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1

Thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Thin film solar cells need for their production only a small amount of materials and energy. By the thin-film-technology a great number of material combinations for solar cells can be realized. The developed systems of CdS/Cusub(x)S and of amorphous silicon are reported and the possibilities to reach higher efficiencies are discussed.

Bloss, W.H. (Stuttgart Univ. (TH) (Germany, F.R.). Inst. fuer Physikalische Elektronik)

1980-07-01

2

Thin-film solar cells  

International Nuclear Information System (INIS)

The rapid progress that is being made with inorganic thin-film photovoltaic (PV) technologies, both in the laboratory and in industry, is reviewed. While amorphous silicon based PV modules have been around for more than 20 years, recent industrial developments include the first polycrystalline silicon thin-film solar cells on glass and the first tandem solar cells based on stacks of amorphous and microcrystalline silicon films ('micromorph cells'). Significant thin-film PV production levels are also being set up for cadmium telluride and copper indium diselenide.

2009-07-01

3

Thin film solar cell module  

Energy Technology Data Exchange (ETDEWEB)

A thin film solar cell module is described comprising a first solar cell panel containing an array of solar cells consisting of a TFS semiconductor sandwiched between a transparent conductive zinc oxide layer and a transparent conductive layer selected from the group consisting of tin oxide, indium tin oxide, and zinc oxide deposited upon a transparent superstrate, and a second solar cell panel containing an array of solar cells consisting of a CIS semiconductor layer sandwiched between a zinc oxide semiconductor layer and a conductive metal layer deposited upon an insulating substrate. The zinc oxide semiconductor layer contains a first relatively thin layer of high resistivity zinc oxide adjacent the CIS semiconductor and a second relatively thick layer of low resistivity zinc oxide overlying the high resistivity zinc oxide layer. The transparent conductive zinc oxide layer of the first panel faces the low resistivity zinc oxide layer of the second panel, the first and second panels being positioned optically in series and separated by a transparent insulating layer.

Gay, R.R.

1987-01-20

4

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

5

Thin film solar cells: why? how? When?  

Energy Technology Data Exchange (ETDEWEB)

Crystallized silicon solar cells remain the best choose for high efficiency applications. Other applications could be developed in industrialized countries, such as building or house integrated solar generators designed to limit peak hours power demand. For these applications with reduced installation costs, thin film solar cells constitute a good solution. This article gives a comparative evaluation of the different technologies, and an analysis of commercial aspects. (D.L.). 22 refs., 11 figs., 3 photos.

Rodot, M.; Ricaud, A.

1994-09-01

6

US polycrystalline thin film solar cells program  

Energy Technology Data Exchange (ETDEWEB)

The Polycrystalline Thin Film Solar Cells Program, part of the United States National Photovoltaic Program, performs R D on copper indium diselenide and cadmium telluride thin films. The objective of the Program is to support research to develop cells and modules that meet the US Department of Energy's long-term goals by achieving high efficiencies (15%-20%), low-cost ($50/m{sup 2}), and long-time reliability (30 years). The importance of work in this area is due to the fact that the polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells and modules have made rapid advances. They have become the leading thin films for PV in terms of efficiency and stability. The US Department of Energy has increased its funding through an initiative through the Solar Energy Research Institute in CuInSe{sub 2} and CdTe with subcontracts to start in Spring 1990. 23 refs., 5 figs.

Ullal, H S; Zweibel, K; Mitchell, R L [Solar Energy Research Inst., Golden, CO (USA)

1989-11-01

7

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

1987-09-18

8

Thin film solar cell. Usumaku taiyo denchi  

Energy Technology Data Exchange (ETDEWEB)

The thin film solar cell in which a back electrode is formed by the printing process has big contact resistance between the printed electrode and the semiconductor layer and its series resistance component is big, hence in using it for power generation under the solar beams, the above resistance component affects greatly the output characteristics of the photoelectric transfer element. In other words, as the quantity of incident light increases, its film factor decreases, restricting the conversion efficiency considerably. In order to remove this defect, concerning the thin film photoelectric transfer element with a photoelectric transfer segment consisting of semiconductor thin films, which derive the photoelectromotive power generated when the light enters into the photoelectric transfer segment through the insulated electroconductive substrate from the transparent electrode on the substrate side and the printed electrode on the side opposite to the substrate, this invention proposes to form the printed electrode, which contains approximately spherical molybdenum powder of 1.2 {mu} m or less in diameter as electroconductive material, by printing and baking the electroconductive paste with phenol resin as a binder. 4 figs.

Sato, H. (Fuji Electric Co. Ltd., Kawasaki (Japan))

1991-02-19

9

Thin film solar cell; Hakumaku taiyo denchi  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to a thin film solar cell which has consecutively laminated p-type semiconductor light absorbing layer, n-type semiconductor intermediate layer, n-type semiconductor intermediate layer, semiconductor window layer, and n-type transparent electrode layer on a substrate provided with electrode layer or on a metallic substrate having electrode property. It is desirable that the light absorbing layer is made of CuInSe2, CuInS2, CuGaSe2, CuGaS2, or their solid solution. The intermediate layer is desirable to be a solution deposited CdS layer. In addition, it is desirable that the window layer is made of ZnO and the transparent electrode layer is made of ZnO or ITO. With this structure, photoelectric conversion between the window layer and the transparent electrode layer is incorporated with the original photoelectric conversion between the light absorbing layer and the intermediate layer with no potential hindrance between the intermediate layer and the window layer, and the electric properties of the window layer, such as electron affinity, work function, and bandgap, are optimized to fabricate a high efficiency thin film solar cell because the photoelectric conversion between the light absorbing layer and the intermediate layer is not affected. 4 figs., 2 tabs.

Terauti, M.; Wada, T. [Matsushita Electric Industrial Co. Ltd., Kadoma, Osaka (Japan)

1997-07-31

10

Transparent conductive oxides for thin-film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination...

Lo?ffler, J.

2005-01-01

11

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

2001-01-01

12

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

Energy Technology Data Exchange (ETDEWEB)

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.

Schock, Hans-Werner; Pfisterer, Fritz [Stuttgart Univ. (Germany). Inst. fuer Physikalische Elektronik

2001-04-01

13

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

14

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

2012-02-01

15

Thin films of tin sulphide for use in thin film solar cell devices  

International Nuclear Information System (INIS)

SnS is of interest for use as an absorber layer and the wider energy bandgap phases e.g. SnS2, Sn2S3 and Sn/S/O alloys of interest as Cd-free buffer layers for use in thin film solar cells. In this work thin films of tin sulphide have been thermally evaporated onto soda-lime glass substrates with the aim of optimising the properties of the material for use in superstrate configuration device structures. The thin films were characterised using energy dispersive X-ray analysis (EDS) to determine the film composition, X-ray diffraction (XRD) to determine the phases present and structure of each phase, transmittance versus wavelength measurements to determine the energy bandgap and scanning electron microscopy (SEM) to observe the surface topology and topography. These properties were then correlated to the deposition parameters. Using the optimised conditions it is possible to produce thin films of tin sulphide that are pinhole free and conformal to the substrate that are suitable for use in thin film solar cell structures

2009-02-02

16

Structuring of thin film solar cells  

Science.gov (United States)

Laser structuring of different types of thin film layers is a state of the art process in the photovoltaic industry. TCO layers and molybdenum are structured with e.g. 1064 nm lasers. Amorphous silicon, microcrystalline silicon or cadmium telluride are ablated with 515/532 nm lasers. Typical pulse durations of the lasers in use for these material ablation processes are in the nanosecond range. Up to now the common process for CIS/CIGS cells is needle structuring. Hard metal needles scribe lines with a width of 30 to 60 ?m into the semiconductor material. A laser technology would have some advantages compared to mechanical scribing. The precision of the lines would be higher (no chipping effects), the laser has no wear out. The dead area (distance from P1 structuring line to P3 structuring line) can be significantly smaller with the laser technology. So we investigate the structuring of CIS/CIGS materials with ultra short pulse lasers of different wavelengths. The ablation rates and the structuring speeds versus the repetition rates have been established. For the different layer thicknesses and line widths we determined the necessary energy densities. After all tests we can calculate the possible reduction of the dead area on the thin film module. The new technology will result in an increase in the efficiency per module of up to 4 %.

Eberhardt, Gabriele; Banse, Henrik; Wagner, Uwe; Peschel, Thomas

2010-02-01

17

Annealing of Solar Cells and Other Thin Film Devices  

Science.gov (United States)

Annealing is a key step in most semiconductor fabrication processes, especially for thin films where annealing enhances performance by healing defects and increasing grain sizes. We have employed a new annealing oven for the annealing of CdTe-based solar cells and have been using this system in an attempt to grow US on top of CdTe by annealing in the presence of H2S gas. Preliminary results of this process on CdTe solar cells and other thin-film devices will be presented.

Escobar, Hector; Kuhlman, Franz; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

2001-01-01

18

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

1985-01-01

19

Development of A Thin Film Crystalline Silicon Solar Cell  

International Nuclear Information System (INIS)

A new design for a single junction, thin film Si solar cell is presented. The cell design is compatible with low-temperature processing required for the use of a low-cost glass substrate, and includes effective light trapping and impurity gettering. Elements of essential process steps are discussed

1998-09-08

20

2D modelling of polycrystalline silicon thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Teodoreanu Ana-Maria; Friedrich Felice; Leihkauf Rainer; Boit Christian; Leendertz Caspar; Korte Lars

2013-01-01

 
 
 
 
21

Photon upconversion for thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this research one of the many possible methods to increase the efficiency of solar cells is described. The method investigated is based on adapting the solar light in such a way that the solar cell can convert more light into electricity. The part of the solar spectrum that is adapted is the part that cannot be absorbed by the solar cells, because the photon energy is too low. This conversion of light is done by so called upconversion, which means that lower energy photons are converted i...

Wild, J.

2012-01-01

22

New thin film solar cells and development of tandem systems  

Energy Technology Data Exchange (ETDEWEB)

The structure and method of functioning of tandem systems in thin-film solar cells is outlined. Problems of putting into practice this kind of layout e.g. selection of suitable semiconductor materials and the layer sequence, are thoroughly discussed. The laboratory data already available indicate that levels of effectiveness approximately equal to or above those of single-crystal solar cells could be attained.

Pfisterer, F.; Schock, H.W.; Arndt, W.; Bloss, W.H.

1982-01-01

23

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

24

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

25

Molybdenum back-contact optimization for CIGS thin film solar cell  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

26

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

2008-08-30

27

Polycrystalline silicon thin-film solar cells on various substrates  

Energy Technology Data Exchange (ETDEWEB)

Thin-film polycrystalline silicon solar cells have been fabricated on various substrates, such as inactive P{sup ++} mono-crystalline silicon substrates, p{sup ++} mono-Si substrates covered by thermally oxidized SiO{sub 2} and ceramic substrates by means of a rapid thermal chemical vapour deposition (RTCVD) technique. Zone melting recrystallization (ZMR) was applied in the process in order to enlarge the grain size of the deposited silicon thin film. The deposition conditions were studied. The scanning rate of the ZMR process was investigated. The best conversion efficiency of 15.12% (AM1.5G, 24.5 C) has been achieved on inactive P{sup ++} mono-crystalline silicon substrates without cell surface texture and 10.21% (AM1.5, 24.5 C) on p{sup ++} c-Si substrates covered by thermally oxidized SiO{sub 2} with the cell area of 1.07 cm{sup 2}. The polycrystalline silicon thin film was also deposited on Al{sub 2}O{sub 3} substrates by a RTCVD process. A simple ZMR process was used without any intermediate layer and cap layers. The maximum grain size of the silicon thin film was about one millimeter in width and a few millimeters in length after ZMR. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Wang, Wenjing [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Xu, Ying [Beijing Solar Energy Research Institute, Beijing 100083 (China); Shen, Hui [Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510070 (China)

2006-03-15

28

Characterization of CdTe thin film solar cells  

International Nuclear Information System (INIS)

The authors present experimental results on two types of solar cells produced from electrodeposited CdTe thin films, i.e., n-i-p CdS/CdTe/ZnTe and n-p CdS/CdTe structures. Some of the unique properties of the n-i-p structure are highlighted. They show that the distribution of the electric field in the entire CdTe layer is crucial to the production of high efficiency

1988-09-26

29

TCOs for nip thin film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Substrate configuration allows for the deposition of thin film silicon (Si) solar cells on non-transparent substrates such as plastic sheets or metallic foils. In this work, we develop processes compatible with low Tg plastics. The amorphous Si (a-Si:H) and microcrystalline Si (c-Si:H) films are deposited by plasma enhanced chemical vapour deposition, at very high excitation frequencies (VHF-PECVD). We investigate the optical behaviour of single and triple ju...

So?derstro?m, T.; Haug, F-j; Niquille, X.; Ballif, C.

2009-01-01

30

Transparent conductive oxides for thin-film silicon solar cells  

Science.gov (United States)

This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150 C and 350 C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the cells on ETP ZnO. The solar cells deposited on the first doped ZnO:Al layers suffered from collection problems reducing the fill factor, and from shunting. This is attributed to the steep trenches, sharp features and vertical steps that have been identified at the TCO surface. ZnO:Al layers with granular structure, deposited at higher argon flow through the cascaded arc plasma source, allowed for fill factors of the solar cells up to 0.70, comparable to cells on undoped ZnO. The best solar cell on doped ZnO:Al deposited by ETP CVD achieved an efficiency of 9.3 % which is comparable to the 9.4 % obtained on Asahi U-type SnO2:F. Fluorinated tin oxide has been deposited by Atmospheric Chemical Vapor Deposition (APCVD) on glass from three different tin precursors, tetramethyltin, monobutyltin trichloride, and tin tetrachloride (TTC). TTC is the Sn precursor which resulted in the TCO with the best performance of a-Si:H pin solar cells. In accordance with the conclusions from our experiments with solar cells on undoped and aluminum doped zinc oxide, a high surface roughness and haze do not necessarily lead to a lower diode quality, and vice versa.

Lffler, J.

2005-04-01

31

Plasmonic versus dielectric enhancement in thin-film solar cells  

DEFF Research Database (Denmark)

Several studies have indicated that broadband absorption of thin-film solar cells can be enhanced by use of surface-plasmon induced resonances of metallic parts like strips or particles. The metallic parts may create localized modes or scatter incoming light to increase absorption in thin-film semiconducting material. For a particular case, we show that coupling to the same type of localized slab-waveguide modes can be obtained by a surface modulation consisting of purely dielectric strips. The purely dielectric device turns out to have a significantly higher broadband enhancement factor compared to its metallic counterpart. We show that the enhanced normalized short-circuit current for a cell with silicon strips can be increased 4 times compared to the best performance for strips of silver, gold, or aluminium. For this particular case, the simple dielectric grating may outperform its plasmonic counterpart due to the larger Ohmic losses associated with the latter.

Dühring, Maria Bayard; Mortensen, N. Asger

2012-01-01

32

Laser annealing of thin film polycrystalline silicon solar cell  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

2013-11-01

33

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

34

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

35

Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells  

Science.gov (United States)

As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

Winans, Joshua David

36

???????????????? 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

37

Thin-film Solar Cells for Space Applications  

Science.gov (United States)

The proposed work supports MURED goals by fostering research and development activities at Fisk and UTEP which contribute substantially to NASA's mission, preparing faculty and students at Fisk and UTEP to successfully participate in the conventional, competitive research and education process, and increasing the number of students to successfully complete degrees in NASA related fields. The project also addresses directly a core need of NASA for space power and is consistent with the Core Responsibilities of the John Glenn Space Center. Current orbital missions are limited by radiation from high energy particles trapped in the Van Allen Belt because that solar radiation degrades cell performance by damaging the crystalline lattice. Some potential orbits have been inaccessible because the radiation is too severe. Thin-film solar cells, if they can be adapted for use in the unfriendly space environment, could open new orbits to satellites by providing a radiation hard source of power. The manned mission to Mars requires photovoltaic devices for both the trip there and as a power supply on the surface. Solar arrays using thin films offer a low power/weight ratio solution that provides reliable photovoltaic power.

Lush, Gregory B.

2003-01-01

38

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.

2011-03-13

39

Chemically Deposited Thin-Film Solar Cell Materials  

Science.gov (United States)

We have been working on the development of thin film photovoltaic solar cell materials that can be produced entirely by wet chemical methods on low-cost flexible substrates. P-type copper indium diselenide (CIS) absorber layers have been deposited via electrochemical deposition. Similar techniques have also allowed us to incorporate both Ga and S into the CIS structure, in order to increase its optical bandgap. The ability to deposit similar absorber layers with a variety of bandgaps is essential to our efforts to develop a multi-junction thin-film solar cell. Chemical bath deposition methods were used to deposit a cadmium sulfide (CdS) buffer layers on our CIS-based absorber layers. Window contacts were made to these CdS/CIS junctions by the electrodeposition of zinc oxide (ZnO). Structural and elemental determinations of the individual ZnO, CdS and CIS-based films via transmission spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive spectroscopy will be presented. The electrical characterization of the resulting devices will be discussed.

Raffaelle, R.; Junek, W.; Gorse, J.; Thompson, T.; Harris, J.; Hehemann, D.; Hepp, A.; Rybicki, G.

2005-01-01

40

Cu(In,Al)S2 Thin Film Solar Cell  

Science.gov (United States)

A Cu(In,Al)S2 thin film solar cell has exhibited good adhesion to Mo-coated glass and comparatively high efficiency. The sputter-deposited metallic precursor was sulfurized and then treated in a KCN solution to remove a CuxS impurity phase and an excessive Al compound from the film surface. When the precursor layer was Cu-rich, the treated sulfide film could be used as an efficient absorber material. It had the same band gap as CuInS2. The spectral response of the cell was increased in a short wavelength range. The bottom region of the film was considered to consist of a Cu(In,Al)S2 alloy that enhanced the film adhesion to the Mo back contact. The film was analyzed using X-ray diffraction, electron probe microanalysis, scanning electron microscopy and field ion microscopy combined with focused ion beam technique.

Inazu, Takuya; Bhandari, Ramesh Kumar; Kadowaki, Yuji; Hashimoto, Yoshio; Ito, Kentaro

2005-03-01

 
 
 
 
41

Optimization of photonics for corrugated thin-film solar cells  

Science.gov (United States)

The amount of solar energy reaching the active (photovoltaic) layer in a thin-film solar cell can be increased by reducing the Fresnel reflection losses at the interfaces. By using corrugated interfaces (at the wavelength scale), adiabatic propagation of the electromagnetic radiation is achieved over a broad wavelength range throughout the structure, which leads to an increase in the light that is absorbed in the active layer and, ultimately, to the improvement of the photovoltaic conversion efficiency. In this article, we have considered the case of corrugated thin-film solar cell structures and we have studied theoretically the optimization of such structures from the point of view of photonics. The focus was put on periodic pyramidal interface corrugations because they were similar to those existing at the surface of corrugated transparent electrodes on which active layers can be deposited. Because of their technological importance, we chose to work with fluorine-doped tin oxide as front electrode material and with amorphous silicon as active material. Using an original three dimensional transfer matrix method, we solved the electromagnetic wave propagation problem in the general case of laterally periodic stratified media and we compared this solution with effective medium approximated solution. On the basis of typical pyramid sizes, we demonstrated, through numerical simulations, the optimization of the global light energy intake by means of corrugations of increasing complexity. The best structures were found to be based on pyramid arrays having subwavelength periods and aspect ratio values close to one. Typically, a pyramidal structure with base and height both equal to 300 nm led to a global energy intake equal to I=0.98 (integrated over the spectral range 400-710 nm), which represented a 24% improvement in comparison with the global energy intake of a planar structure (I=0.79).

Deparis, Olivier; Vigneron, Jean Pol; Agustsson, Otto; Decroupet, Daniel

2009-11-01

42

Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a...

Jong, M. M.

2013-01-01

43

Boron-doped nanocrystalline silicon thin films for solar cells  

International Nuclear Information System (INIS)

This article reports on the structural, electronic, and optical properties of boron-doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films. The films were deposited by plasma-enhanced chemical vapour deposition (PECVD) at a substrate temperature of 150 deg. C. Crystalline volume fraction and dark conductivity of the films were determined as a function of trimethylboron-to-silane flow ratio. Optical constants of doped and undoped nc-Si:H were obtained from transmission and reflection spectra. By employing p+ nc-Si:H as a window layer combined with a p' a-SiC buffer layer, a-Si:H-based p-p'-i-n solar cells on ZnO:Al-coated glass substrates were fabricated. Device characteristics were obtained from current-voltage and spectral-response measurements.

2011-08-15

44

Preferable solar cell absorber - Near stoichiometric or stoichiometric CBD CIAS thin films?  

Science.gov (United States)

Near stoichiometric and stoichiometric [CuIn(1 - x)Al(x)Se2] (CIAS) thin films are prepared by chemical bath deposition (CBD) technique. X-ray diffraction (XRD) analysis have been employed to estimate the structural properties of CBD CIAS thin films and also to identify the near stoichiometric in particular defect free Cu-poor CBD CIAS thin films as preferable solar cell absorber material.

Kavitha, B.; Dhanam, M.

2012-03-01

45

Impedance spectroscopy of CdTe thin film solar cells  

International Nuclear Information System (INIS)

Impedance Spectroscopy (IS) is a widely used method to analyze dielectric properties of specimen as a function of frequency. Typically this characterization method delivers an equivalent circuit diagram of the device under examination to describe its electrical properties. Traditionally IS is used in coating evaluation, corrosion monitoring and in electrochemistry. During the last years the method became more important also in the field of electrical characterization of solar cells. In our work we use IS for the electrical characterization of thin film CdTe solar cells. The measurement is done at room temperature without illumination in a frequency domain from 20 Hz to 2 MHz. The samples are measured under variable forward bias. The results match insufficiently with the model of two resistor-capacitor circuits in series which is commonly used to describe the p-n junction and the blocking back contact. For better consistency, other models from the literature are used and discussed. From the results a conclusion is drawn about the properties of the solar cell such as the nature of the p-n junction or the performance of the back contact.

2012-03-25

46

Thin-film solar cells on commercial ceramic tiles  

Energy Technology Data Exchange (ETDEWEB)

Amorphous silicon solar cells were deposited on porcelain stoneware tiles in order to develop a fully integrated PV building element. In a previous work we demonstrated the feasibility of adopting porcelain stoneware tiles as thin-film solar cell substrates and we fabricated 1 x 1cm{sup 2} solar cells on ''industrial-level'' ceramic substrates showing more than 4% efficiency. In this study we focus our attention on larger area (7cm{sup 2}) devices deposited on 100cm{sup 2} tiles. As the active area increases additional problems arise from the surface of the substrate. In particular we find that short-circuit paths originate from the unfavorable properties of the substrate tiles (roughness, porosity, etc.) having dramatic consequences on the performance of larger area devices. With the assumption that spot-like regions, in which the back layer and the front layer are in electrical contact (local short-circuits), are present all over the device, we propose a new device structure to overcome the substrate drawbacks. A new contacts arrangement was designed in order to minimize the shunting effect of short-circuit paths. As a result an initial efficiency of 2.5% has been obtained using the new device structure for 7cm{sup 2} devices deposited on a 100cm{sup 2} PV mini-module tile. (author)

Iencinella, Daniele; Centurioni, Emanuele; Grazia Busana, Maria [CNR-IMM Bologna, Via P. Gobetti 101, 40129, Bologna (Italy)

2009-02-15

47

R and D activities of silicon-based thin-film solar cells in China  

Energy Technology Data Exchange (ETDEWEB)

The status and progress of R and D activities of silicon-based thin-film solar cells in China are described briefly in this paper, including amorphous Si solar cells and microcrystalline Si film solar cells based on PECVD technology and polycrystalline film solar cells based on RTCVD technology. Especially, the microcrystalline thin-film solar cells and the tandem solar cells of amorphous Si with microcrystalline Si have made great progress. The polycrystalline film solar cells have made remarkable achievements as well. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Zhao, Yuwen; Wang, Wenjing; Li, Xudong; Xu, Ying [Beijing Solar Energy Institute, No. 3 Huayuan Road, Beijing 100083 (China); Geng, Xinhua [Institute of Photo-electronic Thin Film Device and Technology, Nankai University, Tianjin, 300071 (China)

2006-03-15

48

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

49

Progress in Polycrystalline Thin-Film Cu(In,Ga)Se2 Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For some time, the chalcopyrite semiconductor CuInSe2 and its alloy with Ga and/or S [Cu(InGa)Se2 or Cu(InGa)(Se,S)2], commonly referred as CIGS, have been leading thin-film material candidates for incorporation in high-efficiency photovoltaic devices. CuInSe2-based solar cells have shown long-term stability and the highest conversion efficiencies among all thin-film solar cells, reaching 20%. A variety of methods have been reported to prepare CIGS thin film. Efficiency of solar cells dep...

2010-01-01

50

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

51

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

2005-06-01

52

Photovoltaic solar cell from low-cost thin-film technology  

International Nuclear Information System (INIS)

Full text : 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 solar cells have surmounted the barrier to mass production. Pilot manufacturing lines are under construcion 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 benn announced by various companies

2005-06-01

53

Transparent conducting oxide layers for thin film silicon solar cells  

International Nuclear Information System (INIS)

Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells. The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of nanocrystalline silicon (nc-Si) type of solar cells. The stress of the ZnO:Al film changes from tensile to compressive with the increase in substrate temperature of sputter deposition and the rms roughness and the haze of the film seem to have a correlation with the stress of the film prior to etching; the sample made at 150 oC is most tensile and the etching rate and the evolved roughness is least at this condition whereas the sample made at 350 oC with a compressive stress character gives a high roughness. At present the ZnO:Al made at room temperature provides the best combination of the electrical property and the scattering property of the texture etched layer. A current density of ? 24 mA/cm2 has been obtained for a nc-Si cell of 2200 nm thick. To apply such a texturing technique to make rough ZnO:Al TCO layers on PET and PEN substrates for solar cells on plastics, an additional step of embossing the plastics prior to the sputter deposition of the ZnO:Al layers was employed to release the undue stress. The texture etching of such layers on plastics showed excellent scattering properties in addition to the good electrical properties. As far as ZnO:Al as back reflector is concerned, use of a thick, low doped ZnO:Al in combination with white reflectors, instead of metals, will be a possible solution to avoid surface plasmon absorption loss. We have successfully applied this concept using 0.5% Al doped ZnO to a superstrate type a-Si solar cell using upconversion material at the back of the solar cell. In case of substrate type solar cells on plastics, the ZnO:Al layers that are used as the Ag/ZnO:Al back reflector as well as barrier layers, have to be thin and made at a low stress condition. Such a process resulted in ? 6% efficiency of n-i-p a-Si solar cells on PET and PEN substrates.

2010-10-01

54

Cost perspectives of GaAs thin film solar cells  

International Nuclear Information System (INIS)

To become a viable option for grid-connected electricity supply in the Netherlands GaAs thin film solar cell modules should achieve a break-even module cost of ECU 100-170/m2 or ECU 250-350/m2 if social costs are accounted for. The most important bottleneck is formed by the costs of the substrates for epitaxial layer deposition, which are much too high if GaAs or Ge are used as a substrate material. The cost prospects for monocrystalline or semicrystalline silicon substrates appear to be somewhat better (minimum substrate costs of ECU 65/m2) but major technological difficulties still have to be solved for this option. Deposition on low-cost, non-crystalline substrates by means of the grapho-epitaxial method appears even more difficult. The second bottleneck requires that the utilization rate of source gases for Metal Organic Chemical Vapour Deposition (MOCVD) is improved and that their costs are very much reduced. Thirdly, equipment cost of MOCVD reactors will have to become much lower. Finally raw material supplies may become a bottleneck for large-scale application of GaAs cells, especially if GaAs or Ge substrates are used. It is concluded that meeting the cost targets is very difficult but not impossible. It requires major break-through in each of the above areas. 6 refs., 2 tabs

1991-04-08

55

Nanostructured silicon and its application to solar cells, position sensors and thin film transistors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract This paper reports the performances of small area solar cells, 128 linear integrated position sensitive detector arrays and thin film transistors based on nanostructured silicon thin films produced by plasma enhanced chemical vapour deposition technique, close to the onset of dusty plasma conditions, within the transition region from amorphous to microcrystalline. The small area solar cells produced in a modified single chamber reactor exhibit very good electrical characte...

