The Development of CuIn1-xALSe2 Thin Films for Use in Photovoltaic Solar Cells PDF Download
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Author: Paresh S. Nasikkar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The aim of the work presented in this thesis was to develop CuInSe2 (CIS) and CuIni_?Al?Se2 (CIAS) thin films for application in photovoltaic (PV) solar cells. The purpose of the addition of aluminium (Al) in CIS thin films was to modify the energy band gap of the thin films to be nearer to the optimum for PV energy conversion and to replace the less abundant element, gallium (Ga) in CuIni_, Ga, Se2 (CIGS) solar cells. This also makes possible the production of tandem solar cells using CIAS to make the wide energy band gap top cell and the CIS to make the narrow energy band gap lower cell. The use of very thin CIS and CIAS absorber layers in solar cell structures was also investigated; the aim was to reduce the amount of indium (In) in cell production. The CIS and CIAS absorber films were prepared by a sequential two step method in which Cu-In and Cu-In-Al precursor layers were magnetron sputter deposited onto Mo-coated soda lime glass (SLG) substrates; the CIS or CIAS was then formed by heating in a selenium (Se) containing environment. Thin film solar cells were developed in the substrate configuration and had the structure Ni-Al/Indium tin oxide (ITO)/i-ZnO/CdS/CIAS/Mo/SLG. In order to achieve high efficiency solar cells it is an important to optimse the back contact molybdenum (Mo) layer, the absorber layer, the CdS buffer layer, the window layer and top contact layers. The work described in this thesis focused on the optimisation of the back contact and absorber layers. The thin films were characterised mainly using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), secondary ion mass spectroscopy (MiniSIMS), atomic force microscopy (AFM) and using spectroscopy measurements to investigate the effect of processing conditions on the composition, crystal structure, surface morphology and the optical properties of the films. The solar cells were characterised by current-voltage (/- V) and incident photon-to-photocurrent conversion efficiency (IPCE) measurements. Both Mo single and bilayer structures were investigated. It was found that single layers had better properties than Mo bilayers. The optimisation of the Mo deposition sputtering process yielded Mo layers which had good adherence and were conformal to the glass substrates, had low resistivity (29 if .cm), were pin hole free and had good crystallinity. The influence of Cu-In precursor layers with thicknesses in the range 90-400 nm on the microstructure of the CIS thin films (thicknesses in the range 400-1600 nm) was investigated. Solar cells fabricated from the CIS films of thicknesses 500 nm and 900 nm yielded highest cell conversion efficiencies of 4.3% and 8.2%, respectively. The selenisation of the magnetron sputter deposited Cu-In-Al precursor layers was carried out at a temperature of 550?C. Films were poor in surface quality and adhesion. Films prepared from the precursor layer with n [(Al/(Al+In))] = 0.21 had a non-uniform Al depth profile towards the bottom of the film. Although the film was found to be photoactive its effective energy band gap was 0.98 eV suggesting the properties of CIS. This confirmed incomplete mixing of Al in the thin films which was considered to be segregated at the bottom of the film. The thinner layers of Cu-In-Al precursors with thicknesses in the range 0.55?1.00 gm and n [(Al/Al+In)] in the range 0.28-0.54 were magnetron sputter deposited. The precursor layers showed the prominent binary A1Cu4 compound with a uniform distribution of Al in the layer. Thin films converted from these precursor layers of thicknesses in the range 1.3-2.0 pm were fairly uniform in surface structure. Films with x 0.2 were found to have an energy bandgap of 1.10 eV and were also photoactive. Solar cells fabricated from this absorber film yielded a highest cell efficiency of 4.9%. Environmental impact assessments have been made on materials and the processes used in the fabrication of CIS and CIAS and solar cells. It was found that there is no critical environmental impact of materials and associated processes involved in the fabrication of CIS and CIAS thin film solar cells.
