WorldWideScience
 
 
1

Thin-film solar cell:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with the light-collecting surface. In this context, the relationships 45 < alpha < 135 degrees and 45 < beta < 135 degrees apply. The invention also relates to a panel provided with a plurality of such t...

Metselaar, J. W.; Kuznetsov, V. I.

1998-01-01

2

Advances in thin-film solar cells  

CERN Document Server

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

Dharmadasa, I M

2012-01-01

3

Light management in thin-film silicon solar cells:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Isabella, O.

2013-01-01

4

High efficiency thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

Production of photovoltaics is growing worldwide on a gigawatt scale. Among the thin film technologies, Cu(In,Ga)S,Se{sub 2} (CIS or CIGS) based solar cells have been the focus of more and more attention. This paper aims to analyze the success of CIGS based solar cells and the potential of this technology for future photovoltaics large-scale production. Specific material properties make CIS unique and allow the preparation of the material with a wide range of processing options. The huge potential lies in the possibility to take advantage of modern thin film processing equipment and combine it with very high efficiencies beyond 20% already achieved on the laboratory scale. A sustainable development of this technology could be realized by modifying the materials and replacing indium by abundant elements. (orig.)

Schock, Hans-Werner [Helmholtz Zentrum Berlin (Germany). Solar Energy

2012-11-01

5

Plasma texturing of thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A potentially inexpensive way to texture silicon surfaces especially for crystalline silicon thin-film solar cells is the plasma texturing method. This method uses the principle of self-masking and is realised at Fraunhofer ISE using an isotropic and an anisotropic power supply. Even in continuous in-line processing, the process allows a conditioning of the wafer surface in a wide range. In this paper two scientific problems are addressed: first, simulations were performed to find the best te...

Keller, M.; Janz, S.; Reber, S.; Lindekugel, S.

2010-01-01

6

Silicon Thin-Film Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available We review the field of thin-film silicon solar cells with an active layer thickness of a few micrometers. These technologies can potentially lead to low cost through lower material costs than conventional modules, but do not suffer from some critical drawbacks of other thin-film technologies, such as limited supply of basic materials or toxicity of the components. Amorphous Si technology is the oldest and best established thin-film silicon technology. Amorphous silicon is deposited at low temperature with plasma-enhanced chemical vapor deposition (PECVD. In spite of the fundamental limitation of this material due to its disorder and metastability, the technology is now gaining industrial momentum thanks to the entry of equipment manufacturers with experience with large-area PECVD. Microcrystalline Si (also called nanocrystalline Si is a material with crystallites in the nanometer range in an amorphous matrix, and which contains less defects than amorphous silicon. Its lower bandgap makes it particularly appropriate as active material for the bottom cell in tandem and triple junction devices. The combination of an amorphous silicon top cell and a microcrystalline bottom cell has yielded promising results, but much work is needed to implement it on large-area and to limit light-induced degradation. Finally thin-film polysilicon solar cells, with grain size in the micrometer range, has recently emerged as an alternative photovoltaic technology. The layers have a grain size ranging from 1 μm to several tens of microns, and are formed at a temperature ranging from 600 to more than 1000∘C. Solid Phase Crystallization has yielded the best results so far but there has recently been fast progress with seed layer approaches, particularly those using the aluminum-induced crystallization technique.

Guy Beaucarne

2007-12-01

7

Advanced characterization techniques for thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

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 book 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. This book is structured as follows: Part I - Introduction: 1. Introduction to thin-film photovoltaics. Part II - Device characterization: 2. Fundamental electrical characterization of thin-film solar cells; 3. Electroluminescence analysis of thin-film solar modules; 4. Capacitance spectroscopy of thin-film solar cells. Part III - Materials characterization: 5. Characterizing the light trapping properties of textured surfaces with scanning near-field optical microscopy; 6. Ellipsometry; 7. Photoluminescence analysis of Si and chalcopyrite-type thin films for solar cells; 8. Steady state photocarrier grating method; 9. Time-of-flight analysis; 10. Electron Spin Resonance on Si thin films for solar cells; 11. Scanning probe microscopy on thin films for solar cells; 12. Electron microscopy on thin films for solar cells; 13. X-ray and neutron diffraction of materials for thin film solar cells; 14. Raman Spectroscopy on thin films for solar cells; 15. Soft x-ray and electron spectroscopy: a unique ''tool chest'' to characterize the chemical and electronic properties of surfaces and interfaces; 16. Elemental distribution profiling of thin films for solar cells; 17. Hydrogen effusion experiments. Part IV - Materials and device modelling: 18. Ab-initio modelling of semiconductors; 19. One-dimensional electro-optical simulations of thin film solar cells; 20. Two-dimensional electrical simulations of thin film solar cells.

Abou-Ras, Daniel [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Kirchartz, Thomas [Imperial College, London (United Kingdom); Rau, Uwe (eds.) [Forschungszentrum Juelich GmbH (Germany)

2011-07-01

8

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

9

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

International Nuclear Information System (INIS)

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

10

Thin Film Solar Cells: Research in an Industrial Perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Edoff, Marika

2012-01-01

11

Broadband back grating design for thin film solar cells  

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

Janjua, Bilal

2013-01-01

12

UV imprinting for thin film solar cell application  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

13

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

Science.gov (United States)

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

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

2014-05-20

14

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

Energy Technology Data Exchange (ETDEWEB)

SnS is of interest for use as an absorber layer and the wider energy bandgap phases e.g. SnS{sub 2}, Sn{sub 2}S{sub 3} 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.

Ogah, Ogah E.; Zoppi, Guillaume; Forbes, Ian [Northumbria Photovoltaics Applications Centre, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Miles, R.W. [Northumbria Photovoltaics Applications Centre, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom)], E-mail: robert.miles@unn.ac.uk

2009-02-02

15

Efficient light trapping structure in thin film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin film silicon solar cells are believed to be promising candidates for continuing cost reduction in photovoltaic panels because silicon usage could be greatly reduced. Since silicon is an indirect bandgap semiconductor, its absorption coefficient is low for photons in the wavelength ranges between 600nm and 1100nm. For high efficiency thin film modules, effective light trapping is essential. Traditional schemes such as textured transparent conductive oxide (TCO) and metal reflector have se...

Sheng, Xing; Liu, Jifeng; Kozinsky, Inna; Michel, Jurgen; Kimerling, Lionel C.; Agarwal, Anuradha Murthy

2010-01-01

16

Mode Splitting for Efficient Plasmoinc Thin-film Solar Cell  

CERN Document Server

We propose an efficient plasmonic structure consisting of metal strips and thin-film silicon for solar energy absorption. We numerically demonstrate the absorption enhancement in symmetrical structure based on the mode coupling between the localized plasmonic mode in Ag strip pair and the excited waveguide mode in silicon slab. Then we explore the method of symmetry-breaking to excite the dark modes that can further enhance the absorption ability. We compare our structure with bare thin-film Si solar cell, and results show that the integrated quantum efficiency is improved by nearly 90% in such thin geometry. It is a promising way for the solar cell.

Li, Tong; Jiang, Chun

2010-01-01

17

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

18

Simulation of tandem thin-film silicon solar cells  

Science.gov (United States)

A sophisticated light-management is indispensable for silicon thin-film silicon solar cells based on amorphous (a-Si:H) and microcrystalline (?c-Si:H) silicon. The optical properties of thin-film solar cells have a significant influence on the conversion efficiency. The topology of the nano-textured interfaces affects the optical path and absorption. A rough transparent conductive oxide (TCO) film leads to a high quantum efficiency and shortcircuit current density. Simulations of various geometries indicate the optimal texture. Therefore, we simulate 3-dimensional tandem thin-film solar cells with different interfaces. The roughness can be identified by atomic force microscope (AFM) scans. In order to accurately analyze all aspects of the light propagation in solar cells, numerical simulations of Maxwell's equations are needed. By standard simulation programs for solving Maxwell's equations, it is difficult to simulate realistic textures of the solar cell layers. Therefore, a simulation tool based on the finite difference time domain (FDTD) method and the finite integration technique (FIT) is developed, which is able to integrate AFM scan data. To incorporate the nanostructure of a relevant section in the AFM scans, high computational domains are needed. This leads to a large number of grid points in the resulting discretization. Parallel computations on high performance computers are needed to meet the large computational requirements. The simulations show that the light propagation in the investigated thin-film device is a complex phenomenon depending on the wavelength and phase of the incident light.

Jandl, Christine; Dewald, Wilma; Paetzold, Ulrich W.; Gordijn, Aad; Pflaum, Christoph; Stiebig, Helmut

2010-05-01

19

Thin Film Solar Cells and their Optical Properties  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we report on the optical parameters of the semiconductor thin film for solar cell applications determination. The method is based on the dynamical modeling of the spectral reflectance function combined with the stochastic optimization of the initial reflectance model estimation. The spectral dependency of the thin film optical parameters computations is based on the optical transitions modeling. The combination of the dynamical modeling and the stochastic optimization of the initial theoretical model estimation enable comfortable analysis of the spectral dependencies of the optical parameters and incorporation of the microstructure effects on the solar cell properties. The results of the optical parameters ofthe i-a-Si thin film determination are presented.

Robert Brunner

2006-01-01

20

Low cost thin film poly-silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

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

NONE

2005-07-01

 
 
 
 
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

Organic/inorganic hybrid thin films for multijunction solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work is devoted to the study of ternary semiconductor nanocrystals, and their application inhybrid organic/inorganic solar cells. Semiconductor nanocrystals absorb light at controlled wavelength(depending on their size and composition) and are able to transport charges. They form a colloidalsolution in organic solvent compatible with low-cost deposition in thin films. Nowadays, the bestefficiency for such hybrid solar cells is obtained with binary nanocrystals containing lead or cadmium....

Lefranc?ois, Aure?lie

2013-01-01

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

CZTSSe thin film solar cells: Surface treatments  

Science.gov (United States)

Chalcopyrite semiconducting materials, specifically CZTS, are a promising alternative to traditional silicon solar cell technology. Because of the high absorption coefficient; films of the order of 1 micrometer thickness are sufficient for the fabrication of solar cells. Liquid based synthesis methods are advantageous because they are easily scalable using the roll to roll manufacturing techniques. Various treatments are explored in this study to enhance the performance of the selenized CZTS film based solar cells. Thiourea can be used as a sulfur source and can be used to tune band gap of CZTSSe. Bromine etching can be used to manipulate the thickness of sintered CZTSSe film. The etching treatment creates recombination centers which lead to poor device performance. Various after treatments were used to improve the performance of the devices. It was observed that the performance of the solar cell devices could not be improved by any of the after treatment steps. Other surface treatment processes are explored including KCN etching and gaseous H2S treatments. Hybrid solar cells which included use of CIGS nanoparticles at the interface between CZTSSe and CdS are also explored.

Joglekar, Chinmay Sunil

26

Vibrational spectroscopy of organic thin films used for solar cells  

Science.gov (United States)

We review infrared and Raman analyses of thin films of organic semiconductors used for active layers in organic solar cells. We present Raman study of blend (bulk heterojunction) films of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The contents of the crystalline region of P3HT in the blend films prepared by various methods were estimated by Raman spectroscopy. Temperature dependence of photoinduced infrared absorption from a P3HT:PCBM blend film gives the activation energy of the recombination of photoinduced positive and negative carriers. The activation energies for P3HT:PCBM blend films with various PCBM contents were obtained. It has been demonstrated that infrared and Raman spectroscopy is useful for evaluating thin films of P3HT:PCBM blend films used for organic solar cells.

Furukawa, Yukio

2013-09-01

27

Cuinse2 Thin Film For Solar Cell By Flash Evaporation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Deposition of thin films for material solar cell CuInSe2 are relatively simple. In this research mainly focused on the use of flash evaporation method, and the material created can then be characterized by optical and electrical properties. The optical characterization is done by X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS), and transmission and reflection by UV-VIS spectrophotometry. Electrical characterization is done by utilizing the Hall effect equipment. From these chara...

Soepardjo, A. H.

2009-01-01

28

Recrystallized silicon thin-film solar cells on zircon ceramics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work describes the processing of recrystallized silicon thin-film solar cells and its typical defects. Zircon (ZrSiO4) ceramic substrates of technical grade with potential production costs of <; 20 €/m2 were used. Those substrates were encapsulated in crystalline silicon carbide, deposited by atmospheric pressure chemical vapor deposition (APCVD). The active silicon layers were also formed using APCVD. Zone-melting recrystallization (ZMR) was used to enlarge Si grains. Si films crystal...

Schillinger, K.; Janz, S.; Reber, S.

2013-01-01

29

Optical confinement in recrystallised wafer equivalent thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bragg reflectors were used to enhance rear-side optical confinement in crystalline silicon thin film solar cells. Besides the enhancement of reflectivity in the long wavelength region, the layer stack acts as a diffusion barrier. We designed two different Bragg reflectors which were deposited on different silicon substrates. By adjusting the thickness of the single layers and their refractive indices an optimum reflected wavelength region exceeding 800 nm can be created. The amount of reflect...

Janz, S.; Kuenle, M.; Peters, M.; Lindekugel, S.; Mitchell, E. J.; Reber, S.

2007-01-01

30

Nanowired Polymer Thin Film Solar Cells  

Directory of Open Access Journals (Sweden)

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

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

2013-12-01

31

Nanowired Polymer Thin Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Dr K Siddappa Naidu, Dr D. Bhattacharya

2013-01-01

32

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

33

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

CERN Document Server

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

Kodigala, Subba Ramaiah

2013-01-01

34

Transparent conducting oxide layers for thin film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 roughnes...

Rath, J. K.; Liu, Y.; Jong, M. M.; Wild, J.; Schuttauf, J. A.; Brinza, M.; Schropp, R. E. I.

2010-01-01

35

Method for producing thin-film multilayer solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Description: A method for manufacturing high-quality thin film solar cells entirely by the Pulsed Electron Deposition (PED) is presented. The solar cell is a multi-layer architecture composed with an absorber layer with a chalcopyrite structure and the general composition Cu (In, Ga, Al) (Se, S)2 or CIGASS, deposited on a metallic substrate, that is the lower electrical contact or "back contact", by one or more buffer layer(s) and a layer acting as an electrical contact or the higher "top con...

Rampino, Stefano; Gilioli, Edmondo; Bissoli, Francesco; Pattini, Francesco

2010-01-01

36

Photon management by metallic nanodiscs in thin film solar cells  

Science.gov (United States)

We investigate the absorption enhancement by metallic nanodiscs in thin-film amorphous silicon solar cells. The effect is quantitatively evaluated by rigorously solving Maxwell's equations. We show that 50% more photons can be absorbed using geometries accessible for current nanofabrication technologies. Moreover, the thinner the solar cell, the larger the absorption enhancement. Detailed investigations prove that the enhancement can be related to the excitation of localized plasmon polaritons. The simultaneous enhancement in both the near-field amplitude and the scattering cross section at resonance as the leading physical mechanism is discussed in detail.

Rockstuhl, Carsten; Lederer, Falk

2009-05-01

37

Development of thin film solar cell based on Cu{sub 2}ZnSnS{sub 4} thin films  

Energy Technology Data Exchange (ETDEWEB)

Cu{sub 2}ZnSnS{sub 4} (hereafter CZTS) thin films were successfully formed by vapor-phase sulfurization of precursors on a soda lime glass substrate (hereafter SLG) and a Mo-coated one (hereafter Mo-SLG). From the optical properties, we estimate the band-gap energy of this thin film as 1.45-1.6eV which is quite close to the optimum value for a solar cell. By using this thin film as an absorber layer, we could fabricate a new type of thin film solar cell, which was composed of Al/ZnO:Al/CdS/CZTS/Mo-SLG. The best conversion efficiency achieved in our study was 2.62% and the highest open-circuit voltage was 735mV. These device results are the best reported so far for CZTS.

Katagiri, H.; Saitoh, K.; Washio, T.; Shinohara, H.; Kurumadani, T.; Miyajima, S. [Department of Electrical Engineering, Nagaoka National College of Technology, 888 Nishikatakai, Nagaoka, 940-8532 Niigata (Japan)

2001-01-01

38

Modeling of laser patterning of thin-film solar cells  

Science.gov (United States)

We report on theoretical models of the interaction of ultra-short laser pulses with multilayer structures used in thin-film solar cells. A finite-difference based optical model of light propagation within the thin-film system is used to determine the 3D-distribution of absorbed laser power in the structure. The model includes the evolution of the density of charge carriers which may be driven either by direct absorption of the laser radiation or multi-photon absorption and impact ionization of highly excited carriers. Depending on the excitation wavelength and pulse energy absorption occurs in different depths of the structure which has a large effect on the efficiency of the laser ablation process.

Peschel, Thomas; Matthäus, G.; Nolte, S.; Eberhardt, R.; Tünnermann, A.

2014-03-01

39

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

40

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

 
 
 
 
41

Development of CIGS2 thin film solar cells  

International Nuclear Information System (INIS)

Research and development of CuIn1-xGa xSe2-yS y (CIGSS) thin-film solar cells on ultralightweight flexible metallic foil substrates is being carried out at FSEC PV Materials Lab for space applications. Earlier, the substrate size was limited to 3 cm x 2.5 cm. Large-area sputtering systems and scrubber for hydrogen selenide and sulfide have been designed and constructed for preparation of CIGSS thin-films on large (15 cm x 10 cm) substrates. A selenization/sulfurization furnace donated by Shell (formerly Siemens) Solar has also been refurbished and upgraded. The sputtering target assembly design was modified for proper clamping of targets and effective cooling. A new design of the magnetic assembly for large-area magnetron sputtering sources was implemented so as to achieve uniform deposition on large area. Lightweight stainless steel foil and ultralightweight titanium foil substrates were utilized to increase the specific power of solar cells. Sol-gel derived SiO2 layers were coated on titanium foil by dip coating method. Deposition parameters for the preparation of molybdenum back contact layers were optimized so as to minimize the residual stress as well as reaction with H2S. Presently large (15 cm x 10 cm) CuIn1-xGa xS2 (CIGS2) thin film solar cells are being prepared on Mo-coated titanium and stainless steel foil by sulfurization of CuGa/In metallic precursors in diltion of CuGa/In metallic precursors in diluted Ar:H2S(4%). Heterojunction partner CdS layers are deposited by chemical bath deposition. The regeneration sequence of ZnO/ZnO:Al targets was optimized for obtaining consistently good-quality, transparent and conducting ZnO/ZnO:Al bilayer by RF magnetron-sputter deposition. Excellent facilities at FSEC PV Materials Lab are one of its kinds and could serve as a nucleus of a small pilot plant for CIGSS thin film solar cell fabrication

42

Thin-film intermediate band chalcopyrite solar cells  

International Nuclear Information System (INIS)

Chalcopyrite-based solar cells currently lead the efficiency tables of thin-film photovoltaic technologies. Further improvements are foreseen upon implementation of an intermediate band in the absorber layers. We present a theoretical analysis of the efficiency limit for this type of device as a function of factors such as the gap of the host, the relative position of the intermediate band with respect to the band edge and the level of light concentration used as illumination. We have also considered the impact of non-idealities on the performance of the device, particularly the effect of electronic losses related to non-radiative recombination

43

Single crystalline film on glass for thin film solar cells.  

Science.gov (United States)

A simple Ge-on-glass metal-oxide-semiconductor solar cell has been demonstrated by wafer bonding and smart-cut. Since single crystalline Ge is directly bonded on glass, the crystalline substrate is not necessary. The metal-oxide-semiconductor structure can be easily fabricated without n and p dopant diffusion or implantation. The reason for low efficiency is discussed, and then the optimized structures are designed by simulation. An outstanding enhancement on efficiency can be achieved with the Si/Ge/Si structure. The best performance can be achieved by optimization of the position of the Ge layer, the thickness of the Ge layer, and the number of the Ge layers. The efficiency of the thin film Si/Ge/Si solar cell with single layer of 30-nm-thick Ge outside the depletion region reaches 15.9%, as compared to the control Si sample of 11.8%. Based on the simulation and technologies, high efficiency thin film solar cells can be demonstrated in the future. PMID:19504892

Lin, C H; Yang, Y J; Encinas, E; Chen, W Y; Tsai, J J; Liu, C W

2009-06-01

44

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

45

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

46

Volumetric plasmonic resonator architecture for thin-film solar cells  

Science.gov (United States)

We propose and demonstrate a design concept of volumetric plasmonic resonators that relies on the idea of incorporating coupled layers of plasmonic structures embedded into a solar cell in enhanced optical absorption for surface-normal and off-axis angle configurations, beyond the enhancement limit of individual plasmonic layers. For a proof-of-concept demonstration in a thin-film organic solar cell that uses absorbing materials of copper phthalocyanine/perylene tetracarboxylic bisbenzimidazole, we couple two silver grating layers such that the field localization is further extended within the volume of active layers. Our computational results show a maximum optical absorption enhancement level of ˜67% under air mass 1.5 global illumination considering both polarizations.

Sefunc, Mustafa Akin; Okyay, Ali Kemal; Demir, Hilmi Volkan

2011-02-01

47

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

International Nuclear Information System (INIS)

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

48

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

Science.gov (United States)

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

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

2014-09-01

49

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

50

Potential of thin-film solar cell module technology  

Science.gov (United States)

During the past five years, thin-film cell technology has made remarkable progress as a potential alternative to crystalline silicon cell technology. The efficiency of a single-junction thin-film cell, which is the most promising for use in flat-plate modules, is now in the range of 11 percent with 1-sq cm cells consisting of amorphous silicon, CuInSe2 or CdTe materials. Cell efficiencies higher than 18 percent, suitable for 15 percent-efficient flat plate modules, would require a multijunction configuration such as the CdTe/CuInSe2 and tandem amorphous-silicon (a-Si) alloy cells. Assessments are presented of the technology status of thin-film-cell module research and the potential of achieving the higher efficiencies required for large-scale penetration into the photovoltaic (PV) energy market.

Shimada, K.; Ferber, R. R.; Costogue, E. N.

1985-01-01

51

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the angular behavior of the upper bound of absorption provided by the guided modes in thin film solar cells. We show that the 4n^2 limit can be potentially exceeded in a wide angular and wavelength range using two-dimensional periodic thin film structures. Two models are used to estimate the absorption enhancement; in the first one, we apply the periodicity condition along the thickness of the thin film structure but in the second one, we consider imperfect co...