2009-01-01

56

Optical modeling of thin film silicon solar cells with random and periodic light management textures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Better light trapping concepts are a prerequisite for the success of silicon thin film photovoltaics. This thesis presents optical simulations of silicon thin film solar cells with statistical and periodic absorption enhancing textures. For simulation of statistically textured solar cells a rough surface synthesization method is characterized and found applicable for generation of the morphology of commercial fluorine doped tin oxide surfaces. The extended rough interface scatterer is modeled...

Lockau, Daniel

2013-01-01

57

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

Energy Technology Data Exchange (ETDEWEB)

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 CuInSe2. 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. CuInSe2 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, G.A.; Bailey, S.G.; Flood, D.J.

1989-01-01

58

Influence of CuxS back contact on CdTe thin film solar cells  

International Nuclear Information System (INIS)

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

2013-01-01

59

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

60

Electrical Conductivity of Chlorophyll with Polythiophene Thin Film on Indium Tin Oxide as P-N Heterojunction Solar Cell  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work was focused on the study of electrical conductivity to the combination of Polythiophene (PT) thin film and Chlorophyll (CHLO) thin film by layered on Indium Tin Oxide (ITO) substrate as p-n heterojunction solar cell. PT thin film is deposited to the ITO substrate by using electrochemistry method. CHLO thin film is coated on PT thin film by using the spin coating method. Current and voltage of ITO/PT/CHLO thin film are measured in the dark and under different light intensity by using...

2008-01-01

 
 
 
 
61

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

Energy Technology Data Exchange (ETDEWEB)

The present status and current research directions of photovoltaic arrays as primary power systems for space are reviewed. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe{sub 2}) and related I-III-VI(2) 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% AM0 for CuInSe{sub 2}. The radiation tolerance of thin-film materials is far greater than that of single crystal materials. Experimental evidence also suggests that most or all of the radiation damage on thin-film materials can be removed by a low temperature anneal. The possibility of all thin-film cascade multibandgap solar cells is discussed, including the trade-offs between monolithic and mechanically stacked cells and voltage-matched versus current-matched configurations. The best current efficiency for a cascade cell is 12.5% AM0 for an amorphous silicon on CuInSe{sub 2} multibandgap combination. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovoltaic arrays may be a mission-enabling technology. (author).

Landis, G.A.; Bailey, S.G.; Flood, D.J. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center)

1989-01-01

62

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.)

2010-12-01

63

Light trapping in periodically textured amorphous silicon thin film solar cells using realistic interface morphologies.  

Science.gov (United States)

The influence of realistic interface morphologies on light trapping in amorphous silicon thin-film solar cells with periodic surface textures is studied. Realistic interface morphologies are obtained by a 3D surface coverage algorithm using the substrate morphology and layer thicknesses as input parameters. Finite difference time domain optical simulations are used to determine the absorption in the individual layers of the thin-film solar cell. The influence of realistic interface morphologies on light trapping is determined by using solar cells structures with the same front and back contact morphologies as a reference. Finally the optimal surface textures are derived. PMID:24104487

Jovanov, Vladislav; Palanchoke, Ujwol; Magnus, Philipp; Stiebig, Helmut; Hpkes, Jrgen; Sichanugrist, Porponth; Konagai, Makoto; Wiesendanger, Samuel; Rockstuhl, Carsten; Knipp, Dietmar

2013-07-01

64

Local photovoltaic characterization for silicon thin film solar cells using a scanning probe microscope  

Science.gov (United States)

The photovoltaic characterization of silicon thin film solar cells with nano-scale spatial resolution is demonstrated by a new characterization method developed using a scanning microscope. In the surface topography of p-i-n type amorphous silicon thin film solar cells, large and small convex grains corresponding to the textured surface of an Asahi U-type substrate and the crystalline grains in the n-type microcrystalline silicon layer are found. In the local photo-current image, distribution in local photo-current correlated with the structure of the n-type microcrystalline silicon layer is observed in the p-i-n type amorphous silicon (a-Si:H) thin film solar cells. The local surface potential in amorphous silicon thin film solar cells with light irradiation is also evaluated. In the local surface potential image of the p-i-n a-Si:H thin film solar cells without light irradiation, the local surface potential on the large convex grains found in the surface topography is smaller than that in the concave region between the large convex grains. Similar distribution of the local surface potential is observed in the local surface potential images with light irradiation. The local surface potential difference between the large convex grains and the concave region decreases with increasing power of the irradiation light.

Itoh, T.; Natsuhara, H.; Nonomura, S.

2012-08-01

65

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

2009-02-02

66

Thin film Cu/sub 2/S - CdS solar cells  

Energy Technology Data Exchange (ETDEWEB)

Recent advances in photovoltaic performances of thin films Cu/sub 2/S - CdS solar cells are presented. For low cost photopile production, Cu/sub 2/S - CdS are solar cells are prepared by using evaporated or sprayed thin CdS films.

Savelli, M.; Bougnot, J.

1981-04-01

67

Effects of Cd-free buffer layer for CuInSe{sub 2} thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

ZnO buffer layer by a chemical-bath deposition (CBD) method is developed in this study to improve the interface quality between n-ZnO window layer and p-CuInSe{sub 2} (CIS) thin-film absorber in CIS thin-film solar cells as one of the approaches to the fabrication of Cd-free thin-film solar cells. The optimization of the fabrication conditions of CBD-ZnO leads to the efficiency of about 10%. These results indicate the CBD-ZnO buffer layer has rather high capability to fabricate high-efficiency CIS thin-film solar cells.

Nii, T.; Sugiyama, I.; Kase, T.; Sato, M.; Kaniyama, Y.; Kuriyagawa, S.; Kushiya, K.; Takeshita, H. [Showa Shell Sekiyu K.K., Atsugi, Kanagawa (Japan). Central R and D Lab.

1994-12-31

68

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

69

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.

2011-03-01

70

Hydrogen passivation of polycrystalline Si thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

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 V{sub OC} of poly-Si reference samples. Optimum passivation conditions were found by measurements of the breakdown voltage V{sub brk} 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 V{sub brk}. Plasma simulations were carried out, which indicate that best V{sub OC} corresponds to a minimum in ion energy. V{sub OC} 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 V{sub OC} 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 V{sub OC}, 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 T{sub dep}=200-700 C and were characterized by Raman, ESR and V{sub OC} 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 2.5.10{sup 16} cm{sup -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 V{sub OC} 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.)

Gorka, Benjamin

2010-12-15

71

Indium phosphide/cadmium sulfide thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Thin-film InP/CdS structures were prepared by depositing, in sequence, ITO on a low-cost glass substrate, CdS on the ITO by thermal evaporation, and InP on the CdS by planar reactive deposition (PRD). Films of CdS, 15 ..mu..m thick, were recrystallized in flowing H/sub 2//H/sub 2/S at 500/sup 0/C. Lateral dimensions of typical grains were 50..mu..m with values up to 200 ..mu..m. The sheet resistance of the recrystallized CdS (RXCdS) was lowered from greater than 10/sup 5/ ..cap omega../O = cm/sup 2/ to values as low as 16 ..cap omega../O = cm/sup 2/ by annealing in either H/sub 2/ Cd atmospheres. Epitaxy of InP was undertaken on (100) InP at a substrate temperature of 320/sup 0/C. Room-temperature electron mobilities of about 2000 cm/sup 2//V-sec were found. Mobilities and hole concentrations of 60 cm/sup 2//V-sec and 10/sup 17/ cm-/sup 3/, respectively, were achieved with Be-doped films. P-type films with hole concentrations as high as a few times 10/sup 18/cm-/sup 3/ were achieved with increased doping. Be-doped InP was deposited onto the RXCdS/ITO/GLASS substrate to form a thin-film cell. However, p-type InP could not be prepared with CdS as a substrat4e, presumably due to interdiffusion or vapor transport of sulfur. Consequently, blocking action and a photovoltage could only be achieved using a gold Schottky barrier on the InP/RXCdS/ITO/GLASS structure. Plans for the next quarter include determining whether n-type doping from the CdS occurs by either interdiffusion or vapor transport, characterizing InP epitaxy on the RXCdS, and preparing additional thin-film structures.

Zanio, K.

1980-02-01

72

Determining the junction temperature for STC measurements of thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In expectation of high potentials for cost reduction, many new approaches for thin film solar cell concepts achieved increased attention in the last time. With improving efficiencies, the accurate determination of the solar cell parameters has received growing attention. Calibration laboratories, such as the calibration laboratory of Fraunhofer ISE (ISE CalLab PV Cells), need to develop procedures to determine reliable solar cell parameters of such technologies, in accordance with standard te...

Seifert, H.; Hohl-ebinger, J.; Wu?rfel, U.; Zimmermann, B.; Warta, W.

2009-01-01

73

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

74

Thin-film photovoltaic cells  

Energy Technology Data Exchange (ETDEWEB)

Cells formed from films a few micrometers thick could soon provide local electricity in developing countries, and future cells may generate utility-scale electricity. The technology for these new types of photovoltaic cells emerged in the 1960's with attempts to make solar electricity less expensive. The cells absorb light with a thin film of semiconductor material, providing reasonable efficiency at greatly reduced cost. This article covers the following topics: the physics of photovoltaics; the theory of thin films; descriptions of the three kinds of thin film photovoltaics; the production line processing; the economics of thin film photovoltaic manufacture; developing a market; environmental inquiries; the future for photovoltaics. 7 refs., 20 figs.

Zweibel, K. (NREL PV Program, Golden, CO (United States))

75

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

76

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

International Nuclear Information System (INIS)

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/Cu2ZnSnS4 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

2013-10-01

77

Plasmonic effects in amorphous silicon thin film solar cells with metal back contacts.  

Science.gov (United States)

Plasmonic effects in amorphous silicon thin film solar cells with randomly textured metal back contact were investigated experimentally and numerically. The influence of different metal back contacts with and without ZnO interlayer was studied and losses in the individual layers of the solar cell were quantified. The amorphous silicon thin film solar cells were prepared on randomly textured substrates using large area production equipment and exhibit conversion efficiencies approaching 10%. The optical wave propagation within the solar cells was studied by Finite Difference Time Domain simulations. The quantum efficiency of solar cells with and without ZnO interlayer was simulated and the interplay between the reflection, quantum efficiency and absorption in the back contact will be discussed. PMID:22418515

Palanchoke, Ujwol; Jovanov, Vladislav; Kurz, Henning; Obermeyer, Philipp; Stiebig, Helmut; Knipp, Dietmar

2012-03-12

78

Production method of thin film solar cell; Hakumaku taiyo denchi no seizo hoho  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to the film formation of chalcopyrite type compound semiconductor used for thin film solar cell. In the case of CuInS2 thin film, heteromorphic phases such as CuIn5S8, Cu2S, and In2S3 are formed on the top surface together with the CuInS2 phase, resulting in the decrease in junction property when n-type semiconductor layer such as CdS layer is formed on it. According to the invention, p-type semiconductor layer made of chalcopyrite type compound semiconductor is dipped into an ammonia water before being laminated with n-type semiconductor layer. Although higher concentration and higher temperature of the ammonia water accelerates the heteromorphic phase film removal velocity, it also gives rise to higher evaporation rate of ammonia. The preferable concentration and temperature are, therefore, 0.01 - 50% and 5 - 80{degree}C, respectively. In this way, the chalcopyrite type compound semiconductor thin film free from heteromorphic phases on its surface can be produced. The thin film solar cell produced by using such thin film has a high conversion efficiency because of a good junction property with n-type semiconductor. 1 fig.

Oki, K.; Watanabe, T.; Matsui, M.

1996-01-23

79

Nanoscale investigation of potential distribution in operating Cu(In,Ga)Se2 thin-film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin-film solar cells based on CIGS absorber materials show the highest power conversion efficiency among all kinds of thin-film solar cells. The distribution of the electrostatic potential in and between the materials in the solar cell has obviously a major impact on the superior performance of the device. This thesis reported on imaging of the electrostatic potential on untreated cross sections of operating CIGS solar cells using Kelvin probe force microscopy.

Zhang, Zhenhao

2012-01-01

80

Photovoltaic Technology: The Case for Thin-Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for exa...

2013-01-01

 
 
 
 
81

MIS and PN junction solar cells on thin-film polycrystalline silicon  

Energy Technology Data Exchange (ETDEWEB)

The Photovoltaic Advanced Silicon (PVAS) Branch at the Solar Energy Research Institute (SERI) has initiated a comparative study to assess the potential of MIS-type solar cells for low-cost terrestrial photovoltaic systems in terms of performance, stability, and cost-effectiveness. Several types of MIS and SIS solar cells are included in the matrix study currently underway. This approach compares the results of MIS and p/n junction solar cells on essentially identical thin-film polycrystalline silicon materials. All cell measurements and characterizations are performed using uniform testing procedures developed in the Photovoltaic Measurements and Evaluation (PV M and E) Laboratory at SERI. Some preliminary data on the different cell structures on thin-film epitaxial silicon on metallurgical-grade substrates are presented here.

Ariotedjo, A.; Emery, K.; Cheek, G.; Pierce, P.; Surek, T.

1981-05-01

82

Electrochemical etching of CuInS2 thin films for solar cells  

International Nuclear Information System (INIS)

Cu-rich CuInS2 thin films for solar cell application were electrochemically etched to avoid a toxic cyanide treatment. Cu/In ratio and conductivity of the films decreased by anodic electrochemical etching. Although XRD patterns and SEM micrographs have not changed by the etching, Raman spectra revealed that the electrochemical etching was found to be effective for removing Cu-S secondary phases from the surface of the Cu-rich CuInS2 thin films. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

2006-09-01

83

Effect of electrode separation on PECVD deposited nanocrystalline silicon thin film and solar cell properties  

Energy Technology Data Exchange (ETDEWEB)

Hydrogenated silicon thin films were prepared at different electrode separations and total gas flow rates. Nanocrystalline Si:H films with similar crystalline volume fraction deposited at lower electrode separation have lower microstructural factor. Quality of the absorber layer and solar cell performance improve as electrode separation and deposition power density simultaneously decrease. Maximum efficiency of 6.9% is obtained for solar cell with absorber layer deposited at an electrode separation of 1 cm. (author)

Chowdhury, Amartya; Mukhopadhyay, Sumita; Ray, Swati [Energy Research Unit, Indian Association for the Cultivation of Science, Kolkata-700 032 (India)

2010-09-15

84

Optical Layers for Thin-film Silicon Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work we develop and analyze optical layers for use in Micromorph solar cells, a tandem configuration with an amorphous silicon top cell and a microcrystalline silicon bottom cell. The morphology of the front electrode has a decisive role in maximizing the efficiency of a solar cell. To reach a better understanding of the requirements for the front electrode surface, we present a wide range of morphologies that can be obtained with as-grown rou...

Cuony, Peter

2011-01-01

85

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

2003-03-03

86

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

87

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

88

High-efficiency thin-film solar cells for the conversion of concentrated radiation  

Science.gov (United States)

The objective of the study was to investigate the possibility of increasing the efficiency of thin-film solar cells with coplanar back contacts for the conversion of concentrated solar radiation. It is shown that, in the thin-film solar cells described here, the cell shading factor can be reduced to a minimum since it does not depend on the p-contact area but is determined solely by the area of etched grooves in a thin (7 microns) layer of GaAs. The cells used in the study have a shading factor of 2.5 percent, and a further reduction by an order of magnitude is shown to be possible.

Andreev, V. M.; Burba, T. S.; Dorgan, V. V.; Trofim, V. G.; Chumak, V. A.

1987-09-01

89

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

90

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

91

Amorphous silicon/polycrystalline thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

An improved photovoltaic solar cell is described including a p-type amorphous silicon layer, intrinsic amorphous silicon, and an n-type polycrystalline semiconductor such as cadmium sulfide, cadmium zinc sulfide, zinc selenide, gallium phosphide, and gallium nitride. The polycrystalline semiconductor has an energy bandgap greater than that of the amorphous silicon. The solar cell can be provided as a single-junction device or a multijunction device.

Ullal, H.S.

1991-03-13

92

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

93

Light-trapping design of graphene transparent electrodes for efficient thin-film silicon solar cells.  

Science.gov (United States)

In this paper, the performance of solar cells with graphene transparent electrodes is compared with cells using conventional indium tin oxide (ITO) electrodes, and it is demonstrated the optical absorption of solar cells with bare graphene structure is worse than that of bare ITO structure because of the higher refractive index of graphene. To enhance the light trapping of graphene-based thin-film solar cells, a simple two-layer SiO(2)/SiC structure is proposed as antireflection coatings deposited on top of graphene transparent electrodes, and the thickness of each layer is optimized by differential evolution in order to enhance the optical absorption of a-Si:H thin-film solar cells to the greatest degree. The optimization results demonstrate the optimal SiO(2)/SiC/graphene structure can obtain 37.30% enhancement with respect to bare ITO structure, which has obviously exceeded the light-trapping enhancement of 34.15% for the optimal SiO(2)/SiC/ITO structure. Therefore, with the aid of the light-trapping structure, the graphene films are a very promising indium-free transparent electrode substitute for the conventional ITO electrode for use in cost-efficient thin-film silicon solar cells. PMID:22945173

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

2012-09-01

94

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

95

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

96

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

2005-02-15

97

Sub-micron silicon structures for thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The realization of a lateral structured thin solar cell based on silicon is introduced and advantages such as increased internal electric fields, light diffraction into the bulk of the absorber, and improved light trapping are discussed. The key process for the realization of such a solar cell is the interference laser recrystallization of amorphous silicon which has been applied to produce stripe, grid, and dot arrays. The experimental set-up of the laser recrystallization is presented, and a detailed description of electronic properties of laser recrystallized, boron doped silicon films is given. (orig.) 20 refs.

Nebel, C.E.; Dahlheimer, B.; Schoeniger, S.; Stutzmann, M. [Technische Univ. Muenchen, Garching (Germany). Walter-Schottky-Inst. fuer Physikalische Grundlagen der Halbleiterelektronik

1996-03-01

98

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

99

Numerical modeling of SiH4 discharge for Si thin film deposition for thin film transistor and solar cells  

International Nuclear Information System (INIS)

Amorphous and microcrystalline silicon thin films are used in solar cells as a multi-junction photovoltaic device. Plasma enhanced chemical vapor deposition is used and high deposition rate of a few nm/s is required while keeping film quality. SiH4 is used as a precursor diluted with H2. Electron impact processes give complex interdependent plasma chemical reactions. Many researchers suggest keeping high H/SiHx ratio is important. Numerical modeling of this process for capacitively coupled plasma and inductively coupled plasma is done to investigate which process parameters are playing key roles in determining it. A full set of 67 volume reactions and reduced set are used. Under most of conditions, CCP shows 100 times higher H/SiH3 ratio over ICP case due to its spatially localized two electron temperature distribution. Multi hollow cathode type CCP is also modeled as a 2 x 2 hole array. For Ar, the discharge is well localized at the neck of the hole at a few Torr of gas pressure. H2 and SiH4 + H2 needed higher gas pressure and power density to get a multi hole localized density profile. H/SiH3 was calculated to be about 1/10.

2011-08-01

100

Microcrystalline/micromorph silicon thin-film solar cells prepared by VHF-GD technique  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hydrogenated microcrystalline silicon prepared at low temperatures by the glow discharge technique is examined here with respect to its role as a new thin-film photovoltaic absorber material. XRD and TEM characterisations reveal that microcrystalline silicon is a semiconductor with a very complex morphology. Microcrystalline pin cells with open-circuit voltages of up to 560580 mV could be prepared. Micromorph tandem solar cells show under outdoor conditions higher short-circuit...

Meier, Johannes; Vallat-sauvain, Evelyne; Dubail, S.; Kroll, U.; Dubail, J.; Golay, S.; Feitknecht, Luc; Torres, Pedro; Fay?, Sylvie; Fischer, D.; Shah, Arvind

2008-01-01

 
 
 
 
101

Significance of Substrates and Buffer Layers in Cdte Thin Film Solar Cell Fabrication  

Digital Repository Infrastructure Vision for European Research (DRIVER)

CdTe is considered as a viable absorber material for the thin film solar cell because of its excellent material characteristics as well as simple, low cost manufacturability. Despite a theoretical 29% efficiency prediction of the cell, its high work function and coefficient of thermal expansion (CTE) have limited its efficiency to around 17%. One of the remedies of the problem is using a pseudo contact layer, which is called buffer layer in its back contact structure. In this study, different...

2012-01-01

102

Oxide and sulfide semiconductor thin films for solar cells and spintronic devices  

Science.gov (United States)

This dissertation will present the synthesis and characterization of the doped-zinc oxide (ZnO) thin films deposited by various techniques for their potential applications in spintronics devices and solar cells. The research work shows room temperature ferromagnetism in transition metal doped zinc oxide dilute magnetic semiconductors in highly crystalline nanostructured and polycrystalline forms. A spin field effect transistor working as a resistive switch was simulated based on the conductance modulation of the electron channel formed by magnetic impurity doped ZnO. Light scattering properties of nanostructured doped ZnO films has been simulated using Mie scattering theory in view of possible application in light harvesting in solar cells. Band gap bowing effect was achieved in sulfur-alloyed ZnO (zinc oxysulfide) films and a new bowing parameter and stress effect gave a better understanding of the sulfur alloyed effect in these polycrystalline thin films synthesized by chemical spray pyrolysis technique. A novel nanostructure was developed with sulfur-doping of ZnO in the ZnO core and zinc oxysulfide (ZnO1-xSx) shell form. For the first time the ZnO-ZnO1-xSx core-shell nanorods were applied to develop 3-dimenstional organic-inorganic hybrid solar cells. The performance of organic-inorganic hybrid solar cells based on ZnO-ZnO 1-xSx core-shell nanorods thin films was evaluated using the current-voltage characteristics. Further, the role of flux induced crystallization of Cu2ZnSnS4 (CZTS) thin films by chemical spray pyrolysis technique is explored. This dissertation also investigates the interface effects and heterojunction properties of cadmium sulfide/CZTS heterojunction solar cells.

Ramachandran Thankalekshmi, Ratheesh

103

Thin-film solar cells on perlite glass-ceramic substrates  

Science.gov (United States)

For the first time, thin-film CIGS solar cells have been fabricated by co-evaporation on specially developed non-conducting perlite (an aluminum potassium sodium silicate natural mineral of volcanic origin) glass-ceramic substrates to develop a fully integrated photovoltaic and building element. Such glass-ceramic material can meet the physical requirements to solar cells substrates as well as the cost goals. The preliminary data presented show that CIGS solar cells deposited on ceramic substrates can exhibit efficiency higher than 10%.

Petrosyan, Stepan G.; Babayan, Virab H.; Musayelyan, Ashot S.; Harutyunyan, Levon A.; Zalesski, Valery B.; Kravchenko, Vladimir M.; Leonova, Tatyana R.; Polikanin, Alexander M.; Khodin, Alexander A.

2013-06-01

104

Thin film solar cells using impure polycrystalline silicon  

Energy Technology Data Exchange (ETDEWEB)

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 through a simple model, it is shown that this efficiency is limited by both absorption and collection losses in the thin active epilayer. With the help of a brief economic analysis, this technique is compared to the other ones able to make use of cheap UMG-Si.

Rodot, M.; Barbe, M.; Bouree, J.E.

1987-07-01

105

Combining front and back grating structures for broadband absorption enhancement in thin-film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the possibilities of enhancing absorption in thin-film silicon solar cells with grating structures on the front ITO and back Ag contacts simultaneously. Broadband enhancement from complementary effects of each grating is demonstrated.

Abass, Aimi; Le Quang, Khai; Bienstman, Peter; Alu, Andrea; Maes, Bjo?rn; Burgelman, Marc

2011-01-01

106

New inorganic thin film solar cells. Surface properties needed for n-i-p devices  

Energy Technology Data Exchange (ETDEWEB)

The challenges and research needs for developing thin film solar cells using inorganic compound semiconductors are discussed from a materials science point of view. As a promising new band structure for thin film solar cells, an n-i-p heterostructure is proposed based on a variety of possible light absorbing materials avoiding the need for controlled doping. The performance of such a device will crucially depend on successful interface engineering of interfaces like the one between the absorber material and the transparent conductive oxide (TCO) front electrode. To passivate lattice mismatch induced defect states at this interface, ultrathin buffer layers consisting of large gap oxide materials like Al{sub 2}O{sub 3} are investigated as a first step towards this structure. The band alignment of the front (electron) contact of such a modified n-i-p structure is determined by photoelectron spectroscopy for different processing parameters. (orig.)

Fuchs, A.; Klein, A.; Jaegermann, W. [Technische Univ. Darmstadt (Germany). Fachbereich Materialwissenschaft

2010-07-01

107

Commercial-scale process design for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

A preliminary process design for the manufacture of thin-film cadmium sulfide/copper sulfide solar cells is outlined. The total product cost is determined from raw materials, utilities, labor, and capital using engineering economic procedures of the chemical processing industry. Results are given for manufacturing facilities with annual throughout of 10, 100 and 1000 megawatts. Batch and continuous modes of operation are compared and it is shown that thin-film solar cells can be manufactured for less than /0.50 per watt (50 /sub m//sup 2/) in a continuous production facility. Capital investment to meet this low price will be between /263 and /347 million, an investment roughly equivalent to a world-scale methanol plant. 14 refs.

Russell, T.W.F.; Baron, B.N.; Rocheleau, R.E.

1981-01-01

108

TCAD studies of novel nanoplate amorphous silicon alloy thin-film solar cells  

International Nuclear Information System (INIS)

A novel nanoplate-structured thin-film solar cell was investigated that could solve the conflict between light absorption and carrier transport in a p-type amorphous silicon carbide (a-SiC)/i-type amorphous silicon germanide (a-SiGe)/n-type amorphous silicon (a-Si) thin-film solar cell. This structure has an n-type a-Si nanoplate array on the substrate, a-SiC p-layer, and an a-SiGe i-layer which are sequentially grown along the surface of each n-type a-Si nanoplate. Under illumination by sunlight, light is absorbed along the vertical direction of the nanoplate, while the carrier transport is along the horizontal direction. The nanoplate structure may absorb most of the sunlight and provide a thinner film for the effective transport of photon-generated carriers as compared to the conventional planar structure.

2011-12-30

109

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

Science.gov (United States)

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.

Yin, J.; Zhu, H.; Wang, Y.; Wang, Z.; Gao, J.; Mai, Y.; Ma, Y.; Wan, M.; Huang, Y.

2012-10-01

110

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-film solar cells. The parameters of white paint, such as the paint film thickness, the pigment volume concentration (PVC), and the pigment/binder refractive index ratio (RIR), are examined and optimi...

Lipovs?ek, B.; Krc?, J.; Isabella, O.; Zeman, M.; Topic?, M.

2010-01-01

111

Thin film solar cells on glass by transfer of monocrystalline Si films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin film solar cells based on monocrystalline Si films are transferred to a glass superstrate. Chemical vapor deposition serves to epitaxially deposit Si on quasi-monocrystalline Si films obtained from thermal crystallization of a double layer porous Si film on a Si wafer. A separation layer that forms during this crystallization process allows one to separate the epitaxial layer on top of the quasi-monocrystalline film from the starting Si wafer. We presently achieve an independently confir...

Bergmann, R. B.; Rinke, T. J.; Hausner, R. M.; Grauvogl, M.; Vetter, M.; Werner, J. H.

1999-01-01

112

Plasmon supported defect absorption in amorphous silicon thin film solar cells and devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis the influence of metallic nanoparticles on the absorption of hydrogenated amorphous silicon (a-Si:H) thin film solar cell devices is investigated. Small metal nanostructures with lateral dimensions well below 100 nm accompany strong absorption and large electric field amplitudes in their vicinity. This is caused by the localized surface plasmon (LSP) resonances that are excited upon interaction of light with the nanostructures. By combining silver nanoparticles (Ag NPs) with am...

2013-01-01

113

Geometric Light Confinement in a-Si Thin Film Solar Cells on Micro-Structured Substrates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work we propose and study a light trapping scheme for thin film silicon solar cells that is based on geometrical light trapping (instead of textures optimized for light scattering), using periodically arranged pyramidal structures with dimensions larger than the effective wavelength of light. We studied the absorption behavior of amorphous silicon (a-Si) layers on such a pyramidal structured substrate using ray tracing calculations. According to the calculations, for pyramids on a squ...

Jong, M. M.; Rath, J. K.; Schropp, R. E. I.; Sonneveld, P. J.; Swinkels, G. L. A. M.; Holterman, H. J.; Baggerman, J.; Rijn, C. J. M.