Author: Paresh S. Nasikkar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The aim of the work presented in this thesis was to develop CuInSe2 (CIS) and CuIni_?Al?Se2 (CIAS) thin films for application in photovoltaic (PV) solar cells. The purpose of the addition of aluminium (Al) in CIS thin films was to modify the energy band gap of the thin films to be nearer to the optimum for PV energy conversion and to replace the less abundant element, gallium (Ga) in CuIni_, Ga, Se2 (CIGS) solar cells. This also makes possible the production of tandem solar cells using CIAS to make the wide energy band gap top cell and the CIS to make the narrow energy band gap lower cell. The use of very thin CIS and CIAS absorber layers in solar cell structures was also investigated; the aim was to reduce the amount of indium (In) in cell production. The CIS and CIAS absorber films were prepared by a sequential two step method in which Cu-In and Cu-In-Al precursor layers were magnetron sputter deposited onto Mo-coated soda lime glass (SLG) substrates; the CIS or CIAS was then formed by heating in a selenium (Se) containing environment. Thin film solar cells were developed in the substrate configuration and had the structure Ni-Al/Indium tin oxide (ITO)/i-ZnO/CdS/CIAS/Mo/SLG. In order to achieve high efficiency solar cells it is an important to optimse the back contact molybdenum (Mo) layer, the absorber layer, the CdS buffer layer, the window layer and top contact layers. The work described in this thesis focused on the optimisation of the back contact and absorber layers. The thin films were characterised mainly using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), secondary ion mass spectroscopy (MiniSIMS), atomic force microscopy (AFM) and using spectroscopy measurements to investigate the effect of processing conditions on the composition, crystal structure, surface morphology and the optical properties of the films. The solar cells were characterised by current-voltage (/- V) and incident photon-to-photocurrent conversion efficiency (IPCE) measurements. Both Mo single and bilayer structures were investigated. It was found that single layers had better properties than Mo bilayers. The optimisation of the Mo deposition sputtering process yielded Mo layers which had good adherence and were conformal to the glass substrates, had low resistivity (29 if .cm), were pin hole free and had good crystallinity. The influence of Cu-In precursor layers with thicknesses in the range 90-400 nm on the microstructure of the CIS thin films (thicknesses in the range 400-1600 nm) was investigated. Solar cells fabricated from the CIS films of thicknesses 500 nm and 900 nm yielded highest cell conversion efficiencies of 4.3% and 8.2%, respectively. The selenisation of the magnetron sputter deposited Cu-In-Al precursor layers was carried out at a temperature of 550?C. Films were poor in surface quality and adhesion. Films prepared from the precursor layer with n [(Al/(Al+In))] = 0.21 had a non-uniform Al depth profile towards the bottom of the film. Although the film was found to be photoactive its effective energy band gap was 0.98 eV suggesting the properties of CIS. This confirmed incomplete mixing of Al in the thin films which was considered to be segregated at the bottom of the film. The thinner layers of Cu-In-Al precursors with thicknesses in the range 0.55?1.00 gm and n [(Al/Al+In)] in the range 0.28-0.54 were magnetron sputter deposited. The precursor layers showed the prominent binary A1Cu4 compound with a uniform distribution of Al in the layer. Thin films converted from these precursor layers of thicknesses in the range 1.3-2.0 pm were fairly uniform in surface structure. Films with x 0.2 were found to have an energy bandgap of 1.10 eV and were also photoactive. Solar cells fabricated from this absorber film yielded a highest cell efficiency of 4.9%. Environmental impact assessments have been made on materials and the processes used in the fabrication of CIS and CIAS and solar cells. It was found that there is no critical environmental impact of materials and associated processes involved in the fabrication of CIS and CIAS thin film solar cells.
