abstract: The main purposes are to obtain high quality transparent conductive oxide (TCO) based on zinc oxide (ZnO) thin films with high optical transparency in the visible and near infrared spectral range, high electrical conductivity and good light-scattering capability to enhance the path of the light inside the Si-based thin film solar cells. Natively textured surface hydrogenated gallium-doped ZnO (HGZO) thin films have been deposited via pulsed direct current (DC) magnetron sputtering on glass substrates at a substrate temperature of 553 K. These natively textured HGZO thin films exhibit high optical transmittance (over 80%) in the visible and near infrared region ({lambda} = 380-1100 nm) and excellent electrical properties. The optimized HGZO thin film with crater-type textured surface obtained at the hydrogen flow rate of {approx}2.0 sccm exhibits a high electron mobility of 41.3 cm{sup 2}/V s and a relatively low sheet resistance of {approx}7.0 {Omega}. The influences of hydrogen flow rates on the surface morphology, electrical and optical properties of HGZO thin films were investigated in detail. In addition, we put forward a method of gradient H{sub 2} growth technique for fabricating HGZO thin films so as to obtain rough surface structure with good light-scattering capability and high electrical conductivity. 'Crater-like' surface feature size and optical transmittance can be improved through gradient H{sub 2} growth technique.

Wang, Fei [Institute of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Tianjin Key laboratory of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Key laboratory of Opto-electronic Information Science and Technology for Ministry of Education, Nankai University, Tianjin 300071 (China); Chen, Xin-liang, E-mail: cxlruzhou@163.com [Institute of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Tianjin Key laboratory of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Key laboratory of Opto-electronic Information Science and Technology for Ministry of Education, Nankai University, Tianjin 300071 (China); Geng, Xin-hua; Zhang, De-kun; Wei, Chang-chun; Huang, Qian; Zhang, Xiao-dan; Zhao, Ying [Institute of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Tianjin Key laboratory of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Key laboratory of Opto-electronic Information Science and Technology for Ministry of Education, Nankai University, Tianjin 300071 (China)

2012-09-01

303

Newtech - Comparison of three 1 kW thin-film solar cell installations; Newtech. Vergleich 3 x 1 kWp Duennschichtzellenanlagen  

Energy Technology Data Exchange (ETDEWEB)

This final report for the Swiss Federal Office of Energy (SFOE) presents the results of tests made on 3 types of thin-film solar cells by the photovoltaics laboratory at the University of Applied Science in Burgdorf, Switzerland. The three 1-kW{sub p} installations are all mounted on the flat roof of an industrial building and deliver the power produced to the local electricity utility. The thin-film technologies tested are described. These include copper-indium-diselenide (CIS) cells, amorphous silicon tandem cells and amorphous silicon triple cells. The measurement equipment used is described and the results obtained are discussed. These showed that the CIS cells had the highest annual specific yield and that the triple cells had a relatively high performance ratio at low irradiance levels. The performance of the thin-film modules is also compared to that of conventional, crystalline modules installed at a nearby location.

Renken, C.; Haeberlin, H.

2003-07-01

304

Spray deposited ZnO: Au thin films for solar cell application  

Science.gov (United States)

In the present investigation, the ZnO-Au thin films are deposited in-situ with the simple and cost-effective spray pyrolysis technique. The preparative parameters were fine-tuned to yield better quality samples. A surface Plasmon resonance (SPR) induced absorption bands in the visible region have been observed for both the samples deposited at 450C. The structural evolution of Au-ZnO thin films with doping concentrations are reflected in the XRD patterns. The surface morphological study of the synthesized thin films was carried out using FESEM micrographs. The evolution of the SPR absorption with concentration of the Gold incorporation is discussed. The optical studies were carried out by using UV-Vis Spectrophotometer and spectrofluorometer (JASCO FP-750) at room temperature. These thin films were used for photoelectrochemical (PEC) application. Encouraging results are obtained.

Tarwal, N. L.; Harale, N. S.; Jadhav, P. R.; Patil, P. S.

2012-06-01

305

Optimization of processing and modeling issues for thin film solar cell devices: Final report, February 3, 1997--September 1, 1998  

Energy Technology Data Exchange (ETDEWEB)

This final report describes results achieved under a 20-month NREL subcontract to develop and understand thin-film solar cell technology associated to CuInSe{sub 2} and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE's long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development and improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to device structure and module encapsulation.

Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S.; McCandless, B. E.

2000-02-28

306

Improved Energy Conversion Efficiency of TiO2 Thin Films Modified with Ta2O5 in Dye-Sensitized Solar Cells  

Science.gov (United States)

Tantalum-doped TiO2 thin films [(TiO2)1-x(Ta2O5)x, x=0-0.8%] were prepared on fluorine-doped tin oxide (FTO)-coated substrates by sol-gel technology for uses in dye-sensitized solar cells (DSSCs). The effects of Ta content on the growth and properties of the TiO2 thin films were investigated. The crystallization and microstructures of the thin films were examined by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller analyses. The performance of DSSCs based on Ta-doped TiO2 thin films was also studied. From the obtained results, the increases in Jsc and Voc may be due to the increased electron concentration of TiO2 thin film and the flat-band potential of the TiO2 shifted by tantalum doping, respectively. The optimum properties of DSSCs of Voc=0.68 V, Jsc=7.84 mA/cm2, FF=45.1%, and ?=2.4% were obtained using the Ta-doped TiO2 thin film with x=0.5%.

Kao, Ming-Cheng; Chen, Hone-Zern; Young, San-Lin

2013-01-01

307

Photoelectrode thin film of dye-sensitized solar cell fabricated by anodizing method and spin coating and electrochemical impedance properties of DSSC  

Science.gov (United States)

The paper studies the photoelectrode thin film of dye-sensitized solar cell (DSSC) fabricated by anodizing method, explores the structure and properties of the fabricated photoelectrode thin film, measures the photoelectric conversion efficiency of DSSC, and finds the electrochemical impedance properties of DSSCs assembled by photoelectrode thin films in different thicknesses. Besides, in order to increase the specific surface area of nanotubes, this paper deposits TiO2 nanoparticles (TNP) on the surface of titanium oxide nanotube (TNT). As shown in experimental results, the photoelectric conversion efficiency of the DSSC fabricated by the study rises to 6.5% from the original 5.43% without TnB treatment, with an increase of photoelectric conversion efficiency by 19.7%. In addition, when the photoelectrode thin film is fabricated with mixture of TNTs and TNP in an optimal proportion of 2:8 and the photoelectrode thin film thickness is 15.5 ?m, the photoelectric conversion efficiency can reach 7.4%, with an increase of 36.7% from the original photoelectric conversion efficiency at 5.43%. Besides, as found in the results of electrochemical impedance analysis, the DSSC with photoelectrode thin film thickness at 15.5 ?m has the lowest charge-conduction resistance (Rk) value 9.276 ? of recombined electron and conduction resistance (Rw) value 3.25 ? of electrons in TiO2.