2011-01-01

114

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 degrees 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.

2013-01-01

115

First principles study of Bi dopen CdTe thin film solar cells: electronic and optical properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nowadays, efficiency improvement of solar cells is one of the most important issues in photovoltaic systems and CdTe is one of the most promising thin film photovoltaic materials we can found. CdTe reported efficiencies in solar energy conversion have been as good as that found in polycrystalline Si thin film cell [1], besides CdTe can be easily produced at industrial scale.

Semino?vski Pe?rez, Yohanna; Palacios Clemente, Pablo; Wahno?n Benarroch, Perla

2011-01-01

116

Method for the continuous manufacture of thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

A technique for manufacturing durable, reliable solar cells by a continuous process suitable for large-scale manufacture involves, in substance, providing a reel of thin metal foil substrate and forming on the substrate a series of layers operative to form a photovoltaic junction, short prevention blocking layers, contacts and integral encapsulation. The foil substrate is processed as a continuous reel substantially until final testing at which point, if desired, it can be cut into individual cells for deployment. In comparison with a batch process, the continuous technique can reduce manufacturing cost by as much as a factor of two.

Barnett, A.M.; Baron, B.N.; Masi, J.V.; Russell, T.W.

1982-03-09

117

Positron annihilation study on CuInSe{sub 2} solar cell thin films  

Energy Technology Data Exchange (ETDEWEB)

Positron annihilation spectroscopy has been used to investigate CuInSe{sub 2} 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 CuInSe{sub 2} 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: Black-Right-Pointing-Pointer As-grown CuInSe{sub 2} thin films contain large concentration of defects. Black-Right-Pointing-Pointer A defect layer of about 50 nm exists in the CuInSe{sub 2} thin film surface. Black-Right-Pointing-Pointer The defect concentration in the defect layer can be greatly reduced.

Zhang, Lijuan [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Wang, Tao [Institute of Fluid Physics, CAEP, P.O. Box 919-106, Mianyang 621900 (China); Li, Ji [Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Hao, Yingping; Liu, Jiandang [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Zhang, Peng [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Cheng, Bin [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Zhang, Zhongwei [Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Wang, Baoyi [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Ye, Bangjiao, E-mail: bjye@ustc.edu.cn [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

2012-12-15

118

Inline RF sputtered TAZO films for applications in hydrogenated amorphous silicon thin film solar cells  

Science.gov (United States)

In this paper, we aim to evaluate feasibility of replacing tin oxide (SnO2) films by in-line sputtered (titanium, aluminum)-doped zinc oxide (TAZO) as a front electrode of hydrogenated amorphous silicon (a-Si:H) thin film solar cells. The HCl wet-etching process and the device performances are investigated and optimized. The results show that the textured TAZO can have a lower sheet resistance of 7 ?/square and a higher haze of 22% compared to commercial Asahi-U SnO2 films. The a-Si:H solar cells with a TAZO front contact is found to have a low fill factor due to a poor TAZO/p-a-Si:H interface. However, the interface problem can be significantly improved by inserting a microcrystalline p-layer silicon thin-film. In addition, the reproducibility of the wet-etching process is investigated. The fluctuation in the haze of the etched TAZO films can be obviously reduced when a multi-step wet-etching process is used. Moreover, the light soaking test is performed on the TAZO films. Only slight degradation in film properties indicates high stability with respect to time. These results encourage potential adoption of cost-effective in-line sputtered TAZO films as an alternative for the front contact of a-Si:H thin film solar cells.

Lien, Shui-Yang; Hsu, Chia-Hsun; Chang, Chia-Hung; Wu, Hsin-Yu; Hsieh, In-Cha; Wang, Da-Yung

2014-02-01

119

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

120

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

2013-05-15

 
 
 
 
121

High efficiency thin-film GaAs solar cells  

Science.gov (United States)

The paper demonstrates the feasibility of producing high-efficiency GaAs solar cells with high power-to-weight ratios by organic metallic chemical vapor deposition (OM-CVD) growth of thin epi-layers on suitable substrates. An AM1 conversion efficiency of 18% (14% AM0), or 17% (13% AM0) with a 5% grid coverage is achieved for a single-crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer. Thin GaAs epi-layers OM-CVD grown can be fabricated with good crystallographic quality using a Si-substrate on which a thin Ge epi-interlayer is first deposited by CVD from GeH4 and processed for improved surface morphology

Zwerdling, S.; Wang, K. L.; Yeh, Y. C. M.

1981-01-01

122

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

123

Cross-sectional electrostatic force microscopy of thin-film solar cells  

International Nuclear Information System (INIS)

In a recent work, we showed that atomic force microscopy (AFM) is a powerful technique to image cross sections of polycrystalline thin films. In this work, we apply a modification of AFM, namely, electrostatic force microscopy (EFM), to investigate the electronic properties of cleaved II--VI and multijunction thin-film solar cells. We cleave the devices in such a way that they are still working with their nominal photovoltaic efficiencies and can be polarized for the measurements. This allows us to differentiate between surface effects (work function and surface band bending) and bulk device properties. In the case of polycrystalline CdTe/CdS/SnO2/glass solar cells, we find a drop of the EFM signal in the area of the CdTe/CdS interface (50 nm). This drop varies in amplitude and sign according to the applied external bias and is compatible with an n-CdS/p-CdTe heterojunction model, thereby invalidating the possibility of a deeply buried n-p CdTe homojunction. In the case of a triple-junction GaInP/GaAs/Ge device, we observe a variation of the EFM signal linked to both the material work-function differences and to the voltage bias applied to the cell. We attempt a qualitative explanation of the results and discuss the implications and difficulties of the EFM technique for the study of such thin-film devices

2001-01-15

124

Cross-sectional electrostatic force microscopy of thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

In a recent work, we showed that atomic force microscopy (AFM) is a powerful technique to image cross sections of polycrystalline thin films. In this work, we apply a modification of AFM, namely, electrostatic force microscopy (EFM), to investigate the electronic properties of cleaved II--VI and multijunction thin-film solar cells. We cleave the devices in such a way that they are still working with their nominal photovoltaic efficiencies and can be polarized for the measurements. This allows us to differentiate between surface effects (work function and surface band bending) and bulk device properties. In the case of polycrystalline CdTe/CdS/SnO{sub 2}/glass solar cells, we find a drop of the EFM signal in the area of the CdTe/CdS interface ({+-}50 nm). This drop varies in amplitude and sign according to the applied external bias and is compatible with an n-CdS/p-CdTe heterojunction model, thereby invalidating the possibility of a deeply buried n-p CdTe homojunction. In the case of a triple-junction GaInP/GaAs/Ge device, we observe a variation of the EFM signal linked to both the material work-function differences and to the voltage bias applied to the cell. We attempt a qualitative explanation of the results and discuss the implications and difficulties of the EFM technique for the study of such thin-film devices.

Ballif, C.; Moutinho, H. R.; Al-Jassim, M. M.

2001-01-15

125

Morphology dependent dye-sensitized solar cell properties of nanocrystalline zinc oxide thin films  

International Nuclear Information System (INIS)

Research highlights: ? Nano-crystalline zinc oxide thin films were electrosynthesized from an aqueous zinc acetate [Zn(CH3COO)2.2H2O] solution onto FTO coated conducting glass substrates using two different electrochemical routes, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) or SDS (sodium dodecyl sulfate). ? The reproducibility of the catalytic activity of the SDS and PVA surfactants in the modification of the morphologies was observed. ? Vertically aligned nest-like and compact structures were observed from the SDS and PVA mediated films, respectively, while the grain size in the ZnO thin films without an organic surfactant was observed to be ?150 nm. ? The dye sensitized ZnO electrodes displayed excellent properties in the conversion process from light to electricity. The efficiencies of the surfactant mediated nanocrystalline ZnO thin films, viz. ZnO:SDS and ZnO:PVA, sensitized with ruthenium-II (N3) dye were observed to be 0.49% and 0.27%, respectively. - Abstract: Nano-crystalline zinc oxide thin films were electrosynthesized with an aqueous zinc acetate [Zn(CH3COO)2.2H2O] solution on to FTO coated glass substrates. Two different electrochemical baths were used, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) and SDS (sodium dodecyl sulfate). The organic surfactants played an important role in modifying the surface morphology, which influenced the size of the crystallites and dye-sensitized solar cell (DSSC) properties. The vertically aligned thin and compact hexagonal crystallites were observed with SDS mediated films, while the grain size in the films without an organic surfactant was observed to be ?150 nm. The conversion efficiencies of the ZnO:SDS:Dye and ZnO:PVA:Dye thin films were observed to be 0.49% and 0.27%, respectively.

2011-02-03

126

Slow transient photovoltage in thin film Cu{sub x}S/CdS solar cells  

Energy Technology Data Exchange (ETDEWEB)

This letter presents experimental data for work on the complete heterojunction to be found in a Cu{sub x}S/CdS solar cell. The slow transient component of the open-circuit photovoltage was measured. Using a classical fabrication technique, dipping time is shown to influence the spectral response of the open circuit photovoltage. Results indicate that the slow transient decay of the open circuit voltage observed in these heat treated thin film Cu{sub x}S/CdS solar cells is related to an increase in the interface recombination velocity, which leads to a loss of photoexcited electrons. (UK)

Ruxandra, V. [Bucharest Univ. (Romania). Dept. of Physics

1997-11-15

127

Broad-band anti-reflection coupler for a : Si thin-film solar cell  

International Nuclear Information System (INIS)

This work numerically demonstrates a new anti-reflection coupler (ARC) with high coupling efficiency in a Si substrate solar cell. The ARC in which the grating is integrated on a glass encapsulation and a three-layer impedance match layer is proposed. A coupling efficiency of 90% is obtained at wavelengths between 350 and 1200 nm in the TE and TM modes when the incident angle is less than 300. In comparison with a 1?m absorber layer, the integrated absorption of an a-Si thin-film solar cell without a new ARC is doubled, at long wavelengths (750 nm ? ? ? 1200 nm), as calculated by FDTD method

2007-02-07

128

High-temperature CVD silicon films for crystalline silicon thin-film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The deposition of silicon layers plays a central role within the approach of crystalline silicon thin-film solar cells. The introduction of this solar cell type into industrial production lines requires the development of Si-deposition systems which are capable to meet the demands on low cost and high layer quality. At Fraunhofer ISE a Si-APCVD system has been set up, based on a reactor and deposition concept which is expected to meet the imposed requirements. Within this work deposition p...

Bau, Sandra

2003-01-01

129

Improvement of silicon solar cell performance through the use of thin film coatings.  

Science.gov (United States)

Thin film coatings are used universally in solar cell power systems for spacecraft. Antireflective coatings are used to increase the amount of useful energy reaching the active surface of the cell. Multilayer interference filters are employed to reject unwanted portions of the solar spectrum in order to reduce equilibrium temperature and to prevent ultraviolet damage. Glass covers are used in conjunction with these coatings for the purpose of increasing the thermal emittance of the surface. Appreciable performance increases can be obtained through the uses of these filters and coatings. PMID:20048779

Reynard, D L; Andrew, A

1966-01-01

130

Neutrons and photons in materials research for thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The understanding of the interplay between structural and electronic properties of photovoltaic materials as well as a deeper insight into growth pathways and phase formation kinetics of the absorber layer in a thin film solar cell give a crucial contribution to the continuous improvement of the solar cell efficiency. Among the various experimental methods used for the investigation of the structure and microstructure of photovoltaic materials, neutron, and X-ray (photon) scattering are key techniques of choice. Both techniques are complementary, which is demonstrated in the present paper. Neutron powder diffraction is used to detect different kinds of intrinsic point defects in chalcopyrite type and kesterite type semiconductors. The calculated defect concentrations may lead to the expectation of a clustering of anti-site defects and vacancy to the electrical inactive defect pairs (2V{sub Cu}+In{sub Cu}) and (In{sub Cu}+Cu{sub In}). By the means of energy dispersive X-ray diffraction (EDXRD) phase formations and grain growth in thin films are studied in real time. The potential of EDXRD for in situ studies of reactions during the formation of chalcopyrite thin films is demonstrated. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Schorr, Susan [Institute of Geological Sciences, Freie Universitaet Berlin (Germany); Stephan, Christiane; Mainz, Roland; Rodriguez-Alvarez, Humberto; Tovar, Michael [Helmholtz-Zentrum Berlin fuer Materialien und Energie (Germany)

2011-08-15

131

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

132

Thin-Film Solar Cells Based on the Polycrystalline Compound Semiconductors CIS and CdTe  

Directory of Open Access Journals (Sweden)

Full Text Available Thin-film photovoltaic modules based on Cu-In-Ga-Se-S (CIS and CdTe are already being produced with high-quality and solar conversion efficiencies of around 10%, with values up to 14% expected in the near future. The integrated interconnection of single cells into large-area modules of 0.6×1.2m2 enables low-cost mass production, so that thin-film modules will soon be able to compete with conventional silicon-wafer-based modules. This contribution provides an overview of the basic technologies for CdTe and CIS modules, the research and development (R&D issues, production technology and capacities, the module performance in long-term outdoor testing, and their use in installations.

Dieter Bonnet

2007-09-01

133

Aluminium-induced crystallisation of silicon on glass for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Aluminium-induced crystallisation of amorphous silicon is studied for the formation of continuous polycrystalline silicon thin-films on low-temperature glass substrates. It is shown to be a promising alternative to laser crystallisation and solid-phase crystallisation. Silicon grain sizes of larger than 10{mu}m are achieved at temperatures of around 475C within annealing times as short as 1h. The Al doping concentration of the poly-Si films depends on the annealing temperature, as revealed by Hall effect measurements. A poly-Si/Al/glass structure presented here can serve as a seeding layer for the epitaxial growth of polycrystalline silicon thin-film solar cells, or possibly as the base material with the back contact incorporated.

Nast, O.; Pritchard, S.; Aberle, A.G.; Wenham, S.R. [Photovoltaics Special Research Centre, University of New South Wales, 2052 Sydney (Australia); Brehme, S. [Hahn-Meitner-Institut, Kekulestr. 5, D-12489 Berlin (Germany)

2001-01-01

134

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)

2013-09-01

135

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

136

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

137

Enhanced light absorption in thin-film tandem solar cells using a bottom metallic nanograting  

Science.gov (United States)

We introduced a metallic nanograting at the bottom of thin-film tandem solar cells, and carried out an investigation into the light absorption in the top and bottom cells via the electromagnetic simulation. It indicates that broadband and polarization-insensitive light absorption enhancement can be obtained in the bottom cell, while the light absorption in the top cell remains unchanged by the influence of the added metallic nanograting. An overall carrier generation enhancement reaches as much as 60 % for both incident polarizations. This absorption enhancement can survive in a wide range of the cell thickness and the nanograting geometries, which enables us to reduce the thickness of the bottom cell with minimal impact on the light absorption. Thereby, this design could reduce the solar cell production cost, and meanwhile could enhance the solar cell efficiency by decreasing the light-generated carrier recombination rate.

Zhang, Xuanru; Knize, Randy J.; Lu, Yalin

2014-05-01

138

Optical simulation of photonic random textures for thin-film solar cells  

Science.gov (United States)

We investigate light-scattering textures for the application in thin-film solar cells which consist of a random texture, as commonly applied in thin-film solar cells, that are superimposed with a two-dimensional grating structure. Those textures are called photonic random texture. A scalar optical model is applied to describe the light-scattering properties of those textures. With this model, we calculate the angular resolved light scattering into silicon in transmission at the front contact and for reflection at the back contact of a microcrystalline silicon solar cell. A quantity to describe the lighttrapping efficiency is derived and verified by rigorous diffraction theory. We show that this quantity is well suitable to predict the short-circuit current density in the light-trapping regime, where the absorptance is low. By varying the period, height and shape of the unit cell, we optimize the grating structure with respect to the total generated current density. The maximal predicted improvement in the spectral range from 600-900 nm is found to be about 3 mA/cm2 compared to the standard random texture and about 6 mA/cm2 compared to a flat solar cell.

Bittkau, K.; Hoffmann, A.

2014-05-01

139

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 pro...

Owen, Jorj Ian

2011-01-01

140

Photonic and plasmonic structures for enhancing efficiency of thin film silicon solar cells  

Science.gov (United States)

Crystalline silicon solar cells use high cost processing techniques as well as thick materials that are 200m thick to convert solar energy into electricity. From a cost viewpoint, it is highly advantageous to use thin film solar cells which are generally made in the range of 0.1-3m in thickness. Due to this low thickness, the quantity of material is greatly reduced and so is the number and complexity of steps involved to complete a device, thereby allowing a continuous processing capability improving the throughput and hence greatly decreasing the cost. This also leads to faster payback time for the end user of the photovoltaic panel. In addition, due to the low thickness and the possibility of deposition on flexible foils, the photovoltaic (PV) modules can be flexible. Such flexible PV modules are well suited for building-integrated applications and for portable, foldable, PV power products. For economical applications of solar cells, high efficiency is an important consideration. Since Si is an indirect bandgap material, a thin film of Si needs efficient light trapping to achieve high optical absorption. The previous work in this field has been mostly based on randomly textured back reflectors. In this work, we have used a novel approach, a periodic photonic and plasmonic structure, to optimize current density of the devices by absorbing longer wavelengths without hampering other properties. The two dimensional diffraction effect generated by a periodic structure with the plasmonic light concentration achieved by silver cones to efficiently propagate light in the plane at the back surface of a solar cell, achieves a significant increase in optical absorption. Using such structures, we achieved a 50%+ increase in short circuit current in a nano-crystalline (nc-Si) solar cell relative to stainless steel. In addition to nc-Si solar cells on stainless steel, we have also used the periodic photonic structure to enhance optical absorption in amorphous cells and tandem junction amorphous/nano-crystalline cells. These structures have been fabricated on flexible plastic substrates. We will describe the use of periodic structures to achieve increased light absorption and enhanced photocurrents in thin film solar cells, and also compare them systematically with other textured substrates. We discuss the various technological aspects and obstacles faced before successful fabrication of such structure, and during the fabrication of solar cells on these structures. The ideas of periodic texturing and random texturing will be compared and an implementation of them together will be discussed.

Pattnaik, Sambit

 
 
 
 
141

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

142

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

143

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

2013-05-15

144

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

145

One-dimensional simulation study of microcrystalline silicon thin films for solar cell and thin film transistor applications using AMPS-1D  

International Nuclear Information System (INIS)

Electronic transport in hydrogenated microcrystalline silicon (?c-Si:H) films largely depends on size and shape of small crystallites columnar grains, the fraction of amorphous silicon (a-Si:H) matrix, and the highly defective grain boundaries (GBs). Based on these we describe two simple 1-D models of ?c-Si:H depending upon the conduction path. Two applications of these models are presented using AMPS-1D. First, we study the electronic transport in intrinsic ?c-Si:H for thin-film transistor (TFT) application. Second, we analyze the performance of thin film p-i-n ?c-Si:H solar cells with varying column heights in the intrinsic ?c-Si:H layer. Such a study should lead to the identification of optimum process conditions of the preparation of these films by the Cat-CVD process

2006-04-20

146

Cd-free heterojunctions in chalcopyrite based thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Common Cu(In,Ga)(Se,S)2-based thin-film solar cells need for high efficiencies two intermediate layers between the p-type chalcopyrite absorber and the conductive, transparent front contact. These two layers consist of a CdS buffer layer and an undoped ZnO protective layer. The elimination of the heavy metal Cd as well as a reduction of manufacturing costs by a simplification of the necessary process steps is desirable from an industrial point of view.

2012-01-01

147

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

148

Mixed phase silicon oxide layers for thin-film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lower absorption, lower refractive index and tunable resistance are three advantages of doped silicon oxide containing nanocrystalline silicon grains (nc-SiOx) compared to doped microcrystalline silicon, for the use as p- and n-type layers in thin-film silicon solar cells. In this study we show how optical, electrical and microstructural properties of nc-SiOx layers depend on precursor gas ratios and we propose a growth model to explain the phase separation in such films into Si-rich and O-ri...

2011-01-01

149

Angle dependent optics in nano-textured thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Highly effective light trapping and optical light incoupling concepts are essential in realizing highly efficient thin-film solar cells with absorbers in the range of micrometers. To investigate and optimize both effects, wave propagation in thin-film silicon solar cells with integrated grating couplers was modeled in two and three dimensions solving the Maxwell equations by a Finite Difference Time Domain approach. Simulations were carried out for different wavelengths and angles of incidence of light, keeping the period of the grating structure fixed. Simulation results reveal that for small angles of incidence (close to normal incidence) the absorption of the solar cells with integrated couplers is enhanced in comparison to structures without grating couplers. Such behavior is observed for shorter and longer wavelengths (500 nm and 800 nm). For intermediate angles of incidence (30 -60 ) the absorption of the structures without grating couplers exceeds the absorption attained for structures with integrated couplers. As the wavelength of the incident light increases from 500 nm to 800 nm for structures without couplers, the maxima of the absorption shifts from 60 to 40 angle of incidence. Structures with and without grating couplers exhibit similar absorption behavior for angles of incidence larger than 75 .

Dewan, Rahul; Knipp, Dietmar [School of Engineering and Science, Jacobs University Bremen (Germany); Haase, Christian; Stiebig, Helmut [Institute of Photovoltaics, Research Center Juelich (Germany)

2008-07-01

150

13. 4% efficient thin-film CdS/CdTe solar cells  

Energy Technology Data Exchange (ETDEWEB)

Cadmium telluride is a promising thin-film photovoltaic material as shown by the more than 10% efficient CdS/CdTe heterojunction solar cells. In this work, thin-film CdS/CdTe solar cells have been prepared using CdS films grown from an aqueous solution and {ital p}-CdTe films deposited by close-spaced sublimation (CSS). The properties of CdS films deposited from an ammonical solution of a Cd-salt, an ammonium salt, and thiourea have been controlled by optimizing the temperature and composition of the solution. The solution-grown CdS films have a high photoconductivity ratio, and its optical transmission is superior to that of vacuum evaporated CdS films. The properties of {ital p}-CdTe films deposited by CSS have been optimized by controlling the temperature and composition of the source material, and the substrate temperature. The properties of CdS/CdTe heterojunctions have been studied; junction photovoltage spectroscopy is used for the qualitative comparison of junction characteristics. Solar cells of 1-cm{sup 2} area with an AM 1.5 efficiency of 13.4% are reported.

Chu, T.L.; Chu, S.S.; Ferekides, C.; Wu, C.Q.; Britt, J.; Wang, C. (Department of Electrical Engineering, University of South Florida, Tampa, Florida (USA))

1991-12-15

151

Thin film solar cell and its production method; Hakumaku taiyo denchi oyobi sono seizo hoho  

Energy Technology Data Exchange (ETDEWEB)

This invention decreases the degradation of solar cell performance due to the leak current caused by pinhole. In addition, the invention provides a thin film solar cell with less sunlight loss at the window layer. The invented thin film solar cell is equipped with a light absorption layer, an electrode contacting with the said layer, a multi-layered window layer made by laminating the light absorption layer and the opposite electrode, and an electrode which partially contacts with the window layer that is the most far from the light absorption layer. It is characterized by this invention that the carrier concentration, forbidden band width, and the sum of forbidden band width and electron affinity are either equalized or enlarged along with the multi-layered window layer contacting with the light absorption layer. It is preferable to select the light absorption layer material from any of CuInSe2, CuInS2, CuGaSe2, CuGaS2, and solid solution of these materials. It is also preferable to use the CdS layer produced by precipitation from the solution as for the layer contacting with light absorption layer and to use the other multi-layered window layer materials which are substantially the same material. 4 figs., 2 tabs.

Terauchi, M.; Wada, T.

1996-12-13

152

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

153

Nanoscale investigation of potential distribution in operating Cu(In,Ga)Se2 thin-film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The distribution of the electrostatic potential in and between the materials in Cu(In,Ga)Se2 thin-film solar cells has a major impact on their superior performance. This thesis reported on the nanoscale imaging of the electrostatic potential on untreated cross sections of operating Cu(In,Ga)Se2 solar cells using Kelvin probe force microscopy.

Zhang, Zhenhao

2013-01-01

154

Light trapping in thin-film silicon solar cells with submicron surface texture.  

Science.gov (United States)

The influence of nano textured front contacts on the optical wave propagation within microcrystalline thin-film silicon solar cell was investigated. Periodic triangular gratings were integrated in solar cells and the influence of the profile dimensions on the quantum efficiency and the short circuit current was studied. A Finite Difference Time Domain approach was used to rigorously solve the Maxwell's equations in two dimensions. By studying the influence of the period and height of the triangular profile, the design of the structures were optimized to achieve higher short circuit currents and quantum efficiencies. Enhancement of the short circuit current in the blue part of the spectrum is achieved for small triangular periods (P<200 nm), whereas the short circuit current in the red and infrared part of the spectrum is increased for triangular periods (P = 900nm) comparable to the optical wavelength. The influence of the surface texture on the solar cell performance will be discussed. PMID:20052232

Dewan, Rahul; Marinkovic, Marko; Noriega, Rodrigo; Phadke, Sujay; Salleo, Alberto; Knipp, Dietmar

2009-12-01

155

CdTe thin film solar cells prepared by a low-temperature deposition method  

Energy Technology Data Exchange (ETDEWEB)

Low-temperature vacuum deposition instead of the commonly used vacuum deposition at high substrate temperatures has been applied to prepare high efficiency (CdS/CdTe) solar cells. CdS and CdTe thin films have been subsequently deposited on SnO{sub 2}/Corning 7059 glass substrates and examined by using scanning electron microscopy (SEM) and grazing incidence X-ray diffraction (GIXRD) techniques. It has been found that CdTe and CdS films deposited at low substrate temperature (218 K) have very similar grain sizes and surface morphology, necessary for high efficiency photovoltaic performance of the resultant device structures. Particularly, the obtained solar cells have shown efficiencies of more than 14%. The applied preparation method can be regarded as promising for high efficiency CdTe-based solar cell fabrication. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Novruzov, V.D.; Gorur, O.; Tomakin, M. [Rize University, 53100 Rize (Turkey); Fathi, N.M.; Bayramov, A.I.; Mamedov, N. [Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid ave. 33, 1143 Baku (Azerbaijan); Schorr, S. [Institute of Geological Sciences, Free University Berlin, Malteserstr. 74-100, 12249 Berlin (Germany)

2010-03-15

156

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

157

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

158

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

159

10% conversion efficiency in thin film polycrystalline cadmium-zinc sulfide/copper sulfide solar cells  

Science.gov (United States)

Thin film cadmium-zinc sulfide/copper sulfide solar cells have been developed with conversion efficiencies greater than 10% in direct sunlight. The development of these cells was based on decreasing the electron affinity mismatch between the Cu2S and CdS and thereby raising the open-circuit voltage above that achievable with the standard CdS/Cu2S solar cell. The electron affinity of the CdS was reduced by the incorporation of Zn by the co-evaporation of CdS and ZnS. With improved preparation of Cd(1-x)Zn(x)S (with x between .1 and .2) films, and the same process that produced Cu2S/CdS cells with efficiencies in excess of 9%, the increased open-circuit voltage has led to efficiencies greater than 10%.

Hall, R. B.; Birkmire, R. W.; Phillips, J. E.; Meakin, J. D.

160

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

 
 
 
 
161

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.