Author: K.L. Chopra
Publisher: Springer Science & Business Media
ISBN: 9780306411410
Category : Science
Languages : en
Pages : 630
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Book Description
"You, 0 Sun, are the eye of the world You are the soul of all embodied beings You are the source of all creatures You are the discipline of all engaged in work" - Translated from Mahabharata 3rd Century BC Today, energy is the lifeline and status symbol of "civilized" societies. All nations have therefore embarked upon Research and Development pro grams of varying magnitudes to explore and effectively utilize renewable sources of energy. Albeit a low-grade energy with large temporal and spatial variations, solar energy is abundant, cheap, clean, and renewable, and thus presents a very attractive alternative source. The direct conver sion of solar energy to electricity (photovoltaic effect) via devices called solar cells has already become an established frontier area of science and technology. Born out of necessity for remote area applications, the first commercially manufactured solar cells - single-crystal silicon and thin film CdS/Cu2S - were available well over 20 years ago. Indeed, all space vehicles today are powered by silicon solar cells. But large-scale terrestrial applications of solar cells still await major breakthroughs in terms of discovering new and radical concepts in solar cell device structures, utilizing relatively more abundant, cheap, and even exotic materials, and inventing simpler and less energy intensive fabrication processes. No doubt, this extraordinary challenge in R/D has led to a virtual explosion of activities in the field of photovoltaics in the last several years.
Author: Subba Ramaiah Kodigala
Publisher: Newnes
ISBN: 0123971829
Category : Technology & Engineering
Languages : en
Pages : 197
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Book Description
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 development of cells. The characterization analyses such as XPS, XRD, SEM, AFM etc., lead to tailor the physical properties of the absorber layers to fit well for the solar cells. The role of secondary phases such as ZnS, Cu2-xS,SnS etc., which are determined by XPS, XRD or Raman, in the absorber layers is promptly discussed. The optical spectroscopy analysis, which finds band gap, optical constants of the films, is mentioned in the book. The electrical properties of the absorbers deal the influence of substrates, growth temperature, impurities, secondary phases etc. The low temperature I-V and C-V measurements of Cu2ZnSn(S1-xSex)4 thin film solar cells are clearly described. The solar cell parameters such as efficiency, fill factor, series resistance, parallel resistance provide handful information to understand the mechanism of physics of thin film solar cells in the book. The band structure, which supports to adjust interface states at the p-n junction of the solar cells is given. On the other hand the role of window layers with the solar cells is discussed. The simulation of theoretical efficiency of Cu2ZnSn(S1-xSex)4 thin film solar cells explains how much efficiency can be experimentally extracted from the cells. - One of the first books exploring how to conduct research on thin film solar cells, including reducing costs - Detailed instructions on conducting research
Author: E. Ahmed
Publisher:
ISBN:
Category :
Languages : en
Pages : 346
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Author: Ganesh E. Patil
Publisher: LAP Lambert Academic Publishing
ISBN: 9783844390292
Category :
Languages : en
Pages : 112
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Book Description
Solar energy being the most important source of energy, several technologies have been developed for utilization of solar energy. Photovoltaic devices popularly known as solar cells convert solar energy into the electricity which is the most convenient form of energy. Hence thin film photovoltaic technologies are being developed. Thin film solar cell concept is being persued since the inception of photovoltaic devices. For making thin film solar cells many technologies such as CVD, Spray Pyrolysis, Glow Discharge, CBD, Electrodeposition, etc. have been used in the laboratories. The book proposes the simple Chemical Bath Deposition (CBD) technique for synthesizing thin films. The experimental results on synthesis and structural, optical, electrical properties of Cd(S, Se), CdZnS thin films and p-Cu2Se/n-CuBiSe2 hetero- junction thin films for solar cell applications by CBD are discussed. This book will be helpful for students, teachers and researchers for synthesis of thin films by using simple Chemical Bath Deposition technique.