Chang, Ho; Chen, Chih-Hao; Kao, Mu-Jung; Chien, Shu-Hua; Chou, Cheng-Yi

2013-06-01

308

CIGS Thin Film Solar Cells, phase 2 Uppsala University Final report 2006-01-01 - 2007-06-14  

Energy Technology Data Exchange (ETDEWEB)

The project CIGS Thin Film Solar Cells, phase 2 has been going on for 18,5 months and was interrupted in advance on the 14th of June, 2007. The decision to shorten the period was taken by the board of the Swedish Energy Agency the 14th of February. It was decided to reevaluate and re-direct the financial support to the group. A new project, CIGS Thin Film Solar Cells, phase 3, superseded this project and will go on for the initially planned project period (until 2009-12-31). During the project much of the focus has been on research on Cd-free buffer layers, with an emphasis on the interface properties between the CIGS and the buffer layer. (CIGS is a commonly used acronym for Cu(In,Ga)Se{sub 2}, which is the active absorption layer in this type of solar cells) The combination of high quality CIGS and the new buffer layers has been another field of interest. CIGS solar cell module development and computer modelling of solar cells and modules has been the third major research area. The results show that the group still holds a position as one of the leaders in the world in this field. The 18.5 % efficient Cd-free solar cell, which was obtained and independently confirmed is only one percent away from the world record and in addition it is Cd-free using a Zn(O,S) buffer layer (the world record from NREL contains Cd). By alloying ZnO with MgO instead of ZnS almost equally good results can be achieved. During the last half year an 18.1 % cell has been measured with a (Zn,Mg)O buffer layer. Solar cell module technology includes several research issues, both fundamental as e.g. modelling of cell voltage and losses as a function of distance from interconnect to interconnect, but also more development as e.g. encapsulation routines. The harsh environment test (damp heat test) run at 85 deg C and 85 % relative humidity for 1000 hours was passed for both a small (12.5x12.5 cm2) and a large (27.5x30 cm2) module within the degradation limits stated by the IEC standards, using an edge seal technology

Edoff, Marika (Thin Film Solar Cell group, Dep. Technical Sciences, Uppsala Univ., P.O. Box 534, SE-751 21 Uppsala (Sweden)) (and others)

2007-06-15

309

Simultaneous infiltration and recrystallization of SiSiC ceramics for crystalline silicon thin-film solar cells. Paper  

Energy Technology Data Exchange (ETDEWEB)

Crystalline silicon thin-film (CSiTF) solar cells have a good potential to reduce the cost of silicon solar cells. In the so-called high-temperature approach for manufacturing CSiTF solar cells, ceramics shall be used as substrate, amongst other low-cost substrates. This work presents the research done for manufacturing CSiTF solar cells on SiSiC ceramics in a special way. Homogeneous and crack-free Si-SiC-C green tapes were manufactured in large sizes by the tape casting method. Intermediate layers and silicon layers were deposited onto the coked green tape by CVD. A special zone-melting process was applied for simultaneous infiltration and reaction bonding of the green tapes as well as recrystallization of the seeding layer. This so-called 'SIR' process offers a low cost perspective to manufacture coarse-grained silicon seeding layers on top of SiSiC substrates. Efficiencies up to 6.3% could be achieved for solar cells prepared in epitaxially thickened SIR layers. (orig.)

Reber, S.; Eyer, A.; Osswald, D. [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany); Pohlmann, H.J. [TeCe Technical Cermaics GmbH, Selb (Germany); Lutz, C.; Roosen, A. [Erlangen-Nuernberg Univ., Erlangen (Germany)

2001-07-01

310

Improving Si solar cell performance using Mn:ZnSe quantum dot-doped PLMA thin film.  

Science.gov (United States)

Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses of the QD-doped PLMA to monochromatic and AM0 light sources as functions of QD concentration, combined with reflectance and external quantum efficiency measurements. At a QD concentration of 1.6 mg/ml for example, among the efficiency enhancement of 5.96%, about 1.04% was due to the PL conversion, and the rest came from antireflection. Our work indicates that for the practical use of PL conversion in solar cell performance improvement, cautions are to be taken, as the achieved efficiency enhancement might not be wholly due to the PL conversion. PMID:23787125

Cheng, Dan-Chen; Hao, Hong-Chen; Zhang, Miao; Shi, Wei; Lu, Ming

2013-01-01

311

Effect of fluorine plasma treatment with chemically reduced graphene oxide thin films as hole transport layer in organic solar cells  

Science.gov (United States)

The inorganic materials such as V2O5, MoO3 and WO3 were investigated to replace PEDOT:PSS as hole transport layer (HTL) in organic electronic devices such as organic solar cells (OSCs) and organic lighting emission diodes. However, these methods require vacuum techniques that are long time process and complex. Here, we report about plasma treatment with SF6 and CF4 using reactive ion etching on reduced graphene oxide (rGO) thin films that are obtained using an eco-friendly method with vitamin C. The plasma treated rGO thin films have dipoles since they consist of covalent bonds with fluorine on the surface of rGO. This means it is possible to increase the electrostatic potential energy than bare rGO. Increased potential energy on the surface of rGO films is worth applying organic electronic devices as HTL such as OSCs. Consequently, the power conversion efficiency of OSCs increased more than the rGO films without plasma treatment.

Yu, Youn-Yeol; Kang, Byung Hyun; Lee, Yang Doo; Lee, Sang Bin; Ju, Byeong-Kwon

2013-12-01

312

Spray-on PEDOT:PSS and P3HT:PCBM Thin Films for Polymer Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available PEDOT:PSS electron-blocking layer, and PEDOT:PSS + P3HT:PCBM stacked layers are fabricated by ultrasonic atomization and characterized by scanning electron microscopy (SEM and optical profilometry. The measured thicknesses based on SEM and optical profilometry are quite different, indicating the incapability of measurement techniques for non-uniform thin films. The thickness measurements are compared against theoretical estimations and a qualitative agreement is observed. Results indicate that using a multiple pass fabrication strategy results in a more uniform thin film. It was also found that the film characteristics are a strong function of solution concentration and spraying passes, and a weak function of substrate speed. Film thickness increases with solution concentration but despite the prediction of theory, the increase is not linear, indicating a change in the film porosity and density, which can affect physical and opto-electrical properties. Overall, while spray coating is a viable fabrication process for a wide range of solar cells, film characteristics can be easily altered by a change in process parameters.