2010-02-01

162

Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates  

Science.gov (United States)

In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a wide range of applications, such as in green house, lighting etc, are applied in these solar cells for light trapping. Thin silicon films can be produced by decomposing silane gas, using a plasma process. In these types of processes, the temperature of the growing surface has a large influence on the quality of the grown films. Because plastic substrates limit the maximum tolerable substrate temperature, new methods have to be developed to produce device-grade silicon layers. At low temperature, polysilanes can form in the plasma, eventually forming dust particles, which can deteriorate device performance. By studying the spatially resolved optical emission from the plasma between the electrodes, we can identify whether we have a dusty plasma. Furthermore, we found an explanation for the temperature dependence of dust formation; Monitoring the formation of polysilanes as a function of temperature using a mass-spectrometer, we observed that the polymerization rate is indeed influenced by the substrate temperature. For solar cell substrate material, our choice was polycarbonate (PC), because of its low cost, its excellent transparency and its relatively high glass transition temperature of 130-140C. At 130C we searched for deposition recipes for device quality silicon, using a very high frequency plasma enhanced chemical deposition process. By diluting the feedstock silane with hydrogen gas, the silicon quality can be improved for amorphous silicon (a-Si), until we reach the nanocrystalline silicon (nc-Si) regime. In the nc-Si regime, the crystalline fraction can be further controlled by changing the power input into the plasma. With these layers, a-Si thin film solar cells were fabricated, on glass and PC substrates. The adverse effect of the low temperature growth on the photoactive material is further mitigated by using thinner silicon layers, which can deliver a good current only with an adequate light trapping technique. We have simulated and experimentally tested three light trapping techniques, using embossed structures in PC substrates and random structures on glass: regular pyramid structures larger than the wavelength of light (micropyramids), regular pyramid structures comparable to the wavelength of light (nanopyramids) and random nano-textures (Asahi U-type). The use of nanostructured polycarbonate substrates results in initial conversion efficiencies of 7.4%, compared to 7.6% for cells deposited under identical conditions on Asahi U-type glass. The potential of manufacturing thin film solar cells at processing temperatures lower than 130oC is further illustrated by obtained results on texture-etched aluminium doped zinc-oxide (ZnO:Al) on glass: we achieved 6.9% for nc-Si cells using a very thin absorber layer of only 750 nm, and by combining a-Si and nc-Si cells in tandem solar cells we reached an initial conversion efficiency of 9.5%.

de Jong, M. M.

2013-01-01

163

Generation of electrical defects in ion beam assisted deposition of Cu(In,Ga)Se2 thin film solar cells  

International Nuclear Information System (INIS)

Thin films of Cu(In,Ga)Se2 (CIGS) absorber layers for thin film solar cells have been manufactured on polyimide foil in a low temperature, ion beam assisted co-evaporation process. In the present work a set of CIGS thin films was produced with varying selenium ion energy. Solar cell devices have been manufactured from the films and characterized via admittance spectroscopy and capacitance-voltage profiling to determine the influence of the selenium ion energy on the electric parameters of the solar cells. It is shown that the impact of energetic selenium ions in the CIGS deposition process leads to a change in the activation energy and defect density and also in the spatial distribution of electrically active defects. For the interpretation of the results two defect models are taken into account.

2011-08-31

164

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

Science.gov (United States)

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, C. J.; Panjwani, D. R.; Arnold, J. P.; Figueiredo, P. N.; Rezaie, F. K.; Colwell, J.; Baillie, K.; Peppernick, S. J.; Joly, A. G.; Beck, K. M.; Hess, W. P.; Peale, R. E.

2011-09-01

165

Fabrication of thin film nanocrystalline silicon solar cell with low light-induced degradation  

Energy Technology Data Exchange (ETDEWEB)

Nanocrystalline silicon thin films have been deposited at different total gas flow rates and plasma excitation frequencies and samples with similar crystalline volume fraction have been compared. In hydrogenated nanocrystalline silicon solar cells, amorphous component is not necessarily the only determining factor for light-induced degradation. Smaller grain size less than 3 nm diameter and intermediate range order provide a better stability in the i-layer near the p/i interface, thus improving the overall stability of the solar cell. Light-induced degradation (LID) of efficiency of the cell mainly depends on the light-induced degradation of short-circuit current density and light-induced degradation of fill factor (FF). Degradation of open-circuit voltage is less than 1%. Minimum degradation of efficiency obtained in this work is 2%. (author)

Chowdhury, Amartya; Mukhopadhyay, Sumita; Ray, Swati [Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)

2009-05-15

166

Deep level transient spectroscopy measurements on CuInS{sub 2}-thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

During the last decade CuInS2 was investigated for its use as absorber in thin film solar cells. Now these cells are ready for volume production. The advantages against already used materials are e. g. high absorbing capacity and cost-efficient and sustainable production. Because of the great discrepancy between predicted degree of efficiency and the already reached degree more investigations are necessary. To get a better understanding of the electron transport and recombination in order to arise efficiency we characterize the solar cells by deep level transient spectroscopy (DLTS). This method gives information about crystal defects depending on their electric position. Transient capacity measurements in the range of 25 K and 350 K allow us to determine activation energy and concentration of electron traps.

Malek, Stephanie; Knipper, Martin; Parisi, Juergen [Carl-von-Ossietzky-Universitaet, Oldenburg (Germany)

2008-07-01

167

Deep level transient spectroscopy measurements on CuInS2-thin film solar cells  

International Nuclear Information System (INIS)

During the last decade CuInS2 was investigated for its use as absorber in thin film solar cells. Now these cells are ready for volume production. The advantages against already used materials are e. g. high absorbing capacity and cost-efficient and sustainable production. Because of the great discrepancy between predicted degree of efficiency and the already reached degree more investigations are necessary. To get a better understanding of the electron transport and recombination in order to arise efficiency we characterize the solar cells by deep level transient spectroscopy (DLTS). This method gives information about crystal defects depending on their electric position. Transient capacity measurements in the range of 25 K and 350 K allow us to determine activation energy and concentration of electron traps

2008-02-25

168

Light trapping regimes in thin-film silicon solar cells with a photonic pattern.  

Science.gov (United States)

We present a theoretical study of crystalline and amorphous silicon 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 (AR) coating. The study and optimization of the structure as a function of all the photonic lattice parameters, together with the calculation of the absorption in a single layer, allows to identify the different roles of the periodic pattern in determining an increase of the absorbance. From one side, the photonic crystal and the AR coating act as impedance matching layers, 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 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 for patterning of thin-film silicon solar cells. PMID:20389438

Zanotto, Simone; Liscidini, Marco; Andreani, Lucio Claudio

2010-03-01

169

Laser textured substrates for light in-coupling in thin-film solar cells  

Science.gov (United States)

In this work we investigate the use of a picosecond (ps) laser used for monolithic connection to pattern glass substrates to achieve light in-coupling in silicon thin film solar cells. We present our results on the patterning of three commercially available and frequently used multi-component glasses Corning EAGLE XG, Schott BOROFLOAT 33 and Saint-Gobain SGG DIAMANT. We find that the different glass structural components influence the degree of texturing obtained. This can be attributed to the different laser induced electron collision times and recombination rates, and thus the critical electron density evolution leading to ablation. Thus the ablated crater profile is glass composition dependent. The surface texture is altered from periodic to random with decreasing scribing speed. The transmission of the textured substrates gradually decreases while the reflection increases as a consequence of the topological and morphological changes. The angular resolved measurements illustrate that highly textured substrates scatter the light towards greater angles. This demonstrates potential for the application in substrate configuration (nip) thin film solar cells, as the scattering can increase the optical path, and hence the absorption in the absorber layer. Simulations of periodically textured glass substrates demonstrate a focused optical generation rate near the front contact and absorber layer interface. The influence of the modified refractive index region on the optical generation rate and reflection depends on the crater profile. The reflection is generally reduced when a periodic texture in the micrometre range is implemented.

Chakanga, Kambulakwao; Siepmann, Ortwin; Sergeev, Oleg; Geiendrfer, Stefan; von Maydell, Karsten; Agert, Carsten

2014-03-01

170

Microstructure characterization of titanium dioxide nanodispersions and thin films for dye-sensitized solar cell devices  

Energy Technology Data Exchange (ETDEWEB)

This article reports on the microstructure characterization of titanium dioxide nanodispersions and thin films made thereof for dye-sensitized solar cell devices. Structure-property relationships have been investigated mainly using electron microscopy to assess how microstructure (crystalline structure, defects) and morphological (e.g. heterogeneities, inclusions, voids) features in the electron transport element of the solar cell device correlate with electrical performance, namely, short-circuit photocurrent density (Jsc). This work shows that for a nanodispersion synthesized in the laboratory different electrical performances are measurable depending on the thin film forming process, more specifically, heat sintering at 450C or pressure sintering at 500 bar. For the heat sintered device Jsc is about 7.3 mA/cm2 whereas for the pressure sintered device this value is much lower. This difference is being attributed to the existence of inclusions in the titanium dioxide matrix, which are spatially isolated from the rest of the electron transport element, thereby limiting the charge transport process by promoting their premature recombination.

Van Deelen, J.; Kroon, J.M. [ECN Solar Energy, Petten (Netherlands); De Almeida, P.; Catry, C.; Sneyers, H.; Pataki, T.; Andriessen, R.; Van Roost, C. [Agfa-Gevaert, R and D Materials, Mortsel (Belgium)

2004-11-01

171

Cu2SixSn1?xS3 Thin Films Prepared by Reactive Magnetron Sputtering For Low-Cost Thin Film Solar Cells  

International Nuclear Information System (INIS)

We report the preparation of Cu2SixSn1?xS3 thin films for thin film solar cell absorbers using the reactive magnetron co-sputtering technique. Energy dispersive spectrometer and x-ray diffraction analyses indicate that Cu2Si1?xSnxS3 thin films can be synthesized successfully by partly substituting Si atoms for Sn atoms in the Cu2SnS3 lattice, leading to a shrinkage of the lattice, and, accordingly, by 2? shifting to larger values. The blue shift of the Raman peak further confirms the formation of Cu2SixSn1?xS3. Environmental scanning electron microscope analyses reveal a polycrystalline and homogeneous morphology with a grain size of about 200300 nm. Optical measurements indicate an optical absorption coefficient of higher than 104 cm?1 and an optical bandgap of 1.170.01 eV. (cross-disciplinary physics and related areas of science and technology)

2011-10-01

172

Growth and characterization of Cu2ZnSn(S,Se)4 thin films for solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with their band gap energies around 1.45 eV and 1.0 eV, respectively, can be used as the absorber layer in thin film solar cells. By using a mixture of both compounds, Cu2ZnSn(S,Se)4 (CZTSSe), a band gap tuning may be possible. The latter material has already shown promising results such as solar cell efficiencies up to 10.1%. In this work, CZTSSe thin films were grown in order to study its structure and to establish the best growth precurso...

Salome?, P. M. P.; Malaquias, J.; Fernandes, P. A.; Ferreira, M. S.; Cunha, A. F. Da; Leita?o, J. P.; Gonza?lez, J. C.; Matinaga, F. M.

2012-01-01

173

Copper and Transparent-Conductor Reflectarray Elements on Thin-Film Solar Cell Panels  

CERN Document Server

This work addresses the integration of reflectarray antennas (RA) on thin film Solar Cell (SC) panels, as a mean to save real estate, weight, or cost in platforms such as satellites or transportable autonomous antenna systems. Our goal is to design a good RA unit cell in terms of phase response and bandwidth, while simultaneously achieving high optical transparency and low microwave loss, to preserve good SC and RA energy efficiencies, respectively. Since there is a trade-off between the optical transparency and microwave surface conductivity of a conductor, here both standard copper and transparent conductors are considered. The results obtained at the unit cell level demonstrates the feasibility of integrating RA on a thin-film SC, preserving for the first time good performance in terms of both SC and RA efficiency. For instance, measurement at X-band demonstrate families of cells providing a phase range larger than 270{\\deg} with average microwave loss of -2.45dB (resp. -0.25dB) and average optical transpa...

Dreyer, Philippe; Nicolay, Sylvain; Ballif, Christophe; Perruisseau-Carrier, Julien

2013-01-01

174

Thin film solar cells on glass by transfer of monocrystalline Si films  

Directory of Open Access Journals (Sweden)

Full Text Available Thin film solar cells based on monocrystalline Si films are transferred to a glass superstrate. Chemical vapor deposition serves to epitaxially deposit Si on quasi-monocrystalline Si films obtained from thermal crystallization of a double layer porous Si film on a Si wafer. A separation layer that forms during this crystallization process allows one to separate the epitaxial layer on top of the quasi-monocrystalline film from the starting Si wafer. We presently achieve an independently confirmed solar cell conversion efficiency of 9:26%. Ray tracing studies in combination with electrical device simulation indicate an efficiency potential of around 17% using simple device processing and moderate assumptions on minority carrier lifetime and surface recombination.

J. H. Werner

1999-01-01

175

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

176

Designing optimized nano textures for thin-film silicon solar cells.  

Science.gov (United States)

Thin-film silicon solar cells (TFSSC), which can be manufactured from abundant materials solely, contain nano-textured interfaces that scatter the incident light. We present an approximate very fast algorithm that allows optimizing the surface morphology of two-dimensional nano-textured interfaces. Optimized nano-textures scatter the light incident on the solar cell stronger leading to a higher short-circuit current density and thus efficiency. Our algorithm combines a recently developed scattering model based on the scalar scattering theory, the Perlin-noise algorithm to generate the nano textures and the simulated annealing algorithm as optimization tool. The results presented in this letter allow to push the efficiency of TFSSC towards their theoretical limit. PMID:24104492

Jger, Klaus; Fischer, Marinus; van Swaaij, Ren A C M M; Zeman, Miro

2013-07-01

177

Kelvin Probe Measurements on Solar Cells and Other Thin Film Devices  

Science.gov (United States)

The Kelvin Probe (KP) has been used for years to measure the surface potential of metals and semiconductors. The KP is an elegantly simple but powerful tool invented by Lord Kelvin around the turn of the century. Using changes in surface potentials as a result of changing the intensity and wavelength of illumination, the KP returns data on material parameters such as band gap energies and the energy levels of interface states. We have employed the KP in the study of CdTe-based solar cells and quantum dot-based solar cells, as well as other thin-film devices. We hope eventually that the KP will be used as an in-line testing station for a fabrication process so that unfinished devices that will not meet requirements can be thrown out before the processing is completed, thus saving resources. Results of these studies will be presented.

Delk, John; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

2001-01-01

178

Modelling and Degradation Characteristics of Thin-film CIGS Solar Cells  

Energy Technology Data Exchange (ETDEWEB)

Thin-film solar cells based around the absorber material CuIn{sub 1-x}Ga{sub x}Se2 (CIGS) are studied with respect to their stability characteristics, and different ways of modelling device operation are investigated. Two ways of modelling spatial inhomogeneities are detailed, one fully numerical and one hybrid model. In the numerical model, thin-film solar cells with randomized parameter variations are simulated showing how the voltage decreases with increasing material inhomogeneities. With the hybrid model, an analytical model for the p-n junction action is used as a boundary condition to a numerical model of the steady state electrical conduction in the front contact layers. This also allows for input of inhomogeneous material parameters, but on a macroscopic scale. The simpler approach, compared to the numerical model, enables simulations of complete cells. Effects of material inhomogeneities, shunt defects and grid geometry are simulated. The stability of CIGS solar cells with varying absorber thickness, varying buffer layer material and CIGS from two different deposition systems are subjected to damp heat treatment. During this accelerated ageing test the cells are monitored using characterization methods including J-V, QE, C-V and J(V)T. The degradation studies show that the typical VOC decrease experienced by CIGS cells subjected to damp heat is most likely an effect in the bulk of the absorber material. When cells encapsulated with EVA are subjected to the same damp heat treatment, the effect on the voltage is considerably reduced. In this situation the EVA is saturated with moisture, representing a worst case scenario for a module in operation. Consequently, real-life modules will not suffer extensively from the VOC degradation effect, common in unprotected CIGS devices

Palm, Ulf

2008-10-15

179

Optimized light harvesting in thin film organic solar cells - modeling and experimental results  

Energy Technology Data Exchange (ETDEWEB)

Optimal light absorption in the intrinsic layers of organic thin film solar cells is one of the basics for reaching high power conversion efficiencies. However, multilayer interference phenomena have to be taken into account when designing the solar cell stack. Especially in the case of tandem solar cells, consisting of subcells with spectral complementary absorbers, interference effects have to be considered for current matching of the both subcells. We present results of organic solar single and tandem solar cells, based on small molecules, which are designed and optimised by means of optical simulations based on a transfer-matrix-algorithm. The optical simulation is verified by electrical characterization of solar cells with variation in layer thickness and by determining the spectral absorption by reflectance measurements with a fiber optical set-up, which also offers a validation of the layer deposition procedure at functional devices. In addition to well controlled film thicknesses, the optical constants of the used organic materials are crucial for the optical simulation. Therefore, particular attention has to spend when determining theses constants and we present a sensitivity analysis for the predicted current densities with respect to errors in the optical constants.

Merten, Andre; Dirks, Uwe; Furno, Mauro; Meiss, Jan; Timmreck, Ronny; Schueppel, Rico; Leo, Karl; Riede, Moritz [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden (Germany)

2010-07-01

180

Hydrogenated amorphous silicon thin film solar cell with buffer layer of DNA-CTMA biopolymer  

Science.gov (United States)

The characteristics of nip-type a-Si:H thin film solar cells based on DNA-CTMA biopolymer was investigated. The DNA-CTMA was used as the buffer layer in nip-type a-Si:H solar cell. The Eopt of the DNA-CTMA biopolymer was measured with UV-VIS spectrometer. The Eopt of DNA-CTMA was determined as 3.96 eV by the plot of (Ah?)2 versus h?. All films of amorphous materials were deposited by PECVD method. The solar cell with a simple structure of glass/ITO/n-a-Si:H/i-a-Si:H/p-a-Si:H/DNA-CTMA/Al was fabricated. The various values of Voc, Jsc, FF, and conversion efficiency ? were measured under 100 mW/cm2 (AM 1.5) solar simulator irradiation. Consequently, the resulting in solar cell showed an enhancement in conversion efficiency ? compared to conventional nip-type a-Si:H solar cell without buffer layer of DNA-CTMA biopolymer.

Son, Won-Ho; Reddy, M. Siva Pratap; Choi, Sie-Young

2014-05-01

 
 
 
 
181

Temperature dependent electron beam induced current experiments on chalcopyrite thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Electron-beam-induced current (EBIC) profiles of Mo/CuInX{sub 2}/CdS/ZnO thin film solar cells with X=Se, S were recorded at different temperatures. We measure the collection efficiency of cells as a function of the beam energy and subsequently identify the depth dependent collection function. For a CuInS{sub 2} based cell, charge collection is maintained by diffusion transport of minority carriers to the junction with an effective diffusion length of 1.3{plus_minus}0.2 {mu}m. This value is independent on temperature between 123 and 373 K. A CuInSe{sub 2} based cell exhibits increased collection of charge carriers created at the back contact on decreasing temperature. The temperature variation of the EBIC profiles is discussed considering the effect of bulk and grain boundary recombination. {copyright} {ital 1997 American Institute of Physics.}

Scheer, R.; Wilhelm, M. [Hahn-Meitner Institut, Alteilung Grenzflaechen, Glienicker Str. 100, 14109 Berlin (Germany); Stolt, L. [Uppsala University, Teknikum, P.B. 534, S-75121 Uppsala (Sweden)

1997-02-01

182

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

183

Flexible Cu(In,Ga)Se2 thin-film solar cells for space application  

International Nuclear Information System (INIS)

Thin film solar cells (TFSC) with Cu(In,Ga)Se2 (CIGS) as absorber layer have been produced on rigid glass substrates for the terrestrial market. There exist, however, different investigations for manufacturing of TFSC on flexible substrates in order to achieve very thin and highly flexible (rollable) solar cells. Besides their capability to open new terrestrial market segments, they are considered as competitive candidates for future flexible thin film space power generators compared to traditional crystalline solar cells. This paper explains the advantages of flexible TFSC for usage in space, including:-low mass and storage volume, -high power/mass ratio [>100 W/kg at array level], -high radiation resistance against proton and electron radiation and, -lower production costs. These cells can be produced on flexible conductive and insulating substrate materials and have efficiency potentials of up to 15%. We report on the current development steps to adopt the TFSC technology to space requirements as well as the first European industrial approach to the roll-to-roll production of flexible CIGS-TFSC on polyimide as substrate material. Stability issues in space environment concern not only the TFSC itself, but all system components such as interconnects, cell assembly and flexible blankets. The adhesion of the back-contact to the substrate, the emissivity control in the infrared wavelength range, the electrical contacting and interconnection as well as flexible encapsulation are currently under investigation and are discussed in the paper. The production costs for TFSC for space application can be further reduced by sharing resources for the production of flexible TFSC for the terrestrial market; namely by using both, the existing terrestrial investment in production facilities as well as the synergies in R and D

2006-07-26

184

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

185

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

Science.gov (United States)

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 Powe...

D. Slafer V. Dalal

2012-01-01

186

Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates  

Science.gov (United States)

Fabrication of thin-film solar cells (TFSCs) on substrates other than Si and glass has been challenging because these nonconventional substrates are not suitable for the current TFSC fabrication processes due to poor surface flatness and low tolerance to high temperature and chemical processing. Here, we report a new peel-and-stick process that circumvents these fabrication challenges by peeling off the fully fabricated TFSCs from the original Si wafer and attaching TFSCs to virtually any substrates regardless of materials, flatness and rigidness. With the peel-and-stick process, we integrated hydrogenated amorphous silicon (a-Si:H) TFSCs on paper, plastics, cell phone and building windows while maintaining the original 7.5% efficiency. The new peel-and-stick process enables further reduction of the cost and weight for TFSCs and endows TFSCs with flexibility and attachability for broader application areas. We believe that the peel-and-stick process can be applied to thin film electronics as well.

Lee, Chi Hwan; Kim, Dong Rip; Cho, In Sun; William, Nemeth; Wang, Qi; Zheng, Xiaolin

2012-12-01

187

Fabrication of nanocrystal ink based superstrate-type CuInS2 thin film solar cells  

Science.gov (United States)

A CuInS2 (CIS) nanocrystal ink was applied to thin film solar cell devices with superstrate-type configuration. Monodispersed CIS nanocrystals were synthesized by a colloidal synthetic route and re-dispersed in toluene to form an ink. A spray method was used to coat CIS films onto conducting glass substrates. Prior to CIS film deposition, TiO2 and CdS thin films were also prepared as a blocking layer and a buffer layer, respectively. We found that both a TiO2 blocking layer and a CdS buffer layer are necessary to generate photoresponses in superstrate-type devices. The best power conversion efficiency (1.45%) was achieved by the CIS superstrate-type thin film solar cell device with 200 and 100 nm thick TiO2 and CdS films, respectively.

Cho, Jin Woo; Park, Se Jin; Kim, Woong; Koun Min, Byoung

2012-07-01

188

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

189

Tailoring randomly rough textures for light trapping in thin-film solar cells  

Science.gov (United States)

In this contribution, we use a rigorous electro-optical model to study randomly rough crystalline silicon solar cells with the absorber thickness ranging from 1 to 100 ?m. We demonstrate a significant efficiency enhancement, particularly strong for thin cells. We estimate the "region of interest" for thin-film photovoltaics, namely the thickness range for which the energy conversion efficiency reaches maximum. This optimal thickness results from the opposite trends of current and voltage as a function of the absorber thickness. Finally, we focus on surface recombination. In our design, the cell efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore engineering the front surface to a large extent does not reduce the efficiency. The presented model of roughness adds a significant functionality to previous approaches, for it allows performing rigorous calculations at a much reduced computational cost.

Kowalczewski, Piotr; Bozzola, Angelo; Liscidini, Marco; Andreani, Lucio Claudio

2014-05-01

190

Thin film solar cells based on the ternary compound Cu2SnS3  

International Nuclear Information System (INIS)

Alongside with Cu2ZnSnS4 and SnS, the p-type semiconductor Cu2SnS3 also consists of only Earth abundant and low-cost elements and shows comparable opto-electronic properties, with respect to Cu2ZnSnS4 and SnS, making it a promising candidate for photovoltaic applications of the future. In this work, the ternary compound has been produced via the annealing of an electrodeposited precursor in a sulfur and tin sulfide environment. The obtained absorber layer has been structurally investigated by X-ray diffraction and results indicate the crystal structure to be monoclinic. Its optical properties have been measured via photoluminescence, where an asymmetric peak at 0.95 eV has been found. The evaluation of the photoluminescence spectrum indicates a band gap of 0.93 eV which agrees well with the results from the external quantum efficiency. Furthermore, this semiconductor layer has been processed into a photovoltaic device with a power conversion efficiency of 0.54%, a short circuit current of 17.1 mA/cm2, an open circuit voltage of 104 mV hampered by a small shunt resistance, a fill factor of 30.4%, and a maximal external quantum efficiency of just less than 60%. In addition, the potential of this Cu2SnS3 absorber layer for photovoltaic applications is discussed. - Highlights: ? Fabrication of a pn-junction based thin film solar cell based on Cu2SnS3. ? Electro-optical properties of the Cu2SnS3 based solar cell and its limits. ? The potential of Cu2SnS3 based solar cells in terms of its photovoltaic application. ? Structural, morphological, and optical properties of a Cu2SnS3 thin film.

2012-07-31

191

Thin film deposition of Cu{sub 2}O and application for solar cells  

Energy Technology Data Exchange (ETDEWEB)

Deposition conditions of cuprous oxide (Cu{sub 2}O) thin films on glass substrates and nitrogen doping into Cu{sub 2}O were studied by using reactive radio-frequency magnetron sputtering method. The effects of defect passivation by crown-ether cyanide treatment, which simply involves immersion in KCN solutions containing 18-crown-6 followed by rinse, were also studied. By the crown-ether cyanide treatment, the luminescence intensity due to the near-band-edge emission of Cu{sub 2}O at around 680nm was enhanced, and the hole density was increased from 10{sup 16} to 10{sup 17}cm{sup -3}. Finally, polycrystalline p-Cu{sub 2}O/n-ZnO heterojunctions were grown for use in solar cells. Two deposition sequences were studied, ZnO deposited on Cu{sub 2}O and Cu{sub 2}O deposited on ZnO. It was found that the crystallographic orientation and current-voltage characteristics of the heterojunction were significantly influenced by the deposition sequence, both being far superior for the heterojunction with structure Cu{sub 2}O on ZnO than for the inverse structure. We successfully obtained a photoresponse for the first time in the deposited thin film of Cu{sub 2}O/ZnO. (author)

Akimoto, K.; Ishizuka, S.; Yanagita, M.; Nawa, Y.; Paul, Goutam K.; Sakurai, T. [Institute of Applied Physics, University of Tsukuba, CREST, Japan Science and Technology Corporation, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

2006-06-15

192

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

193

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

2003-05-01

194

Single source precursors for fabrication of I-III-VI{sub 2} thin-film solar cells via spray CVD  

Energy Technology Data Exchange (ETDEWEB)

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 CuInS{sub 2}, CuGaS{sub 2} and CuGaInS{sub 2} 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.

Hollingsworth, J.A.; Banger, K.K.; Jin, M.H.-C.; Harris, J.D.; Cowen, J.E.; Bohannan, E.W.; Switzer, J.A.; Buhro, W.E.; Hepp, A.F

2003-05-01

195

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

196

Low-temperature Deposition of Hydrogenated Microcrystalline Silicon Thin Films by Photochemical Vapor Deposition Technique and Their Application to Thin Film Solar Cells  

Science.gov (United States)

Hydrogenated microcrystalline silicon (?c-Si:H) thin films were prepared by mercury-sensitized photochemical vapor deposition (photo-CVD) technique at various deposition temperatures. Crystalline volume fraction showed a monotonic decrease with increasing temperature from 125 to 200 C caused by the enhanced desorption of surface hydrogen atoms. Since a similar decrease has been reported at higher temperatures than 400 C in plasma-enhanced vapor deposition technique, we conclude that photon energy from ultraviolet radiation serves to activate surface species in photo-CVD process. In spite of the low deposition temperature, the obtained films had excellent material properties. Then, thin film solar cells were fabricated on a Type-U substrate with various haze ratios provided by Asahi Glass using such films as the i-layer. A substrate with a high haze ratio of about 50% was effective in realizing a better light-trapping structure. By decreasing the deposition temperature of the i-layer to 140 C, conversion efficiency was improved markedly due to the improved film quality brought about by the contributions of photons from ultraviolet radiation to the enhancement of the surface migration of the radicals for reducing defects in the resulting film. Consequently, a maximum solar cell efficiency of 7.4% was obtained.