Naqavi, Ali; Haug, Franz-josef; So?derstro?m, Karin; Battaglia, Corsin; Paeder, Vincent; Scharf, Toralf; Herzig, Hans Peter; Ballif, Christophe

2013-01-01

52

Cuinse2 Thin Film For Solar Cell By Flash Evaporation  

Directory of Open Access Journals (Sweden)

Full Text Available Deposition of thin films for material solar cell CuInSe2 are relatively simple. In this research mainly focused on the use of flash evaporation method, and the material created can then be characterized by optical and electrical properties. The optical characterization is done by X-ray Diffraction (XRD, Energy Dispersive Spectroscopy (EDS, and transmission and reflection by UV-VIS spectrophotometry. Electrical characterization is done by utilizing the Hall effect equipment. From these characterization, the atomic structure, absorption coefficient, energy gap, material type, composition of each elements and the mobility of CuInSe2 can be measured and determined. During process evaporation were carried out at substrate temperatures the range between 20ºC-415ºC.

A.H. Soepardjo

2009-11-01

53

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.

54

Identification of defects and metastabilities in Cu(In,Ga)Se_2 thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Summary The main objective of this thesis was to develope of an improved knowledge about recombination processes and device-limiting factors in Cu(In,Ga)Se2 (CIGS) thin film solar cells. This led to the investigation of the following main topics: (1) The interpretation of controversially discussed defect spectroscopy characteristics in CIGS thin-film solar cells and (2) The interpretation of metastable phenomena in CIGS solar cells. Chapter 6 deals with the interpretation of the ...

Eisenbarth, Tobias

2010-01-01

55

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...

Singh, Udai P.; Patra, Surya P.

2010-01-01

56

High-efficiency copper ternary thin film solar cells  

Science.gov (United States)

A project is described which developes a high efficiency thin film CuInSe2 solar cell using a low-cost process. The two-stage process involves depositing the metallic elements of Cu and In on a substrate in the form of stacked layers, and then selenizing this stacked metallic film in an atmosphere containing Se. Early research concentrated on the electrodeposition technique for depositing the Cu and In films on Mo-coated glass substrates. This resulted in small-area cells with around 10 percent efficiency, indicating that the technique could yield CuInSe2 films with good electrical and optical properties. The program then involved scaling up the electrodeposition/selenization technique; fixtures for large-area plating were designed and built, but poor adhesion of the CuInSe2 films to the Mo-coated substrates and the stoichiometric non-uniformities encountered in the large-area films hindered the efficiency of the devices. The latter part of the program explored a new approach to the two-stage process. An evaporation/selenization approach, where the elemental layers were evaporated onto the Mo-coated substrates for selenization. Solar cells were produced with efficiencies approaching 11 percent using E-beam evaporated/selenized CuInSe2 films.

Kapur, V. K.; Basol, B. M.; Kullberg, R. C.

1989-09-01

57

Nano-photonic Light Trapping In Thin Film Solar Cells  

Science.gov (United States)

Over the last several decades there have been significant advances in the study and understanding of light behavior in nanoscale geometries. Entire fields such as those based on photonic crystals, plasmonics and metamaterials have been developed, accelerating the growth of knowledge related to nanoscale light manipulation. Coupled with recent interest in cheap, reliable renewable energy, a new field has blossomed, that of nanophotonic solar cells. In this thesis, we examine important properties of thin-film solar cells from a nanophotonics perspective. We identify key differences between nanophotonic devices and traditional, thick solar cells. We propose a new way of understanding and describing limits to light trapping and show that certain nanophotonic solar cell designs can have light trapping limits above the so called ray-optic or ergodic limit. We propose that a necessary requisite to exceed the traditional light trapping limit is that the active region of the solar cell must possess a local density of optical states (LDOS) higher than that of the corresponding, bulk material. Additionally, we show that in addition to having an increased density of states, the absorber must have an appropriate incoupling mechanism to transfer light from free space into the optical modes of the device. We outline a portfolio of new solar cell designs that have potential to exceed the traditional light trapping limit and numerically validate our predictions for select cases. We emphasize the importance of thinking about light trapping in terms of maximizing the optical modes of the device and efficiently coupling light into them from free space. To further explore these two concepts, we optimize patterns of superlattices of air holes in thin slabs of Si and show that by adding a roughened incoupling layer the total absorbed current can be increased synergistically. We suggest that the addition of a random scattering surface to a periodic patterning can increase incoupling by lifting the constraint of selective mode occupation associated with periodic systems. Lastly, through experiment and simulation, we investigate a potential high efficiency solar cell architecture that can be improved with the nanophotonic light trapping concepts described in this thesis. Optically thin GaAs solar cells are prepared by the epitaxial liftoff process by removal from their growth substrate and addition of a metallic back reflector. A process of depositing large area nano patterns on the surface of the cells is developed using nano imprint lithography and implemented on the thin GaAs cells.

Callahan, Dennis M., Jr.

58

Scribing of a-Si thin-film solar cells with picosecond laser  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract The thin-film technology is the most promising technology to achieve a significant cost reduction in solar electricity. Laser scribing is an important step to preserve high efficiency of photovoltaic devices on large areas. The high-repetition-rate laser with the pulse duration of 10 ps was applied in selective ablation of multilayer thin-film a-Si solar cells deposited on flexible and rigid substrates. Two types of solar cells with flexible an...

Gec?ys, P.; Rac?iukaitis, G.

2010-01-01

59

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

60

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

 
 
 
 
61

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

62

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 propertiaddition 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.

63

Utilization of geometric light trapping in thin film silicon solar cells: Simulations and experiments  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, we present a new light absorption enhancement method for p-i-n thin film silicon solar cells using pyramidal surface structures, larger than the wavelength of visible light. Calculations show a maximum possible current enhancement of 45% compared with cells on a flat substrate. We deposited amorphous silicon (a-Si) thin film solar cells directly onto periodically pyramidal-structured polycarbonate (PC) substrates, which show a significant increase (30%) in short-circui...

Jong, M. M.; Sonneveld, P. J.; Baggerman, J.; Rijn, C. J. M.; Rath, J. K.; Schropp, R. E. I.

2012-01-01

64

Qualitative and quantitative evaluation of thin-film solar cells using solar cell local characterization  

Science.gov (United States)

The light-beam-induced current-based CELLO measurement technique (solar CELl LOcal characterization), originally developed for wafer-based silicon solar cells, can successfully be applied to thin-film solar cells, provided that contacting of a single cell is possible. This is shown exemplarily for several crystalline silicon on glass samples, having varying quality with respect to photocurrent extraction, series resistance, and power losses. For the latter, a comparison with results obtained from dark lock-in thermography gives quantitative agreement, provided that the cells are not severely shunted.

Wagner, J.-M.; Carstensen, J.; Schütt, A.; Föll, H.

2013-02-01

65

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

Science.gov (United States)

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

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

2012-11-14

66

A New Approach to Light Scattering from Nanotextured Interfaces for Silicon Thin-Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new approach is presented to determine the angular and spectral characteristics of light diffusely scattered from nanotextured front electrodes into the absorbing silicon layer of thin-film silicon solar cell devices.

Battaglia, Corsin; Domine, Didier Rene?; Haug, Franz-josef; Ballif, Christophe

2010-01-01

67

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

Energy Technology Data Exchange (ETDEWEB)

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

Lai, Kuang-Chieh; Houng, Mau-Phon [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, No.1, Dasyue Rd., East District, Tainan City 701 (China); Liu, Chien-Chih [Department of Electrical Engineering, Nan Jeon Institute of Technology, Tainan County 737 (China); Lu, Chun-hsiung; Yeh, Chih-Hung [NexPower Technology Corporation, Taichung County 421 (China)

2010-03-15

68

The Mott transition and optimal performance of transparent conducting oxides in thin-film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The performance of thin-film solar cells is critically dependent upon the effective operation of transparent conducting oxide (TCO) layers, which play a significant role in both optical and electrical power transmission through these photovoltaic devices. In this article, we model the optical and electrical power transmission through TCO layers in thin-film solar cells as a function of both the electron carrier density, n, and its mobility, ?. The electrical and optical properties of the TCO...

Slocombe, D.; Porch, A.; Pepper, M.; Edwards, Pp

2012-01-01

69

Modelling and Degradation Characteristics of Thin-film CIGS Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin-film solar cells based around the absorber material CuIn1-xGaxSe2 (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 ...

Malm, Ulf

2008-01-01

70

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2014-01-01

71

A novel semiconductor material for the thin film solar cells  

International Nuclear Information System (INIS)

Thin films of the novel alloy, mercury zinc telluride Hg/sub 1-x/Zn/sub x/Te have been produced in polycrystalline form by using the co-evaporation of zinc telluride (ZnTe) and mercury telluride (HgTe). The layers were produced with bandgaps in the range of 0.5 to 2.25 eV by altering the alloy composition. The absorption coefficient alpha, was found to be greater than 10/sup 5/cm/sup -1/ in samples with bandgaps greater than 1.5 eV. The as-grown layers were p-type at room temperature (300 K) with low resistivities between 0.16 to 0.55 to 0.45 micro m. Arrhenius plots of the resistivities gave two straight lines corresponding to an activation energy of 50 +- 5 MeV for temperatures greater than 220 K and an activation energy of 7 +- 4 MeV or temperatures than 220 K. The significance of these results regarding the potential of Hg/sub 1-x/Zn/sub x/Te alloys for their use in multijunction solar cells is discussed. (author)

72

Environmental influences on the performance of thin film solar cells  

International Nuclear Information System (INIS)

The response of thin film photovoltaic devices to changes in the environment is not well understood. There are a large number of conflicting reports, reflecting largely the superimposed nature of the environmental effects. A separation of the effects is not often attempted mainly because of the lack of appropriate spectral data. An experimental system has been designed and operated to facilitate the separation of the environmental effects, including spectral effects. This involves measurements in a controlled laboratory environment as well as outdoor monitoring. Furthermore, a number of analysis tools have been developed and tested for their suitability. In order to develop a system model, the applicability of parametric models for thin film devices is probed. The thermal variation of the underlying physical parameters is investigated and problems of describing thin film devices with parametric models are discussed. It is shown that the magnitude of the spectral effects for thin film devices is potentially much more significant than for conventional crystalline silicon devices. This analysis is centred on the primary spectral effect, i.e. it is conducted purely on the basis of available light and does not consider any absorption profiles or device structures. It is also shown that there is a strong daily and seasonal variation in the fraction of the useful light for devices employing a larger band gap. Environmental effects are observed directly from outdoor measuremee observed directly from outdoor measurements. It is apparent that many of the reported idiosyncrasies occurring during the operation of thin film devices can be explained simply by including spectral effects. It is possible to show the secondary spectral effect for multi-junction devices, i.e. an effect that depends on the composition of the solar irradiance and not purely on the magnitude of spectrally useful irradiance. This effect impacts mainly on the short circuit current and to some extent on the fill factor. Finally, the findings of this work are brought together in a simulation code for thin film photovoltaic devices. It is shown that it is possible to simulate such a photovoltaic system using parametric models, as long as the spectrum is considered. This is used to investigate the operational losses for one particular device. (author)

73

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

Science.gov (United States)

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

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

1989-01-01

74

The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route  

Science.gov (United States)

An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

Li, Ji; Ma, Tuteng; Wei, Ming; Liu, Weifeng; Jiang, Guoshun; Zhu, Changfei

2012-06-01

75

The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route  

International Nuclear Information System (INIS)

An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

76

Influence of CuxS back contact on CdTe thin film solar cells  

Science.gov (United States)

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.

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

2013-01-01

77

Review of thin film solar cell technology and applications for ultra-light spacecraft solar arrays  

Science.gov (United States)

Developments in thin-film amorphous and polycrystalline photovoltaic cells are reviewed and discussed with a view to potential applications in space. Two important figures of merit are discussed: efficiency (i.e., what fraction of the incident solar energy is converted to electricity), and specific power (power to weight ratio).

Landis, Geoffrey A.

1991-01-01

78

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

79

Thin film silicon solar cells grown near the edge of amorphous to microcrystalline transition  

Energy Technology Data Exchange (ETDEWEB)

Thin films of silicon can be grown by glow-discharge decomposition of silane and hydrogen. As the hydrogen dilution increases, a transition from amorphous to microcrystalline phase takes place. The regime below and above this edge has been found to be most suitable for making high efficiency amorphous and microcrystalline solar cells. The status of material research, cell performance and manufacturing of thin film silicon grown near the edge of amorphous to microcrystalline transition is outlined in this paper. (Author)

Guha, Subhendu [United Solar Ovonic, Auburn Hills, MI (United States)

2004-12-01

80

Crystalline silicon thin film growth by ECR plasma CVD for solar cells  

International Nuclear Information System (INIS)

This thesis describes the background, motivation and work carried out towards this PhD programme entitled 'Crystalline Silicon Thin Film Growth by ECR Plasma CVD for Solar Cells'. The fundamental principles of silicon solar cells are introduced with a review of silicon thin film and bulk solar cells. The development and prospects for thin film silicon solar cells are described. Some results of a modelling study on thin film single crystalline solar cells are given which has been carried out using a commercially available solar cell simulation package (PC-1D). This is followed by a description of thin film deposition techniques. These include Chemical Vapour Deposition (CVD) and Plasma-Assisted CVD (PACVD). The basic theory and technology of the emerging technique of Electron Cyclotron Resonance (ECR) PACVD, which was used in this research, are introduced and the potential advantages summarised. Some of the basic methods of material and cell characterisation are briefly described, together with the work carried out in this research. The growth by ECR PACVD at temperatures 2 illumination. The best efficiency in the ECR grown structures was 13.76% using an epitaxial emitter. Cell performance was analysed in detail and the factors controlling performance identified by fitting self-consistently the fight and dark current-voltage and spectral response data using PC-1D. Finally, the conclusions for this research and suggestions for further work are outlined. (author)

 
 
 
 
81

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 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 ...

Ray, J. R.; Shah, N. M.; Desai, M. S.; Panchal, C. J.

2011-01-01

82

Enhanced Efficiency of Light-Trapping Nanoantenna Arrays for Thin Film Solar Cells  

CERN Document Server

We suggest a novel concept of efficient light-trapping structures for thin-film solar cells based on arrays of planar nanoantennas operating far from plasmonic resonances. The operation principle of our structures relies on the excitation of chessboard-like collective modes of the nanoantenna arrays with the field localized between the neighboring metal elements. We demonstrated theoretically substantial enhancement of solar-cell short-circuit current by the designed light-trapping structure in the whole spectrum range of the solar-cell operation compared to conventional structures employing anti-reflecting coating. Our approach provides a general background for a design of different types of efficient broadband light-trapping structures for thin-film solar-cell technologically compatible with large-area thin-film fabrication techniques.

Simovski, Constantin R; Voroshilov, Pavel M; Guzhva, Michael E; Belov, Pavel A; Kivshar, Yuri S

2013-01-01

83

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

84

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

International Nuclear Information System (INIS)

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

85

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Trapping light in silicon solar cells is essential as it allows an increase in the absorption of incident sunlight in optically thin silicon absorber layers. This way, the costs of the solar cells can be reduced by lowering the material consumption and decreasing the physical constraints on the material quality. In this work, plasmonic light trapping with Ag back contacts in thin-film silicon solar cells is studied. Solar cell prototypes with plasmonic back contacts are presented along with o...

Paetzold, Ulrich Wilhelm

2012-01-01

86

Understanding light harvesting in radial junction amorphous silicon thin film solar cells.  

Science.gov (United States)

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

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

2014-01-01

87

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

International Nuclear Information System (INIS)

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

88

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

89

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.

90

Cu2SnS3 Thin-Film Solar Cells from Electroplated Precursors  

Science.gov (United States)

Cu2SnS3 (CTS) contains non-rare metals and it has suitable optical characteristics for the absorber layer of thin-film solar cells. In this study, CTS thin films were fabricated by sulfurizing Cu-Sn precursors deposited by co-electrodeposition. Solar cells with a structure glass/Mo/CTS/CdS/ZnO:Al/Al were fabricated from the films. The best cell had an efficiency of 2.84%. A relatively high conversion efficiency was obtained from films with Cu/Sn?2.

Koike, Junpei; Chino, Kotaro; Aihara, Naoya; Araki, Hideaki; Nakamura, Ryota; Jimbo, Kazuo; Katagiri, Hironori

2012-10-01

91

Textured conducting glass by nanosphere lithography for increased light absorption in thin-film solar cells  

Science.gov (United States)

Nanoscale surface texturing in thin-film solar cells has been shown to enhance device efficiency by increasing light absorption through reduced reflectance and increased light scattering across a broad range of wavelengths and angles. However, light trapping in the industrial thin-film cells is still sub-optimal and creating optimized nanoscale texture over a large area remains challenging. In this article, we present a well-controlled low-cost process to fabricate a periodic nanocone texture optimized for maximum light absorption in thin-film microcrystalline silicon solar cells. The texture is fabricated using nanosphere lithography with the period controlled by the nanosphere diameter and the texture shape and aspect ratio controlled by the reactive ion etching conditions. Finite-difference time-domain optical simulations are used to optimize the texture in the state-of-the-art microcrystalline cells, and optical absorption measurements show that the same cells fabricated on the optimized nanocone-textured substrates exhibit a relative short-circuit current increase of close to 30% compared to a reference state-of-the-art cell with a randomly textured zinc oxide layer. This nanocone texturing technique is compatible with standard thin-film cell fabrication processes and can also be used for other thin-film cells (CIGS, CdTe, CZTS, etc) to maximize light absorption and minimize layer thickness enabling more efficient carrier collection and lower overall cost.

Mailoa, Jonathan P.; Seog Lee, Yun; Buonassisi, Tonio; Kozinsky, Inna

2014-02-01

92

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

93

Cost-effective nanostructured thin-film solar cell with enhanced absorption  

Science.gov (United States)

Nanostructured transparent conductive electrodes are highly interesting for efficient light management in thin-film solar cells, but they are often costly to manufacture and limited to small scales. This work reports on a low-cost and scalable bottom-up approach to fabricate nanostructured thin-film solar cells. A folded solar cell with increased optical absorber volume was deposited on honeycomb patterned zinc oxide nanostructures, fabricated in a combined process of nanosphere lithography and electrochemical deposition. The periodicity of the honeycomb pattern can be easily varied in the fabrication process, which allows structural optimization for different absorber materials. The implementation of this concept in amorphous silicon thin-film solar cells with only 100 nm absorber layer was demonstrated. The nanostructured solar cell showed approximately 10% increase in the short circuit current density compared to a cell on an optimized commercial textured reference electrode. The concept presented here is highly promising for low-cost industrial fabrication of nanostructured thin-film solar cells, since no sophisticated layer stacks or expensive techniques are required.

Wang, Peng Hui; Nowak, Regina-Elisabeth; Geißendörfer, Stefan; Vehse, Martin; Reininghaus, Nies; Sergeev, Oleg; von Maydell, Karsten; Brolo, Alexandre G.; Agert, Carsten

2014-11-01

94

NREL Produces Highly Efficient, Wide-Bandgap, Thin-Film Solar Cells (Fact Sheet)  

Energy Technology Data Exchange (ETDEWEB)

Researchers at the National Renewable Energy Laboratory (NREL) are finding new ways to manufacture thin-film solar cells made from copper, indium, gallium, and selenium - called CIGS cells - that are different than conventional CIGS solar cells. Their use of high-temperature glass, designed by SCHOTT AG, allows higher fabrication temperatures, opening the door to new CIGS solar cells employing light-absorbing materials with wide 'bandgaps.'

2012-09-01

95

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

96

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

Science.gov (United States)

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

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

2014-06-30

97

Effects of Different Parameters In Enhancing The Efficiency of Plasmonic Thin Film Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Efficiency of thin film solar cells are less comparing to thick film solar cells which can be enhanced by utilizing the metal nanoparticles near their localized Plasmon resonance. In this paper, we have reviewed the Plasmon resonance of metallic nanoparticles and its application in solar cell technology. Beside this, we have also reviewed about different parameters which dominate the nanoparticles to increase optical absorption. Thus a cost-effective model has been proposed.

N.Alekhya Reddy

2014-09-01

98

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.

Bär, M., E-mail: marcus.baer@helmholtz-berlin.de [Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), D-14109 Berlin (Germany); Institut für Physik und Chemie, Brandenburgische Technische Universität 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 für 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

99

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

100

Fabrication of nanocrystal ink based superstrate-type CuInS? thin film solar cells.  

Science.gov (United States)

A CuInS? (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, TiO? and CdS thin films were also prepared as a blocking layer and a buffer layer, respectively. We found that both a TiO? 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 TiO? and CdS films, respectively. PMID:22699212

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

2012-07-01

 
 
 
 
101

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

Directory of Open Access Journals (Sweden)

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

Yue-Hui Hu

2010-12-01

102

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

International Nuclear Information System (INIS)

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

103

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

Directory of Open Access Journals (Sweden)

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

???

2011-10-01

104

Fabrication and performance of organic thin film solar cells using a painting method  

Science.gov (United States)

As organic thin film solar cells fabricated by the active layer of organic materials are economical, lightweight, and flexible, as well as generating no CO2, and being easy to fabricate, they have attracted significant attention as green energy sources from a past decade to date. Therefore, their power conversion efficiency (PCE) has been investigated and studied worldwide. In organic thinfilm solar cells, the effect of the performance depends not only on the adopted active material but also relates to the molecular orientation on the electrode. Using a mixed solution of Poly(3-hexylthiophene) and PCBM, both of which were dissolved in a solvent, the organic thin films were fabricated using the paint and spray methods, while the morphology of the thin film was evaluated by an AFM image, UV/vis spectra, and so forth. Based on these data, an organic thin-film solar cell using both solution methods for the active layer was fabricated, and the performance evaluated and examined. For organic thin film solar cells fabricated using a spin-coating method, the open-circuit voltage (Voc) is 0.41V, the short circuit current density (Jsc) is 2.07mA/cm2, and the fill factor is 0.34, while the efficiency ? of PCE become 0.29%. In the spray method, the short circuit current (Isc) is 2.5 mA/cm2, the open circuit voltage (Voc) is 0.45 V, the fill factor (FF) is 0.28, and the power conversion factor (PCE) 0.35%. The area of organic solar cells fabricated by spin coating and spray methods is 1 cm2 respectively. The organic solar cells are not thermally treated, and hence have high respective power conversion efficiencies.