Morteza Eslamian

2014-01-01

313

Spray pyrolysed microporous TiO2 thin films by optimisation of substrate temperature for all sprayed solar cells  

Science.gov (United States)

Titanium dioxide thin films were deposited on glass substrate at temperatures ranging from 300 C to 500 C by a simple, cost effective spray pyrolysis method using commercially available TiO2 powder (Degussa P25). Analyses using scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal the microporous nature of the films at 350 C. X-ray diffraction (XRD) and Raman studies reveal that these films are amorphous in nature. The films were subsequently annealed at 500 C for 2 h, resulting in crystallisation (the tetragonal anatase phase). XPS analysis was effectively used to study the chemical composition of the samples. Finally, optimized microporous TiO2 thin films were used for the fabrication of an all-sprayed solar cell utilizing well-established CuInS2 as the absorber layer. The best device under this study has an open-circuit voltage of 409 mV and a short-circuit current density of 3.90 mA cm?2. The efficiency and fill factor were 0.61% and 38%, respectively.

Santhosh, M. V.; Deepu, D. R.; Geethu, R.; Rajeev Kumar, K.; Sudha Kartha, C.; Vijayakumar, K. P.

2014-11-01

314

Development of thin film space solar cells with multi-junction  

International Nuclear Information System (INIS)

The present and future state of research and development in JAXA are introduced on the downsizing and weight reduction of solar panels. The circumstance of development, special feature and efficiency in the latest solar cells are explained. Further, its radiation resistance is shown by comparison with the three-junction solar cells used at present. (M.H.)

315

Polycrystalline-thin-film thermophotovoltaic cells  

Science.gov (United States)

Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity, portability, silent operation, absence of moving parts, reduced air pollution, rapid start-up, high power densities, potentially high conversion efficiencies, choice of a wide range of heat sources employing fossil fuels, biomass, and even solar radiation are key advantages of TPV cells in comparison with fuel cells, thermionic and thermoelectric convertors, and heat engines. The potential applications of TPV systems include: remote electricity supplies, transportation, co-generation, electric-grid independent appliances, and space, aerospace, and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000-2000 K) black-body or selective radiators is in the 0.5-0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1-xGaxAs, GaSb, and Ga1-xInxSb. Several polycrystalline thin films such as Hg1-xCdxTe, Sn1-xCd2xTe2, and Pb1-xCdxTe, etc., have great potential for economic large-scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells, e.g., 17.1% for CuIn1-xGaxSe2 and 15.8% for CdTe. The best recombination-state density Nt is in the range of 10-15-10-16 cm-3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences, possibility of bandgap tailoring, and use of selective emitters such as rare earth oxides (erbia, holmia, yttria) and rare earth-yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe, it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto-electronic (infrared detectors, lasers, and optical communications) technologies. Low bandgaps and larger fluences employed in TPV cells result in very high current densities which make it difficult to collect the current effectively. Techniques for laser and mechanical scribing, integral interconnection, and multi-junction tandem structures which have been fairly well developed for thin-film PV solar cells could be further refined for enhancing the voltages from TPV modules. Thin-film TPV cells may be deposited on metals or back-surface reflectors. Spectral control elements such as indium-tin oxide or tin oxide may be deposited directly on the TPV convertor. It would be possible to reduce the cost of TPV technologies based on single-crystal materials being developed at present to the range of US 2-5 per watt so as to be competitive in small to medium size commercial applications. However, a further cost reduction to the range of US 35- 1 per watt to reach the more competitive large-scale residential, consumer, and hybrid-electric car markets would be possible only with the polycrystalline-thin film TPV cells.

Dhere, Neelkanth G.

1996-02-01

316

Cadmium sulfide nanowires for the window semiconductor layer in thin film CdS-CdTe solar cells  

Energy Technology Data Exchange (ETDEWEB)

Thin film CdS/CdTe heterojunction device is a leading technology for the solar cells of the next generation. We report on two novel device configurations for these cells where the traditional CdS window layer is replaced by nanowires (NW) of CdS, embedded in an aluminum oxide matrix or free-standing. An estimated 26.8% improvement in power conversion efficiency over the traditional device structure is expected, primarily because of the enhanced spectral transmission of sunlight through the NW-CdS layer and a reduction in the junction area/optical area ratio. In initial experiments, nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved.

Liu Piao; Singh, Vijay P; Jarro, Carlos A; Rajaputra, Suresh, E-mail: vsingh@engr.uky.edu [Center for Nanoscale Science and Engineering (CeNSE), Department of Electrical and Computer Engineering, University of Kentucky, Lexington, KY 40506 (United States)

2011-04-08

317

Preparation of aluminium doped zinc oxide thin films for the transparent conducting electrode application for hydrogenated amorphous solar cells  

International Nuclear Information System (INIS)

Transparent conducting thin films of undoped and aluminium doped zinc oxide have been deposited by spray pyrolysis technique. The substrate temperature, solution spray rate and aluminium concentration have been identified as the important deposition parameters and their effects on the electrical optical and microstructural properties have been studied. Films having Al/Zn ratio of 1.75 at. %, deposited under optimized condition exhibit good transparent conducting properties (T/sub v/ is approx. equal to 83 % and R/sub s/ is approx. equal to 12-20 omega/square). zinc oxide based hydrogenated amorphous silicon solar cells (Glass/ZnO: Al/Pin/Al) have been fabricated by PECVD (Plasma enhanced chemical vapour deposition) technique. The measurement of I-V characteristic and spectral response of these cells has been investigated. (author)

318

Thin film fuel cell electrodes.  

Science.gov (United States)

Earlier work shows that fuel cell electrodes prepared by sputtering thin films of platinum on porous vycor substrates avoid diffusion limitations even at high current densities. The presented study shows that the specific activity of sputtered platinum is not unusually high. Performance limitations are found to be controlled by physical processes, even at low loadings. Catalyst activity is strongly influenced by platinum sputtering parameters, which seemingly change the surface area of the catalyst layer. The use of porous nickel as a substrate shows that pore size of the substrate is an important parameter. It is noted that electrode performance increases with increasing loading for catalyst layers up to two microns thick, thus showing the physical properties of the sputtered layer to be different from platinum foil. Electrode performance is also sensitive to changing differential pressure across the electrode. The application of sputtered catalyst layers to fuel cell matrices for the purpose of obtaining thin total cells appears feasible.

Asher, W. J.; Batzold, J. S.

1972-01-01

319

Self-assembled hollow nanosphere arrays used as low Q whispering gallery mode resonators on thin film solar cells for light trapping.  