Hiza, Shuichi; Yamada, Akira; Konagai, Makoto

2007-04-01

197

Research on polycrystalline thin-film CuGaInSe[sub 2] solar cells  

Energy Technology Data Exchange (ETDEWEB)

This report describes research to fabricate high-efficiency CdZnS/CuInGaSe[sub 2] (CIGS) thin-film solar cells, and to develop improved transparent conductor window layers such as ZnO. A specific technical milestone was the demonstration of an air mass (AM) 1.5 global, 13% efficient, 1-cm[sup 2]-total-area CIGS thin-film solar cell. Our activities focused on three areas. First, a CIGS deposition: system was modified to double its substrate capacity, thus increasing throughput, which is critical to speeding the process development by providing multiple substrates from the same CIGS run. Second, new tooling was developed to enable an investigation of a modified aqueous CdZnS process. The goal was to improve the yield of this critical step in the device fabrication process. Third, our ZnO sputtering system was upgraded to improve its reliability, and the sputtering parameters were further optimized to improve its properties as a transparent conducting oxide. The characterization of the new CIGS deposition system substrate fixturing was completed, and we produced good thermal uniformity and adequately high temperatures for device-quality CIGS deposition. Both the CIGS and ZnO deposition processes were refined to yield a ZnO//Cd[sub 0.82]Zn[sub 0.18]S/CuIn[sub 0.80]Ga[sub 0.20]Se[sub 2] cell that was verified at NREL under standard testing conditions at 13.1% efficiency with V[sub oc] = 0.581 V, J[sub sc] = 34.8 mA/cm[sup 2], FF = 0.728, and a cell area of 0.979 cm[sup 2].

Stanbery, B.J.; Chen, W.S.; Devaney, W.E.; Stewart, J.W. (Boeing Co., Seattle, WA (United States). Defense and Space Systems Group)

1992-11-01

198

Effects of deposition temperature and hydrogen flow rate on the properties of the Al-doped ZnO thin films and amorphous silicon thin-film solar cells  

Science.gov (United States)

A compound of 98 mol% ZnO and 1 mol% Al2O3 (AZO, Al:Zn = 98:2) was sintered at 1350 C as a target and the AZO thin films were deposited on glass using a radio frequency magnetron sputtering system. The effects of deposition temperature (from room temperature to 300 C) on the optical transmission spectrum of the AZO thin films were studied. The Burstein-Moss shift was observed and used to prove that defects in the AZO thin films decreased with increasing deposition temperature. The variations in the optical band gap ( E g) values of the AZO thin films were evaluated from plots of ( ?hv)2= c( h?- E g), revealing that the measured E g values increased with increasing deposition temperature. The effects of the H2 flow rate during deposition (0 %11.76 %, deposition temperature of 200 C) on the crystallization, morphology, resistivity, carrier concentration, carrier mobility, and optical transmission spectrum of the AZO thin films were measured. The chemical structures of the Ar-deposited and 2 % H2-flow rate-deposited AZO thin films (both were deposited at 200 C) were investigated by XPS to clarify the mechanism of improvement in resistivity. The prepared AZO thin films were also used as transparent electrodes to fabricate amorphous silicon thin-film solar cells, and their properties were also measured.

Huang, Chia-Cheng; Wang, Fang-Hsing; Yang, Chen-Fu

2013-09-01

199

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

200

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

2012-02-01

 
 
 
 
201

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

202

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

Science.gov (United States)

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%. PMID:22155981

Dewan, Rahul; Fischer, Stefan; Meyer-Rochow, V Benno; zdemir, Yasemin; Hamraz, Saeed; Knipp, Dietmar

2012-03-01

203

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%.

2012-03-01

204

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

205

Effective Ag doping by He-Ne laser exposure to improve the electrical and the optical properties of CdTe thin films for heterostructured thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The cadmium telluride (CdTe) thin film solar cell is one of the strongest candidates due to the optimum band gap energy (about 1.4 eV) for solar energy absorption, high light absorption capability and lower cost requirements for solar cell production. However, the maximum efficiency of a CdTe thin film solar cell still remains just 16.5% despite its excellent absorption coefficient; i.e., the electrical properties of CdTe thin film, including the resistivity, must be improved to enhance the energy conversion efficiency. Silver (Ag) was doped by using helium-neon (He-Ne) laser (632.8 nm) exposure into sputtering-deposited p-type CdTe thin films. The resistivity of the Ag-doped CdTe thin films was reduced from 2.97 x 10{sup 4} {Omega}-cm to the order of 5.16 x 10'-'2 {Omega}-cm. The carrier concentration of CdTe thin films had increased to 1.6 x 10{sup 18} cm{sup -3} after a 15-minute exposure to the He-Ne laser. The average absorbance value of CdTe thin films was improved from 1.81 to 3.01 by the doping of Ag due to impurity-scattering. These improved properties should contribute to the efficiency of the photovoltaic effect of the photogenerated charged carriers. The methodology in this study is very simple and effective to dope a multilayered thin film solar cell with a relatively short process time, no wet-process, and selective treatment.

Kim, Nam-Hoon; Park, Ju-Sun; Lee, Woo-Sun [Chosun University, Gwangju (Korea, Republic of)

2011-09-15

206

Effects of Bi Incorporation on Cu(In1-x,Gax)Se2 Thin Films and Solar Cells  

Science.gov (United States)

The effects of bismuth (Bi) incorporation into Cu(In1-x,Gax)Se2 (CIGS) thin films and solar cells have been investigated. 10--50-nm-thick Bi thin layers were deposited onto Mo-coated soda-lime glass (SLG) and SiOx-coated SLG substrates by vacuum evaporation. CIGS thin films were then deposited by a three-stage process at substrate temperatures of 450--550 C. The grain growth of CIGS thin films was enhanced, and the open-circuit voltage and hence the conversion efficiency was improved by the Bi incorporation when the SLG substrates were used. However, little effect was observed when the alkali barrier SiOx layer was deposited on SLG substrates. As a result, we found that the Bi incorporation is beneficial for improving the cell performance when sodium exists simultaneously in CIGS layers.

Nakakoba, Hiroya; Yatsushiro, Yuta; Mise, Takahiro; Kobayashi, Taizo; Nakada, Tokio

2012-10-01

207

Effects of Antimony Doping on Cu(In1-x,Gax)Se2 Thin Films and Solar Cells  

Science.gov (United States)

The effects of antimony (Sb) doping into Cu(In1-x,Gax)Se2 (CIGS) thin films and solar cells have been investigated. 10--50-nm-thick Sb thin layers were deposited onto Mo-coated sodalime glass (SLG) and SiOx-coated SLG substrates by vacuum evaporation. CIGS thin films were then deposited by a three-stage process at substrate temperatures of 450--550 C. The grain growth of CIGS thin films was enhanced, and the open-circuit voltage and hence the conversion efficiency improved with the Sb doping when the SLG substrates were used. However, little or no effect was observed when the alkali barrier SiOx layer was deposited on SLG substrates. As a result, we found that Sb doping is beneficial for improving the cell performance when sodium exists simultaneously in CIGS layers.

Yatsushiro, Yuta; Nakakoba, Hiroya; Mise, Takahiro; Kobayashi, Taizo; Nakada, Tokio

2012-10-01

208

High-efficiency, thin-film InP concentrator solar cells  

Science.gov (United States)

High-efficiency, thin-film InP solar cells grown heteroepitaxially on GaAs and Si single-crystal bulk substrates are being developed as a means of eliminating the problems associated with using single-crystal InP substrates ( e.g., high cost, fragility, high mass density and low thermal conductivity). A novel device structure employing a compositionally graded Ga x In1- x As layer (8 ?m thick) between the bulk substrate and the InP cell layers is used to reduce the dislocation density and improve the minority carrier properties in the InP. The structures are grown in a continuous sequence of steps using computer-controlled atmospheric-pressure metalorganic vapor-phase epitaxy (AP-MOVPE). Dislocation densities as low as 3107 cm-2 and minority carrier lifetimes as high as 3.3 ns are achieved in the InP layers with this method using both GaAs or Si substrates. Structures prepared in this fashion are also completely free of microcracks. These results represent a substantial improvement in InP layer quality when compared to heteroepitaxial InP prepared using conventional techniques such as thermally cycled growth and post-growth annealing. The present work is concerned with the fabrication and characterization of thin-film InP solar cells designed for operation at high solar concentration (100 suns) which have been prepared from similar device structures grown on GaAs substrates. The cell performance is characterized as a function of the air mass zero (AM0) solar concentration ratio (1-100 suns) and operating temperature (25-80 C). From these data, the temperature coefficients of the cell performance parameters are derived as a function of the concentration ratio. Under concentration, the cells exhibit a dramatic increase in efficiency and an improved temperature coefficient of efficiency. At 25 C, a peak conversion efficiency of 18.9% (71.8 suns, AM0 spectrum) is reported. At 80 C, the peak AM0 efficiency is 15.7% at 75.6 suns. These are the highest efficiencies yet reported for InP heteroepitaxial cells. Approaches for further improving the cell performance are discussed.

Wanlass, M. W.; Coutts, T. J.; Ward, J. S.; Emery, K. A.; Horner, G. S.

1991-12-01

209

3D epitaxial growth through holes for the fabrication of thin-film solar cells  

Science.gov (United States)

Some interesting effects of three-dimensional epitaxial growth have been observed and simulated during the development of a silicon deposition process for the fabrication of a new type of solar cell. The Epitaxy Wrap-Through (EpiWT) cell is a rear-contacted crystalline silicon epitaxial thin-film solar cell. This means that it consists of thin high-quality silicon layers that are grown on a substrate and wrapped through via holes from the front to the rear side of this substrate. The attempt to grow silicon layers epitaxially in this way three-dimensionally through small via holes, 200 ?m diameter, is a completely new development. A process that provides a very suitable layer structure for the fabrication of the solar cells has been successfully developed. In order to gain a deeper theoretical understanding of this epitaxy-through-holes process, simulations were performed using computational fluid dynamics (CFD). The analysis focuses primarily on the gas flow through the via holes during the deposition. In this way, and by comparison of experimental samples with simulation results, it has been possible to explain some of the characteristics that were observed in the 3D epitaxial growth.

Brinkmann, Nils; Pcza, David; Mitchell, Emily J.; Reber, Stefan

2011-11-01

210

Deposition Ga-doped ZnO films on PEN substrate at room temperature for thin film silicon solar cells  

Science.gov (United States)

ZnO:Ga thin films were deposited by DC magnetron sputtering using two facing Ga-doped ZnO ceramic targets at room temperature. Polyethylene naphthalate (PEN) and Eagle2000 glass were used as substrates. The influence of PEN and glass substrates on the properties of ZnO:Ga thin films has been investigated. The distance between substrate and plasma dependence of micro-structure and electrical properties was also studied. The lowest resistivity obtained was 6.65 10-4 ? cm with a Hall mobility of 17.1 cm2 V-1 s-1 and a carrier concentration of 5.5 1020 cm-3. When those ZnO:Ga thin films were applied to low-temperature flexible a-Si:H solar cells, an initial conversion efficiency of 5.91% was achieved.

Tao, Ke; Sun, Yun; Cai, Hongkun; Zhang, Dexian; Xie, Ke; Wang, Yuan

2012-06-01

211

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

212

Characterisation of Cu(In,Ga)Se2-based thin film solar cells on polyimide  

International Nuclear Information System (INIS)

Thin films of Cu(In,Ga)Se2 (CIGS) were deposited at temperatures below 450 deg. C on polyimide (PI) substrates coated with Mo in a roll-to-roll set up by a combination of co-evaporation and ion-beam techniques. Flexible solar cells ITO/i-ZnO/CdS/CIGS/Mo/PI with and without Na incorporation were then fabricated. The films and solar cells were examined by: X-ray fluorescence spectroscopy (XRF) and Auger electron spectroscopy (AES), to determine the elemental composition, as well as by X-ray diffraction for structure- and scanning electron microscopy (SEM) for morphology-analysis. Photoluminescence (PL) and PL-excitation (PLE) at temperatures from 4.2 to 78 K were also used to estimate the band-gap energy of CIGS, examine the electronic properties and defect nature. The aim of this study was to correlate the incorporation of Na with optical and structural parameters of the CIGS layers as well as with the solar cell performance

2009-02-02

213

Characterisation of Cu(In,Ga)Se{sub 2}-based thin film solar cells on polyimide  

Energy Technology Data Exchange (ETDEWEB)

Thin films of Cu(In,Ga)Se{sub 2} (CIGS) were deposited at temperatures below 450 deg. C on polyimide (PI) substrates coated with Mo in a roll-to-roll set up by a combination of co-evaporation and ion-beam techniques. Flexible solar cells ITO/i-ZnO/CdS/CIGS/Mo/PI with and without Na incorporation were then fabricated. The films and solar cells were examined by: X-ray fluorescence spectroscopy (XRF) and Auger electron spectroscopy (AES), to determine the elemental composition, as well as by X-ray diffraction for structure- and scanning electron microscopy (SEM) for morphology-analysis. Photoluminescence (PL) and PL-excitation (PLE) at temperatures from 4.2 to 78 K were also used to estimate the band-gap energy of CIGS, examine the electronic properties and defect nature. The aim of this study was to correlate the incorporation of Na with optical and structural parameters of the CIGS layers as well as with the solar cell performance.

Zachmann, H. [Solarion AG, Ostende 5, DE-04288, Leipzig (Germany)], E-mail: zachmann@solarion.de; Heinker, S.; Braun, A. [Solarion AG, Ostende 5, DE-04288, Leipzig (Germany); Mudryi, A.V.; Gremenok, V.F.; Ivaniukovich, A.V. [Scientific-Practical Material Research Centre of the National Academy of Science of Belarus, 220072, Minsk, P.Brovki 19 (Belarus); Yakushev, M.V. [Department of Physics, Strathclyde University, Glasgow, G4 0NG (United Kingdom)

2009-02-02

214

CIGS Thin Films for Cd-Free Solar Cells by One-Step Sputtering Process  

Science.gov (United States)

Cu(In1-x Ga x )Se2 (CIGS) thin films were deposited by a one-step radio frequency (RF) magnetron sputtering process using a quaternary CIGS target. The influence of substrate temperature on the composition, structure, and optical properties of the CIGS films was investigated. All the CIGS films exhibited the chalcopyrite structure with a preferential orientation along the (112) direction. The CIGS film deposited at 623 K showed significant improvement in film crystallinity and surface morphology compared to films deposited at 523 and 573 K. To simplify the manufacturing procedure of solar cells and avoid the use of the toxic element Cd, the properties of ZnS films prepared by RF sputtering were also investigated. The results revealed that the sputtered ZnS film exhibits good lattice matching with the sputtered CIGS film with significantly lower optical absorption loss. Finally, all-sputtered Cd-free CIGS-based heterojunction solar cells with the structure SLG/Mo/CIGS/ZnS/AZO/Al grids were fabricated without post-selenization. Furthermore, the results demonstrated the feasibility of using a full sputtering process for the fabrication of Cd-free CIGS-based solar cell.

Xiang, Jun; Huang, Xing; Lin, Gengqi; Tang, Jiang; Ju, Chen; Miao, Xiangshui

2014-04-01

215

Study of ZnO:Al films for silicon thin film solar cells  

Science.gov (United States)

In this study, aluminum doped zinc oxide (ZnO:Al) films deposited from dual rotatable ceramic targets are systematically investigated. The influences of substrate temperature and working pressure as well as discharge power on different properties of ZnO:Al films including deposition rate, surface structure, optical and electrical properties as well as etching behaviors are studied. It is found that in addition to substrate temperature and working pressure the discharge power plays an important role in material properties of ZnO:Al films. Low rate ZnO:Al (LR-AZO) films with high carrier mobility of about 50 Vs/cm2 and high rate ZnO:Al (HR-AZO) films of more than 90 nm m/min with high carrier mobility of about 45 Vs/cm2 are achieved. However, there is only a narrow parameter window to achieve a regulated crater-shape surface structure for ZnO:Al films after a chemical wet etching process. The surface-textured ZnO:Al films were applied in silicon thin film solar cells and high efficiencies of 8.5% and 11.3% are achieved for single junction hydrogenated microcrystalline silicon (?c-Si:H) solar cells and amorphous/microcrystalline silicon (a-Si:H/?c-Si:H) tandem solar cell, respectively.

Zhu, H.; Hpkes, J.; Bunte, E.; Huang, S. M.

2012-11-01

216

CIGS Thin Films for Cd-Free Solar Cells by One-Step Sputtering Process  

Science.gov (United States)

Cu(In1- x Ga x )Se2 (CIGS) thin films were deposited by a one-step radio frequency (RF) magnetron sputtering process using a quaternary CIGS target. The influence of substrate temperature on the composition, structure, and optical properties of the CIGS films was investigated. All the CIGS films exhibited the chalcopyrite structure with a preferential orientation along the (112) direction. The CIGS film deposited at 623 K showed significant improvement in film crystallinity and surface morphology compared to films deposited at 523 and 573 K. To simplify the manufacturing procedure of solar cells and avoid the use of the toxic element Cd, the properties of ZnS films prepared by RF sputtering were also investigated. The results revealed that the sputtered ZnS film exhibits good lattice matching with the sputtered CIGS film with significantly lower optical absorption loss. Finally, all-sputtered Cd-free CIGS-based heterojunction solar cells with the structure SLG/Mo/CIGS/ZnS/AZO/Al grids were fabricated without post-selenization. Furthermore, the results demonstrated the feasibility of using a full sputtering process for the fabrication of Cd-free CIGS-based solar cell.

Xiang, Jun; Huang, Xing; Lin, Gengqi; Tang, Jiang; Ju, Chen; Miao, Xiangshui

2014-07-01

217

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.

2012-01-01

218

Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells  

Science.gov (United States)

Results are presented of the third phase of research in high efficiency, single junction, monolithic, thin-film, a-Si solar cells. Six glow discharge deposition systems, including an in-line multichamber system, were used to grow both doped and undoped a-Si films. In single load lock system, a-Si was deposited over 1000 sq cm substrates with less then a 1 pct variation in thickness and low oxygen impurity levels. The system produced 1000 sq cm submodules with active-area efficiencies of 8.7 pct. A model was developed for light scattering in textured tin oxide that predicts scattered transmission through the air/glass/tin oxide/air configuration to within a few percent. Textured tin oxide films were grown by chemical vapor deposition using tin tetrachloride. Solar cell efficiencies of about 11 pct were obtained in small area p-i-n cells with reflective back contacts of Ti/Ag that exhibit external quantum efficiencies as high as 58.7 pct at 700 nm; other cells with ITO/Ag back contacts have had quantum efficiencies as high as 64 pct at 700 nm. High performance cells were fabricated by employing dopant and carbon concentration gradients near the p/i interface. Total-area efficiencies around 8 pct were obtained for submodules in which the patterning was done by laser scribing.

Carlson, D. E.; Ayra, R. R.; Bennett, M. S.; Brewer, J. A.; Catalano, A. W.; Daiello, R. V.; Dickson, C. R.; Fortmann, C. M.; Newton, J. L.; Odowd, J. G.

1989-09-01

219

Low temperature deposited boron nitride thin films for a robust anti-reflection coating of solar cells  

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline boron nitride thin films deposited at low temperatures (<200 C) are shown here to be well adapted for anti-reflection coating of solar cells. The analyses of the optical properties reveal a nearly constant index of refraction ({proportional_to}2.8) and negligible transmission losses over the useful range of the solar spectrum. Boron nitride thin films are found to be well adapted for integration as anti-reflection coating layers in multi-junction terrestrial and space solar cells due to their spectral stability, their robust ceramic nature and a fairly wide bandgap (6.2 eV). Test fabrication of double layer MgF2/BN anti-reflection coating on GaAs and Si demonstrated minimal reflection losses (<5%) over a wide window of the solar irradiance (1.1-3 eV). (author)

Alemu, Andenet; Freundlich, Alex [Photovoltaic and Nanostructures Laboratory, Center for Advanced Materials, Departments of Physics, and Electrical and Computer Engineering, University of Houston, Houston, Texas 77204-5004 (United States); Badi, Nacer; Boney, Chris; Bensaoula, Abdelhak [Nitride Materials and Devices Laboratory, Center for Advanced Materials, Departments of Physics, and Electrical and Computer Engineering, University of Houston, Houston, Texas 77204-5004 (United States)

2010-05-15

220

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

 
 
 
 
221

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...

2006-01-01

222

Band offset of high efficiency CBD-ZnS/CIGS thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The band offset at the CBD-ZnS/Cu(In,Ga)Se{sub 2} (CIGS) interface and solar cells performance were investigated by means of X-ray photoelectron spectroscopy (XPS). The valence band maximum and valence band offset at the chemical bath deposition (CBD)-ZnS/CIGS interface region was directly measured using a XPS spectral multiplot. We found that the conduction band offset (CBO) at the CBD-ZnS/CIGS (ordered vacancy compound, OVC) interface was smaller than that of the evaporated ZnS/CIGS (OVC) interface. However, the CBO for the CBD-ZnS/CIGS (OVC) interface was still quite large for fabrication of high efficiency devices, although, in fact, high efficiency CBD-ZnS/CIGS devices were fabricated with good run-to-run reproducibility. The bandgap dependence of cell performance for CBD-ZnS/CIGS devices (large CBO) showed a tendency similar to that of CBD-CdS/CIGS devices (small CBO). Therefore, the observed decrease in cell performance for high bandgap devices is not interpreted in terms of the CBO. These results suggest that the band offset is not the predominant factor in achieving high efficiency CBD-ZnS/CIGS thin film solar cells. This finding suggests that the recombination mechanism of those wide-gap alloys is a bulk recombination.

Nakada, Tokio; Hongo, Masashi; Hayashi, Eiji

2003-05-01

223

Band offset of high efficiency CBD-ZnS/CIGS thin film solar cells  

International Nuclear Information System (INIS)

The band offset at the CBD-ZnS/Cu(In,Ga)Se2 (CIGS) interface and solar cells performance were investigated by means of X-ray photoelectron spectroscopy (XPS). The valence band maximum and valence band offset at the chemical bath deposition (CBD)-ZnS/CIGS interface region was directly measured using a XPS spectral multiplot. We found that the conduction band offset (CBO) at the CBD-ZnS/CIGS (ordered vacancy compound, OVC) interface was smaller than that of the evaporated ZnS/CIGS (OVC) interface. However, the CBO for the CBD-ZnS/CIGS (OVC) interface was still quite large for fabrication of high efficiency devices, although, in fact, high efficiency CBD-ZnS/CIGS devices were fabricated with good run-to-run reproducibility. The bandgap dependence of cell performance for CBD-ZnS/CIGS devices (large CBO) showed a tendency similar to that of CBD-CdS/CIGS devices (small CBO). Therefore, the observed decrease in cell performance for high bandgap devices is not interpreted in terms of the CBO. These results suggest that the band offset is not the predominant factor in achieving high efficiency CBD-ZnS/CIGS thin film solar cells. This finding suggests that the recombination mechanism of those wide-gap alloys is a bulk recombination

2003-05-01

224

Indium phosphide/cadmium sulfide thin-film solar cells. Semiannual report, July 1980-December 1980  

Energy Technology Data Exchange (ETDEWEB)

InP thin films were deposited by planar reactive deposition on recyrstallized CdS (RXCdS) and semi-insulating (100) InP substrates and evaluated as potential layers for an all-thin-film solar cell. Films prepared on RXCdS at approximately 330/sup 0/C contained a mixture of grains having both large and submicron lateral dimensions. SIMS analysis showed the interdiffusion profiles to be well behaved and, within the resolution of the analysis, no significant difference in the profiles between structures prepared at 330/sup 0/C and 380/sup 0/C. Be-doped epitaxial films, deposited on semi-insulating InP at 330/sup 0/C, showed both n- and p-type behavior. Films prepared at higher and lower temperatures with a freshly Be-charged In source were p-type and n-type, respectively; the n-type behavior is associated with an excess of n-type native defects. SIMS analyses confirmed the presence of Be in all Be-doped films. Growth with deviation from stoichiometry was initiated at 330/sup 0/C to reduce the concentration of native defects. Growth of Be-doped films at higher substrate temperature with the same Be-doped source after several runs eventually resulted in n-type films. Analyses of the In source and films were initiated to determine the cause of the transient doping. As an alternative to Be doping, p-type Zn-doped InP films were prepared on InP semi-insulating substrates with room-temperature carrier concentration and mobilities of 6 x 10/sup 16/ cm/sup -3/, and 80 cm/sup 2//Vsec, respectively.

Zanio, K.

1981-03-01

225

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

2013-05-15

226

Light trapping and electrical transport in thin-film solar cells with randomly rough textures  

Science.gov (United States)

Using rigorous electro-optical calculations, we predict a significant efficiency enhancement in thin-film crystalline silicon (c-Si) solar cells with rough interfaces. We show that an optimized rough texture allows one to reach the Lambertian limit of absorption in a wide absorber thickness range from 1 to 100 ?m. The improvement of efficiency due to the roughness is particularly substantial for thin cells, for which light trapping is crucial. We consider Auger, Shockley-Read-Hall (SRH), and surface recombination, quantifying the importance of specific loss mechanisms. When the cell performance is limited by intrinsic Auger recombination, the efficiency of 24.4% corresponding to the wafer-based PERL cell can be achieved even if the absorber thickness is reduced from 260 to 10 ?m. For cells with material imperfections, defect-based SRH recombination contributes to the opposite trends of short-circuit current and open-circuit voltage as a function of the absorber thickness. By investigating a wide range of SRH parameters, we determine an optimal absorber thickness as a function of material quality. Finally, we show that the efficiency enhancement in textured cells persists also in the presence of surface recombination. Indeed, in our design the efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore it is possible to engineer the front surface to a large extent without compromising on efficiency.

Kowalczewski, Piotr; Bozzola, Angelo; Liscidini, Marco; Claudio Andreani, Lucio

2014-05-01

227

Effect of p-layer properties on nanocrystalline absorber layer and thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

The influence of the p-layer on the crystallinity of the absorber layer and nanocrystalline silicon thin film solar cells has been studied. Boron doped Si : H p-layers of different crystallinities have been prepared under different power pressure conditions using the plasma enhanced chemical vapour deposition method. The crystalline volume fraction of p-layers increases with the increase in deposition power. Optical absorption of the p-layer reduces as the crystalline volume fraction increases. Structural studies at the p/i interface have been done by Raman scattering studies. The crystalline volume fraction of the i-layer increases as that of the p-layer increases, the effect being more prominent near the p/i interface. Grain sizes of the absorber layer decrease from 9.2 to 7.2 nm and the density of crystallites increases as the crystalline volume fraction of the p-layer increases and its grain size decreases. With increasing crystalline volume fraction of the p-layer solar cell efficiency increases.

Chowdhury, Amartya; Adhikary, Koel; Mukhopadhyay, Sumita; Ray, Swati [Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)], E-mail: ray_swati2004@yahoo.co.in

2008-07-07

228

Comparative investigation of solar cell thin film processing using nanosecond and femtosecond lasers  

International Nuclear Information System (INIS)

The purpose of the present study was to examine the possibility of laser-machining of CuInSe2-based photovoltaic devices. Therefore, ablation thresholds and ablation rates of ZnO, CuInSe2 and Mo thin films have been measured for irradiation with nanosecond laser pulses of ultraviolet and visible light and subpicosecond laser pulses of a Ti : sapphire laser. The experimental results were compared with the theoretical evaluation of the samples heat regime obtained from numerical calculations. In addition, the photo-electrical properties of the solar cells were measured before and after laser-machining. Scanning electron microscopy and energy dispersive x-ray analyses were employed to characterize the laser-induced ablation channels. As a result, two phenomena were found to limit the laser-machining process: (i) residues of Mo that were projected onto the walls of the ablation channel and (ii) the metallization of the CuInSe2 semiconductor close to the channel. Both effects lead to a shunt in the device that decreases the photovoltaic efficiency. As a consequence of these limiting effects, micromachining of CuInSe2-based solar cells was not possible with nanosecond laser pulses. Only subpicosecond laser pulses provided selective or complete ablation of the thin layers without a relevant change in the photoelectrical properties

2006-02-07

229

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

230

Quantitative determination of element distributions in silicon based thin film solar cells using SNMS.  