Ochiai, S.; Ishihara, H.; Mizutani, T.; Kojima, K.

2010-05-01

105

Disorder improves nanophotonic light trapping in thin-film solar cells  

International Nuclear Information System (INIS)

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

106

Disorder improves nanophotonic light trapping in thin-film solar cells  

Science.gov (United States)

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

Paetzold, U. W.; Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Michaelis, D.; Waechter, C.; Carius, R.; Rau, U.

2014-03-01

107

Progress in Polycrystalline Thin-Film Cu(In,GaSe2 Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available For some time, the chalcopyrite semiconductor CuInSe2 and its alloy with Ga and/or S [Cu(InGaSe2 or Cu(InGa(Se,S2], 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 depends upon the various deposition methods as they control optoelectronic properties of the layers and interfaces. CIGS thin film grown on glass or flexible (metal foil, polyimide substrates require p-type absorber layers of optimum optoelectronic properties and n-type wideband gap partner layers to form the p-n junction. Transparent conducting oxide and specific metal layers are used for front and back contacts. Progress made in the field of CIGS solar cell in recent years has been reviewed.

Udai P. Singh

2010-01-01

108

Disorder improves nanophotonic light trapping in thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

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

Paetzold, U. W., E-mail: u.paetzold@fz-juelich.de; Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Carius, R.; Rau, U. [IEK5—Photovoltaik, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Michaelis, D.; Waechter, C. [Fraunhofer Institut für Angewandte Optik und Feinmechanik, Albert Einstein Str. 7, D-07745 Jena (Germany)

2014-03-31

109

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...

Shah, Arvind; Torres, P.; Tscharner, Reto; Wyrsch, N.; Keppner H

2013-01-01

110

Light Harvesting Schemes for High Efficiency Thin Film Silicon Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In Thin Film Silicon (TF-Si) solar cells light harvesting schemes must guarantee an efficient light trapping in the thin absorber layers without decreasing the silicon layers quality and consecutively the p-i-n diodes electrical performance. TF-Si solar cells resilience to the substrate roughness is reported to be possibly improved through optimizations of the cell design and of the silicon deposition processes. By further tailoring the superstrate texture, amorphous silicon / microcrystallin...

Despeisse, Matthieu; Boccard, Mathieu; Battaglia, Corsin; Bugnon, Gregory; Charriere, Mathieu; Garcia, Loic; Bonnet-eymard, Maximilien; Escarre, Jordi; Cuony, Peter; Stuckelberger, Michael; Parascandolo, Gaetano; Haenni, Simon; Loefgren, Linus; Schuettauf, Jan-willem; Ding, Laura

2012-01-01

111

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-06-11

112

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, three kinds of textured ZnO thin-films (the first kind has the textured structure with both columnar and polygon, the second posses pyramid-like textured structure only, and the third has the textured structure with both crater-like and pyramid-like), were prepared by three kinds of methods, and the application of these ZnO thin-films as a front electrode in solar cell was studied, respectively. In the first method with negative bias voltage and appropriate sputtering parameter...

Yue-Hui Hu; Yi-Chuan Chen; Hai-Jun Xu; Hao Gao; Wei-Hui Jiang; Fei Hu; Yan-Xiang Wang

2010-01-01

113

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tec...

Dieter Bonnet; Michael Powalla

2007-01-01

114

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

Science.gov (United States)

The development of photovoltaic arrays beyond the next generation is discussed with attention given to the potentials of thin-film polycrystalline and amorphous cells. Of particular importance is the efficiency (the fraction of incident solar energy converted to electricity) and specific power (power to weight ratio). It is found that 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.

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

1989-01-01

115

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 obncy and the texture of the CdTe film is observed

116

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

Science.gov (United States)

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

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

2007-12-10

117

Optics of thin-film silicon solar cells with efficient periodic light trapping textures  

Science.gov (United States)

The principle of interaction of light waves incident on a surface with a subwavelength nanostructure is a key question in the development of solar cells. Efficient thin-film solar cells based on microcrystalline silicon (?c-Si:H) or amorphous silicon (a-Si:H) with an absorber layer in the micrometer range require effective light trapping and an optimal incoupling of the entire sun spectrum. The established approach to achieve this is the application of randomly textured transparent conductive oxides (TCOs). Previous investigations of light trapping in thin-film devices have been conducted with often misleading far field measurements. Optical simulations based on the Finite Integration Technique (CST Microwave Studios) are a valuable approach to analyze the light propagation in thin-film devices and enable the study the subwavelength optics of nano-textured interfaces by solving the Maxwell equations rigorously in 3D. However, the question regarding the optimized lateral feature size, vertical height, resulting interface angle and shape of the texture is essential to reach high energy conversion efficiencies. Various texture designs are studied by numerical modeling. We present a 3D simulation analysis of thin-film silicon solar cell nano-optics that gives clear design criteria to reach high efficiencies.

Haase, C.; Knipp, D.; Stiebig, H.

2007-09-01

118

Single-layer organic–inorganic-hybrid thin-film encapsulation for organic solar cells  

International Nuclear Information System (INIS)

We demonstrate an organic–inorganic-hybrid thin-film encapsulation technique for organic solar cells. The single-layer encapsulation thin film is deposited from a gas mixture of hexamethyldisiloxane and oxygen by plasma-enhanced chemical vapour deposition at room temperature. The encapsulation film contains organic and inorganic compounds: the inorganic compounds serve as the permeation barriers, and the organic compounds reduce defect propagation. An optical transmission of ?90% in the visible light region and a water vapour transmission rate of 3.6 × 10?6 g m?2 day are obtained for a 1.5 µm thick hybrid film. Efficiency decay is not observed in the inverted organic solar cell coated with this thin film after exposure to air for 3600 h; in contrast, the efficiency of the unencapsulated counterpart degrades rapidly and fails after exposure to air for 120 h. The obtained results show that this organic–inorganic-hybrid thin film is promising for the encapsulation of organic solar cells. (paper)

119

Single-layer organic-inorganic-hybrid thin-film encapsulation for organic solar cells  

Science.gov (United States)

We demonstrate an organic-inorganic-hybrid thin-film encapsulation technique for organic solar cells. The single-layer encapsulation thin film is deposited from a gas mixture of hexamethyldisiloxane and oxygen by plasma-enhanced chemical vapour deposition at room temperature. The encapsulation film contains organic and inorganic compounds: the inorganic compounds serve as the permeation barriers, and the organic compounds reduce defect propagation. An optical transmission of ?90% in the visible light region and a water vapour transmission rate of 3.6 × 10-6 g m-2 day are obtained for a 1.5 µm thick hybrid film. Efficiency decay is not observed in the inverted organic solar cell coated with this thin film after exposure to air for 3600 h in contrast, the efficiency of the unencapsulated counterpart degrades rapidly and fails after exposure to air for 120 h. The obtained results show that this organic-inorganic-hybrid thin film is promising for the encapsulation of organic solar cells.

Li, Yun-Shiuan; Tsai, Chih-Hung; Kao, Shao-Hsuan; Wu, I.-Wen; Chen, Jian-Zhang; Wu, Chih-I.; Lin, Ching-Fuh; Cheng, I.-Chun

2013-10-01

120

ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES  

Directory of Open Access Journals (Sweden)

Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

Peter Pikna

2014-10-01

 
 
 
 
121

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

122

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

123

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

124

Intermediate reflectors in thin film solar cells comprising randomly textured surfaces  

Science.gov (United States)

Along the road towards ubiquitous and low-cost solar cells, solutions to the seemingly mutually exclusive targets of reducing material consumption while increasing the efficiency has to be found. One potential solution seems to lie in thin film tandem solar cells. It offers the promise of moderate efficiencies combined with the advantage of relying on a well-established thin film fabrication technology at reasonable low costs. To finally make them serious competitors, various structures to be exploited for photon management may be incorporated into these solar cells with the aim of increasing their efficiency. Besides reducing reflection losses at the entrance facet via textured surfaces and eliminating the dissipation in the metallic backside reflector, the efficiencies of tandem cells can be significantly boosted by a wavelength-dependent steering of the spatial domain where light gets absorbed, i.e. either the top or the bottom cell. This is mainly possible by placing a spectrally selective intermediate reflector in between both cells. In the present contribution we apply well-adapted numerical routines, which solve Maxwell's equations rigorously, to quantitatively explore various intermediate reflector concepts for thin film solar cells from an optical point of view. The solar cells we focus on are silicon based, where the top layer is made of amorphous and the bottom layer of microcrystalline silicon, respectively. We explore state-of-the-art concepts for the intermediate reflector, such as homogenous layers based on dielectrics characterized by a lower permittivity as well as new photonic (such as, e.g., photonic crystals) and plasmonic concepts. Most notably we will address the issue how randomly textured interfaces, present in thin film solar cells, affect the performance of each intermediate reflector and how the randomness may contribute to the absorption enhancement. Guidelines for designing optimized systems will be given.

Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

2010-05-01

125

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

126

Plasmonic light trapping in thin-film Si solar cells  

International Nuclear Information System (INIS)

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

127

Plasmonic light trapping in thin-film Si solar cells  

Science.gov (United States)

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

Spinelli, P.; Ferry, V. E.; van de Groep, J.; van Lare, M.; Verschuuren, M. A.; Schropp, R. E. I.; Atwater, H. A.; Polman, A.

2012-02-01

128

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

129

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

Science.gov (United States)

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

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

2014-09-23

130

Development of transparent conductive oxide for thin-film silicon solar cells  

International Nuclear Information System (INIS)

Gallium-doped zinc oxide (GZO) films were deposited by DC magnetron sputtering using a GZO ceramic target at various substrate temperatures from 298 to 573 K in order to apply the films to amorphous silicon thin film solar cells. A low resistivity (?4.28 x 10-4 ?cm) and a high transmittance (>90%) were obtained from the film deposited at 573 K. From X-ray diffraction, the films had columnar structures oriented along the c-axis, regardless of the substrate temperature. The lattice images and the grains were observed by using a field emission transmission electron microscope. A grain was overlapped by the crystallite of 10-15 nm, and the size of a grain was about 70 nm. Finally, the texturing conditions of the GZO films were optimized as a function of deposition temperature for potential applications to tandem solar cells and single junction amorphous silicon thin film solar cells.

131

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate  

Science.gov (United States)

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

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

2006-05-30

132

Selectiveness of laser processing due to energy coupling localization: case of thin film solar cell scribing  

Science.gov (United States)

Selectiveness of the laser processing is the top-most important for applications of the processing technology in thin-film electronics, including photovoltaics. Coupling of laser energy in multilayered thin-film structures, depending on photo-physical properties of the layers and laser wavelength was investigated experimentally and theoretically. Energy coupling within thin films highly depends on the film structure. The finite element and two-temperature models were applied to simulate the energy and temperature distributions inside the stack of different layers of a thin-film solar cell during a picosecond laser irradiation. Reaction of the films to the laser irradiation was conditioned by optical properties of the layers at the wavelength of laser radiation. Simulation results are consistent with the experimental data achieved in laser scribing of copper-indium-gallium diselenide (CIGS) solar cells on a flexible polymer substrate using picosecond-pulsed lasers. Selection of the right laser wavelength (1064 nm or 1572 nm) enabled keeping the energy coupling in a well-defined volume at the interlayer interface. High absorption at inner interface of the layers triggered localized temperature increase. Transient stress caused by the rapid temperature rise facilitating peeling of the films rather than evaporation. Ultra-short pulses ensured high energy input rate into absorbing material permitting peeling of the layers with no influence on the remaining material.

Ra?iukaitis, G.; Grubinskas, S.; Ge?ys, P.; Gedvilas, M.

2013-07-01

133

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

134

CIGS thin-film solar cells on steel substrates  

International Nuclear Information System (INIS)

Steel foil is an attractive candidate for use as a flexible substrate material for Cu(Inx,Ga1-x)Se2 solar cells (CIGS). It is stable at the high temperatures involved during CIGS processing and is also commercially available. Stainless chromium (Cr) steel is more expensive than Cr-free steel sheets, but the latter are not stable against corrosion. We processed CIGS solar cells on both types of substrates. The main problem arising here is the diffusion of detrimental elements from the substrate into the CIGS absorber layer. The diffusion of iron (Fe) and other substrate elements into the CIGS layer was investigated by Secondary Ion Mass Spectrometry (SIMS). The influence of the impurities on the solar cell parameters was determined by current voltage (JV) and external quantum efficiency (EQE) measurements. A direct correlation between the Fe content in the CIGS layer and the solar cell efficiency was found. The diffusion of Fe could be strongly reduced by a diffusion barrier layer. Thus we could process CIGS solar cells with a conversion efficiency of 12.8% even on Cr-free steel substrate

135

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

136

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

Energy Technology Data Exchange (ETDEWEB)

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.

Simburger, Edward J. [Aerospace Corporation, El Segundo, CA 90245 (United States)]. E-mail: edward.j.simburger@aero.org; Matsumoto, James H. [Aerospace Corporation, El Segundo, CA 90245 (United States); Giants, Thomas W. [Aerospace Corporation, El Segundo, CA 90245 (United States); Garcia, Alexander [The Aerospace Corporation, El Segundo, CA 90245 (United States); Liu, Simon [Aerospace Corporation, El Segundo, CA 90245 (United States); Rawal, Suraj P. [Lockheed Martin Corporation, Denver, CO 80125 (United States); Perry, Alan R. [Lockheed Martin Corporation, Denver, CO 80125 (United States); Marshall, Craig H. [Lockheed Martin Corporation, Denver, CO 80125 (United States); Lin, John K. [ILC Dover Incorporated, Dover, DE 19946 (United States); Scarborough, Stephen E. [ILC Dover Incorporated, Dover, DE 19946 (United States); Curtis, Henry B. [NASA Glen Research Center, Cleveland, OH 44135 (United States); Kerslake, Thomas W. [NASA Glen Research Center, Cleveland, OH 44135 (United States); Peterson, Todd T. [NASA Glen Research Center, Cleveland, OH 44135 (United States)

2005-02-15

137

Characterization of evaporated solid-phase crystallized silicon thin-film solar cells on glass  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Following our previous study on the material-quality limiting factors of evaporated solid-phase crystallized (SPC) poly-Si thin films fabricated on planar glass for photovoltaic applications, we extend our study to investigate the impurity levels, optical properties, transport properties, and device performance of so-called "EVA" (EVAporated Si) solar cells. These potentially cost-effective cells are systematically characterized with electron microscopy-based techniques, external quantum effi...

Liu, F.; Romero, Mj; Jones, Km; Kunz, O.; Wong, J.; Reedy, Rc; Aberle, Ag; Aljassim, Mm

2009-01-01

138

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-of...

Dreyer, Philippe; Morales-masis, Monica; Nicolay, Sylvain; Ballif, Christophe; Perruisseau-carrier, Julien

2013-01-01

139

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

140

IR-imaging and non-destructive loss analysis on thin film solar modules and cells  

Science.gov (United States)

CIGS thin film solar modules, despite their high efficiency, may contain three different kinds of macroscopic defects referred to as bulk defects, interface defects and interconnect defects. These occur due to the film's sensitivity to inhomogeneities during the manufacturing process and decreasing the electrical power output from a cell or module. In this study, we present infrared (IR) imaging and contactless loss analyses of defects contained in commercially manufactured thin film solar modules. We investigated different relations between the emitted IR-signal (using illuminated lock-in thermography ILIT) and the respective open circuit cell voltage (Voc) as well as the maximum power point (Pmpp). A simulation study, using the 2D finite element method (FEM), provides a deeper understanding as to the impact on electrical performance when defects are present on the cell or module.

Adams, Jens; Fecher, Frank W.; Hoga, Felix; Vetter, Andreas; Buerhop, Claudia; Brabec, Christoph J.

2014-10-01

 
 
 
 
141

2D modeling of silicon based thin film dual and triple junction solar cells  

Science.gov (United States)

Based on Crosslight APSYS, thin film amorphous Si (a-Si:H)/microcrystalline (?c-Si) dual-junction (DJ) and a- Si:H/amorphous SiGe:H (a-SiGe:H)/?c-Si triple-junction (TJ) solar cells are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves for individual junctions are presented for current matching analyses. The whole DJ and TJ cell I-V curves are also presented and the results are discussed with respect to the top surface ZnO:Al TCO layer affinity. The interface texture effect is modeled with FDTD (finite difference time domain) module and results for top junction are presented. The modeling results give possible clues to achieve high efficiency for DJ and TJ thin film solar cells.

Xiao, Y. G.; Uehara, K.; Lestrade, M.; Li, Z. Q.; Li, Z. M. S.

2009-08-01

142

Polycrystalline Silicon Thin-Film Solar Cells on AIT-Textured Glass Superstrates  

Directory of Open Access Journals (Sweden)

Full Text Available A new glass texturing method (AIT—aluminium-induced texturisation has recently been developed by our group. In the present work, the potential of this method is explored by fabricating PLASMA poly-Si thin-film solar cells on glass superstrates that were textured with the AIT method. Using an interdigitated metallisation scheme with a full-area Al rear contact, PLASMA cells with an efficiency of up to 7% are realised. This promising result shows that the AIT glass texturing method is fully compatible with the fabrication of poly-Si thin-film solar cells on glass using solid phase crystallisation (SPC of PECVD-deposited amorphous silicon precursor diodes. As such, there are now two distinctly different glass texturing methods—the AIT method and CSG Solar's glass bead method—that are known to be capable of producing efficient SPC poly-Si thin-film solar cells on glass.

Armin G. Aberle

2007-12-01

143

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, making it an attractive and reliable technique for thin film deposition. Our PVD system is provided with MBE-type Knudsen cells to deposit CIGS thin films on glass/Molibdenum (Mo) substrates. The deposi...

Ndez, J. Sastr U. E. -hern U. E.; Calixto, M. E.; Zquez, M. Tufi U. F. O-vel U. E.; Contreras-puente, G.; Morales-acevedo, A.; Casados-cruz, G.; Rez, M. A. Hern U. E. Ndez-p U. E.; Albor-aguilera, M. L.; Rez, R. Mendoza-p U. E.

2011-01-01

144

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

145

Periodic light coupler gratings in amorphous thin film solar cells  

International Nuclear Information System (INIS)

Efficient light trapping structures for amorphous hydrogenated silicon (a-Si:H) solar cells have been realized using periodically structured aluminum doped zinc oxide (ZnO:Al) with periods between 390 and 980 nm as a transparent front contact. Atomic force microscopy, optical reflection, and diffraction efficiency measurements were applied to characterize solar cells deposited on such gratings. A simple formula for the threshold wavelength of total internal reflection is derived. Periodic light coupler gratings reduce the reflectance to a value below 10% in the wavelength range of 400 - 800 nm which is comparable to cells with an optimized statistical texture. Diffraction efficiency measurements and theoretical considerations indicate that a combination of transmission and reflection gratings contribute to the observed reduction of the reflectance. [copyright] 2001 American Institute of Physics

146

Computational and experimental study of a multi-layer absorptivity enhanced thin film silicon solar cell  

Science.gov (United States)

We report on the computational design, fabrication and validation of a multi-layer silicon based thin film solar cell. The cell structure consists of a thin absorber layer of amorphous silicon deposited on a back-reflector aluminum layer and coated on top with ITO transparent conductive oxide. The structure is mounted on a glass substrate. We first use constrained optimization techniques along with numerical solvers of the electromagnetic equations (i.e. FDTD) to tune the geometry of the design. The resulting structure suggests that photon absorptivity in the thin film silicon can be enhanced by as much as 100% over the uncoated layer. The proposed design is then fabricated using thin film deposition techniques, along with a control sample of bare silicon absorber for comparison. AFM imaging and spectrophotometry experiments are applied to image and record the surface roughness and measure the reflectivity spectrum of the sample. Using the measured reflectivity spectrum, we then use inverse optimization to estimate the realized thin film dimensions, deposition error and unwanted oxidation volume. At the end, we use a statistical Monte Carlo analysis as a second method of verification to demonstrate that the measured spectra are in accordance with the expected curves from simulation, and to estimate the effects of fabrication error.

Hajimirza, Shima; Howell, John R.

2014-08-01

147

Universality of non-Ohmic shunt leakage in thin-film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In, Ga)Se-2 (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V < similar to 0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to t...

Dongaonkar, Sourabh; Servaites, Jonathan D.; Ford, Grayson M.; Loser, Stephen; Moore, James E.; Gelfand, Ryan M.; Mohseni, Hooman; Hillhouse, Hugh W.; Agrawal, Rakesh; Ratner, Mark A.; Marks, Tobin J.; Lundstrom, Mark; Alam, Muhammad A.

2010-01-01

148

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

Science.gov (United States)

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

Woodyard, James R.; Landis, Geoffrey A.

1991-01-01

149

Enhanced efficiency of light-trapping nanoantenna arrays for thin-film solar cells.  

Science.gov (United States)

We suggest a new type of efficient light-trapping structures for thin-film solar cells based on arrays of planar nanoantennas operating far from their plasmon resonances. The operation principle of our structures relies on the excitation of collective modes of the nanoantenna arrays whose electric field is localized between the adjacent metal elements. We calculate a substantial enhancement of the short-circuit photocurrent for photovoltaic layers as thin as 100-150 nm. We compare our light-trapping structures with conventional anti-reflecting coatings and demonstrate that our design approach is more efficient. We show that it may provide a general background for different types of broadband light-trapping structures compatible with large-area fabrication technologies for thin-film solar cells. PMID:24104498

Simovski, Constantin; Morits, Dmitry; Voroshilov, Pavel; Guzhva, Michael; Belov, Pavel; Kivshar, Yuri

2013-07-01

150

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

151

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

Science.gov (United States)

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

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

2011-07-01

152

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 vi...

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

2012-01-01

153

Admittance spectroscopy of Cu2ZnSnS4 based thin film solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this report, we propose an AC response equivalent circuit model to describe the admittance measurements of Cu2ZnSnS4 thin film solar cell grown by sulphurization of stacked metallic precursors. This circuit describes the contact resistances, the back contact, and the heterojunction with two trap levels. The study of the back contact resistance allowed the estimation of a back contact barrier of 246 meV. The analysis of the trap series with varying temperature revealed defect...

Fernandes, P. A.; Sartori, A. F.; Salome?, P. M. P.; Malaquias, J.; Cunha, A. F. Da; Grac?a, M. P. F.; Gonza?lez, J. C.