Science.gov (United States)

Optical micro/nano-spherical cavities can be designed to confine light by generating resonances in whispering gallery modes (WGM) and then couple them into the substrate through leaky modes, which can be potentially used in thin film solar cells for absorption enhancements. In this work, the transparent ZnO electrodes in a hollow nanosphere (HNS) structure were proposed as WGM resonators to trap sunlight for the absorption enhancement in silicon thin film solar cells. A low cost and high throughput template based technology was developed to fabricate the ZnO HNS arrays on the Si substrates. Significant simulated absorption enhancement has been demonstrated on the ZnO HNS arrays decorated thin film solar cell with an active layer down to 250 nm in thickness. A 9.3% enhancement in the short circuit current density can be achieved theoretically by comparing the ZnO HNS array modified amorphous Si thin film solar cell with an anti-reflection layer configured cell. PMID:23999602

Yin, Jun; Zang, Yashu; Yue, Chuang; He, Xu; Li, Jing; Wu, Zhihao; Fang, Yanyan

2013-10-21

320

Process for fabricating polycrystalline semiconductor thin-film solar cells, and cells produced thereby  

Science.gov (United States)

A novel, simplified method for fabricating a thin-film semiconductor heterojunction photovoltaic device includes initial steps of depositing a layer of cadmium stannate and a layer of zinc stannate on a transparent substrate, both by radio frequency sputtering at ambient temperature, followed by the depositing of dissimilar layers of semiconductors such as cadmium sulfide and cadmium telluride, and heat treatment to convert the cadmium stannate to a substantially single-phase material of a spinel crystal structure. Preferably, the cadmium sulfide layer is also deposited by radio frequency sputtering at ambient temperature, and the cadmium telluride layer is deposited by close space sublimation at an elevated temperature effective to convert the amorphous cadmium stannate to the polycrystalline cadmium stannate with single-phase spinel structure.

Wu, Xuanzhi (Golden, CO); Sheldon, Peter (Lakewood, CO)

2000-01-01

 
 
 
 
321

A study of crystallinity in amorphous Si thin films for silicon heterojunction solar cells  

Energy Technology Data Exchange (ETDEWEB)

In this work we analyzed the crystallinity of hydrogenated amorphous Si thin films deposited on n-type Si substrates using the effective medium approximation (EMA) method of a spectroscopic ellipsometer (SE) and evaluated their passivation quality by measuring effective carrier lifetime ({tau}{sub eff}) and implied V{sub oc} using quasi-steady-state photo conductance decay (QSSPC) simultaneously. The crystalline volume fraction of doped a-Si:H layers using RF-PECVD was controlled from {proportional_to}0% (nearly full amorphous phase) to above 90% (nearly polycrystalline phase) through varying deposition conditions. The passivation property depended on the crystallinity more strongly for p-a-Si:H than n-a-Si:H of which crystallinity was more sensitive to deposition rate relatively. The implied V{sub oc} above 650 mV was achieved with crystallinity less than about 5% for p-a-Si:H and 20% for n-a-Si:H. The HRTEM images confirmed the reliability of SE analysis with EMA modeling and showed the maximum part of crystalline phase exists at the interface of a-Si:H and c-Si in the form of epitaxial growth configuration. By the optimization of each a-Si:H deposition conditions 17.17% the cell efficiency was accomplished on non-textured substrate. (author)

Ji, Kwang-sun [Solar Energy Group, Devices and Materials Lab., LG Electronics Advanced Research Institutes, Seoul (Korea, Republic of); Meterials Science and Engineering, Korea University, Seoul (Korea, Republic of); Choi, Junghoon; Yang, Hyunjin; Lee, Heon-Min [Solar Energy Group, Devices and Materials Lab., LG Electronics Advanced Research Institutes, Seoul (Korea, Republic of); Kim, Donghwan [Meterials Science and Engineering, Korea University, Seoul (Korea, Republic of)

2011-01-15

322

Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Aluminum-doped zinc oxide (ZnO:Al) can fulfill many requirements in thin-film solar cells, acting as (1) a transparent contact through which the incident light is transmitted, (2) part of the back reflector, and (3) a source of light scattering. Magnetron sputtered ZnO:Al thin-films are highly transparent, conductive, and are typically texturized by post-deposition etching in a dilute hydrochloric acid (HCl) solution to achieve light scattering. The ZnO:Al thin-film electronic and optical properties, as well as the surface texture after etching, depend on the deposition conditions and the post-deposition treatments. Despite having been used in thin-film solar cells for more than a decade, many aspects regarding the growth, effects of heat treatments, environmental stability, and etching of sputtered ZnO:Al are not fully understood. This work endeavors to further the understanding of ZnO:Al for the purpose improving silicon thin-film solar cell efficiency and reducing ZnO:Al production costs. With regard to the growth of ZnO:Al, the influence of various deposition conditions on the resultant electrical and structural properties and their evolution with film thickness were studied. The surface electrical properties extracted from a multilayer model show that while carrier concentration of the surface layer saturates already at film thickness of 100 nm, the surface mobility continues to increases with film thickness, and it is concluded that electronic transport across grain boundaries limits mobility in ZnO:Al thin films. ZnO:Al deposited onto a previously etched ZnO:Al surface grows epitaxially, preserving both the original orientation and grain structure. Further, it is determined that a typical ZnO:Al used in thin-film silicon solar cells grows Zn-terminated on glass substrates. Concerning the affects of heat treatments and stability, it is demonstrated that a layer of amorphous silicon can protect ZnO:Al from degradation during annealing, and the mobility of ZnO:Al films can be increased up to 76 cm{sup 2}/Vs by annealing at high temperatures. Further, it is observed that this annealing process does not affect the morphology of the film and increases the total transmission in the solar cell relevant portion of the spectrum. Accelerated aging in a damp-heat is shown to affect the mobility primarily, and is thus likely related to poor transport across grain boundaries. Using deuterium as an isotopic marker, it is observed that the deuterium uptake was fairly linear with time and penetrated the whole film within 24 hours. Additionally, the deuterium is quickly replaced by hydrogen upon damp-heat treatment in water. It is concluded that the electrical degradation is related to the penetration of water via grain boundaries, and that the bulk of the reactions causing this degradation are fairly weak, such as the formation of zinc hydroxide. Additionally, the annealed high-mobility ZnO:Al films prove to be very stable in the damp-heat environment, exhibiting electron mobilities above 70 cm{sup 2}/Vs after 1000 hours of exposure. The initial points of attack during HCl etching of ZnO:Al, and the long-term etch evolution are shown to be related to certain grain boundaries built into the film during growth. The density of craters from an HCl etch is controllable by altering the temperature and concentration of the etching solution. It is further demonstrated that most acids exhibit etching behavior similar to that of HCl. Hydrofluoric acid (HF), however, exhibits unique etching characteristics with higher crater densities and sharper features. The crater density and shape are also shown to be controllable by etching in various concentrations of HF and in various mixtures of HF and HCl. Additional etching experiments are made to develop a polycrystalline ZnO:Al etching model. It is shown that basic and acidic solutions attack the same points on a polycrystalline ZnO:Al sample. The dependence of crater density on the acid concentration, temperature, and type holds true for single crystal ZnO. Planar and cross-sectional transmissio

Owen, Jorj Ian

2011-07-01

323

Influence of contaminations on the performance of thin-film silicon solar cells prepared after in situ reactor plasma cleaning  

International Nuclear Information System (INIS)

