Download or read book Improvement of Cu In Ga S Se 2 Thin Film Solar Cells with the Help of Gallium and Sulfur Gradients written by Björn Jakob Müller and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Non vacuum and Low cost Techniques for Cu In Ga Se S 2 Thin Film Solar Cell Processing written by Christopher J. Hibberd and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar photovoltaic modules provide clean electricity from sunlight but will not be able tocompete on an open market until the cost of the electricity they produce is comparable to thatproduced by traditional methods. At present, modules based on crystalline silicon wafer solarcells account for nearly 90% of photovoltaic production capacity. However, it is anticipatedthat the ultimate cost reduction achievable for crystalline silicon solar cell production will besomewhat limited and that thin film solar cells may offer a cheaper alternative in the longterm. The highest energy conversion efficiencies reported for thin film solar cells have beenfor devices based around chalcopyrite Cu(In, Ga)(Se, S)2 photovoltaic absorbers. The most efficient Cu(In, Ga)(Se, S)2 solar cells contain absorber layers deposited by vacuumco-evaporation of the elements. However, the cost of ownership of large area vacuumevaporation technology is high and may be a limiting factor in the cost reductions achievablefor Cu(In, Ga)(Se, S)2 based solar cells. Therefore, many alternative deposition methods areunder investigation. Despite almost thirty companies being in the process of commercialisingthese technologies there is no consensus as to which deposition method will lead to the mostcost effective product. Non-vacuum deposition techniques involving powders and chemical solutions potentiallyoffer significant reductions in the cost of Cu(In, Ga)(Se, S)2 absorber layer deposition ascompared to their vacuum counterparts. A wide range of such approaches has beeninvestigated for thirty years and the gap between the world record Cu(In, Ga)(Se, S)2 solarcell and the best devices containing non-vacuum deposited absorber layers has closedsignificantly in recent years. Nevertheless, no one technique has demonstrated its superiorityand the best results are still achieved with some of the most complex approaches. The work presented here involved the development and investigation of a new process forperforming one of the stages of non-vacuum deposition of Cu(In, Ga)(Se, S)2 absorber layers. The new process incorporates copper into an initial Group III-VI precursor layer, e.g. indiumgallium selenide, through an ion exchange reaction performed in solution. The ion exchangereaction requires only very simple, low-cost equipment and proceeds at temperatures over1000?C lower than required for the evaporation of Cu under vacuum. In the new process, indium (gallium) selenide initial precursor layers are immersed insolutions containing Cu ions. During immersion an exchange reaction occurs and Cu ionsfrom the solution exchange places with Group III ions in the layer. This leads to theformation of an intimately bonded, laterally homogeneous copper selenide? indium (gallium)selenide modified precursor layer with the same morphology as the initial precursor. These modified precursor layers were converted to single phase chalcopyrite CuInSe2 andCu(In, Ga)Se2 by annealing with Se in a tube furnace system. Investigation of the annealingtreatment revealed that a series of phase transformations, beginning at low temperature, leadto chalcopyrite formation. Control of the timing of the Se supply was demonstrated toprevent reactions that were deemed detrimental to the morphology of the resultingchalcopyrite layers. When vacuum evaporated indium (gallium) selenide layers were used asinitial precursors, solar cells produced from the absorber layers exhibited energy conversionefficiencies of up to 4%. While these results are considered promising, the devices werecharacterised by very low open circuit voltages and parallel resistances. Rapid thermal processing was applied to the modified precursor layers in an attempt tofurther improve their conversion into chalcopyrite material. Despite only a small number ofsolar cells being fabricated using rapid thermal processing, improvements in open circuitvoltage of close to 150mV were achieved. However, due to increases in series resistance andreductions in current collection only small increases in solar cell efficiency were recorded. Rapid thermal processing was also used to demonstrate synthesis of single phase CuInS2from modified precursor layers based on non-vacuum deposited indium sulphide. Non-vacuum deposition methods provide many opportunities for the incorporation ofundesirable impurities into the deposited layers. Analysis of the precursor layers developedduring this work revealed that alkali atoms from the complexant used in the ion exchangebaths are incorporated into the precursor layers alongside the Cu. Alkali atoms exhibitpronounced electronic and structural effects on Cu(In, Ga)Se2 layers and are beneficial in lowconcentrations. However, excess alkali atoms are detrimental to Cu(In, Ga)Se2 solar cellperformance and the problems encountered with cells produced here are consistent with theeffects reported in the literature for excess alkali incorporation. It is therefore expected thatfurther improvements in solar cell efficiency might be achieved following reformulation ofthe ion exchange bath chemistry.