2012-01-01

154

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

155

High fidelity transfer of nanometric random textures by UV embossing for thin film solar cells applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the transfer of random nanostructures commonly used in thin film silicon solar cells onto inexpensive substrates, such as glass or flexible polyethylene sheets. Morphological and optical analyses of masters and replicas show the successful transfer of details with sizes much below 1 ?m. These high-quality replicas are obtained by UV nano-imprinting, avoiding the use of PDMS as intermediate mold which has been identified as being responsible for the lack of resolution fou...

Escarre? Palou, Jordi; So?derstro?m, Karin; Battaglia, Corsin; Haug, Franz-josef; Ballif, Christophe

2011-01-01

156

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Omelyanovich, Mikhail; Ovchinnikov, Victor; Simovski, Constantin

2014-01-01

157

Scope of VHF Plasma Deposition for Thin-Film Silicon Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Keppner, H.; Kroll, U.; Torres, P.; Meier, J.; Fischer, D.; Goetz, M.; Tscharner, R.; Shah, A.

1996-01-01

158

Optimization of amorphous silicon thin film solar cells for flexible photovoltaics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate amorphous silicon (a-Si:H) thin film solar cells in the n-i-p or substrate configuration that allows the use of nontransparent and flexible substrates such as metal or plastic foils such as polyethylene- naphtalate (PEN). A substrate texture is used to scatter the light at each interface, which increases the light trapping in the active layer. In the first part, we investigate the relationship between the substrate morphology and the short circui...

So?derstro?m, T.; Haug, F. -j; Terrazzoni-daudrix, V.; Ballif, C.

2008-01-01

159

Resonances and absorption enhancement in thin film silicon solar cells with periodic interface texture  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study absorption enhancement by light scattering at periodically textured interfaces in thin film silicon solar cells. We show that the periodicity establishes resonant coupling to propagating waveguide modes. Ideally, such modes propagate in the high index silicon film where they are eventually absorbed, but waveguide modes exist also in the transparent front contact layer if the product of its refractive index and thickness exceeds half the wavelength. Taking into account that the absorp...

Haug, F. -j; So?derstro?m, K.; Naqavi, A.; Ballif, C.

2011-01-01

160

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...

Lu?kermann, Florian

2013-01-01

 
 
 
 
161

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

162

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

International Nuclear Information System (INIS)

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

163

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

164

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

165

Thin film photovoltaic cell  

Science.gov (United States)

A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

Meakin, John D. (Newark, DE); Bragagnolo, Julio (Newark, DE)

1982-01-01

166

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

International Nuclear Information System (INIS)

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

167

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

168

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

Energy Technology Data Exchange (ETDEWEB)

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.

Paetzold, Ulrich Wilhelm; Zhang, Wendi [Institut für Energie- und Klimaforschung 5 – Photovoltaics, Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Prömpers, Michael [Peter Grünberg Institut 8 – Bioelectronics, Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Kirchhoff, Joachim; Merdzhanova, Tsvetelina; Michard, Stephan; Carius, Reinhard; Gordijn, Aad [Institut für Energie- und Klimaforschung 5 – Photovoltaics, Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Meier, Matthias, E-mail: ma.meier@fz-juelich.de [Institut für Energie- und Klimaforschung 5 – Photovoltaics, Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany)

2013-05-15

169

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

Directory of Open Access Journals (Sweden)

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

Gabriel Onno

2014-02-01

170

Experimental study of Cu2ZnSnS4 thin films for solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cu2ZnSnS4 (CZTS) is a semiconductor with a direct band gap of about 1,5 eV and anabsorption coefficient of 10^4 cm^-1, and is for this reason a potential thin film solarcell material. Demonstrated efficiencies of up to 6,8% as well as use of cheap andabundant elements make CZTS a promising alternative to current solar cells.The aim of this study was to fabricate and characterize CZTS films and to evaluatetheir performance in complete solar cells. For the fabrication of CZTS we applied atwo-st...

Flammersberger, Hendrik

2010-01-01

171

Spectral analysis of the angular distribution function of back reflectors for thin film silicon solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nowadays, one of the most important challenges to enhance the efficiency of thin film silicon solar cells is to increase the short circuit intensity by means of optical confinement methods, such as textured back-reflector structures. In this work, two possible textured structures to be used as back reflectors for n-i-p solar cells have been optically analyzed and compared to a smooth one by using a system which is able to measure the angular distribution function (ADF) of the scattered light ...

Escarre? I Palou, Jordi; Villar, Fernando; Asensi Lo?pez, Jose? Miguel; Bertomeu I Balaguero?, Joan; Andreu I Batalle?, Jordi

2006-01-01

172

Passivation Layer by SiC Thin Film Deposition for High Efficiency Solar Cells  

Science.gov (United States)

Deposition of a polymer derived SiC thin film as a novel, chemically and physically stable passivation layer to enhance the efficiency of solar cells by way of reducing surface recombination was studied. Starfire Matrix Polymer number 10 (SMP-10) is used to produce thin films of SiC on ion implanted silicon wafers. To ascertain the best method to deposit, three methods were tested: spin coating, spray coating, and dip coating are used. Various concentrations of SMP-10 diluted in xylene as an appropriate solvent are examined. To test the films, a contactless inductive coupling method is used. The thinner layers of SiC are grown by a lower percentage of SMP-10 (5%), higher spin speed in spin coating (3000 RPM), and lower pulling out speed in dip coating (50 mm/minute). All of the methods yield controllable, repeatable, and uniform thin films. Although eliminating oxygen as an impurity in the passivation layer remains a challenge, the described approach has promise as a simple, low-cost passivation layers for higher efficiency solar cells.

Haghzedeh, Mahdi; Schmidt, Daniel; Therrien, Joel

2012-02-01

173

Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells  

Energy Technology Data Exchange (ETDEWEB)

Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu{sub 2-x}Se phase was confirmed by XRD pattern and spherical grains of 30 {+-} 4 - 40 {+-} 4 nm in size aggregated over about 130 {+-} 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm{sup 2} light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

Ambade, Swapnil B. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Mane, R.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Kale, S.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Sonawane, S.H. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Shaikh, Arif V. [Department of Electronic Science, AKI' s Poona College of Arts, Science and Commerce, Camp, Pune 411 001 (India); Han, Sung-Hwan [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of)]. E-mail: shhan@hanyang.ac.kr

2006-12-15

174

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

175

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 2.42–2.48 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 300°C 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)

176

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

177

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

Science.gov (United States)

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

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

2002-01-01

178

Effects of potassium doping on solution processed kesterite Cu2ZnSnS4 thin film solar cells  

Science.gov (United States)

Alkaline metals doping is one of the approaches for achieving high efficiency Cu(In,Ga)Se2 (CIGS) solar cell. Recently, potassium doping helps to break the record efficiency of CIGS solar cell doped with sodium. In this paper, we have investigated how incorporation of potassium can influence the properties of Cu2ZnSnS4 (CZTS) thin film and the performance of resulting solar cell. Our results showed that K doping can enhance the (112) preferred orientation, increase the grain size and reduce the second phase ZnS of the CZTS thin films. After K doping, despite of some drop of Voc for CZTS thin film solar cells, the Rs is decreased and the Jsc is improved markedly, and the solar cell efficiency is boosted.

Tong, Zhengfu; Yan, Chang; Su, Zhenghua; Zeng, Fangqin; Yang, Jia; Li, Yi; Jiang, Liangxing; Lai, Yanqing; Liu, Fangyang

2014-12-01

179

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

Science.gov (United States)

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

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

2014-02-26

180

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

 
 
 
 
181

On Generation and Recombination in Cu(In,Ga)Se2 Thin-Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The solar cell technology based on Cu(In,Ga)Se2 (CIGS) thin-films provides a promising route to cost competitive solar electricity. The standard device structure is ZnO:Al/ZnO/CdS/CIGS/Mo films on a glass substrate, where the first three layers are n-type semiconductors with wide bandgaps, forming a pn-junction with the p-type CIGS absorber layer; the Mo layer serves as a back contact. This thesis deals with analysis of the generation and recombination of electron-hole pairs throughout the de...

Malmstro?m, Jonas

2005-01-01

182

Dark current characterization of thin film Cu(InGa)Se2 solar cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin film technologies are one of the most promising new developments in the field of solar research. One such material is Cu(InGa)Se2 (CIGS). In this thesis, CIGS cells fabricated at NREL and Purdue are characterized and the results analyzed to develop a physical model of the cells. The goal of this thesis is to develop a series of accurate and efficient measurement techniques, which can extract material parameters from CIGS cells that can then be used in computer simulation. We will use the...

Moore, James E.

2010-01-01

183

Nano imprint lithography of textures for light trapping in thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Nano Imprint Lithography (NIL) is a versatile and commercially viable technology for fabrication of structures for light trapping in solar cells. We demonstrate the applicability of NIL in thin film silicon solar cells in substrate configuration, where NIL is used to fabricate a textured rear contact of the solar cells. We applied random structures, based on the natural texture of SnO:F grown by APCVD, and designed 2D periodic structures and show that for single junction {mu}c-Si cells these textured rear contacts lead to an increase of Jsc of more than 40 % in comparison to cells with flat rear contacts. Cells on optimized periodic textures showed higher fill factors which can be attributed to reduced microcrack formation, leading to less shunting in comparison to cells on random textures.

Soppe, W.J.; Dorenkamper, M.S.; Notta, J.B.; Pex, P.P.A.C. [ECN-Solliance, High Tech Campus 5, 5656 AE Eindhoven (Netherlands); Schipper, W.; Wilde, R. [Nanoptics GmbH, Innungsstrasse 5, 21244 Buchholz (Germany)

2012-09-15

184

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

Science.gov (United States)

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

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

2013-05-22

185

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

186

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

Science.gov (United States)

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

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

2014-03-28

187

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-04-15

188

Polycrystalline Silicon Thin-Film Solar Cells on AIT-Textured Glass Superstrates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new glass texturing method (AIT—aluminium-induced texturisation) has recently been developed by our group. In the present work, the potential of this method is explored by fabricating PLASMA poly-Si thin-film solar cells on glass superstrates that were textured with the AIT method. Using an interdigitated metallisation scheme with a full-area Al rear contact, PLASMA cells with an efficiency of up to 7% are realised. This promising result shows that the AIT glass texturing metho...

Widenborg, Per I.; Aberle, Armin G.

2007-01-01

189

Analysis of CIGS-based thin film solar cells with graded band gap  

Energy Technology Data Exchange (ETDEWEB)

ZnO/n-CdS/p-Cu(In,Ga)Se{sub 2} thin film solar cells with graded band gap absorber layer have been modelled. The cells are designed to be fabricated on flexible substrates, so, additional requirements and restrictions to metal contacts and interlayer mechanical and electronic properties should be taken into account. The aim is to calculate parameters of Cu(In,Ga)Se{sub 2} (CIGS)-based thin film solar cells, taking into account the buffer layer effect, zone bending and recombination at grain boundaries and another defects, and to introduce band gap gradient in the absorber layer. The model developed is based on one-dimensional drift-diffusion approach using the Poisson's equation and continuity equations for electrons and holes. Modelling for various band gap gradient profiles was performed: positive (from 1.08 up to 1.5 eV), zero (1.21 eV) and inverted (from 1.5 down to 1.08 eV) profiles for CIGS layer, and cells' output parameters have been calculated. The nanostructure effects in solar cells formed on a substrate using porous anodic alumina were considered taking into account processes at grain boundaries and nanoordered back contact. Charge carriers accumulation at the interfaces leads to local effective band gap narrowing at the interfaces reducing the conversion efficiency. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Gremenok, Valery [State Scientific and Production Association ' ' Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus' ' , P. Brovka str. 19, 220072 Minsk (Belarus); Zalesski, Valery; Khodin, Alexander; Ermakov, Oleg [Institute of Physics, National Academy of Sciences of Belarus, Logoiski tract 22, 220090 Minsk (Belarus); Chyhir, Ryhor; Emelyanov, Victor; Syakersky, Valentine [Research and Production Corporation ' ' INTEGLAL' ' , Korjenevskogo str. 12, 220108 Minsk (Belarus)

2009-05-15

190

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 I–V-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 I–V-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. [L’Institut d’Électronique du Solide et des Systèmes, Strasbourg (France); Lindekugel, S. [Fraunhofer-Institut für 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

191

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 I–V-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 I–V-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

192

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

193

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

Energy Technology Data Exchange (ETDEWEB)

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

Paetzold, Ulrich Wilhelm

2013-02-08

194

Incorporation of Cu in Cu(In,Ga)Se2-based thin-film solar cells  

International Nuclear Information System (INIS)

We have fabricated Cu(In,Ga)Se2 (CIGS)-based thin-film solar cells by using a cluster-type deposition system. The system is composed of a DC sputter for the Mo back electrode, a co-evaporator for the CIGS absorption layer, and a RF sputter for the ZnO and the transparent-conductive-oxide (TCO) window layers. The deposition of the CdS buffer layer was performed separately. Two solar cells with an effective area of 0.47 cm2 were fabricated using different processes. One cell, which was prepared with a 1-step process, had a larger atomic concentration of In-Ga than of Cu in the absorption layer and showed a conversion efficiency of 11.1%. The other prepared with a 3-step process had nearly the same In-Ga and Cu concentrations and showed a conversion efficiency of 15.5%. We discuss the incorporation of Cu in the two types of thin-film solar cells.

195

Improving the efficiency of thin film tandem solar cells by plasmonic intermediate reflectors  

Science.gov (United States)

Thin film tandem solar cells made of amorphous and microcrystalline silicon provide renewable energy at the benefit of low material consumption. As a drawback, these materials do not posses the high carrier mobilities of their crystalline counterpart which limits the feasible material thickness. For maintaining the light absorption as high as possible, photon management is required. Here we show that metallic nanodiscs that sustain localized plasmon polaritons can increase the efficiency of such solar cells if they are incorporated into the dielectric intermediate reflector separating the top and the bottom cell. We provide quantitative estimates for the possible absorption enhancement of optimized bi-periodic nanodiscs that are feasible for fabrication. Emphasis is also put on discussing the impact of obliquely incident sun light on the solar cell performance.

Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

2010-09-01

196

Efficiency limitations of thermally evaporated thin-film SnS solar cells  

Science.gov (United States)

Thin-film solar cells with SnS as absorber material were prepared by thermal evaporation of SnS. The cells were built in a superstrate configuration using Al?:?ZnO coated glass as front contact with an intrinsic ZnO buffer layer and/or CdS window layer and a gold back contact. The IV-characteristics and external quantum efficiency of the devices were determined. The best CdS/SnS solar cell showed a conversion efficiency of 1.6%, a short circuit current density of 19 mA cm-2 and an open circuit voltage of 217 mV. Moreover, band alignments at the interfaces AZO/SnS, CdS/SnS and SnS/Au were determined with in situ x-ray photoelectron spectroscopy to correlate the open circuit voltage limitations of the investigated solar cell device structures.

Schneikart, A.; Schimper, H.-J.; Klein, A.; Jaegermann, W.

2013-07-01

197

Efficiency limitations of thermally evaporated thin-film SnS solar cells  

International Nuclear Information System (INIS)

Thin-film solar cells with SnS as absorber material were prepared by thermal evaporation of SnS. The cells were built in a superstrate configuration using Al?:?ZnO coated glass as front contact with an intrinsic ZnO buffer layer and/or CdS window layer and a gold back contact. The IV-characteristics and external quantum efficiency of the devices were determined. The best CdS/SnS solar cell showed a conversion efficiency of 1.6%, a short circuit current density of 19 mA cm?2 and an open circuit voltage of 217 mV. Moreover, band alignments at the interfaces AZO/SnS, CdS/SnS and SnS/Au were determined with in situ x-ray photoelectron spectroscopy to correlate the open circuit voltage limitations of the investigated solar cell device structures. (paper)

198

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

Science.gov (United States)

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

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

2012-06-01

199

Thermally evaporated thin films of SnS for application in solar cell devices  

International Nuclear Information System (INIS)

SnS (tin sulphide) 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 glass and SnO2:coated glass substrates with the aim of optimising the properties of the material for use in photovoltaic solar cell device structures. In particular the effects of source temperature, substrate temperature, deposition rate and film thickness on the chemical and physical properties of the layers were investigated. Energy dispersive X-ray analysis was used to determine the film composition, X-ray diffraction to determine the phases present and structure of each phase, transmittance and reflectance versus wavelength measurements to determine the energy bandgap and scanning electron microscopy to observe the surface topology and topography and the properties correlated to the deposition parameters. Using the optimised conditions it is possible to produce thin films of tin sulphide that are pinhole free, conformal to the substrate and that consist of densely packed columnar grains. The composition, phases present and the optical properties of the layers deposited were found to be highly sensitive to the deposition conditions. Energy bandgaps in the range 1.55 eV-1.7 eV were obtained for a film thickness of 0.8 ?m, and increasing the filmckness of 0.8 ?m, and increasing the film thickness to > 1 ?m resulted in a reduction of the energy bandgap to less than 1.55 eV. The applicability of using these films in photovoltaic solar cell device structures is also discussed.

200

Thermally evaporated thin films of SnS for application in solar cell devices  

Energy Technology Data Exchange (ETDEWEB)

SnS (tin sulphide) is of interest for use as an absorber layer and the wider energy bandgap phases e.g. SnS{sub 2}, Sn{sub 2}S{sub 3} 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 glass and SnO{sub 2}:coated glass substrates with the aim of optimising the properties of the material for use in photovoltaic solar cell device structures. In particular the effects of source temperature, substrate temperature, deposition rate and film thickness on the chemical and physical properties of the layers were investigated. Energy dispersive X-ray analysis was used to determine the film composition, X-ray diffraction to determine the phases present and structure of each phase, transmittance and reflectance versus wavelength measurements to determine the energy bandgap and scanning electron microscopy to observe the surface topology and topography and the properties correlated to the deposition parameters. Using the optimised conditions it is possible to produce thin films of tin sulphide that are pinhole free, conformal to the substrate and that consist of densely packed columnar grains. The composition, phases present and the optical properties of the layers deposited were found to be highly sensitive to the deposition conditions. Energy bandgaps in the range 1.55 eV-1.7 eV were obtained for a film thickness of 0.8 {mu}m, and increasing the film thickness to > 1 {mu}m resulted in a reduction of the energy bandgap to less than 1.55 eV. The applicability of using these films in photovoltaic solar cell device structures is also discussed.

Miles, Robert W., E-mail: robert.miles@northumbria.ac.u [Northumbria Photovoltaics Applications Centre, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Ogah, Ogah E.; Zoppi, Guillaume; Forbes, Ian [Northumbria Photovoltaics Applications Centre, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom)

2009-07-01

 
 
 
 
201

Back contact buffer layer for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

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

Compaan, Alvin D.; Plotnikov, Victor V.

2014-09-09

202

Self-organized broadband light trapping in thin film amorphous silicon solar cells.  

Science.gov (United States)

Nanostructured glass substrates endowed with high aspect ratio one-dimensional corrugations are prepared by defocused ion beam erosion through a self-organized gold (Au) stencil mask. The shielding action of the stencil mask is amplified by co-deposition of gold atoms during ion bombardment. The resulting glass nanostructures enable broadband anti-reflection functionality and at the same time ensure a high efficiency for diffuse light scattering (Haze). It is demonstrated that the patterned glass substrates exhibit a better photon harvesting than the flat glass substrate in p-i-n type thin film a-Si:H solar cells. PMID:23633473

Martella, C; Chiappe, D; Delli Veneri, P; Mercaldo, L V; Usatii, I; Buatier de Mongeot, F

2013-06-01

203

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

Science.gov (United States)

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

Akimov, Yu A; Koh, W S

2010-06-11

204

Unlinking absorption and haze in thin film silicon solar cells front electrodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the respective influence of haze and free carrier absorption (FCA) of transparent front electrodes on the photogenerated current of micromorph thin film silicon solar cells. To decouple the haze and FCA we develop bi-layer front electrodes: a flat indium tin oxide layer assures conduction and allows us to tune FCA while the haze is adjusted by varying the thickness of a highly transparent rough ZnO layer. We show how a minimum amount of FCA leads only to a few percents absorption for...

Boccard, Mathieu; Cuony, Peter; Battaglia, Corsin; Despeisse, Matthieu; Ballif, Christophe

2010-01-01

205

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. This work address these issues by an...

Kieven, David

2012-01-01

206

Self-organized broadband light trapping in thin film amorphous silicon solar cells  

International Nuclear Information System (INIS)

Nanostructured glass substrates endowed with high aspect ratio one-dimensional corrugations are prepared by defocused ion beam erosion through a self-organized gold (Au) stencil mask. The shielding action of the stencil mask is amplified by co-deposition of gold atoms during ion bombardment. The resulting glass nanostructures enable broadband anti-reflection functionality and at the same time ensure a high efficiency for diffuse light scattering (Haze). It is demonstrated that the patterned glass substrates exhibit a better photon harvesting than the flat glass substrate in p–i–n type thin film a-Si:H solar cells. (paper)

207

Coupled optical and electrical analysis for thin-film solar cells with embedded dielectric nanoparticles  

Science.gov (United States)

Combined optical and electrical simulations were performed for thin-film (silicon) solar cell structures with dielectric (silicon-dioxide) nanoparticles embedded in the active region for efficiency enhancement. The efficiency enhancement due to optimally sized nanoparticles is found to be 22% and 15% in the constant coverage area and constant pitch configurations, respectively; further, the enhancement qualitatively follows the trends expected from optical-only simulations. This, however, assumes a good quality dielectric-semiconductor interface, whereas heavy recombination at this interface is seen to degrade the efficiency significantly—setting an upper limit on the surface recombination velocity up to which embedding nanoparticles is beneficial.