This paper addresses the influence of the chemical memory effect (CME) of in situ plasma cleaning by using the fluorinated gases on the properties of subsequently deposited thin-film silicon solar cells and discusses methods to avoid or reduce this effect. Secondary ion mass spectrometry (SIMS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) profiles analysis showed a high impurity concentration in the intrinsic (i)-layer of p-i-n solar cells prepared directly after in situ cleaning. With increasing number of cell depositions these contaminations decrease and the solar cell performance recovers to the standard value. Restoring solar cell performance is accompanied by a decrease of contaminants concentration in the i-layer. The intentional variation of the F-content in the i-layer obtained by adding SiF4 to the process gas mixture during a-Si:H i-layer preparation reveals that for solar cells a fluorine content above 1.5 x 1019 cm-3 is critical. We applied NF3 or SF6 + O2 as cleaning gases and optimized the cleaning procedure. In case of using NF3 as the cleaning gas, the CME was less pronounced as compared to the SF6 + O2 case and by additional procedures, like increasing the total gas flow rate during deposition, hydrogen plasma treatment of reaction chamber, the high solar cell quality could be achieved directly after in situ reactor cleaning. Low concentfter in situ reactor cleaning. Low concentration of impurities in such cells was observed. Also the long-term illumination test (light-soaking for 1000 h, AM1.5 radiation) shows the same stabilized efficiency as compared to reference cells

324

Band alignment in SnS thin-film solar cells: Possible origin of the low conversion efficiency  

Science.gov (United States)

Tin sulfide is an attractive absorber material for low-cost thin-film solar cells. Despite the ideal physical properties of bulk SnS, the photovoltaic conversion efficiencies achieved in devices to date have been no greater than 2%. Assessment of the valence band energy of the stable orthorhombic phase of SnS reveals a low ionisation potential (4.7 eV) in comparison to typical absorber materials (CdTe, CuInSe2, and Cu2ZnSnS4). A band mis-alignment is therefore predicted with commonly used back contact and buffer layers. Alternative configurations are proposed that should improve device performance.

Burton, Lee A.; Walsh, Aron

2013-04-01

325

Nano-scale texturing of borosilicate glasses using CF4-based plasma discharge for application in thin film solar cells.  

Science.gov (United States)

Random plasma treatment techniques were used as a texturing method to reduce the surface reflection of glass substrates in thin film solar cells. Various gas mixtures were used for the plasma discharge in an effort to examine the texturing mechanism. Using a plasma treatment comprising CF4/O2 and CF4/Ar with a gas flow ratio of 1 to 2, the surface reflectance could be decreased to 6.83% and 6.82%, respectively. The surface treatment was very effective with the use of a low RF power of 50 W and an optimal time of 5 min. It is considered that the optical characteristics of the glass substrate are highly correlated to its surface morphology which can be produced not only through nano-scale chemical reactions with radicals but also through ion flux bombardment. PMID:22849147

Kim, Hyung Soo; Lim, Jung Wook; Yun, Sun Jin; Lee, Heon; Lee, Hee Chul

2012-04-01

326

A semiquantitative model of a porous silicon layer used as a light diffuser in a thin film solar cell  

Energy Technology Data Exchange (ETDEWEB)

An optical model of a porous silicon layer used as a light diffuser in thin-film solar cells is proposed in the framework of Twersky's multiple scattering theory of electromagnetic waves in random media. A clear distinction is made between the coherent and diffuse components of the field. The optical properties of the coherent field are described in terms of a complex refractive index calculated using Foldy-Twersky's integral equation, while the diffuse component is estimated by means of the Boltzmann-like radiative transfer equation. A brief description of the experimental verification of the model is then given. The model gives very good results for a low-porosity porous silicon layer sandwiched between the two crystalline silicon layers, but will hopefully give a good qualitative picture in more general situations.

Ghannam, M.Y. [ECE Department, College of Engineering and Petroleum, Kuwait University, Kuwait (Kuwait); Abouelsaood, A.A. [Department of Engineering Math. and Physics, Faculty of Engineering, Cairo University, Cairo (Egypt); Nijs, J.F. [IMEC, Kapeldreef 75, Leuven (Belgium)

2000-01-15

327

Chemical properties of the Cu(In,Ga)Se2/Mo/glass interfaces in thin film solar cells  

International Nuclear Information System (INIS)

The Cu(In,Ga)Se2/Mo and the Mo/glass interfaces in high efficiency thin film solar cells have been investigated by surface-sensitive photoelectron spectroscopy and bulk-sensitive X-ray emission spectroscopy. The interfaces were accessed by a suitable lift-off technique. Our experiments show a strong Se diffusion from the absorber into the Mo film, suggesting the formation of a MoSe2 layer in the surface-near region of the back contact. In addition, we find a Ga diffusion into the Mo back contact, while no diffusion of In and Cu occurs. Furthermore, we derive a detailed picture of the Na distribution near the back and front side of the Cu(In,Ga)Se2 absorber

328

Fabrication of dye sensitized solar cell using Cr doped Cu-Zn-Se type chalcopyrite thin film  

Energy Technology Data Exchange (ETDEWEB)

Chalcopyrites are a versatile class of semiconductors known for their potential in photovoltaic applications. Considering the well established CuInSe{sub 2} as a prototype system, a new compound of the chalcopyrite type, Cu{sub 1-x}Zn{sub 1-y}Se{sub 2-{delta}}, by replacing In with Zn, has been prepared (both undoped and 2% Cr doped) by the metallurgical method. Thin films have been deposited by the thermal evaporation technique using the stabilized polycrystalline compounds as charge. Structural, compositional, morphological, and optical properties of the films are analyzed and reported. Use of these films as electrodes in dye sensitized solar cell (DSSC) is demonstrated. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Joseph, D. Paul; Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India); Ganesan, S.; Suthanthiraraj, S. Austin; Maruthamuthu, P. [Department of Energy, University of Madras, Guindy Campus, Chennai 600 025 (India); Kovendhan, M. [Department of Physics, Presidency College, Chennai 600 005 (India)

2011-09-15

329

Photoluminescence of epitactical and polycrystalline CuInS2 layers for thin-film solar cells  

International Nuclear Information System (INIS)

The present thesis deals with one- and polycrystalline CuInS2 absorber layers for thin-film solar cells and especially with their optical and structural characterization. By means of detailed temperature- and power-dependent photoluminescence measurements in epitactical and polycrystalline absorber layers different radiative transitions could be analyzed and identified. The spectra were dominated by broad luminescence bands of deep perturbing levels. The implantation of hydrogen at low energies led to a passivation of these perturbing levels. On the base of the optical studies on epitactical and polycrystalline absorber layers a new improved defect model for CuInS2 could be developed. The model contains two donor and two acceptor levels with following ionization energies: D-1=46 meV, D-2=87 meV, A-1=70 meV, and A-2=119 meV

330

Photoelectrochemical solar cell properties of heteropolytungstic acid-incorporated TiO{sub 2} nanodisc thin films  