Download or read book Electrical Characterisation Modelling and Simulation of Cu In Ga Se S 2 Solar Cells written by Tetiana Lavrenko and published by . This book was released on 2019* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CIGS solar cells, sequential growth process, sulfur-gradient, gallium-gradient, bandgap grading, reciprocity relation, admittance measurements, time-resolved photoluminescence.

Download or read book Chalcogenide Photovoltaics written by Roland Scheer and published by John Wiley & Sons. This book was released on 2011-03-31 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Optimisation of Cu In Ga Se 1tn2 Thin Film Solar Cells and Modules for Low Irradiance Conditions written by Alessandro Virtuani and published by . This book was released on 2004 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alternative Buffer Layer Development in Cu In Ga Se2 Thin Film Solar Cells written by Peipei Xin and published by . This book was released on 2017 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cu(In,Ga)Se2-based thin film solar cells are considered to be one of the most promising photovoltaic technologies. Cu(In,Ga)Se2 (CIGS) solar devices have the potential advantage of low-cost, fast fabrication by using semiconductor layers of only a few micrometers thick and high efficiency photovoltaics have been reported at both the cell and the module levels. CdS via chemical bath deposition (CBD) has been the most widely used buffer option to form the critical junction in CIGS-based thin film photovoltaic devices. However, the disadvantages of CdS can’t be ignored - regulations on cadmium usage are getting stricter primarily due to its toxicity and environmental impacts, and the proper handling of the large amount of toxic chemical bath waste is a massive and expensive task. ☐ This dissertation is devoted to the development of Cd-free alternative buffer layers in CIGS-based thin film solar cells. Based on the considerations of buffer layer selection criteria and extensive literature review, Zn-compound buffer materials are chosen as the primary investigation candidates. Radio frequency magnetron sputtering is the preferred buffer deposition approach since it’s a clean and more controllable technique compared to CBD, and is readily scaled to large area manufacturing. ☐ First, a comprehensive study of the ZnSe1-xOx compound prepared by reactive sputtering was completed. As the oxygen content in the reactive sputtering gas increased, ZnSe1-xOx crystallinity and bandgap decreased. It’s observed that oxygen miscibility in ZnSe was low and a secondary phase formed when the O2 / (O2 + Ar) ratio in the sputtering gas exceeded 2%. Two approaches were proposed to optimize the band alignment between the CIGS and buffer layer. One method focused on the bandgap engineering of the absorber, the other focused on the band structure modification of the buffer. As a result, improved current of the solar cell was achieved although a carrier transport barrier at the junction interface still limited the device performance. ☐ Second, an investigation of Zn(S,O) buffer layers was completed. Zn(S,O) films were sputtered in Ar using a ZnO0.7S0.3 compound target. Zn(S,O) films had the composition close to the target with S / (S+O) ratio around 0.3. Zn(S,O) films showed the wurtzite structure with the bandgap about 3.2eV. The champion Cu(In,Ga)Se2 / Zn(S,O) cell had 12.5% efficiency and an (Ag,Cu)(In,Ga)Se2 / Zn(S,O) cell achieved 13.2% efficiency. Detailed device analysis was used to study the Cu(In,Ga)Se2 and (Ag,Cu)(In,Ga)Se2 absorbers, the influence of absorber surface treatments, the effects of device treatments, the sputtering damage and the Na concentration in the absorber. ☐ Finally alternative buffer layer development was applied to an innovative superstrate CIGS configuration. The superstrate structure has potential benefits of improved window layer properties, cost reduction, and the possibility to implement back reflector engineering techniques. The application of three buffer layer options – CdS, ZnO and ZnSe was studied and limitations of each were characterized. The best device achieved 8.6% efficiency with a ZnO buffer. GaxOy formation at the junction interface was the main limiting factor of this device performance. For CdS / CIGS and ZnSe / CIGS superstrate devices extensive inter-diffusion between the absorber and buffer layer under CIGS growth conditions was the critical problem. Inter-diffusion severely deteriorated the junction quality and led to poorly behaved devices, despite different efforts to optimize the fabrication process.