Mopurisetty, Sundara Murthy; Bajaj, Mohit; Sathaye, Ninad D.; Ganguly, Swaroop

2015-01-01

208

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

International Nuclear Information System (INIS)

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

209

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

International Nuclear Information System (INIS)

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

210

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

211

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

International Nuclear Information System (INIS)

Thin-film solar cells based on GaAs/AlxGa(1?x)As showing open circuit voltages of (1100–1170) mV and fill factors of (0.80–0.87) have been exposed to external electrical stresses, and current–voltage characteristics were monitored in order to study the effects of defects present in the device structure. It has been found that peculiar kinks, sudden jumps and various deformations occur in current–voltage curves which could be caused when the Fermi level moves position at the device interface. These changes occur when there is a group of defect levels and the Fermi level is forced to move across these levels. The reproducibility and performance of solar cells heavily depend on the properties of these defect structures, and external forces such as electrical stresses, illumination and temperature variations cause changes in the measured current–voltage characteristics. The observed variations during this work together with examples from the literature are presented and discussed in this paper. It is concluded that the control of these defects present in device structures is crucial in developing stable, durable and high-efficiency thin-film solar cells

212

Towards numerical simulation of nonhomogeneous thin-film silicon solar cells  

Science.gov (United States)

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

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

2014-03-01

213

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

214

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

215

Novel concepts for low-cost and high-efficient thin film solar cells  

Science.gov (United States)

This work presents the activities carried out at ITMA Materials Technology related to the building integration of thin film (TF) photovoltaics (PV). Three different approaches have been developed in order to achieve high efficient solar cells at low manufacturing costs: (i) a new route for manufacturing monolithical silicon based thin film solar cells on building materials, (ii) the use of metallic nanoparticles for light trapping (plasmonic effects and light scattering) and (iii) the luminescent sol-gel coating on glass for solar concentration. In the first case, amorphous silicon modules (single junction) have been successfully manufactured at lab scale on steel and commercial ceramic substrates with efficiencies of 5.4% and 4.0%, respectively. Promising initial attempts have been also made in ethylene tetrafluoroethylene (ETFE), a polymer with high potential in textile architecture. In a similar way, the development of nanotechnology based coatings (metallic nanoparticles and luminescent materials) represent the most innovative part of the work and some preliminary results are showed.

Gómez, D.; Menéndez, A.; Sánchez, P.; Martínez, A.; Andrés, L. J.; Menéndez, M. F.; Campos, N.; García, A.; Sánchez, B.

2011-09-01

216

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

217

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

Science.gov (United States)

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

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

1989-01-01

218

Light confinement in e-beam evaporated thin film polycrystalline silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline Si thin-film (poly-Si) solar cells need effective light-trapping to compensate for the moderate absorption. Recent developments in the poly-Si cell technology focus on film fabrication by e-beam evaporation due to its manufacturing benefits, such as a very high deposition rate above 15 nm/s and inline compatible process. However, evaporated poly-Si cells exhibit limited compatibility with textured glass. In this Letter, the coupling of the light in the absorber layer is enhanced by introducing a rough interface at the back of the solar cells. This increases the conversion efficiency from 6% to 7.1% for, respectively, planar and back textured interface with current density of 26.6 mA/cm{sup 2} for only 3.6 {mu}m absorber thickness. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Soderstrom, T.; Wang, Q.; Omaki, K.; Varlamov, S. [ARC Photovoltaics Centre of Excellence, UNSW, Sydney NSW 2052 (Australia); Kunz, O.; Ong, D. [CSG Solar Pty Ltd, 82 Bay Street, Botany NSW 2019 (Australia)

2011-06-15

219

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses...

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

2013-01-01

220

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

International Nuclear Information System (INIS)

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

 
 
 
 
221

MOCVD of thin film photovoltaic solar cells—Next-generation production technology?  

Science.gov (United States)

This paper will review the chalcogenide thin film photovoltaic (PV) solar cells, based on cadmium telluride (CdTe) and copper indium diselenide (CIS) and discuss the potential for metalorganic chemical vapour deposition (MOCVD) to enable more advanced devices in the second generation of CdTe module production. The current generation of production methods is based on physical vapour deposition (PVD) or close-spaced sublimation (CSS). This paper concentrates on the less well-known topic of MOCVD of thin film chalcogenide cells, and in particular that of CdTe. Efficient CdTe PV solar cells (>10% AM1.5) have been demonstrated from deposition of the CdS, CdTe and CdCl 2 films in a single MOCVD chamber. The CdTe layer was doped with As and an additional high As concentration CdTe layer provides effective low resistance contacting without the need for wet etching the surface. The high level of flexibility in using MOCVD has been demonstrated where the CdS window layer has been alloyed with Zn to improve the blue response of the PV device and improve AM1.5 efficiency to 13.3%.

Irvine, S. J. C.; Barrioz, V.; Lamb, D.; Jones, E. W.; Rowlands-Jones, R. L.

2008-11-01

222

Simulation of polycrystalline silicon thin film solar cells - model calibration and sensitivity analysis  

Energy Technology Data Exchange (ETDEWEB)

To gain a better insight into the efficiency-limiting processes in polycrystalline silicon (poly-Si) thin film solar cells, we developed a simulation model for the J-V characteristics and minority carrier lifetime based on experimental results using the numerical 1D simulation program AFORS-HET. The calibration of the model has been achieved through simultaneously fitting the measured dark and light J-V curves of twelve poly-Si thin film minimodules with dissimilar thickness and absorber doping concentration. Effective defect density, capture cross section products of 10..100 cm{sup -1} have been determined in the poly-Si absorber by this procedure. Transient photoconductance decay measurements of the poly-Si absorbers have also been conducted in the low injection regime (4.5.10{sup 14} cm{sup -3}). High lifetimes of 100 {mu} s have been found which can be explained within our simulation model by field effect passivation. Furthermore simulations indicate that this field effect leads to a strong injection-dependence of carrier lifetime in the operation range of the solar cell. The sensitivity analysis performed with our calibrated model shows that the defects in the absorber layer are crucial for the cell efficiency. Thus, the improvement of the emitter and back surface field layers becomes important only if the absorber itself is of better quality. Moreover we discuss the optimum absorber thickness subject to different doping levels and absorber defect densities.

Teodoreanu, Ana-Maria; Leendertz, Caspar; Sontheimer, Tobias; Rech, Bernd [Helmholtz-Zentrum Berlin, Kekulestr. 5. 12489 Berlin (Germany)

2011-07-01

223

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 130-140°C. At 130°C 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

224

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 lfate). 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.

225

Optimization of the p-i interface properties in thin film microcrystalline silicon solar cell  

Energy Technology Data Exchange (ETDEWEB)

Hydrogenated microcrystalline silicon ({mu}c-Si:H) has become attractive for use in thin-film silicon solar cells. The external quantum efficiency (EQE) of {mu}c-Si:H solar cells extends up to 1100 nm, which is exploited in tandem solar cells. Properties of p-i interface are critical for performance as it affects carrier collection, which is visible in the blue response. Here, we report how {mu}c-Si:H p- and i-layer material properties influence the p-i interface of {mu}c-Si:H solar cells. The effect of RF PECVD parameters of these layers on the p-i interface was investigated. We find that the blue response of the solar cell is sensitive to the crystallinity of both the p- and i-layers. We demonstrate that transient depletion during i-layer deposition affects the blue response of {mu}c-Si:H solar cell. We obtained a narrow process window for optimal solar-cell performance. At the optimal deposition pressure of 9 mbar and using transient depletion, an EQE at 400 nm of 0.6 was obtained, achieving 16% higher short-circuit current density. Reducing the diborane flow during p-layer deposition yielded 13% relative increase in efficiency. (author)

Agbo, S.N.; van Swaaij, R.A.C.M.M.; Zeman, M. [Delft University of Technology-DIMES, Electrical Energy Conversion Unit, P.O. Box 5053, 2600 GB Delft (Netherlands); Krc, J. [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, 1000 Ljubljana (Slovenia)

2010-11-15

226

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-08-11

227

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

228

Correlation between surface topography and short-circuit current density for thin-film silicon solar cells  

Science.gov (United States)

The scattering of light by the textured transparent conductive oxide (TCO) in thin-film silicon solar cells is frequently described by transmission haze and angular intensity distribution (AID) at the interface between the TCO and air. The scattering is expected to improve the light trapping and, therefore, the absorption of the solar cell. Using these scattering properties as input parameters for the electrical modeling of thin-film solar cells leads to significant deviations from the measurements for short circuit current densities. The major disadvantage of the AID measurement at the TCO/air interface is that in real thin-film silicon solar cells the TCO/Si interface is relevant. We use a model that is based on scalar scattering theory to calculate the scattering properties at the transition into air and into silicon. The model takes into account the measured surface topography and the optical constants of the adjacent media. For a series of ?c-Si:H cells on ZnO:Al with different surface topographies, AID and the transmission haze into a ?c-Si:H half space are calculated. From these results, a quantity is derived that describes the scattering efficiency. This quantity is compared to the short circuit current densities of ?c-Si:H solar cells showing good agreement. It will be shown that for artificially modified textures an increase in the short-circuit current density and thus, the efficiency of thin-film silicon solar cells can be achieved.

Hoffmann, A.; Jost, G.; Bittkau, K.; Carius, R.

2012-06-01

229

Depth Selective Laser Scribing for Thin-Film Silicon Solar Cells on Flexible Substrates  

Energy Technology Data Exchange (ETDEWEB)

Roll-to-roll production facilitates flexible PV modules and a significant decrease of production cost for thin-film silicon solar cells. However, no standard processes for monolithic series interconnection on opaque foil substrates are readily available. In this contribution, we present different approaches to achieve depth selective laser scribing of thin-film silicon solar cells on electrically insulated steel foil. Besides paving the way to series interconnection on opaque flexible substrates, this concepts also allows to significantly reduce the number of process steps during module manufacturing. The required depth selective scribes can be obtained with all three employed Diode Pumped Solid State-lasers (wavelengths of 355 nm, 532 nm, and 1064 nm). Actually, several laser parameter combinations (wavelength, pulse energy, spot overlap, single/multi-pass) have been found to make scribes that meet the requirements of the device architecture. Currently, the electrical validation of the observed scribes that meet the requirements of the device architecture is in progress. In a next step, fully series interconnected modules will be manufactured following the presented device and processing concepts.

Loeffler, J.; Wipliez, L.A.; De Keijzer, M.A.; Bosman, J.; Soppe, W.J. [ECN Solar Energy, Petten (Netherlands)

2009-06-15

230

Spatially Resolved Cathodoluminescence of CdTe Thin Films and Solar Cells  

Energy Technology Data Exchange (ETDEWEB)

We have investigated the spatial distribution of different transitions identified in the emission spectra of CdTe thin films and solar cells by cathodoluminescence spectroscopic imaging (CLSI). Prior to back-contact deposition, the spectra are dominated by excitons (X) and donor-to-acceptor (DAP) transitions. After contacting, Cu acceptor states are found in addition to the X and DAP recombination processes. A very systematic behavior found in CdTe is that DAP transitions occur preferentially at grain boundaries (GBs). The distribution of these states responsible for the passivation of GBs is not affected by further processing, although additional levels participate in the recombination process. We believe that this stability is one of the reasons for the success of thin-film CdTe solar cells. Estimates of the densities of different donors and acceptors participating in the recombination process are possible from the analysis of the evolution of the emission spectra with the excitation level. It is found that the back contact suppresses some intrinsic acceptors (associated with the A center) near the back-contact interface and, therefore, Cu acceptor states should be responsible for the p-typeness of the back surface more than a reduction of compensation. CLSI measurements are shown to be helpful in understanding the physics of back-contact formation.

Romero, M. J.; Metzger, W.; Gessert, T. A.; Albin, D. S.; Al-Jassim, M. M.

2003-05-01

231

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

Science.gov (United States)

Thin-film photovoltaics based on alkylammonium lead iodide perovskite light absorbers have recently emerged as a promising low-cost solar energy harvesting technology. To date, the perovskite layer in these efficient solar cells has generally been fabricated by either vapor deposition or a two-step sequential deposition process. We report that flat, uniform thin films of this material can be deposited by a one-step, solvent-induced, fast crystallization method involving spin-coating of a DMF solution of CH3NH3PbI3 followed immediately by exposure to chlorobenzene to induce crystallization. Analysis of the devices and films revealed that the perovskite films consist of large crystalline grains with sizes up to microns. Planar heterojunction solar cells constructed with these solution-processed thin films yielded an average power conversion efficiency of 13.9±0.7% and a steady state efficiency of 13% under standard AM 1.5 conditions. PMID:25047967

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

2014-09-01

232

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structur...

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

2014-01-01

233

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 200–300 nm. Optical measurements indicate an optical absorption coefficient of higher than 104 cm?1 and an optical bandgap of 1.17±0.01 eV. (cross-disciplinary physics and related areas of science and technology)

234

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

235

Processing issues for thin film CdTe/CdS solar cells  

Science.gov (United States)

Processing options addressing critical issues associated with fabrication of high efficiency thin film CdTe/CdS solar cells are presented. Particular focus is given to methods for: minimizing CdS loss during CdCl2 heat treatment; obtaining high open circuit voltages; obtaining spatially uniform properties; and forming ohmic contacts. Data is presented for cells deposited by physical vapor deposition (PVD) which demonstrates that CdS loss can be overcome by use of CdTe1-xSx absorber layers and by controlling the delivery of CdCl2 vapor species during heat treatment. The CdCl2 vapor treatments are shown to produce residue-free surfaces and uniform film properties which leads to uniform cell performance. State of the art open circuit voltages (>850 mV) are obtained with PVD cells by performing a short high temperature anneal prior to CdCl2 treatment. Low resistance contacts using diffused Cu doping followed by surface etching are demonstrated on CdTe/CdS thin films deposited by five methods.

McCandless, Brian E.; Birkmire, Robert W.; Jensen, D. Garth; Phillips, James E.; Youm, Issakha

1997-02-01

236

CIGS2 thin-film solar cells on flexible foils for space power  

Energy Technology Data Exchange (ETDEWEB)

CuIn{sub 1-x}Ga{sub x}S{sub 2}(CIGS2) thin-film solar cells on flexible stainless steel foil are of interest for space power because of the near optimum bandgap, potential for higher specific power, and superior radiation resistance. This paper describes development of CIGS2 solar cells on 127-{mu}m and 20-{mu}m thick, flexible SS foils for space power. A large-area, dual-chamber, deposition system has been fabricated. Cu-rich Cu-Ga/In layers were sputter-deposited on unheated Mo-coated foils, p-type CIGS2 thin films were obtained by etching Cu-rich surface layer from CIGS2 films prepared by sulfurization in Ar:H{sub 2}S 1:0.04 mixture at 475{sup o}C for 60 min with an intermediate 30-min annealing step at 135{sup o}C. Solar cells were completed by deposition of CdS/ZnO/ZnO:Al layers and Ni/Al contact fingers. AMO PV parameters of a CIGS2 solar cell on 127-{mu}m thick SS foil measured at NASA-GRC were: V{sub OC} = 802.9 mV, J{sub SC} = 25.07 mA/cm{sup 2}, FF = 60.06%, and efficiency = 8.84%. For this cell, AM1.5 PV parameters measured at NREL were V{sub OC} = 763 mV, J{sub SC} = 20.6 mA/cm{sup 2}, FF = 67.4%, and efficiency 10.4%. (author)

Dhere, N.G.; Ghongadi, S.R.; Pandit, M.B.; Jahagirdar, A.H. [Florida Solar Energy Center, Cocoa, FL (United States); Scheiman, D. [NASA Glenn Research Center, Cleveland, OH (United States). Ohio Aerospace Institute

2002-07-01

237

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

Science.gov (United States)

Recently, we have suggested a dielectric metamaterial composed of 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 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 previous 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, M.; Ovchinnikov, V.; Simovski, C.

2015-02-01

238

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

239

Hydrophobic perfluoropolymer thin-film encapsulation for enhanced stability of inverted polymer solar cells  

Science.gov (United States)

We report hydrophobic perfluoropolymer thin-film encapsulation for enhancing the air ambient stability of inverted polymer solar cells (PSCs). Using a perfluoropolymer, poly(perfluorodecylmethacrylate) (PFDMA), as an encapsulation material, an orthogonal process that enables a solution-processing of encapsulation polymers to be coated directly on the inverted PSCs without damaging the underlying organic components is possible. Particularly, with PFDMA encapsulation, the air ambient stability was significantly enhanced, showing only an efficiency reduction of 23.3% after 456 hours of air exposure. The enhanced device stability can be attributed to the hydrophobic property of the PFDMA surface, which suppresses the transmission of air ambient gas molecules into the solar cells. Thus, the PFDMA coating can be beneficial in achieving high-stability organic electronics by using an easy-to-use route.

Kim, Jae-Hyun; Park, Sung Kyu; Lee, Jung-Wook; Yoo, Byungwook; Lee, Jin-Kyun; Kim, Yong-Hoon

2014-11-01

240

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

International Nuclear Information System (INIS)

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

 
 
 
 
241

A photonic-plasmonic structure for enhancing light absorption in thin film solar cells  

Science.gov (United States)

We describe a photonic-plasmonic nanostructure, for significantly enhancing the absorption of long-wavelength photons in thin-film silicon solar cells, with the promise of exceeding the classical 4n2 limit for enhancement. We compare identical solar cells deposited on the photonic-plasmonic structure, randomly textured back reflectors and silver-coated flat reflectors. The state-of-the-art back reflectors, using annealed Ag or etched ZnO, had high diffuse and total reflectance. For nano-crystalline Si absorbers with comparable thickness, the highest absorption and photo-current of 21.5 mA/cm2 was obtained for photonic-plasmonic back-reflectors. The periodic photonic plasmonic structures scatter and reradiate light more effectively than a randomly roughened surface.

Bhattacharya, Joydeep; Chakravarty, Nayan; Pattnaik, Sambit; Dennis Slafer, W.; Biswas, Rana; Dalal, Vikram L.

2011-09-01

242

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

243

Impact of transparent conductive oxide on the admittance of thin film solar cells  

Science.gov (United States)

The impact of transparent electrically conducting oxide (TCO) on the admittance measurements of thin film p-i-n a-Si:H solar cells was investigated. Admittance measurements on solar cell devices, with different area and geometry, in a wide range of frequencies and biases were performed. The admittance measurements of the investigated solar cells, which use the TCO as an electrical contact, showed that the high frequency admittance per area unit depends on the area. This effect increases both with the probe frequency and the size of the solar cells. Transmission line model valid for strip geometry which explains how the resistivity of the TCO layer impacts the measured admittance of the p-i-n diode was presented. An estimate of the critical length of the strip solar cell over which the measured diode capacitance is affected by the TCO is given. The transmission line model allows to estimate also the lumped parasitic series resistance Rs of solar cells with strip geometry.

Principato, F.; Cannella, G.; Lombardo, S.; Foti, M.

2010-11-01

244

Time Domain Characterization of Light Trapping States in Thin Film Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Spectral interferometry of the backscattered radiation reveals coherence lifetimes of about 150 fs for nanolocalized electromagnetic modes in textured layered nanostructures as they are commonly used in thin film photovoltaics to achieve high cell efficiencies.

Pfeiffer W.

2013-03-01

245

Selective Front Side Patterning of CZTS Thin-Film Solar Cells by Picosecond Laser Induced Material Lift-Off Process  

Science.gov (United States)

The thin-film Cu-chalcopyrite based solar cell technologies become more attractive due to their lower cost and optimal performance. Efficiency of cells with a large area might be maintained if small segments are interconnected in series in order to reduce photocurrent in thin films and resistance losses, and laser scribing is crucial for performance of the device. We present our results on the material lift-off effect investigations in the CZTS thin-film solar cell structures which can be applied for the damage-free front-side scribing processes. The results of the P2 and P3 type scribe formation with the fundamental harmonics of a picosecond laser are presented.

Gecys, P.; Markauskas, E.; Raciukaitis, G.; Repins, I.; Beall, C.

246

Electrical impact of MoSe2 on CIGS thin-film solar cells.  

Science.gov (United States)

The CIGS solar cell is one of the most promising photovoltaic devices due to the achievement of the highest conversion efficiency (>20%) among all thin-film solar cells. The CIGS cell has a glass/Mo/CIGS/CdS/TCO configuration, and the CIGS-Mo interface is a Schottky barrier to holes. During the sulfurization-after-selenization (SAS) CIGS formation process with H2Se gas, the Mo surface transforms naturally into MoSe2 at the CIGS-Mo interface. In this work, the electrical impact of MoSe2 on CIGS solar cells was investigated. Different CIGS-Mo interfaces were prepared with two CIGS processes. One is SAS, and the other is the sequential-sputtering-selenization CIGS process with Se gas. Formation of MoSe2 is hardly observed in the latter process. Samples were characterized by XRD, the van der Pauw method, reflectance, and visual inspection. Besides, Schottky barrier heights of cells were extracted from J-V-T measurements. For the first time, it was experimentally shown that the existence of thin MoSe2 film can decrease the apparent Schottky barrier height of CIGS solar cells. In addition, 1-dimensional numerical simulation showed that a larger barrier height affects both the fill factor and open-circuit voltage. Therefore, the formation of MoSe2 during the CIGS process should minimize the negative effect of Schottky barrier on solar-cell performances, especially with large Schottky barrier. PMID:24068110

Hsiao, Kuo-Jui; Liu, Jing-Da; Hsieh, Hsing-Hua; Jiang, Ting-Shiuan

2013-11-01

247

Optical Thickness Monitoring System for a High Vacuum Deposition Chamber for Thin Film Photovoltaic Solar Cells  

Science.gov (United States)

Groups at the University of Toledo studying CdTe/CdS based thin film photovoltaic solar cells require precise measurement and variation of film parameters to produce the most efficient cells possible. Controlling film thickness of the CdTe and CdS layers is essential to optimizing cell efficiency and desired cell characteristics. A non-destructive film thickness monitoring system for in-situ, real time chamber depositions in the AJA International Inc High Vacuum RF magnetron sputtering chamber was constructed. The monitoring system visualizes interference fringes of reflected laser light from front and back surfaces of the deposited film. Sample thickness is determined from known optical properties of the film material. Complications due to sample rotation during growth, background noise, and limitations from chamber geometry were overcome to achieve clear signal detection.

Zeller, Ryan

2007-10-01

248

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

Directory of Open Access Journals (Sweden)

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

J. Sastr\\u00E9-Hern\\u00E1ndez

2011-01-01

249

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 µm). 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 µm, 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., Sastré-Hernández; M.E., Calixto; M., Tufiño-Velázquez; G., Contreras-Puente; A., Morales-Acevedo; G., Casados-Cruz; M.A., Hernández-Pérez; M.L., Albor-Aguilera; R., Mendoza-Pérez.

