Utilizing Photoelectron Spectroscopy to Influence the Design of Earth-abundant Solution-Processed Chalcogenide Thin-film Photovoltaics PDF Download

Author: Eric Bergmann
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Solution processing offers many key advantages to the manufacturing of photovoltaic cells. This includes lower costs, higher throughput and lower temperature conditions resulting in shorter energy payback times and better scalability. Solar cells developed using these techniques then offer greater potential to fill the growing demand for low cost and sustainable energy production. Presented in this thesis is the characterization of each primary interface in solution-deposited Cu2BaSnSxSe4-x (CBTSSe) solar cells using photoelectron spectroscopy techniques. This material is set to improve upon high efficiency predecessor Cu2ZnSnSxSe4-x (CZTSSe) materials by suppressing inherent antisite defect formation through dissimilar ionic-sizes and coordination mismatch. From the electron affinity (EA) values determined by ultraviolet and inverse photoelectron spectroscopies a large conduction band offset of -0.6 eV was measured at the buffer/absorber (CdS/CBTSSe) interface, meaning the conduction band edge of CdS is significantly lower than that of CBTSSe. A cliff-like band profile of this magnitude can promote charge carrier recombination at this interface, lowering the open circuit voltage of the photovoltaic cell and therefore reducing its power conversion efficiency. It is then suggested, based on these findings, that lower electron affinity electron transport materials need to be developed for future optimization of these devices.

Author: Thomas James Whittles
Publisher: Springer
ISBN: 3319916653
Category : Technology & Engineering
Languages : en
Pages : 362

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Book Description
This book examines the electronic structure of earth-abundant and environmentally friendly materials for use as absorber layers within photovoltaic cells. The corroboration between high-quality photoemission measurements and density of states calculations yields valuable insights into why these materials have demonstrated poor device efficiencies in the vast literature cited. The book shows how the materials’ underlying electronic structures affect their properties, and how the band positions make them unsuitable for use with established solar cell technologies. After explaining these poor efficiencies, the book offers alternative window layer materials to improve the use of these absorbers. The power of photoemission and interpretation of the data in terms of factors generally overlooked in the literature, such as the materials’ oxidation and phase impurity, is demonstrated. Representing a unique reference guide, the book will be of considerable interest and value to members of the photoemission community engaged in solar cell research, and to a wider materials science audience as well.

Author: Benjamin D. Weil
Publisher:
ISBN:
Category :
Languages : en
Pages :

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CIGS is currently the highest efficiency chalcogenide absorber, with a record cell efficiency of 20.3%. One of the main challenges of CIGS manufacturing is reducing costs and scaling up manufacturing. The use of toxic elements (Se, Te, Cd) and rare earth elements (In, Te) further complicates the materials processing. The development of non-toxic, earth abundant materials to replace these technologies is underway. Furthermore, there is a need to develop scalable and high-throughput manufacturing techniques that could reduce costs and improve manufacturing of chalcogenide solar cells. Solution-based deposition techniques are widely considered to be a route to low-cost, high-throughput photovoltaic device fabrication. Nanoparticle based inks are one means of achieving low-cost and high-throughput solution-processed devices. I study the properties of CuInS2 nanoparticles and their application to solar cell fabrication. I also establish a methodology for a highly scalable deposition process and report the synthesis of an air-stable, vulcanized ink from commercially available precursors. Using this air-stable solution process, solar cells are made with an absorber layer that is flat, contaminant-free, and composed of large-grained CuInS2. I demonstrate an initial power efficiency of 2.15%. To address the challenge of reducing elemental toxicity and the use of rare elements in chalcogenide solar cells, I will discuss some alternative absorbers that don't contain Indium, Cadmium, Tellurium, or Selenium. I demonstrate a 2.2% Cu2SnS3/CdS solar cell using rapid thermal processing and address the challenges facing this material to improve efficiency.

Author: Hsin-Sheng Duan
Publisher:
ISBN:
Category :
Languages : en
Pages : 118

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Book Description
During the last few decades, numerous promising solar cell concepts, ranging from single-crystal silicon to thin-film technologies, have been developed and are being researched intensely by a growing number of scientific groups and companies. Thin-film kesterite Cu2ZnSn(S, Se)4 (CZTS) photovoltaic technology, in which the indium in Cu(In, Ga)(S, Se)2 (CIGS) is replaced with more abundant and less expensive zinc and tin, has emerged as a potential absorber material in next generation thin film solar cells. Despite the recent demonstration of solution-processed CZTS devices over 11% power conversion efficiency, the development of CZTS as an absorber material is still behind in terms of both fundamental understanding of the material system and in the capability to precisely control the material properties for device fabrication, as compared with those of CIGS and CdTe. This dissertation targets the three key areas in this field: (1) Defect characterization and understanding in order to recover Voc loss; (2) Phase stability and processing control to produce a purer absorber material and (3) Solution-processing with environmentally friendly solvents for large-scale production. We start by exploring various precursor systems (hydrazine, benign organic solvents and nanoparticles) and have successfully processed CZTS from a molecular solution in a benign solvent system. A single component precursor has also been developed and proved to offer more precise phase and composition control. Lastly, using electrical and optical characterization, we have conducted detailed investigations on the bulk and the interface defects that govern the carrier recombination and the resulting device characteristics. They reveal the effects of the anions in CZTS on the defect concentration and on voltage losses of the solar cells.