Energy Technology Data Exchange (ETDEWEB)

Thin film of heteropolytungstic acid (HPA)-incorporated TiO{sub 2} nanodisc was fabricated, and its photovoltaic performances were observed as a function of irradiation wavelength from 400 nm to 750 nm. Its incident photon-to-current efficiency (IPCE) was determined to be 18.6% around 500 nm, with energy conversion efficiency of 6.9%, which were observed to be further enhanced to 23% and 9%, respectively, by adsorption of ruthenium or porphyrin dyes. Complementary electron transports from both HPA and dyes to TiO{sub 2} nanodisc seems to avoid most of the backward electron or hole transfer reactions to enhance the photoelectrochemical efficiencies of dye-sensitized solar cells. (author)

Parayil, Sreenivasan Koliyat; Lee, Yu.Min; Yoon, Minjoong [Department of Chemistry, Chungnam National University, 220 Gun-dong, Yuseong-gu, Daejeon 305-764 (Korea)

2009-06-15

331

Preparation and characterization of TiO/sub 2/ thin films for photo electrochemical solar cells  

International Nuclear Information System (INIS)

TiO/sub 2/ thin films are deposited by electron beam evaporation technique at varying substrate temperature and accelerating voltages. Three samples are prepared at room temperature for different accelerating voltages. Three more samples are prepared for different substrate temperature, varied from room temperature to 300 deg. C, and at fixed accelerating voltage. The thin films so prepared are characterized optically, electrically and structurally. It is found that the resulting films have high transmission values, are of low resistivity and are amorphous in nature. (author)

332

Preparation routes based on magnetron sputtering for tungsten disulfide (WS{sub 2}) films for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The semiconductor tungsten disulfide (WS{sub 2}) exhibits van der Waals bonding, crystallizes in a layer-type structure and is of interest as an absorber layer for thin-film solar cells. In this review article different preparation routes for WS{sub 2} thin films, based on magnetron sputtering, are reviewed. Films prepared by direct magnetron sputtering, though exhibiting quite a good structural quality, are not or only poorly photoactive. This can be attributed to the generation of recombination centers, especially sulfur vacancies, during the ion bombardment of the films, due to the low defect-formation energy of tungsten disulfide, an intrinsic property of transition metal dichalcogenides. A promising preparation route, which leads to photoactive WS{sub 2} films, is a two-step process, where, in a first step, a sulfur-rich, X-ray amorphous tungsten sulfide is deposited at low substrate temperatures onto a thin metal film (Ni, Co). This film sandwich is after wards annealed in an ampoule in a sulfur atmosphere or in flowing gas with a sufficient H{sub 2}S partial pressure. From in-situ transmission electron microscopy and energy-dispersive X-ray diffraction, it was found that the WS{sub 2} film crystallization with a pronounced (001) texture is closely related to the formation of the liquid (eutectic) metal-sulfur phase. Based on these in-situ investigations the growth of the 2-dimensional WS{sub 2} nanosheets from an amorphous WS{sub 3+x} precursor can be described as an amorphous solid-liquid-crystalline solid process (SLS), somewhat similar to the well-known vapor-liquid-solid (VLS) process for the growth of whiskers or nanorods and nanotubes. Research opportunities, to overcome current limitations for a broad use of WS{sub 2} (and MoS{sub 2}) as thin-film solar cell absorbers are given. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Ellmer, K. [Hahn-Meitner-Institut, Abt. Solare Energetik, Berlin (Germany)

2008-09-15

333

Band gap grading and photovoltaic performance of solution-processed Cu(In,Ga)S2 thin-film solar cells.  

Science.gov (United States)

The photophysical properties of CuInxGa1-xS2 (CIGS) thin films, prepared by solution-based coating methods, are investigated to understand the correlation between the optical properties of these films and the electrical characteristics of solar cells fabricated using these films. Photophysical properties, such as the depth-dependent band gap and carrier lifetime, turn out to be at play in determining the energy conversion efficiency of solar cells. A double grading of the band gap in CIGS films enhances solar cell efficiency, even when defect states disturb carrier collection by non-radiative decay. The combinational stacking of different density films leads to improved solar cell performance as well as efficient fabrication because a graded band gap and reduced shunt current increase carrier collection efficiency. The photodynamics of minority-carriers suggests that the suppression of defect states is a primary area of improvement in CIGS thin films prepared by solution-based methods. PMID:25387997

Sohn, So Hyeong; Han, Noh Soo; Park, Yong Jin; Park, Seung Min; An, Hee Sang; Kim, Dong-Wook; Min, Byoung Koun; Song, Jae Kyu

2014-11-19

334

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

International Nuclear Information System (INIS)

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 pin 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%

335

Directly electrospinning growth of single crystal Cu2ZnSnS4 nanowires film for high performance thin film solar cell  

Science.gov (United States)

Quaternary kesterite-type Cu2ZnSnS4 nanowires can be used as absorbing materials for thin film solar cells. The structural, morphological, compositional, and optical properties of the CZTS nanowires have been studied using X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and optical absorption techniques respectively. The Cu2ZnSnS4 nanowires, fabricated by electrospinning process and sintered at 600 C in Argon atmosphere, the cells exhibits a power conversion efficiency of 6.18% under AM 1.5 solar irradiation in the thin film solar cells. This study suggests that the optimized Cu2ZnSnS4 composite nanowire is a promising absorbing material for high performance solar cells.

Chen, Lin-Jer; Chuang, Yu-Ju

2013-11-01

336

Hybrid solar cells based on thin-film silicon and P3HT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hybrid concepts based on a nanoscale combination of organic and inorganic semiconductors are a promising way to enhance the cost efficiency of solar cells through a better use of the solar spectrum, a higher aspect ratio of the interface, and the good processability of polymers. A new type of solar cells has been investigated. It is based on a heterojunction between regio-regular poly(3-hexylthiophene) as an organic electron donor and silicon as an inorganic electron acceptor. In a first step...

Alet, Pierre-jean; Palacin, Serge; Roca I Cabarrocas, Pere; Kalache, Billel; Firon, Muriel; Bettignies, Re?mi

2007-01-01

337

Comparative study of organic thin film tandem solar cells in alternative geometries  

Science.gov (United States)

Optical modeling of one folded tandem solar cell and four types of stacked tandem solar cells has been performed using the finite element method and the transfer matrix method for the folded cell and the stacked cells, respectively. The results are analyzed by comparing upper limits for short circuit currents and power conversion efficiencies. In the case of serial connected tandems all of the five cell types may be compared, and we find that the folded cells are comparable to stacked tandem cells in terms of currents and power conversion efficiencies.

Andersson, B. Viktor; Persson, Nils-Krister; Ingans, Olle

2008-12-01

338

Controlling the texture and crystallinity of evaporated lead phthalocyanine thin films for near-infrared sensitive solar cells.  