2011-10-11

250

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

251

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

International Nuclear Information System (INIS)

Highlights: ? Synthesis of CZTS thin films by PLD. ? Effect of stoichiometry, its deviation on the physical properties. ? Improvement in conversion efficiency using CZTS absorber layer. - Abstract: The performance of CZTS thin films deposited by using pulsed laser deposition technique is investigated as a function of target composition. The chemical composition ratio a = Cu/(Zn + Sn) of the target material has been varied from 0.8 to 1.2 in step of 0.1 by keeping Zn/Sn constant. The effect of the chemical composition in the precursor thin films on the structural, morphological, chemical and optical properties of the CZTS thin films has been investigated. X-ray diffraction and X-ray photoelectron spectroscopy studies showed that the annealed CZTS thin films are of a single kesterite crystal structure without any other secondary phases. The direct band gap energy of the CZTS thin films is found to decrease from 1.72–1.53 eV with increase of ‘a’. The estimated band-gap energy from the quantum efficiency measurements is about 1.54 eV. The solar cell fabricated with Glass/Mo/CZTS/CdS/ZnO:Al/Al structure grown using [a = Cu/(Zn + Sn) = 1.1] showed the best conversion efficiency of 4.13% with Voc = 700 mV, Jsc = 10.01 mA/cm2 and FF = 0.59.

252

Silicon Light: a European FP7 project aiming at high efficiency thin film silicon solar cells on foil. Monolithic series interconnection of flexible thin-film PV devices  

Energy Technology Data Exchange (ETDEWEB)

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/{mu}c-Si tandem cells with more than 11% efficiency.

Soppe, W. [ECN Solar Energy, P.O. Box 1, 1755 ZG Petten (Netherlands); Haug, F.J. [Ecole Polytechnique Federale de Lausanne EPFL, Photovoltaics and Thin Film Electronics Laboratory, Rue A.-L. Breguet 2, 2000 Neuchatel (Switzerland); Couty, P. [VHFTechnologies SA, Rue Edouard-Verdan 2, CH-1400 Yverdon-les-Bains (Switzerland); Duchamp, M. [Technical University of Denmark, Center for Electron Nanoscopy, DK-2800 Kongens Lyngby (Denmark); Schipper, W. [Nanoptics GmbH, Innungstr.5, 21244 Buchholz (Germany); Krc, J. [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000 Ljubljana (Slovenia); Sanchez, G. [Universidad Politecnica de Valencia, I.U.I. Centro de Tecnologia Nanofotonica, 46022 Valencia (Spain); Leitner, K. [Umicore Thin Film Products AG, Balzers (Liechtenstein); Wang, Q. [Shanghai Jiaotong University, Research Institute of Micro/Nanometer Science and Technology, 800 Dongchuan Road, Min Hang, 200240 Shanghai (China)

2011-09-15

253

Ion beam assisted sputter deposition of ZnO for silicon thin-film solar cells  

Science.gov (United States)

Ion beam assisted deposition (IBAD) is a promising technique for improving the material quality of ZnO-based thin films. The operation of an auxiliary Ar+ ion source during deposition of ZnO?:?Ga thin films by dc magnetron sputtering led to an improvement in crystalline texture, especially at low temperatures due to momentum transfer from the ions to the growing film. Etching of IBAD-ZnO?:?Ga films in diluted HCl revealed crater-like surface structures with crater diameters of up to 600 nm. These structures are usually achieved after deposition at high substrate temperatures. This is an indication that the grain structure was remarkably changed by bombarding these films during deposition in terms of increasing the compactness of the ZnO?:?Ga films. Subsequent annealing procedures led to an improvement in the electrical and optical properties. Hydrogenated microcrystalline silicon (µc-Si?:?H) solar cells exhibited enhanced efficiency as compared to cells on other low-temperature sputtered reference ZnO films. This improvement was ascribed to light trapping by the modified etching behaviour of the IBAD-ZnO?:?Ga films as well as improved transparency after the vacuum annealing step.

Warzecha, M.; Köhl, D.; Wuttig, M.; Hüpkes, J.

2014-03-01

254

Indium tin oxide thin films by bias magnetron rf sputtering for heterojunction solar cells application  

International Nuclear Information System (INIS)

In this investigation ITO thin films were prepared by bias magnetron rf sputtering technique at substrate temperature of 180 deg. C and low substrate-target distance for future a-Si:H/c-Si heterojunction (HJ) solar cells application. Microstructure, surface morphology, electrical and optical properties of these films were characterized and analyzed. The effects of ion bombardments on growing ITO films are well discussed. XRD analysis revealed a change in preferential orientation of polycrystalline structure from (2 2 2) to (4 0 0) plane with the increase of negative bias voltage. Textured surface were observed on AFM graphs of samples prepared at high negative bias. Hall measurements showed that the carrier density and Hall mobility of these ITO films are sensitive to the bias voltage applied. We attributed these effects to the sensitivity of energy of Ar+ ions bombarding on growing films to the applied bias voltage in our experiments. At last the figure of merit was calculated to evaluate the quality of ITO thin films, the results of which show that sample prepared at bias voltage of -75 V is good to be used in HJ cells application

255

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

256

Polycrystalline ZnO: B grown by LPCVD as TCO for thin film silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

Conductive zinc oxide (ZnO) grown by low pressure chemical vapor deposition (LPCVD) technique possesses a rough surface that induces an efficient light scattering in thin film silicon (TF Si) solar cells, which makes this TCO an ideal candidate for contacting such devices. IMT-EPFL has developed an in-house LPCVD process for the deposition of nanotextured boron doped ZnO films used as rough TCO for TF Si solar cells. This paper is a general review and synthesis of the study of the electrical, optical and structural properties of the ZnO:B that has been performed at IMT-EPFL. The influence of the free carrier absorption and the grain size on the electrical and optical properties of LPCVD ZnO:B is discussed. Transport mechanisms at grain boundaries are studied. It is seen that high doping of the ZnO grains facilitates the tunnelling of the electrons through potential barriers that are located at the grain boundaries. Therefore, even if these potential barriers increase after an exposition of the film to a humid atmosphere, the heavily doped LPCVD ZnO:B layers show a remarkable stable conductivity. However, the introduction of diborane in the CVD reaction induces also a degradation of the intra-grain mobility and increases over-proportionally the optical absorption of the ZnO:B films. Hence, the necessity to finely tune the doping level of LPCVD ZnO:B films is highlighted. Finally, the next challenges to push further the optimization of LPCVD ZnO:B films for thin film silicon solar cells are discussed, as well as some remarkable record cell results achieved with LPCVD ZnO:B as front electrode.

Fay, Sylvie, E-mail: Sylvie.fay@epfl.c [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland); Steinhauser, Jerome [Now at Oerlikon Solar Lab, Neuchatel CH-2000 (Switzerland); Nicolay, Sylvain; Ballif, Christophe [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland)

2010-03-31

257

Epitaxially grown polycrystalline silicon thin-film solar cells on solid-phase crystallised seed layers  

Science.gov (United States)

This paper presents the fabrication of poly-Si thin film solar cells on glass substrates using seed layer approach. The solid-phase crystallised P-doped seed layer is not only used as the crystalline template for the epitaxial growth but also as the emitter for the solar cell structure. This paper investigates two important factors, surface cleaning and intragrain defects elimination for the seed layer, which can greatly influence the epitaxial grown solar cell performance. Shorter incubation and crystallisation time is observed using a simplified RCA cleaning than the other two wet chemical cleaning methods, indicating a cleaner seed layer surface is achieved. Cross sectional transmission microscope images confirm a crystallographic transferal of information from the simplified RCA cleaned seed layer into the epi-layer. RTA for the SPC seed layer can effectively eliminate the intragrain defects in the seed layer and improve structural quality of both of the seed layer and the epi-layer. Consequently, epitaxial grown poly-Si solar cell on the RTA treated seed layer shows better solar cell efficiency, Voc and Jsc than the one on the seed layer without RTA treatment.

Li, Wei; Varlamov, Sergey; Xue, Chaowei

2014-09-01

258

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-06-15

259

Near-field assisted nanoscale patterning for improved absorption in thin film silicon solar cell  

Science.gov (United States)

Near field optics concepts have introduced a paradigm shift in a wide variety of engineering fields in the recent past and the most significant applications of this fundamental physics concepts have been in the applied engineering problems such as improved broad band light absorption thereby enhancing the conversion efficiency of thin silicon solar cells. Also, for writing patterned structures or features using non contact optical methodologies have enabled near field optics assisted fabrication and related applications. The technology involving optics concepts and methodologies targeting energy sector have seen the impact of the same with a challenging trend to achieve smaller features or devices with micro- or nano-scale features. This demands automatically the need for achieving much smaller features beyond the forecasted sub- 30nm feature patterning methodologies. To meet such demands, a new branch of near- field optical concepts for improving patterning resolution has started developing which have been receiving considerable attention for its ability to produce high density sub-wavelength features that can find tremendous energy harvesting applications. This paper in this context mainly focuses on the review of different near field optical concepts and approaches developed for patterning by the author's group at NTU. Different concepts were explored incorporating surface Plasmon waves ( LSPs, SPPs, LRSPs), gap modes as well as their interference in order to high resolution features and pattern dimensions at nano-scales. The absorbance of near band gap light is small and hence structuring of thin film solar cell is very important for increasing the absorbance by light trapping. The manuscript conclude by correlating the above said aspects and the challenges in achieving improved light conversion in thin film solar cells.

Murukeshan, V. M.; Prabhathan, P.; Sidharthan, R.

2014-10-01

260

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. 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.

 
 
 
 
261

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

International Nuclear Information System (INIS)

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

262

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

Science.gov (United States)

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

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

2012-06-01

263

Interfacial alkali diffusion control in chalcopyrite thin-film solar cells.  

Science.gov (United States)

Alkali elements, specifically sodium (Na), are key materials to enhance the energy conversion efficiencies of chalcopyrite and related thin-film photovoltaic solar cells. Recently, the effect of potassium (K) has also attracted attention because elemental K has unique effects different from Na as well as a similar beneficial effect in improving device performance. In this study, the control of selective alkali K and Na diffusion into chalcopyrite thin-films from soda-lime glass substrates, which serve as the monolithic alkali source material and contain both K and Na, is demonstrated using ternary CuGaSe2. Elemental K is found to be incorporated in the several ten nanometer thick Cu-deficient region, which is formed on the CuGaSe2 film surface, while Na is ejected, although both K and Na diffuse from the substrate to the CuGaSe2 film surface during growth. The alkali [K]/[Na] concentration ratio in the surface region of CuGaSe2 films strongly depends on the film structure and can be controlled by growth parameters under the same substrate temperature conditions. The results we present here offer new concepts necessary to explore and develop emerging new chalcopyrite and related materials and optimize their applications. PMID:25004458

Ishizuka, Shogo; Yamada, Akimasa; Fons, Paul J; Shibata, Hajime; Niki, Shigeru

2014-08-27

264

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

International Nuclear Information System (INIS)

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

265

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

266

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; López-Santos, Maria C; Guillén, Elena; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

2014-04-14

267

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

International Nuclear Information System (INIS)

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

268

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

269

Heterojunction solar cells with integrated Si and ZnO nanowires and a chalcopyrite thin film  

Energy Technology Data Exchange (ETDEWEB)

ZnO nanowires (NWs) have been successfully synthesized using a hydrothermal technique on both glass and silicon substrates initially coated with a sputtered ZnO thin film layer. Varying ZnO seed layer thicknesses were deposited to determine the effect of seed layer thickness on the quality of ZnO NW growth. The effect of growth time on the formation of ZnO NWs was also studied. Experimental results show that these two parameters have an important effect on formation, homogeneity and vertical orientation of ZnO NWs. Silicon nanowires were synthesized by a Ag-assisted electroless etching technique on an n-type Si (100) wafer. SEM observations have revealed the formation of vertically-aligned Si NWs with etching depth of ?700 nm distributed over the surface of the Si. An electron-beam evaporated chalcopyrite thin film consisting of p-type AgGa{sub 0.5}In{sub 0.5}Se{sub 2} with ?800 nm thickness was deposited on the n-type ZnO and Si NWs for the construction of nanowire based heterojunction solar cells. For the Si NW based solar cell, from a partially illuminated area of the solar cell, the open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency were 0.34 V, 25.38 mA cm{sup ?2}, 63% and 5.50%, respectively. On the other hand, these respective parameters were 0.26 V, 3.18 mA cm{sup ?2}, 35% and 0.37% for the ZnO NW solar cell. - Highlights: • ZnO nanowires using hydrothermal technique have been synthesized successfully. • Silicon nanowires were synthesized by Ag-assisted electroless etching technique. • A p-type AGIS was deposited on the n-type ZnO and n-Si NWs for nanowire based solar cells. • Power conversion efficiency of 5.50% was obtained for Si nanowires based solar cell.

Karaagac, Hakan, E-mail: hkaraagac@ucdavis.edu [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States); Department of Physics, Middle East Technical University, 06531 Ankara (Turkey); Parlak, Mehmet [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey); Yengel, Emre; Islam, M. Saif [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States)

2013-06-15

270

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

271

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

272

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

273

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%.

274

Roll to roll fabrication process of thin film silicon solar cells on steel foil  

Energy Technology Data Exchange (ETDEWEB)

ECN is developing a novel fabrication process for thin film silicon solar cells on steel foil. Key features in this process chain are: (1) application of an insulating barrier layer which enables texturization of the rear contact with submicron structures for light trapping; (2) Si deposition with remote, linear PECVD; and (3) series interconnection by laser scribing and printing after deposition of the layers (reducing the total number of process steps). The barrier layer is primarily an enabler for monolithic series interconnection of cells, but we show that we can also fabricate any arbitrary sub-micron structure in this layer by hot embossing to achieve optimum light trapping in the solar cells. For deposition of doped and intrinsic silicon layers we use novel remote and linear plasma sources, which are excellently suited for continuous rollto- roll processing. We have been able to fabricate devicequality amorphous and microcrystalline silicon layers with these sources. First pin a-Si solar cells have been made on FTO glass, yielding initial efficiencies up to 4.5%. First n-i-p a-Si cells made on steel foil plus textured barrier layer yielded efficiencies of about 3.7%.

Van Aken, B.B.; Doerenkaemper, M.; Devilee, C.; Heijna, M.C.R.; Loeffler, J.; Soppe, W.J. [ECN Solar Energy, Petten (Netherlands)

2009-06-15

275

Development of Earth-Abundant Tin(II) Sulfide Thin-Film Solar Cells by Vapor Deposition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To sustain future civilization, the development of alternative clean-energy technologies to replace fossil fuels has become one of the most crucial and challenging problems of the last few decades. The thin film solar cell is one of the major photovoltaic technologies that is promising for renewable energy. The current commercial thin film PV technologies are based on \\(Cu(In,Ga)Se_2\\) and CdTe. Despite their success in reducing the module cost below $1/Wp, these absorber materials face limit...

Sinsermsuksakul, Prasert

2013-01-01

276

Overview and Challenges of Thin Film Solar Electric Technologies  

Energy Technology Data Exchange (ETDEWEB)

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

Ullal, H. S.

2008-12-01

277

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 m...

Abou-ras, D.; Kavalakkatt, J.; Nichterwitz, M.; Scha?fer, N.; Harndt, S.; Wilkinson, Aj; Tsyrulin, K.; Schulz, H.; Bauer, F.

2013-01-01

278

Plasmonic rear reflectors for thin-film solar cells: design principles from electromagnetic modelling  

Science.gov (United States)

The use of plasmonic structures to enhance light trapping in solar cells has recently been the focus of significant research, but these structures can be sensitive to various design parameters or require complicated fabrication processes. Nanosphere lithography can produce regular arrays of nanoscale features which could enhance absorption of light into thin films such as those used in novel solar cell designs. Finite-difference-time-domain simulations are used to model a variety of structures producible by this technique and compare them against the use of mirrors as rear reflectors. Through analysis of these simulations, sensitivity of device performance to parameters has been investigated. Variables considered include the feature size and array period, as well as metal and absorber materials selection and thickness. Improvements in idealized photocurrent density are calculated relative to the use of rear mirrors that are a standard for solar cells. The maximum simulated increase to photocurrent density was 3.58mA/cm2 or 21.61% for a 2?m thick Si cell relative to the case where a silver mirror is used as a rear reflector. From this, an initial set of design principles for such structures are developed and some avenues for further investigation are identified.

Disney, Claire E. R.; Pillai, Supriya; Johnson, Craig M.; Xu, Qi; Green, Martin A.

2014-10-01

279

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

International Nuclear Information System (INIS)

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

280

The Cu{sub 2}ZnSnSe{sub 4} thin films solar cells synthesized by electrodeposition route  

Energy Technology Data Exchange (ETDEWEB)

An electrodeposition route for preparing Cu{sub 2}ZnSnSe{sub 4} thin films for thin film solar cell absorber layers is demonstrated. The Cu{sub 2}ZnSnSe{sub 4} thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu{sub 2}ZnSnSe{sub 4} thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10{sup -4} cm{sup -1}, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu{sub 2}ZnSnSe{sub 4}/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

Li Ji; Ma Tuteng; Wei Ming; Liu Weifeng; Jiang Guoshun [CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Zhu Changfei, E-mail: cfzhu@ustc.edu.cn [CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China)

2012-06-15

 
 
 
 
281

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-02-15

282

Light trapping in thin-film solar cells measured by Raman spectroscopy  

International Nuclear Information System (INIS)

In this study, Raman spectroscopy is used as a tool to determine the light-trapping capability of textured ZnO front electrodes implemented in microcrystalline silicon (?c-Si:H) solar cells. Microcrystalline silicon films deposited on superstrates of various roughnesses are characterized by Raman micro-spectroscopy at excitation wavelengths of 442?nm, 514?nm, 633?nm, and 785?nm, respectively. The way to measure quantitatively and with a high level of reproducibility the Raman intensity is described in details. By varying the superstrate texture and with it the light trapping in the ?c-Si:H absorber layer, we find significant differences in the absolute Raman intensity measured in the near infrared wavelength region (where light trapping is relevant). A good agreement between the absolute Raman intensity and the external quantum efficiency of the ?c-Si:H solar cells is obtained, demonstrating the validity of the introduced method. Applications to thin-film solar cells, in general, and other optoelectronic devices are discussed.

283

Characteristics of In-Substituted CZTS Thin Film and Bifacial Solar Cell.  

Science.gov (United States)

Implementing bifacial photovoltaic devices based on transparent conducting oxides (TCO) as the front and back contacts is highly appealing to improve the efficiency of kesterite solar cells. The p-type In substituted Cu2ZnSnS4 (CZTIS) thin-film solar cell absorber has been fabricated on ITO glass by sulfurizing coelectroplated Cu-Zn-Sn-S precursors in H2S (5 vol %) atmosphere at 520 °C for 30 min. Experimental proof, including X-ray diffraction, Raman spectroscopy, UV-vis-NIR transmission/reflection spectra, PL spectra, and electron microscopies, is presented for the interfacial reaction between the ITO back contact and CZTS absorber. This aggressive reaction due to thermal processing contributes to substitutional diffusion of In into CZTS, formation of secondary phases and electrically conductive degradation of ITO back contact. The structural, lattice vibrational, optical absorption, and defective properties of the CZTIS alloy absorber layer have been analyzed and discussed. The new dopant In is desirably capable of improving the open circuit voltage deficit of kesterite device. However, the nonohmic back contact in the bifacial device negatively limits the open circuit voltage and fill factor, evidencing by illumination-/temperature-dependent J-V and frequency-dependent capacitance-voltage (C-V-f) measurements. A 3.4% efficient solar cell is demonstrated under simultaneously bifacial illumination from both sides of TCO front and back contacts. PMID:25340540

Ge, Jie; Chu, Junhao; Jiang, Jinchun; Yan, Yanfa; Yang, Pingxiong

2014-12-10

284

Photoluminescence properties of a-Si:H based thin films and corresponding solar cells  

International Nuclear Information System (INIS)

Amorphous hydrogenated silicon (a-Si:H) is a well-known semiconductor with metastable properties. Direct surface exposure, as it occurs e.g. in rf plasma equipments, introduces damage due to the charged particle bombardment. The paper deals with photoluminiscence properties of virgin, oxide layer covered and chemically treated (in KCN solutions) surfaces of a-Si:H and corresponding solar cell structures. The cyanide treatment improves the electrical characteristics of MOS structures as well as solar cells. X-ray diffraction at grazing incidence and reflectance spectroscopy complete the study. The photoluminescence measurements were performed at liquid helium temperatures at 6 K using an Ar laser and lock-in signal recording device containing the PbS and Ge photodetectors. Photoluminescence bands were observed as broad luminescent peaks between 1.05-1.7 eV. Two new peaks were detected at 1.38 and 1.42 eV. The evolution of the band at ?1.2 eV related to microcrystalline silicon is investigated. The fitting and simulation of photoluminiscence spectra are presented. The surface luminescent properties of a-Si:H based structures (double layers, single thin film solar cells) before and after the passivation are compared with those of very thin oxide layers and chemically treated surfaces

285

Light trapping in thin-film solar cells measured by Raman spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

In this study, Raman spectroscopy is used as a tool to determine the light-trapping capability of textured ZnO front electrodes implemented in microcrystalline silicon (?c-Si:H) solar cells. Microcrystalline silicon films deposited on superstrates of various roughnesses are characterized by Raman micro-spectroscopy at excitation wavelengths of 442?nm, 514?nm, 633?nm, and 785?nm, respectively. The way to measure quantitatively and with a high level of reproducibility the Raman intensity is described in details. By varying the superstrate texture and with it the light trapping in the ?c-Si:H absorber layer, we find significant differences in the absolute Raman intensity measured in the near infrared wavelength region (where light trapping is relevant). A good agreement between the absolute Raman intensity and the external quantum efficiency of the ?c-Si:H solar cells is obtained, demonstrating the validity of the introduced method. Applications to thin-film solar cells, in general, and other optoelectronic devices are discussed.