Science.gov (United States)

The determination of elemental distributions in thin film solar cells based on amorphous silicon using electron beam SNMS is possible by quantifying the measured ion intensities. The relative sensitivity factors (RSFs) for all elements measured have to be known. The RSFs have been determined experimentally using implantation and bulk standards with known concentrations of the interesting elements. The measured RSFs have been compared with calculated RSFs. The model used for the calculation of the RSFs takes into account the probability for electron impact ionization and the dwell time of the neutrals inside the postionization region. The comparison between measured and calculated RSF shows, that this model is capable to explain the RSFs for most elements. Differences between calculated and measured values can be explained by the formation of hydride and fluoride molecules (in case of H and F) and influences of the angular distribution of the sputtered neutrals in case of Al. The experimentally determined RSFs have been used for a quantification of depth profiles of the i-, buffer-, p- and front contact layers of a-Si solar cells. PMID:15048522

Gastel, M; Breuer, U; Holzbrecher, H; Becker, J S; Dietze, H J; Kubon, M; Wagner, H

1995-10-01

231

High-efficiency solar cells based on Cu(InAl)Se2 thin films  

Science.gov (United States)

A Cu(InAl)Se2 solar cell with 16.9% efficiency is demonstrated using a Cu(InAl)Se2 thin film deposited by four-source elemental evaporation and a device structure of glass/Mo/Cu(InAl)Se2/CdS/ZnO/indium tin oxide/(Ni/Algrid)/MgF2. A key to high efficiency is improved adhesion between the Cu(InAl)Se2 and the Mo back contact layer, provided by a 5-nm-thick Ga interlayer, which enabled the Cu(InAl)Se2 to be deposited at a 530 degC substrate temperature. Film and device properties are compared to Cu(InGa)Se2 with the same band gap of 1.16 eV. The solar cells have similar behavior, with performance limited by recombination through trap states in the space charge region in the Cu(InAl)Se2 or Cu(InGa)Se2 layer.

Marsillac, S.; Paulson, P. D.; Haimbodi, M. W.; Birkmire, R. W.; Shafarman, W. N.

2002-08-01

232

Semi-coherent optical modelling of thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

At NEXT ENERGY the experimental investigation of thin film silicon solar cells is combined with numerical simulations using the software Sentaurus TCAD from Synopsys. We present the results of optical modelling with Sentaurus TCAD based on the one-dimensional semi-coherent optical model by Janez Krc. The idea of this model is that after interacting with a rough interface the incident light is split into a direct coherent part treated as electromagnetic waves and in a diffuse incoherent part treated as light beams. The proportion of either direct or diffuse part is determined by the haze parameter which can be obtained from spectrometer data. In order to describe the scattering effects at rough interfaces the intensities of the diffuse light are scaled with angular distribution functions. These functions are obtained from angle resolved scattering measurements. The optical model will be verified by experimental data and compared to the Raytracer and the Transfer Matrix Model. Furthermore the influence of different angles of incidence and of the spectral dependency on the solar cell performance will be investigated.

Walder, Cordula; Lacombe, Juergen; Maydell, Karsten von; Agert, Carsten [EWE-Forschungszentrum fuer Energietechnologie e.V., Carl-von-Ossietzky-Strasse 15, 26129 Oldenburg (Germany)

2011-07-01

233

Fabrication and characterization of highly efficient thin-film polycrystalline-silicon solar cells based on aluminium-induced crystallization  

International Nuclear Information System (INIS)

Thin-film polycrystalline-silicon solar cells might become an alternative to bulk silicon solar cells if sufficiently high efficiencies can be obtained. In this work we made pc-Si layers using aluminium-induced crystallization and thermal CVD on alumina substrates. By using plasma texturing and optimizing the cell structure, we increased the current density of our cells and achieved a cell efficiency of 8.0%. At present, our cell efficiency seems to be mainly limited by the presence in our layers of a high density of electronically active intragrain defects. Intragrain quality improvement will therefore be very important to further increase our pc-Si cell efficiency

2008-08-30

234

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

235

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

236

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

237

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)

2008-05-07

238

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

239

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

240

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)

2012-10-12

 
 
 
 
241

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.

2013-05-24

242

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

2009-01-01

243

Photoluminescence study of polycrystalline CdS/CdTe thin film solar cells  

International Nuclear Information System (INIS)

To achieve high efficiencies in CdS/CdTe thin film solar cells, it is known that a CdCl2 activation process is necessary. In addition, the presence of oxygen during this treatment can have a beneficial effect. The mechanisms involved in this process are not fully understood. In this work, we present a photoluminescence (PL) study of two sample types: cells that received their CdCl2 activation in an air ambient and cells that were treated in vacuum. The luminescence at the front (through the glass substrate) and at the back surfaces (after the partial removal of the back contact by ion sputtering) is investigated. Three main luminescence bands are observed: an excitonic emission around 1.59 eV, an emission band at 1.55 eV and a broad band at 1.4 eV, related to cadmium vacancy-chlorine defect complexes. The 1.55 eV emission is shown to be related to oxygen. Using measurements at very low excitation intensity, we were able to resolve two components: a donor-acceptor pair (DAP) transition and a free electron-acceptor transition. The acceptor level involved is located at approximately 47 meV above the valence band. The 1.4 eV band, related to a cadmium vacancy-chlorine complex, is broader at the junction than at the free surface and shifted to lower energy, possibly related to sulfur interdiffusion at the interface

2005-06-01

244

Investigation of recombinatoric loss mechanisms in Cu(In,Ga)Se2 thin film solar cells  

International Nuclear Information System (INIS)

Today solar cells based on the compound semiconductor Cu(In,Ga)Se2 (CIGSe) present the highest lab scale efficiency among all thin-film technologies. The performance of elementary cells in photovoltaic modules might however be different due to thicker conductive ZnO:Al window layers, missing anti-reflection coating and occasionally less defined absorber formation on large scales. One approach to improve the elementary cell efficiency is to fine-tune the absorber composition and the in-depth band gap grading. In this work we investigated CIGSe samples with varied absorber composition in order to quantify the minority carrier collection efficiency (CE). CE is directly related to the electron diffusion length LD,n and the characteristics of the space charge region (SCR). LD,n was deduced by relating the inverse internal quantum efficiency to the penetration depth of incident photons and the SCR characteristics were obtained from capacitance-profiling of the samples. Based on these results we discuss the different photovoltaic performance observed for samples with varied CIGSe absorber composition.

2011-03-13

245

Intensity dependence of quantum efficiency and photo-gating effects in thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Steady-state photoconductivity measurements have been carried out on thin-film silicon pin structures of i-layer thickness typically 4 {mu}m, where crystalline composition has been varied by adjustment of the silane concentration in the process gas. In amorphous and low-crystallinity cells, strongly-absorbed light incident from the p-side at photon fluxes in excess of 10{sup 14} cm{sup -2} s{sup -1} produces strongly sub-linear intensity dependence, S shaped reverse current-voltage curves and amplification of a second weakly-absorbed beam, termed photogating. These effects are linked to the formation of space charge and attendant low-field region close to the p-i interface, as confirmed by computer simulation. More crystalline devices exhibit little or no such behaviour. At lower intensities of strongly-absorbed light there is a markedly steeper increase in reverse current vs. voltage in low-crystalline when compared to amorphous cells, particularly with light incident from the n-side. This suggests the mobility-lifetime product for holes is much larger in the former case, consistent with the higher hole mobilities reported in time of flight studies. Thus the prospect of composition-dependent changes in mobility as well as defect density should be borne in mind when developing materials for application in microcrystalline silicon solar cells. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Reynolds, Steve; Main, Charles [Carnegie Laboratory of Physics, University of Dundee (United Kingdom); Smirnov, Vladimir [IEF-5 Photovoltaik, Forschungszentrum Juelich (Germany); Meftah, Amjad [Laboratoire des Materiaux Semiconducteurs et Metalliques, Departement de Physique, Universite Mohammed Khider, Biskra (Algeria)

2010-04-15

246

CIGS thin film solar cell prepared by reactive co-sputtering  

Science.gov (United States)

The reactive co-sputtering was developed as a new way of preparing high quality CuInGaSe2(CIGS) films from two sets of targets; Cu0.6Ga 0.4 and Cu0.4In0.6 alloy and Cu and (In0.7Ga0.3)2Se3 compound targets. During sputtering, Cu, In, Ga metallic elements as well as the compound materials were reacted to form CIGS simultaneously in highly reactive elemental Se atmosphere generated by a thermal cracker. CIGS layer had been grown on Mo/soda-lime glass(SLG) at 500C. For both sets of targets, we controlled the composition of CIGS thin film by changing the RF power for target components. All the films showed a preferential (112) orientation as observed from X-ray diffraction analysis. The composition ratios of CIGS were easily set to 0.71-0.95, 0.10-0.30 for [Cu]/[III] and [Ga]/[III], respectively. The grain size and the surface roughness of a CIGS film increased as the [Cu]/[III] ratios increased. The solar cells were fabricated using a standard base line process in the device structure of grid/ITO/i-ZnO/CdS/CIGS/Mo/ SLG. The best performance was obtained the performance of Voc = 0.45 V, Jsc =35.6, FF = 0.535, ? = 8.6% with a 0.9 ?m-CIGS solar cell from alloy targets while Voc = 0.54 V, Jsc =30.8, FF = 0.509, ? = 8.5% with a 0.8 ?m-CIGS solar cell from Cu and (In0.7Ga0.3)2Se3.

Kim, Jeha; Lee, Ho-Sub; Park, Nae-Man

2013-09-01

247

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

2008-07-01

248

Computer analysis of thin-film amorphous silicon heterojunction solar cells  

Energy Technology Data Exchange (ETDEWEB)

A two-dimensional numerical computer analysis for thin-film-based hydrogenated amorphous silicon (i.e. a-Si : H) solar cells is presented. A comparative performance assessment for various absorbing layers such as a-Si, a-SiGe, a-SiC, combined a-Si+a-SiGe, a-Si/a-SiGe-graded layers and tandem (tdm) design is shown. The device performance is evaluated by implementing special surface recombination model, thermionic field emission model for transport at the heterojunctions and interface traps model at top and bottom side of the heterojunction interfaces. Single absorber with a graded design gives an efficiency of 10.1% for 800 nm thick multiband absorption. Similarly, tandem design shows an efficiency of 10.4% with a total absorber of thickness of 800 nm at bandgap of 1.75 eV and 1.0 eV for the top a-Si and bottom a-SiGe component cells. Numerical simulations predict improved efficiency for tandem design over large range of band discontinuity and interface trap density. Although comparable, the efficiency performance for graded design (i.e. absorbing layer of a-Si and a-SiGe graded layers) approach is very sensitive to the limited range of band discontinuity and interface trap density available at the heterojunctions.

Nawaz, Muhammad, E-mail: Nawaz@unik.no [University Graduate Centre (UNIK), Gunnar Randers Vei 19, PO Box 70, NO-2027, Kjeller (Norway)

2011-04-13

249

The photoresponse of CdS/CuInSe/sub 2/ thin - film heterojunction solar cells  

Energy Technology Data Exchange (ETDEWEB)

The effect of light bias on the spectral current response and spectral capacitance characteristics of CdS/CuInSe/sub 2/ thin-film heterojunction solar cells has been investigated. Monochromatic light bias has been used to identify specific wavelength regions responsible for the spectral behavior seen under white light bias. Variations with light or voltage bias are consistent with the effect of the field on interface recombination in both high and low CdS resistivity devices. Devices with high CdS resistivity show spectrally dependent enhancement and quenching effects very similar to those reported for CdS/Cu/sub 2/S devices in which the space charge region was primarily in the CdS. It is concluded that in high CdS resistivity devices the junction behavior is controlled by the photoconductive CdS as has been established in CdS/Cu/sub 2/S cells. Low CdS resistivity CdS/CuInSe/sub 2/ devices show none of these effects.

Hegedus, S.S.

1984-05-01

250

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.

2011-08-31

251

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

252

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

253

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

254

Band alignment of SnS/Zn(O,S) heterojunctions in SnS thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Band alignment is critical to the performance of heterojunction thin film solar cells. In this letter, we report band alignment studies of SnS/Zn(O,S) heterojunctions with various compositions of Zn(O,S). Valence band offsets (VBOs) are measured by femtosecond laser pump/probe ultraviolet photoelectron spectroscopy (fs-UPS) from which conduction band offsets (CBOs) are calculated by combining with band gaps obtained by optical transmission/reflection measurements. The SnS/Zn(O,S) heterojuncti...

Sun, Leizhi; Haight, Richard; Sinsermsuksakul, Prasert; Bok Kim, Sang; Park, Helen Hejin; Gordon, Roy Gerald

2013-01-01

255

Growth mechanism of nanocrystalline silicon at the phase transition and its application in thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nanocrystalline (or microcrystalline) silicon (nc-Si:H or ?c-Si:H) is an absorber material that is crucial for obtaining thin film silicon tandem solar cells with high efficiency. This material is conventionally produced by direct plasma-enhanced chemical vapor deposition (PECVD), which is based on the dissociation of silane (SiH4) and hydrogen (H2) in a radiofrequency (rf) plasma. During the last few decades, the plasma deposition parameter regime has been explored intensively, in particula...

Schropp, R. E. I.; Rath, J. K.; Li, Hongbo

2009-01-01

256

Reactive sputtering and composition measurements of precursors for Cu2ZnSnS4 thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cu2ZnSnS4 (CZTS) is a thin film solar cell material that only contains abundant elements and for which promising conversion efficiencies of 9.2 % have been shown. In this thesis composition measurements and reactive sputtering of precursors for CZTS films have been studied. These precursors can be annealed to create high quality CZTS films. Accurate control and measurement of composition are important for the synthesis process. The composition of a reference sample was determined using Ruther...

Ericson, Tove

2013-01-01

257

Microscopic properties of grain boundaries in Cu(In,Ga)Se2 and CuInS2 thin-film solar cells studied by transmission electron microscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polycrystalline Cu(In,Ga)Se2 and Cu(In,Ga)S2 thin films are employed as absorber layers in highly efficient thin-film solar cells. The impact of grain boundaries on the electronic properties of these thin films and consequently on the conversion efficiency of the corresponding solar cells is not sufficiently understood. In the present work, methods in transmission electron microscopy were employed in order to study the microscopic properties of grain boundaries in Cu(In,Ga)(Se,S)2 layers with...

Schmidt, Sebastian Simon

2011-01-01

258

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

259

Development of Commercial Technology for Thin Film Silicon Solar Cells on Glass: Cooperative Research and Development Final Report, CRADA Number CRD-07-209  

Energy Technology Data Exchange (ETDEWEB)

NREL has conducted basic research relating to high efficiency, low cost, thin film silicon solar cell design and the method of making solar cells. Two patents have been issued to NREL in the above field. In addition, specific process and metrology tools have been developed by NREL. Applied Optical Sciences Corp. (AOS) has expertise in the manufacture of solar cells and has developed its own unique concentrator technology. AOS wants to complement its solar cell expertise and its concentrator technology by manufacturing flat panel thin film silicon solar cell panels. AOS wants to take NREL's research to the next level, using it to develop commercially viable flat pane, thin film silicon solar cell panels. Such a development in equipment, process, and metrology will likely produce the lowest cost solar cell technology for both commercial and residential use. NREL's fundamental research capability and AOS's technology and industrial background are complementary to achieve this product development.

Sopori, B.

2013-03-01

260

Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin-Film Solar Cells: Preprint  

Energy Technology Data Exchange (ETDEWEB)

The stability of intrinsic and Al-doped single- and bi-layer ZnO for thin-film CuInGaSe2 solar cells, along with Al-doped Zn1-xMgxO alloy and Sn-doped In2O3 (ITO) and F-doped SnO2, was evaluated by direct exposure to damp heat (DH) at 85oC and 85% relative humidity. The results show that the DH-induced degradation rates followed the order of Al-doped ZnO and Zn1-xMgxO >> ITO > F:SnO2. The degradation rates of Al:ZnO were slower for films of higher thickness, higher substrate temperature in sputter-deposition, and with dry-out intervals. As inferred from the optical micro-imaging showing the initiation and propagation of degrading patterns and regions, the degradation behavior appears similar for all TCOs, despite the obvious difference in the degradation rate. A degradation mechanism is proposed to explain the temporal process involving thermal hydrolysis.

Pern, F. J.; Noufi, R.; Li, X.; DeHart, C.; To, B.

2008-05-01

 
 
 
 
261

Physical properties of hematite ?-Fe2O3 thin films: application to photoelectrochemical solar cells  

International Nuclear Information System (INIS)

The physical properties and photoelectrochemical characterization of aluminium doped hematite ?-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (III) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2+/3+ with an electron mobility 300 K of 1.08 cm2/(Vs). The ?-Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I - V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at % Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (-0.87 VSCE) is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot. (semiconductor materials)

2011-01-01

262

Influence of front and back grating on light trapping in microcrystalline thin-film silicon solar cells.  

Science.gov (United States)

The optics of microcrystalline thin-film silicon solar cells with textured interfaces was investigated. The surface textures lead to scattering and diffraction of the incident light, which increases the effective thickness of the solar cell and results in a higher short circuit current. The aim of this study was to investigate the influence of the frontside and the backside texture on the short circuit current of microcrystalline thin-film silicon solar cells. The interaction of the front and back textures plays a major role in optimizing the overall short circuit current of the solar cell. In this study the front and back textures were approximated by line gratings to simplify the analysis of the wave propagation in the textured solar cell. The influence of the grating period and height on the quantum efficiency and the short circuit current was investigated and optimal grating dimensions were derived. The height of the front and back grating can be used to control the propagation of different diffraction orders in the solar cell. The short circuit current for shorter wavelengths (300-500 nm) is almost independent of the grating dimensions. For intermediate wavelengths (500 nm - 700 nm) the short circuit current is mainly determined by the front grating. For longer wavelength (700 nm to 1100 nm) the short circuit current is a function of the interaction of the front and back grating. An independent adjustment of the grating height of the front and the back grating allows for an increased short circuit current. PMID:21445224

Madzharov, Darin; Dewan, Rahul; Knipp, Dietmar

2011-03-14

263

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

264

Efficiency limitations of polycrystalline thin film solar cells: case of Cu(In,Ga)Se2  

International Nuclear Information System (INIS)

Small-area Cu(In,Ga)Se2 thin film solar cells have reached more than 19% efficiencies. Compared to other polycrystalline materials this efficiency value is remarkable. Nevertheless, the 19% for Cu(In,Ga)Se2 range more than 6% (absolute) below the world's best single-crystalline Si cells and almost 14% below the upper theoretical limit of 33% for an ideal black body cell with infinitely large mobility and radiative recombination only. About 4% out of the 14% are of optical nature, additional 3% stem from the limited mobility/diffusion length and from band gap fluctuations with a standard deviation no. sigmano. gno. approxno. 50 meV due to spatial variations of composition and stoichiometry of the quaternary compound Cu(In,Ga)Se2. Thus, about 26% efficiency would be possible if there were only these band gap fluctuations. Additional, voltage-dependent electrostatic potential fluctuations push down the efficiency further to 19%: The polycrystalline Cu(In,Ga)Se2 which is unavoidably structurally inhomogeneous due to dislocations, grain boundaries, point defects, etc. is also electrostatically inhomogeneous because of charged defects. Electrostatic potential fluctuations at the valence and conduction band edge may be not only responsible for a high saturation current density but also for the ideality factor in the current/voltage curve. The band gap and electrostatic potential fluctuations make the effective band gap which controls the intrinsic carrier density smaller than the average optical gap. The (zero bias) electrostatic potential fluctuations are here derived from the ideality factors of the current/voltage curve. The ideality factor reflects the voltage-induced electrostatic homogenization of the sample. For the world's best Cu(In,Ga)Se2 cells with an ideality factor of n id=1.5, we estimate zero bias electrostatic potential fluctuations with a standard deviation no. sigmano. elecno. approxno. 140 meV

2005-06-01

265

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

Energy Technology Data Exchange (ETDEWEB)

The most important accomplishments during this period were to demonstrate and to elucidate further the complex effects that occur during the aging of Cu/sub 2/S/CdS thin-film solar cells in flowing wet oxygen. There are two distinct effects. At constant illumination, the short-circuit current of cells aged at room temperature consistently decreases with time. The second effect, related to diode opposing current, is more involved and may result from several competing mechanisms. Over the short term (approx. 4 to 5 hours), the magnitude of diode opposing current decreases. After approx. 20 hours of aging, opposing current generally returns to the level achieved after hydrogen annealing which immediately preceded the aging sequence. Optical measurements of the spectral transmission of the Cu/sub 2/S layers in a cell content have been made using a silicon detector epoxied to the back of a CdS cell after the copper foil substrate was removed. There is no significant change in Cu/sub 2/S transmission behavior for wavelengths ranging from 525 to 1000 nm during wet-oxygen aging for periods of 2 to 36 hours. This suggests that the decrease in J/sub SC/ at constant illumination, for the aging experiments in a flowing wet-oxygen ambient, arises because of changes in minority-carrier transport properties of the Cu/sub 2/S. Before developing a method for using an epoxied silicon detector to measure optical behavior of the Cu/sub 2/S layer, we explored the possibility of using a junction-containing wafer of silicon as a substrate for deposited CdS films. Some monolithic structures were successfully fabricated. Comparisons were made of CdS grain structure details in the junction detector area and in an adjacent metallized area.

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

1982-03-08

266

Experimental study of Cu2ZnSn(Se,S)4 thin films for solar cell applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cu2ZnSn(Se,S)4 (CZT(Se,S)) has recently been shown to be a promising material to use in thin film solar cells. It has a band gap of between 1eV (CZTSe) and 1.5eV (CZTS). CZT(Se,S) solar cells have reached 10% efficiency. The aim of this project was to find an effective way to selenise metallic Cu, Zn, Sn films in order to produce Cu2ZnSnSe4 (CZTSe) films, without destroying the metallic molybdenum (Mo) back contact. Another aim was to make films containing both Se and S and to study the po...

Engman, Jessica

2011-01-01

267

Optimized nano-textured interfaces for thin-film silicon solar cells: identifying the limit of randomly textured interfaces  

Science.gov (United States)

Thin-film solar cells contain nano-textured interfaces that scatter the incident light, leading to increased absorption and hence increased current densities in the solar cell. In this manuscript we systematically study optimized random nano-textured morphologies for three different cases: amorphous hydrogenated silicon solar cells (a-Si:H, bandgap 1.7 eV), nano-crystalline silicon solar cells (nc-Si:H, bandgap 1.1 eV) and tandem solar cells consisting of an a-Si:H and a nc-Si:H junction. For the optimization we use the Perlin texture algorithm, the scalar scattering theory, and a semi-coherent optical device simulator.

Jger, Klaus; Linssen, Dane N. P.; Isabella, Olindo; Zeman, Miro

2014-05-01

268

Carbon-Nanotube Conductive Layers for Thin-Film Solar Cells  

Science.gov (United States)

Thin, transparent layers comprising mats of carbon nanotubes have been proposed for providing lateral (that is, inplane) electrical conductivities for collecting electric currents from the front surfaces of the emitter layers of thin-film solar photovoltaic cells. Traditionally, thin, semitransparent films of other electrically conductive materials (usually, indium tin oxide, zinc oxide, or cadmium sulfide) have been used for this purpose. As in the cases of the traditional semitransparent conductive films, the currents collected by the nanotube layers would, in turn, be further collected by front metal contact stripes. Depending on details of a specific solar-cell design, the layer of carbon nanotubes would be deposited in addition to, or instead of, a semitransparent layer of one of these traditional conductive materials (see figure). The proposal is expected to afford the following advantages: The electrical conductivity of the carbon- nanotube layer would exceed that of the corresponding semitransparent layer of traditional electrically conductive material. The greater electrical conductivity of the carbon-nanotube layer would make it possible to retain adequate lateral electrical conductivity while reducing the thickness of, or eliminating entirely, the traditional semitransparent conductive layer. As a consequence of thinning or elimination of the traditional semitransparent conductive layer, less light would be absorbed, so that more of the incident light would be available for photovoltaic conversion. The greater electrical conductivity of the carbon-nanotube layer would make it possible to increase the distance between front metal contact stripes, in addition to (or instead of) thinning or eliminating the layer of traditional semitransparent conductive material. Consequently, the fraction of solar-cell area shadowed by front metal contact stripes would be reduced again, making more of the incident light available for photovoltaic conversion. The electrical conductivities of individual carbon nanotubes can be so high that the mat of carbon nanotubes could be made sparse enough to be adequately transparent while affording adequate lateral electrical conductivity of the mat as a whole. The thickness of the nanotube layer would be chosen so that the layer would contribute significant lateral electrical conductivity, yet would be as nearly transparent as possible to incident light. A typical thickness for satisfying these competing requirements is expected to lie between 50 and 100 nm. The optimum thickness must be calculated by comparing the lateral electrical conductivity, the distance between front metal stripes, and the amount of light lost by absorption in the nanotube layer.

Landis, Geoffrey A.

2005-01-01

269

Thin film solar cells based on the ternary compound Cu{sub 2}SnS{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

Thin films of kesterite (Cu{sub 2}ZnSn(S/Se){sub 4}) semiconductors are considered promising absorber layer materials for low cost thin film photovoltaic devices. Experimental and theoretical investigations show, however, that the existence region of a single phase kesterite is relatively small making it difficult to grow single phase absorbers. The semiconducting compound Cu{sub 2}SnS{sub 3} is a common secondary phase that forms in Cu and Sn rich kesterite thin films during growth. Its appearance in a kesterite device would limit the V{sub OC} due to its smaller band gap. However, the band gap of about 1 eV, reported hole concentrations of 10{sup 18}cm{sup -3}, and an absorption coefficient in the visible region of 10{sup 5} cm{sup -1} make the Cu{sub 2}SnS{sub 3} compound itself a promising candidate for low cost photovoltaic applications. In this report we demonstrate the successful fabrication of a thin film solar cell based on Cu{sub 2}SnS{sub 3} via a precursor annealing process. The precursor is prepared by low cost electrodeposition. A maximum external quantum efficiency of about 60% at 800 nm and a band gap of 1.0 eV could be measured. To the best of our knowledge, there have been no other reports on the fabrication of Cu{sub 2}SnS{sub 3} based solar cell devices so far. Loss mechanisms and ways to increase efficiency are discussed.

Berg, Dominik M.; Dale, Phillip J.; Siebentritt, Susanne [University of Luxembourg, Laboratory for Photovoltaics, 41 rue du Brill, L-4422 Belvaux (Luxembourg)

2011-07-01

270

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.

2009-07-01

271

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 application of ...

Carreras Segui?, Paz

2013-01-01

272

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

273

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

274

TiO2 thin film encapsulated ZnO nanorod and nanoflower dye sensitized solar cells  

International Nuclear Information System (INIS)

The performance of dye-sensitized solar cells based on ZnO nanorods and nanoflowers coated with thin shells of TiO2 thin film prepared by sol-gel deposition are described. It is found that shells act as insulating barriers that improve cell open-circuit voltage and short-circuit current density. The superior performance of the ZnO-TiO2 core-shell cells is a result of a radial electron transport within each ZnO nanorods and nanoflowers that decreases the rate of recombination and percolation of the electron in these devices.

2011-01-01

275

Characterization of CdS/CdTe and CdS/CuInSe2 thin film solar cells  

Science.gov (United States)

A study on low cost polycrystalline thin film CdS/CdTe and CdS/CuInSe2 solar cells using measurements of spectral response and capacitance-voltage-frequency relationships was performed. Because of high concentrations of localized levels in the energy gap existing in materials and at interfaces, the redistribution of charge among the levels due to illumination plays an important role in the collection of light-generated current in these cells. The results illustrate some related phenomena observed in these cells.

Cheng, L. J.; Nguyen, T. T.; Shyu, C. M.; Basol, B. M.; Yoo, H. I.

1984-01-01

276

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

277

Study of thin-film GaAs solar cells with cylindrical Ag nanoparticles and distributed Bragg reflector  

Science.gov (United States)

An efficient light-trapping structure, which consists of the periodic Ag nanoparticles and a distributed Bragg reflector (DBR) with high reflectivity, is presented for the thin-film gallium arsenide (GaAs) solar cells. The effects of both Ag nanoparticles and DBR on the optical absorption of GaAs solar cells are theoretically investigated by using finite-difference time-domain (FDTD) method. The optimization process of parameters for the solar cell with both structures is analyzed systematically. The great absorption enhancement in GaAs layer is demonstrated, especially in the wavelength region near the GaAs band gap. It is observed that the superposition of the two effects excited by Ag nanoparticles and DBR results in the obvious absorption enhancement. By using cylindrical Ag nanoparticles and DBR together, the maximum enhancement factor of the solar cell is obtained as 4.83 in the simulation.