Author: Martin A. Green
Publisher:
ISBN: 9780642191519
Category : Solar cells
Languages : en
Pages : 24
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Author: Rémi Aninat
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Cu-In, Cu-Al and Cu-In-Al metallic precursor layers were deposited using radio-frequency magnetron sputtering and selenised to produce thin films of CuInSe2 (CIS), CuAlSe2 (CAS) and CuIn1-xAlxSe2 (CIAS), respectively. The selenisation stage of this 2-stage process was carried out in a tube furnace (TF) or a rapid thermal processor (RTP) in the presence of elemental Se, either deposited on top of the precursor film or provided from an external source in the chamber, in order to fabricate the chalcopyrite material. The aim was to produce single phase, device quality CIS, CAS and CIAS for use as an absorber layer material in thin film photovoltaic solar cells. Profilometry performed on the as-deposited Cu-In-Al metallic precursors showed an important increase in surface roughness compared to the Cu-In and Cu-Al precursors. This was found to be due to the preferential formation of Cu9(In,Al)4, which stoichiometry led the excess In to form island-shaped In phases at the surface of the bulk, while only Cu2In and CuIn2 formed in Cu-In precursors. Regarding the selenisation, temperatures ranging from 250°C to 550°C were used, and the resulting samples were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) and glow-discharge optical emission spectroscopy (GD-OES). Thin films of single phase CIS and CAS were successfully produced with energy band gaps of 0.99 eV and 2.68 eV, respectively. However the incorporation of Al proved to be difficult. The results showed that no incorporation of the Al into the chalcopyrite lattice was achieved in the samples selenised in the RTP, which was believed to be due to the oxidation of the element Al into amorphous Al2O3. In the tube furnace, possibly due to lower levels of oxidation, incorporation occurred more readily but Al and In segregated towards the back and front of the layer, respectively. The causes of the segregation were studied and solutions to avoid it developed, resulting under certain conditions in successful production of CuIn1-xAlxSe2. Samples were tested in a photoelectrochemical cell and showed (apparent) external quantum efficiency values comparable to a CuInSe2 (CIS) sample used as a standard.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
We have fabricated high-efficiency thin-film CuIn1-xGaxSe2 (CIGS)-based photovoltaic devices from solution-based electroplated (EP) and auto-plated (AP) precursors. As-deposited precursors are Cu-rich CIGS. Compositions were adjusted to CuIn1-xGaxSe2 with additional In and Ga by physical vapor deposition (PVD) to the EP and AP precursor films. Auger analysis and grazing incident X-ray diffraction(GIXRD) were performed on devices prepared from EP and AP precursor films. We have also analyzed and compared EP, AP, and an PVD CIGS device by deep-level transient spectroscopy (DLTS).
Author: Ankur A. Kadam
Publisher:
ISBN:
Category : Copper indium selenide
Languages : en
Pages : 139
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Book Description
High efficiency CuIn[subscript 1-x]Ga[subscript x]Se[subscript 2-y]S[subsript y] (CIGSS)/CdS thin-film solar cells were prepared by optimizing the Mo back contact layer and optimizing the parameters for preparing CIGSS absorber layer using diethylselenide as selenium source. Mo is used as back contact layer in I-III-VI2 compound thin-film solar cells. The Mo film was sputter deposited on 2.5 cm x 10 cm soda-lime glass using DC magnetron sputtering for studying the adhesion to the substrate and chemical reactivity of Mo with selenium and sulfur containing gas at maximum film growth temperature. Mo being a refractory material develops compressive and tensile stresses depending on the deposition conditions. Films deposited at a sputtering power 300 Watts and 0.3 x 10−3 Torr working argon pressure develop compressive stresses, while the films deposited at 200 Watts and 5 x 10−3 Torr pressure develops tensile stresses. Four sets of experiments were carried out to achieve an optimum deposition cycle to deposit stress free Mo. In a series of experiments, initially Mo with a thickness of 138 nm was deposited at 300 W power and 0.3 x 10−3 Torr pressure to create compressive stresses. In a second experiment Mo with a thickness of 127 nm was deposited at a power of 200W and a pressure of 5 x 10−3 Torr. In a third experiment, two high power cycles were sandwiched between three low power cycles with a total film thickness of 330 nm. In a fourth experiment two low power cycles were sandwiched between three high power cycles resulting in an effective thickness of 315 nm. It was found that the deposition sequence with two tensile stressed layers sandwiched between three compressively stressed layers had the best adhesion, limited reactivity and compact nature.