Ledinský, M., E-mail: ledinsky@fzu.cz [Laboratory of Nanostructures and Nanomaterials, Institute of Physics, Academy of Sciences of the Czech Republic, v. v. i., Cukrovarnická 10, 162 00 Prague (Czech Republic); Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, CH-2000 Neuchâtel (Switzerland); Moulin, E.; Bugnon, G.; Meillaud, F.; Ballif, C. [Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering (IMT), École Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, CH-2000 Neuchâtel (Switzerland); Ganzerová, K.; Vetushka, A.; Fejfar, A. [Laboratory of Nanostructures and Nanomaterials, Institute of Physics, Academy of Sciences of the Czech Republic, v. v. i., Cukrovarnická 10, 162 00 Prague (Czech Republic)

2014-09-15

286

Dyadic Green’s functions of thin films: Applications within plasmonic solar cells  

DEFF Research Database (Denmark)

Optimization and design of silicon solar cells by exploiting light scattering frommetal nanoparticles to increase the efficiency is addressed in the small particle limit from a fundamental point of view via the dyadic Green’s function formulation. Based on the dyadic Green’s function (Green’s tensor) of a three-layer geometry, light scattering from electric point dipoles (representing small metal scatterers) located within a thin layer sandwiched between a substrate and a superstrate is analyzed. Starting from the full dyadic Green’s function we derive analytical near- and far-field approximations. The far-field approximations enable efficient, exact, and separate evaluation of light scattering into waves that propagate in the substrate or the superstrate. Based on the near-field approximation we present a semianalytical expression for the total near-field absorption in the substrate. The theoretical approach is used to analyze realistic configurations for plasmon-assisted silicon solar cells. We showthat by embedding metal nanoscatterers in a thin film with a high refractive index (rutile TiO2 with n ? 2.5) on top of the silicon, the fraction of scattered light that couples into the solar cell can become larger than 96%, and an optical path length enhancement of more than 100 can be achieved.

Jung, Jesper; SØndergaard, Thomas

2011-01-01

287

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

288

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

Directory of Open Access Journals (Sweden)

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

Michard S.

2013-12-01

289

Light trapping in thin-film solar cells measured by Raman spectroscopy  

Science.gov (United States)

In this study, Raman spectroscopy is used as a tool to determine the light-trapping capability of textured ZnO front electrodes implemented in microcrystalline silicon (?c-Si:H) solar cells. Microcrystalline silicon films deposited on superstrates of various roughnesses are characterized by Raman micro-spectroscopy at excitation wavelengths of 442 nm, 514 nm, 633 nm, and 785 nm, respectively. The way to measure quantitatively and with a high level of reproducibility the Raman intensity is described in details. By varying the superstrate texture and with it the light trapping in the ?c-Si:H absorber layer, we find significant differences in the absolute Raman intensity measured in the near infrared wavelength region (where light trapping is relevant). A good agreement between the absolute Raman intensity and the external quantum efficiency of the ?c-Si:H solar cells is obtained, demonstrating the validity of the introduced method. Applications to thin-film solar cells, in general, and other optoelectronic devices are discussed.

Ledinský, M.; Moulin, E.; Bugnon, G.; Ganzerová, K.; Vetushka, A.; Meillaud, F.; Fejfar, A.; Ballif, C.

2014-09-01

290

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

Science.gov (United States)

Cu(In,Ga)Se2 thin film solar cells have attracted a lot of interest because they have shown the highest achieved efficiency (21%) among thin film photovoltaic materials, long-term stability, and straightforward optical bandgap engineering by changing relative amounts of present elements in the alloy. Still, there are several opportunities to further improve the performance of the Cu(In,Ga)Se2 devices. The interfaces between layers significantly affect the device performance, and knowledge of their chemical and electronic structures is essential in identifying performance limiting factors. The main goal of this research is to understand the characteristics of the Cu(In,Ga)Se2-back contact interface in order to design ohmic back contacts for Cu(In,Ga)Se2-based solar cells with a range of band gaps and device configurations. The focus is on developing either an opaque or transparent ohmic back contact via surface modification or introduction of buffer layers in the back surface. In this project, candidate back contact materials have been identified based on modeling of band alignments and surface chemical properties of the absorber layer and back contact. For the first time, MoO3 and WO 3 transparent back contacts were successfully developed for Cu(In,Ga)Se 2 solar cells. The structural, optical, and surface properties of MoO 3 and WO3 were optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. Valence band edge energies were also obtained by analysis of the XPS spectra and used to characterize the interface band offsets. As a result, it became possible to illuminate of the device from the back, resulting in a recently developed "backwall superstrate" device structure that outperforms conventional substrate Cu(In,Ga)Se2 devices in the absorber thickness range 0.1-0.5 microm. Further enhancements were achieved by introducing moderate amounts of Ag into the Cu(In,Ga)Se2 lattice during the co-evaporation method resulting in a 9.7% cell (with 0.3 microm thickness) which has the highest efficiency reported for ultrathin CIGS solar cells to date. In addition, sulfized back contacts including ITO-S and MoS 2 are compared. Interface properties of different contact layers with (Ag,Cu)(In,Ga)Se2 absorber layers with various Ga/(Ga+In) and Ag/(Ag+Cu) ratios are discussed based on the XPS analysis and thermodynamics of reactions.

Simchi, Hamed

291

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.

292

Universality of non-Ohmic shunt leakage in thin-film solar cells  

Science.gov (United States)

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In,Ga)Se2 (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (Ish), across all three solar cell types considered, is characterized by the following common phenomenological features: (a) voltage symmetry about V =0, (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited (SCL) current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism.

Dongaonkar, S.; Servaites, J. D.; Ford, G. M.; Loser, S.; Moore, J.; Gelfand, R. M.; Mohseni, H.; Hillhouse, H. W.; Agrawal, R.; Ratner, M. A.; Marks, T. J.; Lundstrom, M. S.; Alam, M. A.

2010-12-01

293

Compatibility of glass textures with E-beam evaporated polycrystalline silicon thin-film solar cells  

Science.gov (United States)

For polycrystalline silicon thin films on glass, E-beam evaporation capable of high-rate deposition of amorphous silicon (a-Si) film precursor up to 1 ?m/minute is a potentially low-cost solution to replace the main stream a-Si deposition method—plasma enhanced chemical vapour deposition (PECVD). Due to weak absorption of near infrared light and a target of 2 ?m Si absorber thickness, glass substrate texturing as a general way of light trapping is vital to make E-beam evaporation commercially viable. As a result, the compatibility of e-beam evaporation with glass textures becomes essential. In this paper, glass textures with feature size ranging from ˜200 nm to ˜1.5 micron and root-mean-square roughness (Rms) ranging from ˜10 nm to 200 nm are prepared and their compatibility with e-beam evaporation is investigated. This work indicates that e-beam evaporation is only compatible with small smooth submicron sized textures, which enhances J sc by 21 % without degrading V oc of the cells. Such textures improve absorption-based J sc up to 45 % with only 90 nm SiN x as the antireflection and barrier layer; however, the enhancement degrades to ˜10 % with 100 nm SiO x +90 nm SiN x as the barrier layer. The absorption-based J sc is abbreviated by J sc(A), which is deduced by integrating the multiplication product of the measured absorption and the AM1.5G spectrum in the wavelength range 300-1050 nm assuming unity internal quantum efficiency at each wavelength. This investigation is also relevant to other thin-film solar cell technologies which require evaporating the absorber onto textured substrate/superstrate.

Cui, Hongtao; Campbell, Patrick R.; Green, Martin A.

2013-06-01

294

CIGSS Thin Film Solar Cells: Final Subcontract Report, 10 October 2001-30 June 2005  

Energy Technology Data Exchange (ETDEWEB)

This report describes the I-III-VI2 compounds that are developing into a promising material to meet the energy requirement of the world. CuInSe2 (CIS) and its alloy with Ga and S have shown long-term stability and highest conversion efficiency of 19.5%. Among the various ways of preparing CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells, co-evaporation and sputtering techniques are the most promising. Sputtering is an established process for very high-throughput manufacturing. ARCO Solar, now Shell Solar, pioneered the work in CIS using the sputtering technique. The two-stage process developed by ARCO Solar involved sputtering of a copper and indium layer on molybdenum-coated glass as the first step. In the second step, the copper-indium layers were exposed to a selenium-bearing gas such as hydrogen selenide (H2Se) mixed with argon. The hydrogen selenide breaks down and leaves selenium, which reacts and mixes with the copper and indium in such a way to produce very high-quality CIS absorber layer. Sputtering technology has the added advantage of being easily scaled up and promotes roll-to-roll production on flexible substrates. Preliminary experiments were carried out. ZnO/ZnO:Al deposition by RF magnetron sputtering and CdS deposition by chemical-bath deposition are being carried out on a routine basis.

Dhere, N. G.

2006-02-01

295

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

296

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

297

Optimization of thin film silicon solar cells on highly textured substrates  

Energy Technology Data Exchange (ETDEWEB)

Doped layers made of nanostructured silicon phases embedded in a silicon oxide matrix were implemented in thin film silicon solar cells. Their combination with optimized deposition processes for the silicon intrinsic layers is shown to allow for an increased resilience of the cell design to the substrate texture, with high electrical properties conserved on rough substrates. The presented optimizations thus permit turning the efficient light trapping provided by highly textured front electrodes into increased cell efficiencies, as reported for single junction cells and for amorphous silicon (a-Si)/microcrystalline silicon tandem cells. Initial and stabilized efficiencies of 12.7 and 11.3%, respectively, are reported for such tandem configuration implementing a 1.1 {mu}m thick microcrystalline silicon bottom cell. SEM image after FIB cut of an amorphous silicon/microcrystalline silicon tandem cell reported with a stabilized efficiency of 11.3% for a bottom cell thickness of about 1.1 {mu}m. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Despeisse, Matthieu; Battaglia, Corsin; Boccard, Mathieu; Bugnon, Gregory; Charriere, Mathieu; Cuony, Peter; Haenni, Simon; Loefgren, Linus; Meillaud, Fanny; Parascandolo, Gaetano; Soederstroem, Thomas; Ballif, Christophe [Photovoltaics and Thin Film Electronics Laboratory, Institute of Micro-engineering (IMT), Ecole Polytechnique Federale de Lausanne (EPFL), Rue Breguet 2, 2000 Neuchatel (Switzerland)

2011-08-15

298

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

299

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

With the growing population and the increasing environmental problems of the 'common' fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic (PV) systems, can play a major role in the urgently needed energy transition in electricity production. At the present time PV module production is dominated by the crystalline wafer technology. Thin film silicon technology is an alternative solar energy technol...

Franken, R. H. -j

2006-01-01

300

Influence of the substrate geometrical parameters on microcrystalline silicon growth for thin-film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The effect of substrate morphology on the growth and electrical properties of single-junction microcrystalline silicon cells is investigated. A large variety of V-shaped and U-shaped substrates are characterized by scanning electron microscopy (SEM) and the growth of thin-film microcrystalline silicon ({mu}c-Si:H) devices is observed by cross-sectional transmission electron microscopy (TEM). It is shown that enhanced electrical properties of solar cells are obtained when U-shaped substrates are used and the effect is universal, i.e. independent of the substrate or feature size. U-shaped substrates prevent the formation of two dimensional ''cracks'', which are identified as zones of porous material, from propagating throughout the active part of the solar cell. A numerical growth simulation program reproduces satisfactorily these experimental observations. According to these simulations, shadowing effect due to surface morphology and low adatom surface diffusion length are responsible for the formation of cracks in {mu}c-Si:H material. (author)

Python, M.; Madani, O.; Domine, D.; Meillaud, F.; Vallat-Sauvain, E.; Ballif, C. [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering IMT, Photovoltaics and thin film electronics laboratory, Breguet 2, 2000 Neuchatel (Switzerland)

2009-10-15

 
 
 
 
301

Interface properties of Cd-free buffer layers on on CIGSe thin film solar cells  

International Nuclear Information System (INIS)

In order to replace the toxic Cadmium, the substitution of the CdS buffer layer in thin film solar cells based on Cu(In,Ga)(S,Se)2 (CIGSSe) is of great interest. Alternative buffer layers like (In,Al)2S3, In2S3, or (Zn1-x,Mgx)O deposited by conventional sputter and chemical bath deposition techniques, have shown efficiencies close to or comparable to those of CdS containing solar cells. To understand the chemical and electronic properties of these buffer layers and its influence on the absorber, we studied the buffer-absorber interface using photoelectron spectroscopy (XPS, UPS) and inverse photoelectron spectroscopy (IPES). The combination of these non-destructive techniques provides detailed information about the chemical properties of the studied surface, as well as can be used for a direct determination of the conduction and valence band alignment at the heterojunction. Band-gap values at the surface as derived by UPS and IPES are also verified by electron energy loss spectroscopy (EELS). The results are discussed in conjunction with the respective cell parameters.

302

Development of high-efficiency thin-film Si solar cells using zone-melting recrystallization  

Energy Technology Data Exchange (ETDEWEB)

The Via-hole Etching for the Separation of Thin films (VEST) process has been developed based on SOI technology of zone-melting recrystallization (ZMR). In order to obtain high-quality thin-film polycrystalline Si, it was found that the thickness of recrystallized Si film is an important factor. On the other hand, we have newly investigated the module process for the VEST cells. As a result, we have achieved 13.1% efficiency (V{sub oc}: 5.257V, I{sub sc}: 3.43A, FF:0.6695) with a module size of 924.2cm{sup 2}.

Morikawa, H.; Kawama, Y.; Matsuno, Y.; Hamamoto, S.; Imada, K.; Ishihara, T.; Kojima, K.; Ogama, T. [Advanced Technology R and D Center, Mitsubishi Electric Corporation, 4-1, Mizuhara, Itami, Hyogo (Japan)

2001-01-01

303

AgSb(SxSe1?x)2 thin films for solar cell applications  

International Nuclear Information System (INIS)

Highlights: ? AgSb(SxSe1?x)2 thin films were formed by heating Na2SeSO3 dipped Sb2S3/Ag layers. ? S/Se ratio was varied by changing the dipping time in Na2SeSO3 solution. ? Characterized the films using XRD, XPS, SEM, Optical and electrical measurements. ? Band gap engineering of 1?1.1 eV for x = 0.51 and 0.52 respectively. ? PV Glass/FTO/CdS/AgSb(SxSe1?x)2/C were prepared showing Voc = 410 mV, Jsc = 5.7 mA/cm2. - Abstract: Silver antimony sulfoselenide (AgSb(SxSe1?x)2) thin films were prepared by heating glass/Sb2S3/Ag layers after selenization using sodium selenosulphate solution. First, Sb2S3 thin films were deposited on glass substrates from a chemical bath containing SbCl3 and Na2S2O3. Then Ag thin films were thermally evaporated onto glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of selenium dipping was varied as 30 min and 2 h. The heating condition was at 350 °C for 1 h in vacuum. Analysis of X-ray diffraction pattern of the thin films formed after heating showed the formation of AgSb(SxSe1?x)2. Morphology and elemental analysis were done by scanning electron microscopy and energy dispersive X-ray detection. Depth profile of composition of the thin films was performed by X-ray Photoelectron Spectroscopy. The spectral study showed the presence of Ag, Sb, S, and Se, and the corresponding binding energy analysis confirmed the formation of AgSb(SxSe1?x)2. Photovoltaic structures (PV) were prepared using AgSb(SxSe1?x)2 thin films as absorber and CdS thin films as window layers on FTO coated glass substrates. The PV structures were heated at 60–80 °C in air for 1 h to improve ohmic contact. Analysis of J–V characteristics of the PV structures showed Voc from 230 to 490 mV and Jsc 0.28 to 5.70 mA/cm2, under illumination of AM1.5 radiation using a solar simulator

304

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

305

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

Science.gov (United States)

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

Ehsan, Md Amimul

306

Electro deposition of cuprous oxide for thin film solar cell applications  

Science.gov (United States)

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

Shahrestani, Seyed Mohammad

307

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

Science.gov (United States)

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

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

2012-10-01

308

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

Science.gov (United States)

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

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

2014-09-01

309

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

International Nuclear Information System (INIS)

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

310

Fabrication of CZTS-based thin film solar cells using all-solution processing and pulsed light crystallization  

Science.gov (United States)

Solar cells can be produced using thin film based photovoltaic materials; these are highly efficient with respect to their optical properties and manufacturing cost. The prospective thin film solar cells are composed of Copper, Zinc, Tin, and Sulfide, or `CZTS', this contains chemicals, which are both earth-abundant and non-toxic. The all-solution based process is investigated which is on a single-step electro-chemistry deposition that provides all constituents from the same electrolyte. This investigation was successful in our research group with a high degree of success and a photo-thermal energy driven sintering process that forms a CZTS material from the as-deposited chemicals was added. This enables the as-deposited chemicals to be covalently bonded and crystallized without using a costly vacuum process. In post-heat treatment, a homemade intense pulsed lighting (IPL) system was utilized for rapid thermal annealing. The successful deposition of the CZTS thin film was then evaluated and analyzed using cyclic voltammetry (CV), SEM/EDAX, and XRD. It has been concluded that photovoltaic thin film fabrication is truly comparable to the conventional deposition and annealing methods in terms of photovoltaic efficiency and cost-effectiveness.

Munn, Carson; Haran, Shivan; Seok, Ilwoo

2013-04-01

311

Modified textured surface MOCVD-ZnO:B transparent conductive layers for thin-film solar cells  

Science.gov (United States)

Modified textured surface boron-doped ZnO (ZnO:B) transparent conductive layers for thin-film solar cells were fabricated by low-pressure metal organic chemical vapor deposition (LP-MOCVD) on glass substrates. These modified textured surface ZnO:B thin films included two layers. The first ZnO:B layer, which has a pyramid-shaped texture, was deposited under conventional growth conditions, and the second layer, which has a sphere-like structure, at a relatively lower growth temperature. Typical bi-layer ZnO:B thin films exhibit a high electron mobility of 27.6 cm2/(V·s) due to improved grain boundary states. For bi-layer ZnO:B, the haze value increases and the total transmittance decreases with the increasing film thickness of the second modification layer. When applied in hydrogenated microcrystalline silicon (?c-Si:H) thin-film solar cells, the modified textured surface ZnO:B layers present relatively higher conversion efficiency than conventional ZnO:B films.

Xinliang, Chen; Congbo, Yan; Xinhua, Geng; Dekun, Zhang; Changchun, Wei; Ying, Zhao; Xiaodan, Zhang

2014-04-01

312

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

Science.gov (United States)

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

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

2014-07-01

313

Nanostructured thin film silicon solar cells efficiency improvement using gold nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

We report the computational modeling of localized surface plasmon effects arising on gold (Au) nanoparticles deposited on silicon nanohole (SiNH) textured surface for thin film silicon solar cells application. Detailed balance analysis is carried out for the limiting efficiency of an optimized SiNH array textured surface in combination with the surface and bottom-of-a-trench Au nanoparticle array described herein. We found that for the proposed geometry of the solar cell, the short circuit current density (J{sub SC}) and the power conversion efficiency (PCE) are 31.57 mA/cm{sup 2} and 25.42%, respectively, that compare favorably to the predicted J{sub SC} and PCE values of 25.45 mA/cm{sup 2} and 20.87% for an optimized SiNH textured surface without Au nanoparticles. We optimized the silicon dioxide/silicon nitride (SiO{sub 2}/Si{sub 3}N{sub 4}) stack as a passivation layer, retaining the higher optical absorption. The scattering of incident radiation by the Au nanoparticles near their localized plasmon resonance is responsible for higher optical absorption and hence the higher predicted values for J{sub SC} and PCE. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Pudasaini, Pushpa Raj; Ayon, Arturo A. [MEMS Research Lab., Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249 (United States)

2012-08-15

314

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

Science.gov (United States)

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

Meng, Xianqin; Depauw, Valérie; Gomard, Guillaume; El Daif, Ounsi; Trompoukis, Christos; Drouard, Emmanuel; Jamois, Cécile; Fave, Alain; Dross, Frédéric; Gordon, Ivan; Seassal, Christian

2012-07-01

315

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

316

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

317

Applications of microcrystalline hydrogenated cubic silicon carbide for amorphous silicon thin film solar cells  

International Nuclear Information System (INIS)

We demonstrated the fabrication of n-i-p type amorphous silicon (a-Si:H) thin film solar cells using phosphorus doped microcrystalline cubic silicon carbide (?c-3C-SiC:H) films as a window layer. The Hot-wire CVD method and a covering technique of titanium dioxide TiO2 on TCO was utilized for the cell fabrication. The cell configuration is TCO/TiO2/n-type ?c-3C-SiC:H/intrinsic a-Si:H/p-type ?c- SiCx (a-SiCx:H including ?c-Si:H phase)/Al. Approximately 4.5% efficiency with a Voc of 0.953 V was obtained for AM-1.5 light irradiation. We also prepared a cell with the undoped a-Si1-xCx:H film as a buffer layer to improve the n/i interface. A maximum Voc of 0.966 V was obtained

318

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-12-15

319

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

320

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 material’s 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

 
 
 
 
321

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

Science.gov (United States)

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.

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

2013-05-01

322

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. PMID:22997169

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

2012-10-12

323

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

International Nuclear Information System (INIS)

A p-Cu2O/n-TiO2 thin film heterojunction solar cell has been fabricated by electrodeposition of Cu2O on radio-frequency sputtered n-TiO2 thin film. The heterojunction solar cell was characterized by X-ray diffraction, scanning electron microscopy and UV spectroscopy. 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: ? p-Cu2O/n-TiO2 thin film heterojunction was fabricated. ? Conduction and valance band discontinuities were measured. ? The maximum efficiency of solar cell was measured to be 0.15%. ? The defects, band discontinuity and large mismatch caused low efficiency.

324

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

CERN Document Server

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

Wang, DongLin

2014-01-01

325

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

Science.gov (United States)

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

Wang, DongLin; Su, Gang

2014-01-01

326

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)

327

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

Science.gov (United States)

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

Wang, Donglin; Su, Gang

2014-11-01

328

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 the ...

Aberle, A. G.; Wong, J.; Ouyang, Z.; Kunz, O.

2009-01-01

329

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.

330

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

331

Liquid-phase pulsed laser ablation and electrophoretic deposition for chalcopyrite thin-film solar cell application.  