Li, Xiao-nan; Yuan, Zong-heng; Zhou, Long

2014-01-01

278

Photoluminescence and time-resolved photoluminescence in Cu(In,Ga)Se2 thin films and solar cells  

International Nuclear Information System (INIS)

Photoluminescence (PL) and time-resolved PL (TR-PL) studies have been carried out on Cu(In,Ga)Se2 (CIGS) thin films and solar cells (ZnO/CdS/CIGS) to study the recombination of the photo-excited carriers. The CIGS solar cells exhibited intense near-band-edge (NBE) PL compared with the CIGS films by two orders of magnitude. PL decay time of the cell is strongly dependent on the repetition frequency of the excitation light. PL decay time of the cell is longer than that of the corresponding CIGS thin film. The chemical bath deposition of the CdS buffer layer on CIGS leads to changes in PL intensity, defect-related PL and the PL decay time. They are discussed with relation to the substitution of Cd atom at the Cu site at the Cu-deficient surface of CIGS thin film. Under the open circuit condition, NBE-PL is stronger and the decay time is longer compared with those under the short circuit condition. PL of the cell under the load was examined, and PL intensity and PL decay time are related to the photovoltage during PL measurements. Low temperature PL suggests that the Cd diffusion during the CBD process is pronounced for low Ga content CIGS. The authors demonstrate the effectiveness of PL as a powerful non-destructive device and photovoltaic characterization methods of CIGS solar cells. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

2009-05-01

279

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

280

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

Science.gov (United States)

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. Project supported by Hi-Tech Research and Development Program of China (Grant Nos. 2007AA05Z436 and 2009AA050602), Science and Technology Support Project of Tianjin (Grant No. 08ZCKFGX03500), the National Basic Research Program of China (Grant Nos. 2011CB201605 and 2011CB201606), the National Natural Science Foundation of China (Grant No. 60976051), International Cooperation Project between China-Greece Government (Grant No. 2009DFA62580), and Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0295).

Jiao, Bao-Chen; Zhang, Xiao-Dan; Wei, Chang-Chun; Sun, Jian; Ni, Jian; Zhao, Ying

2011-03-01

 
 
 
 
281

High-efficiency, thin-film solar cells. Annual subcontractor report, 1 July 1991--30 June 1992  

Energy Technology Data Exchange (ETDEWEB)

This report describes work on a 3-year research program to investigate thin-film GaAs/GaInP cells using the cleavage of lateral epitaxial film for transfer (CLEFT) technique, and to determine the process to enable overgrowth of GaAs films using organometallic chemistry. Application of the CLEFT thin-film technique to GaInP/GaAs solar cells and organometallic overgrowth was investigated. A problem of alloy contamination was identified and controlled, leading to higher quality layers. Solar cell structures were grown and fabricated using previously determined growth parameters for GaAs and GaInP. With the improved materials developed significant improvements were made in solar cell performance. Conditions for in-situ overgrowth by organometallic chemical vapor deposition (OMCVD) were determined and continuous GaAs layers were grown over a separation mask layer. The layers were successfully separated from their substrate using the CLEFT process, demonstrating the application of overgrowth using OM chemistry with HCl.

Gale, R.P. [Kopin Corp., Taunton, MA (United States)

1994-01-01

282

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

Science.gov (United States)

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.

Bai, Yi-Ming; Wang, Jun; Chen, Nuo-Fu; Yao, Jian-Xi; Zhang, Xing-Wang; Yin, Zhi-Gang; Zhang, Han; Huang, Tian-Mao

2011-08-01

283

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)

2011-08-01

284

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

285

Low pressure chemical vapor deposited Zinc Oxide for thin film silicon solar cells: optical and electrical properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transparent conductive oxides (TCO), such as LPCVD ZnO:B (low pressure chemical vapor deposited zinc oxide doped with boron), play a major role as contacts in thin film silicon photovoltaic solar cells. This document study the "LPCVD ZnO:B layers, from the deposition process to the final application" and focus especially on their electrical and optical properties. This work intended on understanding the physics of the LPCVD ZnO:B film properties in order to efficiently optimize its ch...

2009-01-01

286

Significance of interference effects in thin film Cu/sub 2/S/CdS solar cells  

Energy Technology Data Exchange (ETDEWEB)

The generation rate of electron-hole pairs in the Cu/sub 2/S layer of a thin film Cu/sub 2/S/CdS solar cell is calculated according to a semicoherent model. In this model the coherent addition of light waves is strictly limited to the Cu/sub 2/S layer. In contrast with the results of a fully coherent model, in which coherent addition is assumed throughout the whole structure, the interference effects have no significant influence on the photocurrent.

Walle, C. van de; Visschere, P. de

1983-09-01

287

Photoluminescence of CuInS{sub 2} thin films and solar cells modified by postdeposition treatments  

Energy Technology Data Exchange (ETDEWEB)

The photoluminescence of CuInS{sub 2} thin films and solar cells is investigated as a function of postdeposition treatments for different temperatures and excitation intensities. Annealing in hydrogen atmosphere causes an increase of PL intensity at 1.445 eV by more than a factor of 100, while subsequent annealing in oxygen or air ambient passivates this transition, which is ascribed to a donor-acceptor pair recombination between a sulphur vacancy and a copper vacancy. A defect mechanism is suggested that assumes the passivation of sulphur vacancies by oxygen in grain surfaces which can be activated by hydrogen annealing. {copyright} {ital 1997 American Institute of Physics.}

Toepper, K.; Bruns, J.; Scheer, R.; Weber, M.; Weidinger, A.; Braeunig, D. [Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany)

1997-07-01

288

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

289

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; Rodrguez, Francisco J; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

2014-01-01

290

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.

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

2014-01-01

291

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

International Nuclear Information System (INIS)

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

2013-05-15

292

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

293

Investigation of coevaporated Cu(In,Ga)Se{sub 2} thin films in highly efficient solar cell devices  

Energy Technology Data Exchange (ETDEWEB)

In order to further improve Cu(In,Ga)Se{sub 2} based thin film solar cell devices, it is important to understand the electronic defects in the absorber layer material. For this study Cu(In,Ga)Se{sub 2} thin film solar cells with a layer sequence Mo/Cu(In,Ga)Se{sub 2}/CdS/ZnO/ZnO:Al have been produced on float glass substrates using a 3-stage coevaporation process together with a precise in-situ laser light scattering process control. The Cu/(In + Ga) ratio has been varied by means of altering the duration of the 3rd stage of the process. Although the spectral quantum efficiencies measured on the resulting solar cell devices have not been affected by this variation, the open circuit voltage V{sub oc} measured under AM1.5 illumination increases when the final Cu/(In + Ga) ratio of the absorber layer is closer to stoichiometry. Indium and gallium depth profiles, which are recorded as energy dispersive X-ray spectroscopy line scans along device cross-sections, together with the results from the previously performed defect spectroscopy on identical samples, are correlated with the increase in V{sub oc}.

Kaufmann, C.A. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany)]. E-mail: kaufmann@hmi.de; Unold, T. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Abou-Ras, D. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Bundesmann, J. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Neisser, A. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Klenk, R. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Scheer, R. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany); Sakurai, K. [Unit 24412, AIST Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Schock, H.-W. [Hahn-Meitner-Institut Berlin GmbH, Abteilung SE3 Glienickerstrasse 100, D-14109 Berlin (Germany)

2007-05-31

294

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

295

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

296

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.

2010-11-01

297

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

298

Structural and optical properties of electrodeposited culnSe2 thin films for photovoltaic solar cells  

International Nuclear Information System (INIS)

Optical an structural properties of electrodeposited copper indium diselenide, CulnSe2, thin films were studied for its application in photovoltaic devices. X-ray diffraction patterns showed that thin films were grown in chalcopyrite phase after suitable treatments. Values of Eg for the CulnSe2 thin films showed a dependence on the deposition potential as determined by optical measurements. (Author) 47 refs

1990-01-01

299

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)

2010-10-01

300

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.)

2008-09-01

 
 
 
 
301

Room temperature synthesis of compact TiO2 thin films for 3-D solar cells by chemical arrested route  

International Nuclear Information System (INIS)

Essential requirement of compact TiO2 thin films for 3-D solar cells prefers high temperature techniques (?400 deg. C) such as spray pyrolysis or sputtering. Under optimized preparative conditions, compact, uniform, adherent and pinhole free, TiO2 thin films were synthesized at room temperature by using arrested precipitation technique on ITO substrates. As-deposited and heat-treated TiO2 films were amorphous with small enlargement in grain size as evidenced from XRD and SEM studies. Small blue shift was detected due to annealing and attributed to change in grain size. As deposited and heat-treated TiO2 films were used in this study showed water contact angles 66.14 deg. and 66.44 deg., respectively. Efforts were also taken to use these films in dye-sensitized solar cells after introducing cis-dithiocyanato (4,4'-dicarboxylic acid-2,2'-bipyridide) ruthenium (II) (N3) dye but no significant improvement due to low contact angle in photo-electrochemical cell performance was observed due to high compactness

2005-06-15

302

Thin film absorber for a solar collector  

Science.gov (United States)

This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Wilhelm, William G. (Cutchogue, NY)

1985-01-01

303

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

304

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

305

Electrical and electromagnetic hazards in the manufacture of thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

In the manufacture of thin film photovoltaic cells, electrical and electromagnetic fields generated from process equipment may present health and safety hazards. Radio-frequency plasma-deposition and sputtering equipment may emit non-ionizing radiation into the occupational work-space. Lasers and other electrical equipment may present hazards to employees in the form of electrical shock, eye injury and electromagnetic radiation. These hazards are characterized by reference to their potential to affect health and by reference to people exposed. The identified hazards are occupational; they do not jeopardize the health and safety of the public outside the plant. Existing controls of electromagnetic radiation are adequate, but monitoring techniques and devices should be improved, and frequent measurement programs should be introduced. Control technology effective in preventing hazards from lasers and high-voltage devices is well-established. Control technology options are reviewed.

Fthenakis, V.M.

1986-11-01

306

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

Science.gov (United States)

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 simultaneous resonance from both nanoparticle layers. 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 a total quantum efficiency of 62.35% for a 300nm thick a-Si substrate.

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

2014-05-01

307

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

308

Damp-heat induced sulfate formation in Cu(In,Ga)(S,Se)2-based thin film solar cells  

Science.gov (United States)

To investigate the impact of damp heat treatments on the electronic and chemical structure of Cu(In,Ga)(S,Se)2-based thin film solar cells, we have performed a detailed soft x-ray emission study of the ZnO/CuIn(S,Se)2 and ZnO/CdS/CuIn(S,Se)2 interfaces. By comparing the sulfur L2,3 emission spectra of pristine and damp-heat treated samples, we find a sulfate formation at the ZnO/CuIn(S,Se)2 and the ZnO/CdS interface. The intensity behavior as a function of ZnO film thickness further reveals a diffusion of sulfur atoms into the ZnO film, leading to the formation of zinc sulfate in the ZnO window layer of damp-heat-treated Cu(In,Ga)(S,Se)2-based solar cells.

Heske, C.; Groh, U.; Weinhardt, L.; Fuchs, O.; Holder, B.; Umbach, E.; Bostedt, C.; Terminello, L. J.; Zweigart, S.; Niesen, T. P.; Karg, F.

2002-12-01

309

Scattering analysis of the indium-tin-oxide (ITO) nanowhiskers on ITO film substrate for thin film solar cell  

Science.gov (United States)

Light trapping techniques such as textured interfaces and highly reflective back contacts are important to thin-film solar cells. Scattering at rough interfaces inside a solar cell leads to enhanced absorption due to an increased optical path length in the active layers, which is generally characterized by a haze ratio. In this work, we demonstrate the measured haze characteristics of indium tin oxide nano-whiskers deposited on an ITO-coated glass substrate. A theoretical model based on a modified Mie theory is also employed to analyze the scattering effects of nano-whiskers. Instead of spherical model, a cylindrical condition is imposed to better fit the shapes of the whiskers. The calculated haze-ratio of an ITO whisker layer matches the measurement closely.

Liu, Hsiao-Wei; Chang, Chia-Hua; Lin, Chien Chung; Yu, Peichen

2012-02-01

310

Pulsed electrically detected magnetic resonance study of spin relaxation and recombination in thin-film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

We have investigated the influence of paramagnetic states on electronic transport processes in thin-film pin solar cells with pulsed Electrically Detected Magnetic Resonance (pEDMR) at X-Band frequency and low temperature (10 K). The solar cells consist of an intrinsic microcrystalline absorber layer and amorphous or microcrystalline n/p contacting layers. In addition to the identification of the participating paramagnetic centres by their g-factors, pEDMR can be used to study the dynamics of the electronic processes in detail. We present measurements of modified EPR pulse sequences in order to identify the dominating relaxation mechanisms within correlated solid-state spin-pairs. By this technique a monitoring of the spin and charge motion is possible. In the outlook we present measurements of the electron spin echo envelope and critically discuss modulations in terms of dipolar coupling within the spin-pairs or hyperfine couplings to surrounding nuclei.

Fehr, Matthias; Behrends, Jan; Schnegg, Alexander; Lips, Klaus; Rech, Bernd [Helmholtz-Zentrum Berlin, Silizium Photovoltaik, Berlin (Germany); Astakhov, Oleksander; Finger, Friedhelm [Forschungszentrum Juelich (Germany). IEF-5 Photovoltaik

2009-07-01

311

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

312

Development of a rapid thermal annealing process for polycrystalline silicon thin-film solar cells on glass  

International Nuclear Information System (INIS)

In this report, we discuss the influence of rapid thermal annealing (RTA) on the performance of polycrystalline Si (poly-Si) thin-film solar cells on glass where the poly-Si layers are differently prepared. The first part presents a comprehensive study of RTA treatments on poly-Si thin-films made by solid phase crystallization (SPC) (standard material of CSG Solar AG, Thalheim). By varying both plateau temperature (up to 1050 deg. C) and duration (up to 1000 s) of the annealing profile, we determined the parameters for a maximum open-circuit voltage (VOC). In addition, we applied our standard plasma hydrogenation treatment in order to passivate the remaining intra-grain defects and grain boundaries by atomic hydrogen resulting in a further increase of VOC. We found, that the preceding RTA treatment increases the effect of hydrogenation already at comparable low RTA temperatures. The effect on hydrogenation increases significantly with RTA temperature. In a second step we investigated the effect of the RTA and hydrogenation on large-grained poly-Si films based on the epitaxial thickening of poly-Si seed layers.

2009-03-15

313

Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration  

Science.gov (United States)

Real time spectroscopic ellipsometry (RTSE), and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization techniques capable of performance optimization and scale-up evaluation of thin film solar cells used in various photovoltaics technologies. These non-invasive optical probes employ multichannel spectral detection for high speed and provide high precision parameters that describe (i) thin film structure, such as layer thicknesses, and (ii) thin film optical properties, such as oscillator variables in analytical expressions for the complex dielectric function. These parameters are critical for evaluating the electronic performance of materials in thin film solar cells and also can be used as inputs for simulating their multilayer optical performance. In this Thesis, the component layers of thin film hydrogenated silicon (Si:H) solar cells in the n-i-p or substrate configuration on rigid and flexible substrate materials have been studied by RTSE and ex-situ mapping SE. Depositions were performed by magnetron sputtering for the metal and transparent conducting oxide contacts and by plasma enhanced chemical vapor deposition (PECVD) for the semiconductor doped contacts and intrinsic absorber layers. The motivations are first to optimize the thin film Si:H solar cell in n-i-p substrate configuration for single-junction small-area dot cells and ultimately to scale-up the optimized process to larger areas with minimum loss in device performance. Deposition phase diagrams for both i- and p -layers on 2" x 2" rigid borosilicate glass substrate were developed as functions of the hydrogen-to-silane flow ratio in PECVD. These phase diagrams were correlated with the performance parameters of the corresponding solar cells, fabricated in the Cr/Ag/ZnO/n/i/ p/ITO structure. In both cases, optimization was achieved when the layers were deposited in the protocrystalline phase. Identical solar cell structures were fabricated on 6" x 6" borosilicate glass with 256 cells followed by ex-situ mapping SE on each cell to achieve better statistics for solar cell optimization by correlating local structural parameters with solar cell parameters. Solar cells of similar structure were also fabricated on flexible polymer substrates in the roll-to-roll configuration. In this configuration as well, RTSE was demonstrated as an effective process monitoring and control tool for thin film photovoltaics.

Dahal, Lila Raj

314

8% Efficient thin-film polycrystalline-silicon solar cells based on aluminium-induced crystallization and thermal CVD  

Energy Technology Data Exchange (ETDEWEB)

A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline-silicon (pc-Si) thin films on inexpensive substrates. We recently showed promising solar cells results using pc-Si layers obtained by aluminium-induced crystallization (AlC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc-Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk-Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc-Si solar cells on alumina substrates made by AlC in combination with thermal CVD. Our present pc-Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 8.0%. Spin-on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a-Si layers that yield much higher V{sub oc} values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc-Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc-Si solar cells based on the AlC seed layer approach. (author)

Gordon, I.; Carnel, L.; Van Gestel, D.; Beaucarne, G.; Poortmans, J. [IMEC VZW, Leuven (Belgium)

2006-07-01

315

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

316

The Preparation and Properties of Al-Doped ZnO Thin Films as Transparent Electrodes for Solar Cell  

Science.gov (United States)

Transparent conductive oxides based on ZnO are promising materials for application in thin-film solar photovoltaic cells. Al-doped ZnO thin films with a large area of 1 m 1.5 m were prepared by magnetic sputtering on glass substrate using a ceramic target (98 wt. % ZnO, 2 wt. % Al2O3) in different Ar+H2 ambient at different substrate temperature. SiO2 layer with a thickness of 20 nm was deposited as a resistant layer. To investigate the influence of H2-flow on the properties of AZO films, H2-flow rate was changed during the growth process with a fixed Ar-flow rate. The effect of the substrate temperature and the H2-flow rate on the structure, electrical and optical properties was studied. In order to enhance light scattering and absorption inside the cell, suitable surface texture is needed. The influence of wet chemical etching on surface roughness and haze of AZO were also investigated.

Ding, J. N.; Tan, C. B.; Yuan, N. Y.; Feng, X. W.; Chang, X. Y.; Ye, F.

317

New diarylmethanofullerene derivatives and their properties for organic thin-film solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available A number of diarylmethanofullerene derivatives were synthesized. The cyclopropane ring of the derivatives has two aryl groups substituted with electron-withdrawing and -donating groups, the latter with long alkyl chains to improve solubility in organic solvents, an important property in processing cells. First reduction potentials of most derivatives were less negative than that of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM, which is possibly ascribed to their electron-withdrawing nature. Organic thin-film photovoltaic cells fabricated with poly(3-hexylthiophene (P3HT as the electron-donor and diarylmethanofullerene derivatives as the electron-acceptor material were examined. The {(methoxycarbonylphenyl[bis(octyloxyphenyl]methano}fullerene showed power conversion efficiency as high as PCBM, but had higher solubility in a variety of organic solvents than PCBM. The Voc value was higher than that of PCBM, which is derived from the electron-donating (octyloxyphenyl group, possibly raising the LUMO level. Photovoltaic effects of the devices fabricated with the derivatives having some electron-withdrawing groups were also examined.

Daisuke Sukeguchi

2009-02-01

318

Textured surface boron-doped ZnO transparent conductive oxides on polyethylene terephthalate substrates for Si-based thin film solar cells  

International Nuclear Information System (INIS)

Textured surface boron-doped zinc oxide (ZnO:B) thin films were directly grown via low pressure metal organic chemical vapor deposition (LP-MOCVD) on polyethylene terephthalate (PET) flexible substrates at low temperatures and high-efficiency flexible polymer silicon (Si) based thin film solar cells were obtained. High purity diethylzinc and water vapors were used as source materials, and diborane was used as an n-type dopant gas. P-i-n silicon layers were fabricated at ? 398 K by plasma enhanced chemical vapor deposition. These textured surface ZnO:B thin films on PET substrates (PET/ZnO:B) exhibit rough pyramid-like morphology with high transparencies (T ? 80%) and excellent electrical properties (Rs ? 10 ? at d ? 1500 nm). Finally, the PET/ZnO:B thin films were applied in flexible p-i-n type silicon thin film solar cells (device structure: PET/ZnO:B/p-i-n a-Si:H/Al) with a high conversion efficiency of 6.32% (short-circuit current density JSC = 10.62 mA/cm2, open-circuit voltage VOC = 0.93 V and fill factor = 64%).

2011-12-01

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

Properties of ZnTe:Cu thin films and CdS/CdTe/ZnTe solar cells  

Energy Technology Data Exchange (ETDEWEB)

The effects of Cu doping and post-deposition annealing on the properties of ZnTe thin films and CdS/CdTe solar cells with the ZnTe:Cu/Au back contact were investigated. The structural, compositional, and electrical properties of ZnTe films were studied systematically using x-ray diffraction (XRD), electron microprobe analysis, atomic force microscopy (AFM), electrical resistivity and Hall effect measurements. ZnTe films with Cu concentrations of 1--6 at.% were used successfully as a back contact layer, providing fill factors over 0.70. The stability of CdTe/ZnTe/Au cells under accelerated temperature stress tests was investigated. I-V and C-V measurements, scanning Auger electron spectroscopy (AES) and X-ray photoemission spectroscopy (XPS) were used to clarify possible degradation mechanisms. Significant Cu and Te diffusion into Au layer and Au diffusion into ZnTe were observed after annealing.

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

1997-12-31

 
 
 
 
321

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

International Nuclear Information System (INIS)

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

2011-12-01

322

Structural and Optical Properties Analysis of Sputtered ZnO: Al Thin Films for Cigs Based Solar Cells  

International Nuclear Information System (INIS)

Al-doped zinc oxide (ZnO: Al) is an outstanding transparent conductive oxide, material with higher bandgap for CIGS based solar cells. Promising results on the optical properties and morphology of deposited ZnO: Al were investigated. Al-dope zinc oxide (ZnO: Al) targets have been deposited on top of ITO coated substrates by RF magnetron sputtering with different thickness. The characterized of films by UV-Vis was show that the transmittances of the films in the visible range are greater than 85 %. From XRD result was indicated that the data of deposited films shows polycrystalline nature with hexagonal wurtzite structure and dominant peak were obtained with preferential orientation (101). Numerous the influences of ZnO:Al investigated which can lead to the fabrication of high efficiency CIGS thin film soar cells. (author)

2011-07-04

323

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

324

High-Efficiency Cadmium and Zinc Telluride Based Thin-Film Solar Cells: Annual Report, June 1, 1987-May 31, 1988.  

Science.gov (United States)

This report contains results of research on high-efficiency cadmium and zinc telluride based thin-film solar cells from June 1987 to May 1988. CdTe and CdZnTe and CdTe and CdMnTe films were grown on CdS/SnO sub 2 /glass substrates by molecular beam epitax...

A. Rohatgi C. J. Summers A. Erbil R. Sudharsanan Ringel. S

1989-01-01

325

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

326

Light harvesting quasicrystalline nanophotonic structures for crystalline silicon thin-film solar cells  

Science.gov (United States)

We present our results on optical absorption enhancement in crystalline silicon (c-Si) absorber structured with transversely quasicrystalline lattice geometry for thin-film photovoltaics. c-Si nanoarchitectures are prepared on the nanoimprinted ten-fold symmetry quasicrystalline textured substrate. The structural features of the fabricated Si nanostructures are analyzed to confirm the defining characteristics of the quasicrystalline texturing of the absorber film. We present the optical absorption plots for a spectrum of incident light for varying angle of light incidence in these fabricated higher symmetry crystalline Si architectures. Neither any back reflector nor antireflection coating is considered in the present study, where use of such layers could further improve the light absorption. The realized quasicrystalline textured silicon nanoarchitectures with higher rotational symmetry lattice geometry are observed to improve the isotropic and broad band absorption properties of the thin film c-Si absorber and envisaged to have efficiency enhanced thin film photovoltaics effective in terms of cost and performance.

Xavier, Jolly; Probst, Jrgen; Wyss, Philippe; Eisenhauer, David; Back, Franziska; Rudigier-Voigt, Eveline; Hlsen, Christoph; Lchel, Bernd; Becker, Christiane

2014-05-01

327

XPS characterization of sensitized n-TiO{sub 2} thin films for dye-sensitized solar cell applications  

Energy Technology Data Exchange (ETDEWEB)

TiO{sub 2} thin films, employed in dye-sensitized solar cells, were prepared by the sol-gel method or directly by Degussa P25 oxide and their surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of adsorption of the cis-[Ru(dcbH{sub 2}){sub 2}(NCS){sub 2}] dye, N3, on the surface of films was investigated. From XPS spectra taken before and after argon-ion sputtering procedure, the surface composition of inner and outer layers of sensitized films was obtained and a preferential etching of Ru peak in relation to the Ti and N ones was identified. The photoelectrochemical parameters were also evaluated and rationalized in terms of the morphological characteristics of the films.

Patrocinio, Antonio Otavio T. [Laboratory of Inorganic Photochemistry and Energy Conversion, Instituto de Quimica, Universidade de Sao Paulo (Brazil); Paniago, Eucler B. [Departamento de Quimica, Universidade Federal de Ouro Preto (Brazil); Paniago, Roberto M. [Departamento de Fisica, Universidade Federal de Minas Gerais (Brazil); Iha, Neyde Y. Murakami [Laboratory of Inorganic Photochemistry and Energy Conversion, Instituto de Quimica, Universidade de Sao Paulo (Brazil)], E-mail: neydeiha@iq.usp.br

2008-01-15

328

XPS characterization of sensitized n-TiO 2 thin films for dye-sensitized solar cell applications  

Science.gov (United States)

TiO 2 thin films, employed in dye-sensitized solar cells, were prepared by the sol-gel method or directly by Degussa P25 oxide and their surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of adsorption of the cis-[Ru(dcbH 2) 2(NCS) 2] dye, N3, on the surface of films was investigated. From XPS spectra taken before and after argon-ion sputtering procedure, the surface composition of inner and outer layers of sensitized films was obtained and a preferential etching of Ru peak in relation to the Ti and N ones was identified. The photoelectrochemical parameters were also evaluated and rationalized in terms of the morphological characteristics of the films.

Patrocnio, Antonio Otvio T.; Paniago, Eucler B.; Paniago, Roberto M.; Iha, Neyde Y. Murakami

2008-01-01

329

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

2007-05-31

330

Band Gap Energy of Chalcopyrite Thin Film Solar Cell Absorbers Determined by Soft X-Ray Emission and Absorption Spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

The chemical and electronic structure of high efficiency chalcopyrite thin film solar cell absorbers significantly differs between the surface and the bulk. While it is widely accepted that the absorber surface exhibits a Cu-poor surface phase with increased band gap (Eg), a direct access to the crucial information of the depth-dependency of Eg is still missing. In this paper, we demonstrate that a combination of x-ray emission and absorption spectroscopy allows a determination of Eg in the surface-near bulk and thus complements the established surface- and bulk-sensitive techniques of Eg determination. As an example, we discuss the determination of Eg for a Cu(In,Ga)Se2 absorber [(1.52 +- 0.20) eV].

Bar, M.; Weinhardt, L.; Pookpanratana, S.; Heske, C.; Nishiwaki, S.; Shafarman, W.; Fuchs, O.; Blum, M.; Yang, W.; Denlinger, J.D.

2008-05-11

331

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

2007-01-01

332

Surface textured MF-sputtered ZnO films for microcrystalline silicon-based thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Highly conductive and transparent aluminum-doped zinc oxide (ZnO:Al) films were prepared by reactive mid-frequency (MF) magnetron sputtering at high growth rates. By varying the deposition pressure, pronounced differences with respect to film structure and wet chemical etching behavior were obtained. Optimized films develop good light-scattering properties upon etching leading to high efficiencies when applied to amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) silicon-based thin-film solar cells and modules. Initial efficiencies of 7.5% for a {mu}c-Si:H single junction and 9.7% for an a-Si:H/{mu}c-Si:H tandem module were achieved on an aperture area of 64cm{sup 2}. (author)

Huepkes, J.; Rech, B.; Kluth, O.; Repmann, T.; Zwaygardt, B.; Mueller, J. [Institute of Photovoltaics (IPV), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Drese, R.; Wuttig, M. [Institute for Physics of New Materials, Department of Physics, RWTH Aachen, D-52056 Aachen (Germany)

2006-11-23

333

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

334

Na-Doped Mo Target Sputtering for CIGS Thin Film Solar Cells on Stainless Steel Substrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study deposited Cu(In,Ga)Se2(CIGS) thin films on Mo/SiOx/SS431 substrates using magnetron sputtering. Our objectives were to introduce a Mo-5%Na target as a source of incorporate Na to the chalcopyrite structure and investigate its influence on the crystallinity of CIGS thin films. Experimental results demonstrate that adding Na in this manner can enhance the distribution of Na on the surface as well as the depth profile. When the thickness ratio of Mo-5%Na: Mo was 2.8%, the atomic ratio...