Science.gov (United States)

To achieve organic solar cells with a broadened spectral absorption, we aim to promote the growth of the near-infrared (NIR)-active polymorph of lead phthalocyanine (PbPc) on a relevant electrode for solar cell applications. We studied the effect of different substrate modification layers on PbPc thin film structure as a function of thickness and deposition rate (rdep). We characterized crystallinity and orientation by grazing incidence X-ray diffraction (GIXD) and in situ X-ray reflectivity (XRR) and correlated these data to the performance of bilayer solar cells. When deposited onto a self-assembled monolayer (SAM) or a molybdenum oxide (MoO3) buffer layer, the crystallinity of the PbPc films improves with thickness. The transition from a partially crystalline layer close to the substrate to a more crystalline film with a higher content of the NIR-active phase is enhanced at low rdep, thereby leading to solar cells that exhibit a higher maximum in short circuit current density (JSC) for thinner donor layers. The insertion of a CuI layer induces the formation of strongly textured, crystalline PbPc layers with a vertically homogeneous structure. Solar cells based on these templated donor layers show a variation of JSC with thickness that is independent of rdep. Consequently, without decreasing rdep we could achieve JSC=10 mA/cm2, yielding a bilayer solar cell with a peak external quantum efficiency (EQE) of 35% at 900 nm, and an overall power conversion efficiency (PCE) of 2.9%. PMID:23905883

Vasseur, Karolien; Broch, Katharina; Ayzner, Alexander L; Rand, Barry P; Cheyns, David; Frank, Christian; Schreiber, Frank; Toney, Michael F; Froyen, Ludo; Heremans, Paul

2013-09-11

339

Advances in Evaporated Solid-Phase-Crystallized Poly-Si Thin-Film Solar Cells on Glass (EVA  

Directory of Open Access Journals (Sweden)

Full Text Available Polycrystalline silicon thin-film solar cells on glass obtained by solid-phase crystallization (SPC of PECVD-deposited a-Si precursor diodes are capable of producing large-area devices with respectable photovoltaic efficiency. This has not yet been shown for equivalent devices made from evaporated Si precursor diodes (“EVA” solar cells. We demonstrate that there are two main problems for the metallization of EVA solar cells: (i shunting of the p-n junction when the air-side metal contact is deposited; (ii formation of the glass-side contact with low contact resistance and without shunting. We present a working metallization scheme and first current-voltage and quantum efficiency results of 2 cm2 EVA solar cells. The best planar EVA solar cells produced so far achieved fill factors up to 64%, series resistance values in the range of 4-5 Ωcm2, short-circuit current densities of up to 15.6 mA/cm2, and efficiencies of up to 4.25%. Using numerical device simulation, a diffusion length of about 4 μm is demonstrated for such devices. These promising results confirm that the device fabrication scheme presented in this paper is well suited for the metallization of EVA solar cells and that the electronic properties of evaporated SPC poly-Si materials are sufficient for PV applications.

A. G. Aberle

2009-01-01

340

Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.  

Science.gov (United States)

A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell. PMID:25138735

Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

2014-10-01

 
 
 
 
341

Development of a Thin-Film Solar Cell Interconnect for the Powersphere Concept  

Science.gov (United States)

Dual junction amorphous silicon (a-Si) solar cells produced on polyimide substrate have been selected as the best candidate to produce a lightweight solar array for the PowerSphere program. The PowerSphere concept features a space-inflatable, geodetic solar array approximately 0.6 meters in diameter and capable of generating about 20W of electrical power. Trade studies of various wiring concepts and connection methods led to an interconnect design with a copper contact that wraps around the edge, to the back of the solar cell. Applying Plasma Vapor Deposited (PVD) copper film to both sides and the edge of the solar cell produces the wrap around contact. This procedure results in a contact pad on the back of the solar cell, which is then laser welded to a flex circuit material. The flex circuit is constructed of copper in a custom designed routing pattern, and then sandwiched in a Kapton insulation layer. The flex circuit then serves as the primary power distribution system between the solar cells and the spacecraft. Flex circuit material is the best candidate for the wiring harness because it allows for low force deployment of the solar cells by the inflatable hinges on the PowerSphere. An additional frame structure, fabricated and assembled by ILC Dover, will reinforce the wrap around contact-flex blanket connection, thus providing a mechanically robust solar cell interconnect for the PowerSphere multifunctional program. The PowerSphere team will use the wraparound contact design approach as the primary solution for solar cell integration and the flex blanket for power distribution.

Simburger, Edward J.; Matsumoto, James H.; Giants, Thomas W.; Garcia, Alexander, III; Liu, Simon; Rawal, Suraj P.; Perry, Alan R.; Marshall, Craig; Lin, John K.; Scarborough, Stephen E.

2005-01-01

342

Towards high efficiency thin-film crystalline silicon solar cells: The roles of light trapping and non-radiative recombinations  

International Nuclear Information System (INIS)

Thin-film solar cells based on silicon have emerged as an alternative to standard thick wafers technology, but they are less efficient, because of incomplete absorption of sunlight, and non-radiative recombinations. In this paper, we focus on the case of crystalline silicon (c-Si) devices, and we present a full analytic electro-optical model for p-n junction solar cells with Lambertian light trapping. This model is validated against numerical solutions of the drift-diffusion equations. We use this model to investigate the interplay between light trapping, and bulk and surface recombination. Special attention is paid to surface recombination processes, which become more important in thinner devices. These effects are further amplified due to the textures required for light trapping, which lead to increased surface area. We show that c-Si solar cells with thickness of a few microns can overcome 20% efficiency and outperform bulk ones when light trapping is implemented. The optimal device thickness in presence of light trapping, bulk and surface recombination, is quantified to be in the range of 1080??m, depending on the bulk quality. These results hold, provided the effective surface recombination is kept below a critical level of the order of 100?cm/s. We discuss the possibility of meeting this requirement, in the context of state-of-the-art techniques for light trapping and surface passivation. We show that our predictions are within the capability of present day silicon technologies

343

Towards high efficiency thin-film crystalline silicon solar cells: The roles of light trapping and non-radiative recombinations  

Science.gov (United States)

Thin-film solar cells based on silicon have emerged as an alternative to standard thick wafers technology, but they are less efficient, because of incomplete absorption of sunlight, and non-radiative recombinations. In this paper, we focus on the case of crystalline silicon (c-Si) devices, and we present a full analytic electro-optical model for p-n junction solar cells with Lambertian light trapping. This model is validated against numerical solutions of the drift-diffusion equations. We use this model to investigate the interplay between light trapping, and bulk and surface recombination. Special attention is paid to surface recombination processes, which become more important in thinner devices. These effects are further amplified due to the textures required for light trapping, which lead to increased surface area. We show that c-Si solar cells with thickness of a few microns can overcome 20% efficiency and outperform bulk ones when light trapping is implemented. The optimal device thickness in presence of light trapping, bulk and surface recombination, is quantified to be in the range of 10-80 ?m, depending on the bulk quality. These results hold, provided the effective surface recombination is kept below a critical level of the order of 100 cm/s. We discuss the possibility of meeting this requirement, in the context of state-of-the-art techniques for light trapping and surface passivation. We show that our predictions are within the capability of present day silicon technologies.