Science.gov (United States)

We report ligand-free synthesis of colloidal metallic nanoparticles using liquid-phase pulsed laser ablation, and electrophoretic deposition of the nanoparticles for fabrication of Cu(In,Ga)Se(2) (CIGS) thin film solar cells. First, colloidal metallic nanoparticles of Cu-In and Cu-Ga alloys are produced by pulsed laser ablation in common organic solvents without using stabilizing ligands. The nanoparticles are examined for phase, composition, and electrical surface charging and charge modulation mechanisms. Metallic precursor thin films with high purity and precise composition are produced by electrophoretic deposition of the colloids without transferring to another solvent and without using binders. Finally, we demonstrate fabrication of CIGS solar cells on Mo sheet substrates with an (active area) energy conversion efficiency up to 7.37%. PMID:23206317

Guo, Wei; Liu, Bing

2012-12-01

332

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 500°C. 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

333

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

Energy Technology Data Exchange (ETDEWEB)

In this work, we report on the performances of superstrate Cu(In,Ga)Se{sub 2} (CIGS) thin film solar cells with an alternative SLG/SnO{sub 2}:F/CIGS/In{sub 2}Se{sub 3}/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 In{sub 2}Se{sub 3} buffer and CIGS absorber layers and the SnO{sub 2}:F layer is just a transparent conducting oxide (TCO). The simulation has been carried out by lighting through SnO{sub 2}: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 In{sub 2}Se{sub 3} 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.

Bouchama, I., E-mail: bouchama_idris@yahoo.fr [Laboratoire Procedes Materiaux et Energie solaire PROMES-CNRS, Rambla de la Thermodynamique, Technosud, 66100 Perpignan (France); Laboratoire L.I.S., Universite Ferhat Abbas de Setif (Algeria); Djessas, K. [Laboratoire Procedes Materiaux et Energie solaire PROMES-CNRS, Rambla de la Thermodynamique, Technosud, 66100 Perpignan (France); Djahli, F. [Laboratoire L.I.S., Universite Ferhat Abbas de Setif (Algeria); Bouloufa, A. [Laboratoires C.C.N.S. et E. M., Universite Ferhat Abbas de Setif (Algeria)

2011-08-31

334

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

International Nuclear Information System (INIS)

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

335

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.

336

Numerical modeling of thin-film solar cells with Cu(In,Ga)Se2 (CIGS) and CdTe absorbers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis analyses the world of thin-film solar cells focusing on two kind of technologies, the first based on copper-indium-gallium diselenide, also called CIGS, the second one on cadmium telluride. The aim of this work in particular is giving suggestions on how to increase the conversion efficiency of these devices by improving knowledge and understanding of their physical behavior. Thin-film solar cells based on CIGS or CdTe absorbers have been studied in research la...

Troni, Fabrizio

2013-01-01

337

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

338

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

339

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Aeberhard, Urs

2014-01-01

340

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

 
 
 
 
341

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

342

Improved Thin Film Solar Cells Made by Vapor Deposition of Earth-Abundant Tin(II) Sulfide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tin(II) sulfide (SnS) is an earth-abundant, inexpensive, and non-toxic absorber material for thin film solar cells. SnS films are deposited by atomic layer deposition (ALD) through the reaction of a tin precursor, bis(N,N'-diisopropylacetamidinato)tin(II), and hydrogen sulfide. The SnS films demonstrate excellent surface morphology, crystal structure, phase purity, stoichiometry, elemental purity, and optical and electrical properties.

Sun, Leizhi

2014-01-01

343

Thin-film monocrystalline-silicon solar cells based on a seed layer approach with 11% efficiency  

Science.gov (United States)

Solar modules made from thin-film crystalline-silicon layers of high quality on glass substrates could lower the price of photovoltaic electricity substantially. Almost half of the price of wafer-based silicon solar modules is currently due to the cost of the silicon wafers themselves. Using crystalline-silicon thin-film as the active material would substantially reduce the silicon consumption while still ensuring a high cell-efficiency potential and a stable cell performance. One way to create a crystalline-silicon thin film on glass is by using a seed layer approach in which a thin crystalline-silicon layer is first created on a non-silicon substrate, followed by epitaxial thickening of this layer. In this paper, we present new solar cell results obtained on 10-micron thick monocrystalline-silicon layers, made by epitaxial thickening of thin seed layers on transparent glass-ceramic substrates. We used thin (001)-oriented silicon single-crystal seed layers on glass-ceramic substrates provided by Corning Inc. that are made by a process based on anodic bonding and implant-induced separation. Epitaxial thickening of these seed layers was realized in an atmospheric-pressure chemical vapor deposition system. Simple solar cell structures in substrate configuration were made from the epitaxial mono-silicon layers. The Si surface was plasma-textured to reduce the front-side reflection. No other light trapping features were incorporated. Efficiencies of up to 11% were reached with Voc values above 600 mV indicating the good electronic quality of the material. We believe that by further optimizing the material quality and by integrating an efficient light trapping scheme, the efficiency potential of these single-crystal silicon thin films on glass-ceramics should be higher than 15%.

Gordon, I.; Qiu, Y.; Van Gestel, D.; Poortmans, J.

2010-09-01

344

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

345

Photonic crystal structures for light trapping in thin-film Si solar cells: Modeling, process and optimizations  

Science.gov (United States)

In this paper, we present our efforts on studying light trapping in thin-film silicon solar cells using photonic crystal (PC) based structures. Specifically, we propose a photonic backside texture combining periodic gratings and a distributed Bragg reflector (DBR). The mechanisms of this integrated photonic design are theoretically studied and compared with conventional PCs. We experimentally fabricate the texture using lithographic and self-assembled method on thin-film single crystalline Si (c-Si) and micro-crystalline Si (?c-Si) cells. We analyze the effects of the photonic textures on different cells and demonstrate the performance improvements. A numerical method is developed to explore the optimal multiscale textured surface and investigate light trapping limits in the wave optics regime. Using a detailed balance analysis, we show that it is possible to reach over 20% efficiency for 1.5 ?m Si cells through optimal device design and fabrication.

Sheng, Xing; Broderick, Lirong Z.; Kimerling, Lionel C.

2014-03-01

346

Mimicry of Sputtered i-ZnO Thin Films Using Chemical Bath Deposition for Solution-Processed Solar Cells.  

Science.gov (United States)

Solution processing provides a versatile and inexpensive means to prepare functional materials with specifically designed properties. The current challenge is to mimic the structural, optical, and/or chemical properties of thin films fabricated by vacuum-based techniques using solution-based approaches. In this work we focus on ZnO to show that thin films grown using a simple, aqueous-based, chemical bath deposition (CBD) method can mimic the properties of sputtered coatings, provided that the kinetic and thermodynamic reaction parameters are carefully tuned. The role of these parameters toward growing highly oriented and dense ZnO thin films is fully elucidated through detailed microscopic and spectroscopic investigations. The prepared samples exhibit bulk-like optical properties, are intrinsic in their electronic characteristics, and possess negligible organic contaminants, especially when compared to ZnO layers deposited by sol-gel or from nanocrystal inks. The efficacy of our CBD-grown ZnO thin films is demonstrated through the effective replacement of sputtered ZnO buffer layers within high efficiency solution processed Cu2ZnSnS4xSe4(1-x) solar cells. PMID:25506738

Della Gaspera, Enrico; van Embden, Joel; Chesman, Anthony S R; Duffy, Noel W; Jasieniak, Jacek J

2014-12-24

347

Nanophotonic light trapping in polycrystalline silicon thin-film solar cells using periodically nanoimprint-structured glass substrates  

Science.gov (United States)

A smart light trapping scheme is essential to tap the full potential of polycrystalline silicon (poly-Si) thin-film solar cells. Periodic nanophotonic structures are of particular interest as they allow to substantially surpass the Lambertian limit from ray optics in selected spectral ranges. We use nanoimprint-lithography for the periodic patterning of sol-gel coated glass substrates, ensuring a cost-effective, large-area production of thin-film solar cell devices. Periodic crystalline silicon nanoarchitectures are prepared on these textured substrates by high-rate silicon film evaporation, solid phase crystallization and chemical etching. Poly-Si microhole arrays in square lattice geometry with an effective thickness of about 2?m and with comparatively large pitch (2 ?m) exhibit a large absorption enhancement (A900nm = 52%) compared to a planar film (A900nm ~ 7%). For the optimization of light trapping in the desired spectral region, the geometry of the nanophotonic structures with varying pitch from 600 nm to 800 nm is tailored and investigated for the cases of poly-Si nanopillar arrays of hexagonal lattice geometry, exhibiting an increase in absorption in comparison to planar film attributed to nanophotonic wave optic effects. These structures inspire the design of prospective applications such as highly-efficient nanostructured poly-Si thin-film solar cells and large-area photonic crystals.

Becker, Christiane; Xavier, Jolly; Preidel, Veit; Wyss, Philippe; Sontheimer, Tobias; Rech, Bernd; Probst, Jürgen; Hülsen, Christoph; Löchel, Bernd; Erko, Alexei; Burger, Sven; Schmidt, Frank; Back, Franziska; Rudigier-Voigt, Eveline

2013-09-01

348

Manufacture of mullite substrates from andalusite for the development of thin film solar cells  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this work is the manufacture of dense thin mullite substrates by tape casting of the natural silicate mineral andalusite. The targeted application for such substrates is the manufacture of thin film solar cells. Indeed, in addition to a good resistance at high temperature (up to 1200 {sup o}C), this application requires a good correspondence between the thermal expansion coefficient of the substrate and silicon film in order to lower the stresses in the film and in the substrate after cooling. The work was performed in three successive stages. First, the study of the transformation during sintering of andalusite+alumina mixtures. Second, the optimisation of the slurries and of the parameters for tape casting. Finally, green tapes prepared from various powder compositions were characterised before and after sintering. The addition of alumina to andalusite reduces the final amount of vitreous phase. This limits the risk of impurity diffusion in the silicon film. However, the addition of alumina also slows down the sintering process leading to more porosity in the substrates. A good compromise is obtained with an initial mixture of 80 wt.% andalusite with 20 wt.% alumina. In that case, the thermal expansion behaviour is very close to pure mullite and the mechanical properties of the substrates can be considered as sufficient for the targeted application. (author)

Mazel, F.; Gonon, M.; Fantozzi, G. [GEMPPM - UMR CNRS 5510 - INSA-Lyon (France)

2001-07-01

349

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

Science.gov (United States)

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

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

2013-09-01

350

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

351

POLYCRYSTALLINE THIN FILM SOLAR CELLS:Present Status and Future Potential  

Science.gov (United States)

Polycrystalline thin film solar cells on copper indium diselenide (CulnSe2) and its alloys and cadmium telluride (CdTe) appear to be the most promising candidates for large-scale application of photovoltaic energy conversion because they have shown laboratory-efficiences in excess of 15%. Heterojunction devices with n-type cadmium sulfide (CdS) films show very low minority carrier recombination at the absorber grain boundaries and at the metallurgical interface, which results in high quantum efficiences. Open circuit voltages of these devices are relatively low owing to the recombination in the space charge region in the absorber. Further improvements in efficiency can be achieved by reducing the recombination current, especially in devices based on CulnSe2 and its alloys. Low-cost manufacturing of modules requires better resolution of a number of other technical issues. For modules based on CulnSe2 and its alloys, the role of Na and higher deposition rates on device performance need to be better understood. In addition, replacing the chemical bath deposition method for CdS film deposition with an equally effective, but more environmentally acceptable process is needed. For modules based on CdTe, more fundamental understanding of the effect of chloride/oxygen treatment and the development of more reproducible and manufacturable CdTe contacting schemes are necessary.

Birkmire, Robert W.; Eser, Erten

1997-08-01

352

An Al x In1- x As/GaAs heterojunction ultra-thin film solar cell with 20% efficiency  

Science.gov (United States)

An ultra-thin film photovoltaic cell, which incorporates an Al x In1- x As/GaAs heterojunction, is simulated using Adept 1D simulation tool, and it is with an energy conversion efficiency of 20.06% (under 1 sun, AM1.5G illumination) for 604 nm cell thickness (excluding the substrate thickness), and optimized layer thickness and doping concentration for each layer of the device. The device has an n-type AlAs window layer (highly doped), an n-type Al x In1- x As emitter layer and a p-type GaAs base layer. Germanium (Ge) substrate is used for the structure. The device parameters are optimized separately for each layer. Based on these optimizations, the ultra-thin film solar cell design is proposed after careful consideration of lattice mismatch between two adjacent layers of the device.

Haque, K. A. S. M. Ehteshamul

2013-05-01

353

A pilot investigation on laser annealing for thin-film solar cells: Crystallinity and optical properties of laser-annealed CdTe thin films by using an 808-nm diode laser  

Science.gov (United States)

Compared to conventional furnace and rapid thermal annealing, laser annealing for heterojunctioned thin-film solar cells has several advantages including excellent annealing selectivity to the under-layers with a localized high temperature for a short process time. A continuous wave 808-nm diode laser was used for the laser annealing process of CdTe thin films for various output powers. The grains in the laser-annealed CdTe thin films grew along the C (111), H (110), and C (311) planes. Laser annealing resulted in an increase in grain size and a decrease in surface roughness. The optical band gap energy of the CdTe thin films was affected directly by the grain size, showing 1.460 eV and 1.415 eV for the as-deposited and laser-annealed CdTe thin films, respectively. The absorbance of the CdTe thin films with better crystallinity showed an improved value of 99.5-99.9% in the visible spectral region after laser annealing at an output power of 0.91 W.

Kim, Nam-Hoon; Park, Chan Il; Park, Jinseong

2013-02-01

354

Polycrystalline silicon thin film solar cells prepared by PECVD-SPC  

Energy Technology Data Exchange (ETDEWEB)

Among the most promising technological alternatives for the development of photovoltaic modules and cells of a low cost, good energetic conversion and feasibility for mass production, polycrystalline silicon thin film solar cells deposited directly on a transparent substrate are currently being considered the best. We have developed in our laboratory a PECVD reactor capable of producing the deposition of amorphous hydrogenated silicon at rates of above 2 nm/seg, allowing a significant production per line on the plant. Discharge gas is silane, to which diborane or phosphine is added so as to form the cell. Basically, work is done on a structure of cell type TCO/n+/p-/p+/M, which has 2 {mu}m of total thickness. Schott AF-37 glass is used as a substrate, for their ability to withstand temperatures of up to 800 C. The amorphous cell is subsequently annealed at gradual temperatures of 100 C to achieve dehydrogenation up to 650-700 C for 12 h until their complete crystallization is achieved. Our results show a complete crystallization of silicon with a grain size of less than a micron, with a dehydrogenation process at 500 C, leaving a remainder of less than 1% in hydrogen as monohydrate. The parameters of the cell estimated from the IV curve yield low values, FF<0.55, Icc <200 {mu}A and Voc<420 mV. The high series resistance is due to the grain size and defect density, which will be attempted to be improved by post-hydrogenation and rapid thermal annealing (RTA) methods at high temperatures. (author)

Buitrago, R.H.; Risso, G.A.; Cutrera, M.; Battioni, M.; De Bernardez, L.; Schmidt, J.A.; Arce, R.D.; Koropecki, R.R. [Instituto de Desarrollo Tecnologico para la Industria Quimica, CONICET-UNL, Guemes 3450, CP 3000, Santa Fe (Argentina)

2008-07-15

355

Plasmonic-photonic arrays with aperiodic spiral order for ultra-thin film solar cells.  

Science.gov (United States)

We report on the design, fabrication and measurement of ultra-thin film Silicon On Insulator (SOI) Schottky photo-detector cells with nanostructured plasmonic arrays, demonstrating broadband enhanced photocurrent generation using aperiodic golden angle spiral geometry. Both golden angle spiral and periodic arrays of various center-to-center particle spacing were investigated to optimize the photocurrent enhancement. The primary photocurrent enhancement region is designed for the spectral range 600nm-950nm, where photon absorption in Si is inherently poor. We demonstrate that cells coupled to spiral arrays exhibit higher photocurrent enhancement compared to optimized periodic gratings structures. The findings are supported through coupled-dipole numerical simulations of radiation diagrams and finite difference time domain simulations of enhanced absorption in Si thin-films. PMID:22712091

Trevino, Jacob; Forestiere, Carlo; Di Martino, Giuliana; Yerci, Selcuk; Priolo, Francesco; Dal Negro, Luca

2012-05-01

356

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2013-01-01

357

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

358

Band Gap Profiling and High Speed Deposition of Cu(In,Ga)Se2 for Thin Film Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Cu(In,Ga)Se2-based thin film solar cell is a promising candidate for becoming one of the more important solar cell technologies in the near future. In order to realize such a development a significant reduced production cost of the Cu(In,Ga)Se2 (CIGS) layer is needed. This work shows a possible way towards such a reduction by increasing the deposition rate and decreasing the CIGS thickness with almost maintained device efficiency. Obtaining an improved device performance in CIGS-based sol...

Lundberg, Olle

2003-01-01

359

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

360

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.

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

2014-05-01

 
 
 
 
361

In situ monitoring the growth of thin-film ZnS/Zn (S,O) bilayer on Cu-chalcopyrite for high performance thin film solar cells  

International Nuclear Information System (INIS)

This paper highlights the crucial role that the control of the chemical bath deposition (CBD) process plays for buffer production of Cu-chalcopyrite solar-cell devices. ZnS/Zn (S,O) bilayer was deposited on CuInS2 (CIS) and Cu(In,Ga)(SSe)2 (CIGSSe) and monitored using turbidity measurements of the solution. The results were correlated to the X-ray photoemission spectra of the samples obtained by interruption of the process at sequential stages. Two different feature regimes were distinguished: In the first stage, a heterogeneous reaction takes place on the absorber resulting in the formation of pure ZnS. The second stage of the process is homogeneous, and the in-situ turbidity measurement shows a loss in the transmission of light through the CBD solution. The measured ZnL3M45M45 Auger-peaks, during this second stage of the process, show a shift of the kinetic energy from pure ZnS to a solid-solution ZnS/ZnO ('Zn (S,O)') with decreasing amount of sulfur. These results are supported by the observations from Energy-filtered transmission electron microscopy. This paper also demonstrates that monitoring of the CBD process combined with the basic understanding using surface and interface analysis have contributed to improve the reproducibility and to enhance the photovoltaic performance of Cu-chalcopyrite thin-film solar modules

362

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

International Nuclear Information System (INIS)

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

363

Quantitative analysis of the contribution of nanocone gratings to the efficiency of crystalline Si thin-film solar cells  

Science.gov (United States)

Quantitative analysis of the contribution from different physics mechanisms induced by nanocone gratings (NCG) to the efficiency of crystalline Si thin-film solar cells is systematically demonstrated through the performance comparison of such a nanotextured Si solar cell, an equivalent reflection planar Si solar cell, an equivalent volume planar Si solar cell and an actually planar Si solar cell, when their back-interface is a perfect-matched layer or air and their thickness is 1 µm or 10 µm. The results indicate that the contribution of each physics mechanism to the ultimate efficiency and their total contribution are significantly influenced by the thickness of their active layer. When the height of the NCG structure is comparable to the thickness of the active layer, the contribution from each physics mechanism to the efficiency must be considered. In that respect, the contribution from the guided-mode resonance effect is the largest, and even surpasses the contribution of the active layer itself. When the active layer is significantly thicker than the height of the NCG structure, the contribution from antireflection induced by such a nanostructure rises up to the most, and the volume reduction effect can be ignored. In addition, the cavity-resonance effect exhibits a weak contribution and seems to be insensitive to the active layer thickness and interface reflection. Such an investigation provides a methodology to optimize nanostructure-textured thin-film solar cells. Furthermore, the comparison of efficiency between a 1 µm thick NCG-textured solar cell and a 10 µm thick planar solar cell indicates that higher efficiency can be achieved in a thinner Si solar cell by the use of the optimized NCG structure, which just fulfils the expectation of third generation of Si solar cells.

Zhang, R. Y.; Zhang, Z.; Shao, B.; Dong, J. R.; Yang, H.

2013-04-01

364

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

365

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

366

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

International Nuclear Information System (INIS)

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

367

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.)

368

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

Science.gov (United States)

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 (SiH 4) and hydrogen (H 2) in a radiofrequency (rf) plasma. During the last few decades, the plasma deposition parameter regime has been explored intensively, in particular to improve the quality of nc-Si:H and to increase its deposition rate. The desired formation of nanocrystallites occurs under growth conditions close to the transition regime. A technique that is not plasma based is hot-wire CVD (HWCVD), which is based on catalytic decomposition of SiH 4 and dissociation of H 2 gases on a hot filament. Because source gases are catalytically decomposed, the method is often referred to as catalytic CVD (Cat-CVD). The HWCVD technique has been shown to be a viable method for the deposition of silicon-based thin films and solar cells. We discuss the progress at our laboratory. Specifically, recent single junction and multijunction n-i-p-type solar cells are highlighted. Improvements have been achieved by addressing, among others, the morphology of the light-scattering rough surfaces, to avoid cavities and shunting paths, and by studying the structural evolution of the nanocrystalline phase during growth. The obtained solar cells are highly stable against light soaking.

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

2009-01-01

369

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-04-15

370

Fabrication of solution processed 3D nanostructured CuInGaS2 thin film solar cells  

Science.gov (United States)

In this study we demonstrate the fabrication of CuInGaS2 (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ˜1.3 ?m. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ˜6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions.

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

2014-03-01

371

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Moulin, Etienne

2009-01-01

372

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

International Nuclear Information System (INIS)

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

373

A study of the applicability of ZnO thin-films as anti-reflection coating on Cu{sub 2}ZnSnS{sub 4} thin-films solar cell  

Energy Technology Data Exchange (ETDEWEB)

Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF{sub 2}. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

Ray, Abhijit; Patel, Malkeshkumar; Tripathi, Brijesh; Kumar, Manoj [School of Solar Energy, Panditdeendayal Petroleum University, Raisan, Gandhinagar, Gujarat (India)

2012-06-25

374

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

375

Opto-electronic properties of rough LP-CVD ZnO:B for use as TCO in thin-film silicon solar cells  

International Nuclear Information System (INIS)

Polycrystalline Boron-doped ZnO films deposited by low pressure chemical vapor deposition technique are developed for their use as transparent contacts for thin-film silicon solar cells. The size of the columnar grains that constitute the ZnO films is related to their light scattering capability, which has a direct influence on the current generation in thin-film silicon solar cells. Furthermore, if the doping level of the ZnO films is kept below 1 x 1020 cm-3, the electron mobility can be drastically enhanced by growing large grains, and the free carrier absorption is reduced. All these considerations have been taken in account to develop ZnO films finely optimized for the fabrication of microcrystalline thin-film silicon solar cells. These TCO allow the achieve