Download or read book Growth and Characterisation of Cu In Ga Se2 Thin Films for Solar Cell Applications written by E. Ahmed and published by . This book was released on 1995 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Characterization Techniques for Thin Film Solar Cells written by Daniel Abou-Ras and published by John Wiley & Sons. This book was released on 2016-07-13 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book focuses on advanced characterization methods for thin-film solar cells that have proven their relevance both for academic and corporate photovoltaic research and development. After an introduction to thin-film photovoltaics, highly experienced experts report on device and materials characterization methods such as electroluminescence analysis, capacitance spectroscopy, and various microscopy methods. In the final part of the book simulation techniques are presented which are used for ab-initio calculations of relevant semiconductors and for device simulations in 1D, 2D and 3D. Building on a proven concept, this new edition also covers thermography, transient optoelectronic methods, and absorption and photocurrent spectroscopy.

Download or read book Nanoscale investigation of potential distribution in operating Cu In Ga Se2 thin film solar cells written by Zhenhao Zhang and published by KIT Scientific Publishing. This book was released on 2014-10-16 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The distribution of the electrostatic potential in and between the materials in Cu(In,Ga)Se2 thin-film solar cells has a major impact on their superior performance. This thesis reported on the nanoscale imaging of the electrostatic potential on untreated cross sections of operating Cu(In,Ga)Se2 solar cells using Kelvin probe force microscopy.

Download or read book Enhancement of the Deposition Processes of Cu In Ga Se2 and Cds Thin Films Via In situ and Ex situ Measurements for Solar Cell Application written by Vikash Ranjan and published by . This book was released on 2011 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin films of Cu(In, Ga)Se2 deposited by 1-stage, 2-stage and 3-stage co-evaporation processes result into the highest efficiency solar cells. Controlling the rate and sequences of individual sources during these co-evaporation processes are important for better quality Cu(In, Ga)Se2 absorber layers. At the same time, spectroscopic ellipsometry due to its ex-situ as well as in-situ application is considered as a very powerful tool to understand the material properties as well as to monitor the process. Nevertheless, spectroscopic ellipsometry was not properly utilized until now to characterize Cu(In, Ga)Se2 thin films. In this study, one of our goal is to understand the optical and electrical properties of Cu(In, Ga)Se2 as a function of process and composition. In the first part of this study, we implemented ex-situ spectroscopic ellipsometry (SE) along with other characterization techniques like Secondary ion mass spectroscopy (SIMS), Scanning electron microscopy (SEM), Auger electron spectroscopy (AES), x-ray diffraction (XRD), atomic force microscopy (AFM) etc. to compare Cu(In, Ga)Se2 thin films deposited by the above mentioned three co-evaporation processes. During this study, we were able to use SE to find the thickness, roughness, band gap, Ga grading of the Cu(In, Ga)Se2 deposited by 2-stage and 3-stage process. Finding of SE were correlated by SIMS, AES, SEM etc. In the case of Cu(In, Ga)Se2 deposited by 1-stage process, due to the high surface roughness, we are not able to implement the ex-situ spectroscopic ellipsometry. In the second and third part of this study, real time spectroscopic ellipsometry is implemented to study the material properties of Cu(In, Ga)Se2 thin films as a function of Cu and Ga concentration. Effectively, in a 3-stage co-evaporation process, the composition of the film changes during the process. To monitor and control the composition of Cu(In, Ga)Se2 during the 3-stage process by in-situ ellipsometry, it was necessary to understand the optical properties of Cu(In, Ga)Se2 as a function of Cu atomic percentage (at.%) as well as Ga at.%. Along with this, the inability to implement ex-situ SE for Cu(In, Ga)Se2 thin film motivated us to implement the spectroscopic ellipsometry in real time i.e. during the growth of the film. This in-situ real time application of SE helped us in understanding the micostructural evolution and dependence of the band gap with the Cu atomic percentage (at.%) as well as the Ga at.%. We also used this opportunity to understand the shift in the critical points as a function of temperature for CuInSe2 alloys. Characterization like AES, XRD, AFM etc were performed after the growth at room temperature to corroborate the RTSE findings. In the fourth and last part of this study, the growth of CdS on a Cu(In, Ga)Se2 surface as a function of time was studied using SE as well as AFM. We also used this opportunity to compare the growth of CdS on another substrate (SiO2). Spectroscopic ellipsometry and AFM revealed a quantum confinement effect in the case of CdS on SiO2 whereas no such effect was observed for CdS on Cu(In, Ga)Se2 surface due to the growth of compact CdS layers.