2013-01-01

335

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%

2013-06-01

336

Thin films of polyfluorene:fullerene blends - Morphology and its role in solar cell performance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sun provides us daily with large quantities of energy in the form of light. With the worlds increasing demand of electrical energy the prospect of converting this solar light into electricity is highly tempting. In the strive towards mass-production and low cost solar cells, new types of solar cells are being developed, e.g. solar cells completely based on organic molecules and polymers. These materials offer a promising potential of low cost and large scale manufacturing and have the ...

Bjo?rstro?m Svanstro?m, Cecilia

2007-01-01

337

A new poly(thienylenevinylene) derivative with high mobility and oxidative stability for organic thin-film transistors and solar cells  

Energy Technology Data Exchange (ETDEWEB)

A novel thiophene-thienylenevinylene copolymer is synthesized and evaluated for use in organic field-effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin-film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Lim, Bogyu; Baeg, Kang-Jun; Jeong, Hyung-Gu; Jo, Jang; Kim, Hyungsoo; Park, Jeong-Woo; Vak, Doojin; Park, Jeong-Ho; Park, Ji-Woong; Kim, Dong-Yu [Heeger Center for Advanced Materials (HCAM), Department of Materials Science and Engineering Gwangju Institute of Science and Technology (GIST), Buk-Gu Gwangju (Korea); Noh, Yong-Young [Convergence Components and Materials Laboratory Electronics and Telecommunications Research Institute (ETRI), Yuseong-gu Daejeon (Korea)

2009-07-20

338

Thin film poly-Si solar cell with ``STAR structure`` on glass substrate fabricated at low temperature  

Energy Technology Data Exchange (ETDEWEB)

The performances of thin film poly-Si solar cells with a thickness of less than 5 {micro}m on a glass substrate have been systematically investigated as a function of thickness. The cell of glass/back reflector/n-i-p poly-Si/ITO is well characterized by the structure of naturally surface texture and enhanced absorption with a back reflector (STAR), where the active i-layer was fabricated by plasma chemical vapor deposition (CVD) at low temperature. The cell with a thickness of 3.5 {micro}M and 2.5 {micro}m demonstrated an intrinsic efficiency of 9.8%, as independently confirmed by Japan Quality Assurance. The optical confinement effect explains the excellent spectral response at long wavelength for the cells through the PC1D analysis. The higher sensitivity at long-wavelength of the cell appeared in quantum efficiency curves is well correlated to the result of reflectance measurement. The open circuit voltage of 0.526 mV and the efficiency of 9.3% has been achieved for the cell with a thickness of 1.5 {micro}m, which was proved to be entirely stable with respect to the light-soaking. The stabilized efficiency of the developed a-Si:H/poly-Si/poly-Si stacked solar cell exhibits the efficiency of 11.5%.

Yamamoto, Kenji; Yoshimi, Masashi; Suzuki, Takayuki; Okamoto, Yoshifumi; Tawada, Yuko; Nakajima, Akihiko [Kaneka Corp., Kobe (Japan). Central Research Labs.

1997-12-31

339

Investigation of CdZnTe for Thin-Film Tandem Solar Cell Applications: Preprint  

Energy Technology Data Exchange (ETDEWEB)

Modeling of two-junction tandem devices shows that for optimal device performance, the bandgap of the top cell should be around 1.6-1.8 eV. CdZnTe alloys can be tailored to yield bandgaps in the desired range. In this study, we considered were used to fabricate these films, using close-spaced sublimation (CSS) and radio-frequency sputtering (RFS) techniques. In the first approach, we used mixed powders of CdTe and ZnTe as the source for film deposition by CSS. Even for the ZnTe/CdTe (95:5 ratio) source material, the deposited films were entirely CdTe due to higher vapor pressure of CdTe. In the second approach, we used pre-alloyed CdZnTe powders (CERAC, Inc.) as the source. Due to the lower sticking coefficient of Zn, even for the source composition of 75% Zn, these films contained very low quantities of Zn (~5%). We tried unsuccessfully to increase the Zn content in the films by confining Zn vapor by enclosing the region between the source and substrate, reducing the substrate temperature to 400C, and adjusting the source/substance distance. Finally, we used thin-film couples consisting of 300-nm-thick CdTe deposited by CSS and 300-nm-thick ZnTe deposited by RFS; the samples were then heat-treated in cadmium chloride vapor. Compositional analysis of the samples showed extensive interdiffusion of Cd and Zn for the annealed samples. We will present the data on the various stack configurations of CdTe and ZnTe, the effect of different post-deposition anneals, the effect of oxygen on the interdiffusion and alloy formation and its possible correlation to the device performance degradation.

Dhere, R.; Gessert, T.; Zhou, J.; Asher, S.; Pankow, J.; Moutinho, H.

2003-04-01

340

Atomic-scale distribution of impurities in CuInSe2-based thin-film solar cells  

International Nuclear Information System (INIS)

Atom Probe Tomography was employed to investigate the distribution of impurities, in particular sodium and oxygen, in a CuInSe2-based thin-film solar cell. It could be shown that sodium, oxygen, and silicon diffuse from the soda lime glass substrate into the CuInSe2 film and accumulate at the grain boundaries. Highly dilute concentrations of sodium and oxygen were measured in the bulk. Selenium was found to be depleted at the grain boundaries. These observations could be confirmed by complementary energy dispersive X-ray spectroscopy studies. Our results support the model proposed by Kronik et al. (1998) , which explains the enhanced photovoltaic efficiency of sodium containing CuInSe2 solar cells by the passivation of selenium vacancies at grain boundaries. -- Research highlights: ? Atom Probe Tomography was employed to investigate the elemental distribution in the CIS absorber layer. ? Na and O atoms were found to be distributed homogeneously in the CuInSe2 grains. ? Correlated enrichments of Na and O atoms were detected, presumably at a grain boundary. ? These enrichments are accompanied by Se depletion in agreement with the 'defect chemical model' proposed by Kronik. ? The 'Na effect' in our CIS-based solar cell can be explained by the passivation of VSe (detrimental donor defects) by O, where Na acts as a catalyst.

2011-05-01

 
 
 
 
341

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

342

Effects of ZnO coating on the performance of TiO{sub 2} nanostructured thin films for dye-sensitized solar cells  

Energy Technology Data Exchange (ETDEWEB)

ZnO-coated TiO{sub 2} (ZTO) thin films were deposited on ITO substrates by a sol-gel method for application as the work electrode for dye-sensitized solar cells (DSSCs). The I-V curve and the incident photon-to-current conversion efficiency (IPCE) value of DSSCs for ZTO thin films were studied and compared with single TiO{sub 2} films. The results show that the short-circuit photocurrent (J{sub sc}) and open-circuit voltage (V{sub oc}) values increased from 3.7 mA/cm{sup 2} and 0.68 V for the DSSCs with a single TiO{sub 2} film to 4.5 mA/cm{sup 2} and 0.72 V, respectively, for the DSSCs with a ZTO thin film. It indicated that the DSSCs with a ZTO thin film contributed to provide an inherent energy barrier that suppressed charge recombination significantly. In addition, the higher IPCE value in the ZTO thin film is attributed to the better charge separation by a fast electron transfer process using two semiconductors with different conduction band edges and energy positions. (orig.)

Kao, M.C.; Chen, H.Z.; Young, S.L. [Hsiuping Institute of Technology, Department of Electronic Engineering, Taichung (China)

2009-11-15

343

Solution-processed Fe3O4 magnetic nanoparticle thin film aligned by an external magnetostatic field as a hole extraction layer for polymer solar cells.  

Science.gov (United States)

We report, for the first time, the effect of a solution-processed Fe3O4 magnetic nanoparticle (MNP) thin film and a Fe3O4 MNP thin film aligned by an external magnetostatic field, used as a hole extraction layer (HEL), respectively, in polymer solar cells (PSCs). The thin film of a Fe3O4 MNP shows a smoother surface, better transparency, and higher electrical conductivity than that of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin layer. Moreover, the thin film of a Fe3O4 MNP aligned by an external magnetostatic field possesses an enhanced electrical conductivity and lower internal series resistance, thus leading to greater than 13% enhancement in the power conversion efficiency of PSCs than those using a PEDOT:PSS thin film. It was also found that PSCs incorporated with a Fe3O4 MNP shows better stability compared with those using PEDOT:PSS as an anode buffer layer. These results demonstrated that utilization of a Fe3O4 MNP as a HEL in PSCs blazes a trail to achieve highly efficient and long-time-stable devices. PMID:24063636

Wang, Kai; Ren, He; Yi, Chao; Liu, Chang; Wang, Hangxing; Huang, Lin; Zhang, Haoli; Karim, Alamgir; Gong, Xiong

2013-10-23

344

Solar cells made in thin film polycristalline silicon. Realization, characterization, perspectives  

Energy Technology Data Exchange (ETDEWEB)

We review the main recent results about epitaxial solar cells made on UMG (upgraded metallurgical grade) - Si: quality of the epilayer, cell efficiency (now 10.3%), cell spectral response. We then correlate epilayer quality and cell efficiency, using a simple model.

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

1987-01-01

345

Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells. Final subcontract report, 1 July 1988--31 December 1991  

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

346

In-depth elemental characterization of Cu(In,Ga)Se2 thin film solar cells by means of RBS and PIXE techniques  

Science.gov (United States)

Thin films based on Cu(In,Ga)Se2 are used as absorber cells in photovoltaic devices. In and Ga graded depth profiles are designed to optimize the solar cell performance. Simultaneous Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE) with 3 MeV 4He ions were used in conjunction to determine the depth profile of all the heavy elements in Cu(In,Ga)Se2 absorbers and complete solar cells. The RBS and PIXE data from one sample were analyzed synergistically, providing reliable depth profiles that satisfy all the data collected. An uncertainty analysis was done, probing the sensitivity of the analysis to different assumptions. The analytical possibilities of the combined RBS/PIXE alpha beam measurements of the CIGSe thin film solar cells, as well as the uncertainties induced in the quantitative methodology are discussed and critically assessed.

Karydas, A. G.; Bogdanovic Radovic, I.; Streeck, C.; Kaufmann, C.; Caballero, R.; Rissom, T.; Kanngieer, B.; Beckhoff, B.; Jaksic, M.; Barradas, N. P.

2014-07-01

347

Cocktails of paste coatings for performance enhancement of CuInGaS(2) thin-film solar cells.  

Science.gov (United States)

To fabricate low-cost and printable wide-bandgap CuInxGa1-xS2 (CIGS) thin-film solar cells, a method based on a precursor solution was developed. In particular, under this method, multiple coatings with two pastes with different properties (e.g., viscosity) because of the different binder materials added were applied. Paste A could form a thin, dense layer enabling a high-efficiency solar cell but required several coating and drying cycles for the desired film thickness. On the other hand, paste B could easily form one-micrometer-thick films by means of a one-time spin-coating process but the porous microstructure limited the solar cell performance. Three different configurations of the CIGS films (A + B, B + A, and A + B + A) were realized by multiple coatings with the two pastes to find the optimal stacking configuration for a combination of the advantages of each paste. Solar cell devices using these films showed a notable difference in their photovoltaic characteristics. The bottom dense layer increased the minority carrier diffusion length and enhanced the short-circuit current. The top dense layer could suppress interface recombination but exhibited a low optical absorption, thereby decreasing the photocurrent. As a result, the A + B configuration could be suggested as a desirable simple stacking structure. The solar cell with A + B coating showed a highly improved efficiency (4.66%) compared to the cell with a film prepared by paste B only (2.90%), achieved by simple insertion of a single thin (200 nm), dense layer between the Mo back contact and a thick porous CIGS layer. PMID:24377257

An, Hee Sang; Cho, Yunae; Park, Se Jin; Jeon, Hyo Sang; Hwang, Yun Jeong; Kim, Dong-Wook; Min, Byoung Koun

2014-01-22

348

Light trapping in thin film solar cells using textured photonic crystal  

Energy Technology Data Exchange (ETDEWEB)

A solar cell includes a photoactive region that receives light. A photonic crystal is coupled to the photoactive region, wherein the photonic crystal comprises a distributed Bragg reflector (DBR) for trapping the light.

Yi, Yasha (Somerville, MA); Kimerling, Lionel C. (Concord, MA); Duan, Xiaoman (Amesbury, MA); Zeng, Lirong (Cambridge, MA)

2009-01-27

349

Optimization-based design of surface textures for thin-film Si solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We numerically investigate the light-absorption behavior of thin-film silicon for normal-incident light, using surface textures to enhance absorption. We consider a variety of texture designs, such as simple periodic gratings and commercial random textures, and examine arbitrary irregular periodic textures designed by multi-parameter optimization. Deep and high-index-contrast textures exhibit strong anisotropic scattering that is outside the regime of validity of the Lambertian models commonl...

2011-01-01

350

On the diffusion length and grain size homogeneity requirements for efficient thin-film polycrystalline silicon solar cells  

International Nuclear Information System (INIS)

We examine the influence of intragrain defects and grain boundaries on the macroscopic performance of a thin film polycrystalline silicon solar cell. In addition, we evaluate the effect of grain size inhomogeneity on the cell performance via circuit simulations. From an analytical study of charge transport in individual grains and homogeneous grain systems, we obtain the grain size and intragrain diffusion length requirements for a desired efficiency. We identify the conditions under which the grain size and the intragrain diffusion length dominate the cell characteristics. In devices with intragrain effective diffusion length Lmono ? 100 m and grain boundary recombination velocity SGB ? 104 cm s-1, achieving a larger grain size beyond several m is not crucial. The inhomogeneous distribution circuit simulations show that grain size inhomogeneity is not the main limiting factor in polycrystalline silicon solar cells. This is so even in thin polycrystalline silicon films with a broad grain size distribution such as those made with aluminum-induced crystallization at low annealing temperature. The main reason is that the optimum bias point for grains of different sizes only differ by about ?50 mV over a fairly wide grain diameter range 0.5-50 m even when Lmono = 100 m and SGB = 105 cm s-1.

2013-01-30

351

Study of ZnTe:Cu back contacts on CdTe/CdS thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Vacuum-evaporated Cu-doped ZnTe films have been studied as the intermediate layer between CdTe and metal contacts in CdTe/CdS thin-film solar cells for the formation of low resistance back contacts. Different metals (Au, Ni, Co) have been investigated as the contact material to the ZnTe layer. The effects of Cu concentration, ZnTe:Cu layer thickness, and ZnTe post-deposition annealing temperature on the cell performances have been investigated. The authors found that different metal contacts on the ZnTe layer lead to different doping densities in the CdTe layer and different open-circuit photovoltages of the solar cells. The possible formation of a back contact diode at the CdTe/ZnTe interface was explored, based on capacitance-voltage analysis. The series resistance of the CdTe/CdS cells was reduced significantly by the introduction of the ZnTe layer. Fill factors greater than 0.76 and an energy conversion efficiency of 12.9% have been achieved using ZnTe back contacts on electrodeposited CdTe.

Tang, J.; Feng, L.; Mao, D.; Song, W.; Zhu, Y.; Trefny, J.U. [Colorado School of Mines, Golden, CO (United States). Dept. of Physics

1996-12-31

352

Thin-film solar cell on the basis of polycrystalline cadmium telluride  

International Nuclear Information System (INIS)

The I-U characteristics of the p-CdTe-n-CdTe-n-CdS and p-CdTe-n-CdTe-n-Zn/sub x/Cd/sub 1-x/S solar cells have been investigated under solar irradiation of approximately 60 mW/cm2. The values of photosensitivity and collection efficiency have been determined. Investigations of I-U and C-U curves have confirmed the p-n junction in CdTe. The irradiation of prepared solar cells with protons and gamma radiation with energy of E >= 1 MeV and varying radiation doses has been studied and discussed

1984-06-16

353

A new approach to the manufacture of chalcogenide thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Glass beads of 0.2 mm diameter are covered with molybdenum, copper and indium. The copper/indium layers are transformed into copper indium disulfide (CIS) by exposing the glass beads to a hydrogensulfide/argon mixture at temperatures of around 500 {sup o}C. The CIS covered glass beads serve as the basis material for the formation of solar cells. The main advantage of this approach is the separation between absorber and cell/module formation. In this paper the different process steps necessary for cell manufacturing are described. Some properties of solar cells made out of CIS covered glass beads are presented.

Geyer, V. [Scheuten Research, van Heemskerckweg 9, NL 5928 Venlo (Netherlands)], E-mail: vgeyer@scheuten.nl; Schuurmans, F.; Linden, H.; Buerger, C.; Beinlich, M.; Dam, R. van; Heuvel, P. van den; Linden, J. van der; Timmers, R. [Scheuten Research, van Heemskerckweg 9, NL 5928 Venlo (Netherlands)

2008-05-30

354

A new approach to the manufacture of chalcogenide thin film solar cells  

International Nuclear Information System (INIS)

Glass beads of 0.2 mm diameter are covered with molybdenum, copper and indium. The copper/indium layers are transformed into copper indium disulfide (CIS) by exposing the glass beads to a hydrogensulfide/argon mixture at temperatures of around 500 oC. The CIS covered glass beads serve as the basis material for the formation of solar cells. The main advantage of this approach is the separation between absorber and cell/module formation. In this paper the different process steps necessary for cell manufacturing are described. Some properties of solar cells made out of CIS covered glass beads are presented

2008-05-30

355

Thin film solar cells based on the ternary compound Cu{sub 2}SnS{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

Alongside with Cu{sub 2}ZnSnS{sub 4} and SnS, the p-type semiconductor Cu{sub 2}SnS{sub 3} also consists of only Earth abundant and low-cost elements and shows comparable opto-electronic properties, with respect to Cu{sub 2}ZnSnS{sub 4} and SnS, making it a promising candidate for photovoltaic applications of the future. In this work, the ternary compound has been produced via the annealing of an electrodeposited precursor in a sulfur and tin sulfide environment. The obtained absorber layer has been structurally investigated by X-ray diffraction and results indicate the crystal structure to be monoclinic. Its optical properties have been measured via photoluminescence, where an asymmetric peak at 0.95 eV has been found. The evaluation of the photoluminescence spectrum indicates a band gap of 0.93 eV which agrees well with the results from the external quantum efficiency. Furthermore, this semiconductor layer has been processed into a photovoltaic device with a power conversion efficiency of 0.54%, a short circuit current of 17.1 mA/cm{sup 2}, an open circuit voltage of 104 mV hampered by a small shunt resistance, a fill factor of 30.4%, and a maximal external quantum efficiency of just less than 60%. In addition, the potential of this Cu{sub 2}SnS{sub 3} absorber layer for photovoltaic applications is discussed. - Highlights: Black-Right-Pointing-Pointer Fabrication of a pn-junction based thin film solar cell based on Cu{sub 2}SnS{sub 3}. Black-Right-Pointing-Pointer Electro-optical properties of the Cu{sub 2}SnS{sub 3} based solar cell and its limits. Black-Right-Pointing-Pointer The potential of Cu{sub 2}SnS{sub 3} based solar cells in terms of its photovoltaic application. Black-Right-Pointing-Pointer Structural, morphological, and optical properties of a Cu{sub 2}SnS{sub 3} thin film.

Berg, Dominik M., E-mail: berg@udel.edu [University of Luxembourg, Laboratory for Photovoltaics, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Djemour, Rabie; Guetay, Levent [University of Luxembourg, Laboratory for Photovoltaics, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Zoppi, Guillaume [Northumbria University, Northumbria Photovoltaics Applications Centre, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Siebentritt, Susanne; Dale, Phillip J. [University of Luxembourg, Laboratory for Photovoltaics, 41, rue du Brill, L-4422 Belvaux (Luxembourg)

2012-07-31

356

Novel device structure for Cu(In,Ga)Se{sub 2} thin film solar cells using transparent conducting oxide back and front contacts  

Energy Technology Data Exchange (ETDEWEB)

Cu(In{sub 1-x}Ga{sub x})Se{sub 2} (CIGS)-based thin film solar cells fabricated using transparent conducting oxide (TCO) front and back contacts were investigated. The cell performance of substrate-type CIGS devices using TCO back contacts was almost the same as that of conventional CIGS solar cells with metallic Mo back contacts when the CIGS deposition temperatures were below 500 {sup o}C for SnO{sub 2}:F and 520 {sup o}C for ITO. CIGS thin film solar cells fabricated with ITO back contacts had an efficiency of 15.2% without anti-reflection coatings. However, the cell performance deteriorated at deposition temperatures above 520 {sup o}C. This is attributed to the increased resistivity of the TCOs due to the removal of fluorine from SnO{sub 2} or undesirable formation of a Ga{sub 2}O{sub 3} thin layer at the CIGS/ITO interface. The formation of Ga{sub 2}O{sub 3} was eliminated by inserting an intermediate layer such as Mo between ITO and CIGS. Furthermore, bifacial CIGS thin film solar cells were demonstrated as being one of the applications of semi-transparent CIGS devices. The cell performance of bifacial devices was improved by controlling the thickness of the CIGS absorber layer. Superstrate-type CIGS thin film solar cells with an efficiency of 12.8% were fabricated using a ZnO:Al front contact. Key techniques include the use of a graded band gap Cu(In,Ga){sub 3}Se{sub 5} phase absorber layer and a ZnO buffer layer along with the inclusion of Na{sub 2}S during CIGS deposition.. (author)

Nakada, Tokio; Hirabayashi, Yutaka; Tokado, Takehito; Ohmori, Daiske; Mise, Takahiro [Aoyama Gakuin Univ., Kanagawa (Japan). Dept. of Electrical Engineering and Electronics

2004-12-01

357

Research on polycrystalline thin-film materials, cells, and modules  

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy (DOE) supports research activities in polycrystalline thin films through the Polycrystalline Thin-Film Program at the Solar Energy Research Institute (SERI). This program includes research and development (R D) in both copper indium diselenide and cadmium telluride thin films for photovoltaic applications. The objective of this program is to support R D of photovoltaic cells and modules that meet the DOE long-term goals of high efficiency (15%--20%), low cost ($50/m{sup 2}), and reliability (30-year life time). Research carried out in this area is receiving increased recognition due to important advances in polycrystalline thin-film CuInSe{sub 2} and CdTe solar cells and modules. These have become the leading thin-film materials for photovoltaics in terms of efficiency and stability. DOE has recognized this potential through a competitive initiative for the development of CuInSe{sub 2} and CdTe modules. This paper focuses on the recent progress and future directions of the Polycrystalline Thin-Film Program and the status of the subcontracted research on these promising photovoltaic materials. 26 refs., 12 figs, 1 tab.

Mitchell, R.L.; Zweibel, K.; Ullal, H.S.

1990-11-01

358

Photosensitivity of ZnO/CdS/Cu(In,Ga)Se{sub 2}/Mo thin-film solar cells fabricated on various substrates  

Energy Technology Data Exchange (ETDEWEB)

The results of measuring the first spectra of relative quantum efficiency for photoconversion in thin-film ZnO/CdS/Cu(In,Ga)Se{sub 2}/Mo solar cells fabricated on rigid (glass) and flexible (polyimide) substrates are reported. The character of interband transitions has been studied and the values of the band gap for direct and indirect transitions in thin Cu(In,Ga)Se{sub 2} films are determined. It is found that a shift of the maximal photosensitivity for the obtained solar cells to shorter wavelengths is observed as rigid substrates are replaced by flexible ones. It is concluded that thin-film Cu(In,Ga)Se{sub 2} structures can be used as broad-band photoconverters of solar radiation.

Rud, V. Yu., E-mail: rudvas.spb@gmail.com [St. Petersburg State Polytechnical University (Russian Federation); Rud, Yu. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Gremenok, V. F. [National Academy of Sciences of Belarus, Scientific-Practical Material Research Center (Belarus); Terukov, E. I.; Bairamov, B. Kh. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Song, Y. W. [Korea Polytechnic University (Korea, Republic of)

2012-02-15

359

Variation of sulfur content in Cu(In,Ga)(S,Se){sub 2} thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Chalcopyrite thin film solar cells made of the compound semiconductor Cu(In,Ga)(S,Se){sub 2} (CIGSSe) have a strong potential for achieving high efficiencies at low production costs. Volume production of CIGSSe-modules has already started to exploit their favorable attributes such as low cost processing and reasonable module efficiency. In this study we studied industrially produced CIGSSe modules obtained from rapid thermal processing (RTP) for sulfurization. In detail, we investigated the effect of sulfur offer and RTP temperature (500 C to 580 C) on the photoelectric characteristics of small-area solar cells cut from the modules. Current-voltage profiling under standard test conditions revealed a strong influence of the particular process recipe on the open circuit voltage whereas significant variations of the maximum quantum efficiency can be observed. X-ray diffraction was employed to relate these effects to the crystallographic structure of the actual CIGSSe films. Lock-in thermographic imaging was employed to link apparent film inhomogeneities and disruptions to the specific process recipe.

Knipper, Martin; Knecht, Robin; Riedel, Ingo; Parisi, Juergen [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg (Germany)

2011-07-01

360

Property control of expanding thermal plasma deposited textured zinc oxide with focus on thin film solar cell applications  

International Nuclear Information System (INIS)

Property control of expanding thermal plasma deposited textured zinc oxide is demonstrated considering intrinsic, i.e. bulk, and extrinsic transparent conducting oxide quality relevant for application in thin film amorphous silicon pin solar cells. Particularly the interdependence of electrical conductivity, film composition and film morphology, i.e. structure, feature shape and roughness of the surface, is addressed. Control of film composition is mainly governed by plasma production and gas phase chemistry inherently inducing a significant contribution to film morphology, whereas control of film morphology solely is governed by near-substrate conditions. Especially the ratio of zinc to oxygen and the reactor chamber pressure appear to be determinative in obtaining zinc oxide exhibiting the appropriate intrinsic and extrinsic quality, i.e. a high electrical conductivity, a high transmittance, a textured rough surface morphology and a strong hydrogen plasma resistance. The solar cell performance of appropriate undoped and aluminium doped textured zinc oxide inherently obtained during deposition is comparable with respect to Asahi U-type fluorine-doped tin oxide

2005-12-01

 
 
 
 
361

Analysis of impact of non-uniformities on thin-film solar cells and modules with two-dimesional simulations  

Science.gov (United States)

Clean and environmentally friendly photovoltaic (PV) technologies are now generally recognized as an alternative solution to many global-scale problems such as energy demand, pollution, and environment safety. The cost ($/kWh) is the primary challenge for all PV technologies. In that respect, thin-film polycrystalline PV technology (CdTe, Cu(In,Ga)Se2, etc), due to its fast production line, large area panels and low material usage, is one of the most promising low-cost technologies. Due to their granular structure, thin-film solar cells are inherently non-uniform. Also, inevitable fluctuations during the multistep deposition process of large area thin-film solar panels and specific manufacturing procedures such as scribing result in non-uniformities. Furthermore, non-uniformities can occur, become more severe, or increase in size during the solar-panel's life cycle due to various environmental conditions (i.e. temperature variation, shading, hail impact, etc). Non-uniformities generally reduce the overall efficiency of solar cells and modules, and their effects therefore need to be well understood. This thesis focuses on the analysis of the effect of non-uniformities on small size solar cells and modules with the help of numerical simulations. Even though the 2-D model developed here can analyze the effect of non-uniformities of any nature, only two specific types of microscopic non-uniformities were addressed here: shunts and weak-diodes. One type of macroscopic non-uniformity, partial shading, was also addressed. The circuit model developed here is a network of diodes, current-sources, and transparent-conductive-oxide (TCO) resistors. An analytic relation between the TCO-resistor, which is the primary model parameter, and TCO sheet resistance rhoS, which is the corresponding physical parameter, was derived. Based on the model several useful general results regarding a uniform cell were deduced. In particular, a global parameter delta, which determines the performance of a uniform solar cell depending on sheet resistance rhoS, cell length L, and other basic parameters, was found. The expression for the lumped series resistance in terms of physical parameters was also derived. Primary power loss mechanisms in the uniform case and their dependence on rhoS, L, and light generated current JL were determined. Similarly, power losses in a small-area solar cell with either a shunt or a weak-microdiode were identified and their dependence on rho S, JL, and location of the non-uniformity with respect to the current collecting contact was studied. The impact of multiple identical non-uniformities (shunts or weak-diodes) on the performance of a module was analyzed and estimates of efficiency loss were presented. It was found that the efficiency of the module strongly depends not only on the severity and fractional area of non-uniformities but also on their distribution pattern. A numerical parameter characterizing distribution pattern of non-uniformities was int