Author: Matevž Bokalič
Publisher: Springer
ISBN: 9783319146508
Category : Technology & Engineering
Languages : en
Pages : 0

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Book Description
The book is devoted to the spatial characterization of solar cells and PV modules. It is written both as a monograph as well as a succinct guide for the state-of-the-art spatial characterization techniques and approaches. Amongst the approaches discussed are visual imaging, electro- and photo-luminescence imaging, thermography, and light beam induced mapping techniques. Emphasis is given on the luminescence image acquisition and interpretation due to its great potential. Characterization techniques are accompanied by simulation tools. The contents are aimed at a readership of students and senior researchers in R&D as well as engineers in industry who are newcomers to the spatial characterization of either solar cells or PV modules. The concepts and approaches presented herein are based on but not limited to case studies of real thin-film PV devices. Key features:  Review of spatially resolved characterization techniques and accompanying SPICE simulations in photovoltaics  Use of spatially resolved characterization techniques and their combinations for the identification of inhomogeneities in small area CdTe and dye-sensitized solar cells  Case studies of electroluminescence imaging of commercial PV modules (c-Si, CIGS, CdTe, a-Si, tandem and triple junction thin-film-Si) The contents are aimed at a readership of students and senior researchers in R&D as well as engineers in industry who are newcomers to the spatial characterization of either solar cells or PV modules. The concepts and approaches presented herein are based on but not limited to case studies of real thin-film PV devices. Key features:  Review of spatially resolved characterization techniques and accompanying SPICE simulations in photovoltaics  Use of spatially resolved characterization techniques and their combinations for the identification of inhomogeneities in small area CdTe and dye-sensitized solar cells  Case studies of electroluminescence imaging of commercial PV modules (c-Si, CIGS, CdTe, a-Si, tandem and triple junction thin-film-Si)

Author: Alexander Halley Ip
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: John K. Katahara
Publisher:
ISBN:
Category : Photoluminescence
Languages : en
Pages : 110

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Book Description
Widespread adoption of photovoltaics (PV) as an alternative electricity source will be predicated upon improvements in price performance compared to traditional power sources. Solution processing of thin-film PV is one promising way to reduce the capital expenditure (CAPEX) of manufacturing solar cells. However, it is imperative that a shift to solution processing does not come at the expense of device performance. One particularly problematic parameter for thin-film PV has historically been the open-circuit voltage (VOC). As such, there is a pressing need for characterization tools that allow us to quickly and accurately evaluate the potential performance of solution-processed PV absorber layers. This work describes recent progress in developing photoluminescence (PL) techniques for probing optoelectronic quality in semiconductors. We present a generalized model of absorption that encompasses ideal direct-gap semiconductor absorption and various band tail models. This powerful absorption model is used to fit absolute intensity PL data and extract quasi-Fermi level splitting (maximum attainable VOC) for a variety of PV absorber technologies. This technique obviates the need for full device fabrication to get feedback on optoelectronic quality of PV absorber layers and has expedited materials exploration. We then use this absorption model to evaluate the thermodynamic losses due to different band tail cases and estimate tail losses in Cu2ZnSn(S,Se)4 (CZTSSe). The effect of sub-bandgap absorption on PL quantum yield (PLQY) and voltage is elucidated, and new analysis techniques for extracting VOC from PLQY are validated that reduce computation time and provide us even faster feedback on material quality. We then use PL imaging to develop a mechanism describing the degradation of solution-processed CH3NH3PbI3 films under applied bias and illumination.

Author: Roland Scheer
Publisher: John Wiley & Sons
ISBN: 3527633723
Category : Technology & Engineering
Languages : en
Pages : 398

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Book Description
This first comprehensive description of the most important material properties and device aspects closes the gap between general books on solar cells and journal articles on chalcogenide-based photovoltaics. Written by two very renowned authors with years of practical experience in the field, the book covers II-VI and I-III-VI2 materials as well as energy conversion at heterojunctions. It also discusses the latest semiconductor heterojunction models and presents modern analysis concepts. Thin film technology is explained with an emphasis on current and future techniques for mass production, and the book closes with a compendium of failure analysis in photovoltaic thin film modules. With its overview of the semiconductor physics and technology needed, this practical book is ideal for students, researchers, and manufacturers, as well as for the growing number of engineers and researchers working in companies and institutes on chalcogenide photovoltaics.

Author: Wilfried G. J. H. M. van Sark
Publisher: Springer Science & Business Media
ISBN: 3642222757
Category : Technology & Engineering
Languages : en
Pages : 588

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Book Description
Today’s solar cell multi-GW market is dominated by crystalline silicon (c-Si) wafer technology, however new cell concepts are entering the market. One very promising solar cell design to answer these needs is the silicon hetero-junction solar cell, of which the emitter and back surface field are basically produced by a low temperature growth of ultra-thin layers of amorphous silicon. In this design, amorphous silicon (a-Si:H) constitutes both „emitter“ and „base-contact/back surface field“ on both sides of a thin crystalline silicon wafer-base (c-Si) where the electrons and holes are photogenerated; at the same time, a-Si:H passivates the c-Si surface. Recently, cell efficiencies above 23% have been demonstrated for such solar cells. In this book, the editors present an overview of the state-of-the-art in physics and technology of amorphous-crystalline heterostructure silicon solar cells. The heterojunction concept is introduced, processes and resulting properties of the materials used in the cell and their heterointerfaces are discussed and characterization techniques and simulation tools are presented.

Author: Martin A. Green
Publisher: Trans Tech Publications Ltd
ISBN: 3035739641
Category : Technology & Engineering
Languages : en
Pages : 240

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Book Description
The early chapters comprehensively review the optical and transport properties of silicon. Light trapping is described in detail. Limits on the efficiency of silicon cells are discussed as well as material requirements necessary to approach these limits. The status of current approaches to passifying surfaces, contacts and bulk regions is reviewed. The final section of the book describes the most practical approaches to the fabrication of high-efficiency cells capable of meeting the efficiency targets for both concentrated and non-concentrated sunlight, including a discussion of design and processing approaches for non-crystalline silicon.