Bozzola, A.; Kowalczewski, P.; Andreani, L. C.

2014-03-01

344

A porous silicon intermediate reflector in thin film epitaxial silicon solar cells as a gettering site of impurities  

Energy Technology Data Exchange (ETDEWEB)

In this work, we study the gettering properties of a porous silicon (Psi) intermediate reflector. This type of reflector is used currently in the thin film epitaxial silicon solar cell approach. The porous layers are electrochemically etched into low-cost, highly contaminated UMG (Upgraded Metallurgical Grade) Si in order to investigate the influence of impurity diffusion to the active layer due to the high thermal budget during epitaxial growth. When implemented into a solar cell, a porous silicon (Psi) multilayer stack consisting of layers with alternating porosities can serve as a gettering site for impurities that originate from the substrate. This statement is confirmed in our present work by several techniques such as SIMS (Secondary Ion Mass Spectrometry) and TXRF (Total Reflection X-Ray Fluorescence). Additionally to these experiments, solar cell results are presented, for which the active layer is grown with two different growth rates on top of porous silicon (Psi) multilayer stack and on two different types of multicrystalline silicon substrates: UMG (Upgraded Metallurgical Grade) and OFFSPEC (Out-of spec silicon material treated as a waste from Integrated Circuits industry). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Kuzma-Filipek, Izabela; Duerinckx, Filip; Nieuwenhuysen, Kris van; Beaucarne, Guy; Poortmans, Jef; Mertens, Robert [Imec, SOLO/SCT, Leuven (Belgium)

2009-07-15

345

Effect of chlorine activation treatment on electron beam induced current signal distribution of cadmium telluride thin film solar cells  

Science.gov (United States)

We have investigated CdTe thin film solar cells without activation treatment and with CdCl2 activation treatment at temperatures between 370 and 430 C using a constant activation time of 25 min. For this purpose, CdS/CdTe layers were deposited by closed-space-sublimation on FTO coated float glass. The solar cells were characterized by measurements of the JV characteristics and quantum efficiencies. In addition, ion polished cross sections of the solar cells were prepared for high-resolution FE-SEM imaging of the microstructure and the simultaneous registration of electron beam induced current (EBIC) signal distribution. By measurement of the EBIC signal distribution, it can be shown that without activation treatment the CdTe grain boundaries itself and grain boundary near regions exhibit no EBIC signal, whereas centres of some singular grains already show a distinct EBIC signal. In contrast, after the chlorine activation treatment, the grain boundary near regions exhibit a significant higher EBIC signal than the centre of the grains. The results can be discussed as a direct evidence for defect passivation of grain boundary near regions by the chlorine activation treatment. At activation temperature of 430 C, additionally, a significant grain growth and agglomeration of the CdS layer can be recognized, which is linked with the formation of voids within the CdS layer and a deterioration of pn junction properties.

Zywitzki, Olaf; Modes, Thomas; Morgner, Henry; Metzner, Christoph; Siepchen, Bastian; Spth, Bettina; Drost, Christian; Krishnakumar, Velappan; Frauenstein, Sven

2013-10-01

346

Surface modification of ZnO-Films as transparent conductive oxide layer for silicon thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Transparent conductive oxides are used as front electrode in thin film solar cells. Especially ZnO deposited by Low Pressure Chemical Vapor Deposition provides useful features for solar cells. On the one hand ZnO shows a good conductivity and on the other hand a rough surface consisting of pyramidal grains which possess a good light scattering capability. To influence this light scattering, two different kinds of treatments have been applied on the ZnO surface: etching with diluted HCl and Reactive Ion Etching with Ar and O{sub 2}. The main interest is focused on the change of surface morphology and the resulting changes in light scattering and transmission. HCl etching leads to an increasing surface roughness as well as diffuse transmittance. Ar/O{sub 2} bombardment decreases the roughness and thus the scattering. The lowered roughness enhances the growth of the a-Si absorber layer and reduces the formation of pinholes. Finally the properties of amorphous silicon solar cells deposited on treated ZnO-films are compared with those deposited on untreated films.

Luekermann, Florian; Moenkemoeller, Viola; Brechling, Armin; Sacher, Marc; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Kurz, Henning; Hamelmann, Frank; Stiebig, Helmut [Malibu GmbH, Bielefeld (Germany)

2009-07-01

347

The effect of the CdCl2 treatment on CdTe/CdS thin film solar cells studied using deep level transient spectroscopy  

International Nuclear Information System (INIS)

Thin film CdTe/CdS solar cells have been studied using deep level transient spectroscopy. The correlation-deep level transient spectroscopy (DLTS) technique was utilized as conventional analysis methods such as the boxcar-based approach were found to be inadequate under certain experimental conditions. The primary objective was to study the effect of a key processing step in the fabrication of thin film CdTe solar cells, namely the post-deposition heat treatment in the presence of CdCl2. The substrate temperature as well as the ambient used during this process were varied around predetermined conditions for optimum solar cell performance, in order to identify performance-limiting defects, and in general improve our understanding of thin film CdTe solar cells. Solar cells without the CdCl2 heat treatment were also fabricated. A series of electron and hole traps were found in the various devices studied, with electron traps being present primarily in solar cells with limited performance

348

Structural, morphological, optical and compositional characterization of spray deposited Ga doped ZnO thin film for Dye-Sensitized Solar Cell application  

Science.gov (United States)

Zinc Oxide and Gallium doped Zinc Oxide films have been deposited by the Spray Pyrolysis method onto preheated glass substrates using Zinc acetate and Gallium (III) acetyl acetonate as precursors for Zn and Ga ions, respectively. The effect of ZnO and Ga doping on the structural, morphological, optical and chemical properties of sprayed ZnO and Gallium doped ZnO thin films were investigated. XRD studies reveal that the films are crystalline with hexagonal (wurtzite) crystal structure. The average transparency in the visible range was around 75% for the thin film deposited using Gallium doping. X-ray Photoelectron Spectroscopy (XPS) was utilized to view the changes in the oxidation state of ZnO and Gallium doped ZnO thin films. The ZnO and Gallium doped ZnO thin film has been deposited above the Indium Tin Oxide (ITO) coated glass substrate. The efficiency of the obtained DSSC measured for 0.1 M ZnO thin film by sensitizing for 12 h was, ? = 2.5%. Similarly for Gallium doped Zinc Oxide, the efficiency ? is found to be 3.9%, 4.1% and 4.3% for every increase in doping of Gallium concentrations which is utilized for the application of Dye-Sensitized Solar Cell.

Amala Rani, A.; Ernest, Suhashini

2014-11-01