Download or read book Optimization of Cu In Ga S Se 2 Thin Film Solar Cell Using Sequential Sputtering selenization and Sulfurization written by 黃鵬丞 and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Cu In Ga Se2 Superstrate Thin Film Solar Cells written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Physics of Cu In Ga Se2 Solar Cells and Their Layer Components written by Abedl-Rahman Ibdah and published by . This book was released on 2016 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycrystalline Cu(In1-xGax)Se2 (CIGS) thin film technology has emerged as a promising candidate for low cost and high performance solar modules. The efficiency of CIGS solar cells is strongly influenced by several key factors. Among these factors include Ga composition and its profile in the absorber layer, copper content in this layer, and the solar cell multilayer structure. As a result, tools for the characterization of thin film CIGS solar cells and their layer components are becoming increasingly essential in research and manufacturing. Spectroscopic ellipsometry is a non-invasive technique that can serve as an accurate probe of component layer optical properties and multilayer structures, and can be applied as a diagnostic tool for real-time, in-line, and off-line monitoring and analysis in small area solar cell fabrication as well as in large area photovoltaics manufacturing. Implementation of spectroscopic ellipsometry provides unique insights into the properties of complete solar cell multilayer structures and their layer components. These insights can improve our understanding of solar cell structures, overcome challenges associated with solar cell fabrication, and assist in process monitoring and control on a production line. In this dissertation research, Cu(In,Ga)Se2 films with different Cu contents have been prepared by the one stage co-evaporation process. These films have been studied by real time spectroscopic ellipsometry (RTSE) during deposition, and by in-situ SE at the deposition temperature as well as at room temperature to extract the dielectric functions (e1, e2) of the thin film materials. Analytical expressions for the room temperature dielectric functions were developed, and the free parameters that describe these analytical functions were in turn expressed as functions of the Cu content. As a result of this parameterization, the dielectric function spectra (e1, e2) can be predicted for any desired composition within the range of the samples investigated. This capability was applied for mapping the structural and compositional variations of CIGS thin films deposited over a 10 cm × 10 cm substrate area. In another application presented in this dissertation, a non-invasive method utilizing ex-situ spectroscopic ellipsometry analysis has been developed and applied to determine non-destructively the Ga compositional profile in CIGS absorbers. The method employs parameterized dielectric function spectra (e1, e2) of CIGS versus Ga content to probe the compositional variation with depth into the absorber. In addition, a methodology for prediction of the external quantum efficiency (QE) including optical gains and losses for a CIGS solar cell has been developed. The methodology utilizes ex-situ spectroscopic ellipsometry analysis of a complete solar cell, with no free parameters, to deduce the multilayer solar cell structure non-invasively and simulate optical light absorption in each of the layer components. In the case of high efficiency CIGS solar cells, with minimal electronic losses, QE spectra are predicted from the sum of optical absorption in the active layer components. For such solar cells with ideal photo-generated charge carrier collection, the SE-predicted QE spectra are excellent representation of the measured ones. Since the QE spectra as well as the short circuit current density (Jsc) can be calculated directly from SE analysis results, then the predicted QE from SE can be compared with the experimental QE to evaluate electronic losses based on the difference between the spectra. Moreover, the calculated Jsc can be used as a key parameter for the design and optimization of anti-reflection coating structures. Because the long term production potential of CIGS solar modules may be limited by the availability of indium, it becomes important to reduce the thickness of the CIGS absorber layer. Thickness reduction would reduce the quantity of indium required for production which would in turn reduce costs. A decrease in short-circuit current density (Jsc) is expected, however, upon thinning the CIGS absorber due to incomplete absorption. To clarify the limits of obtainable Jsc in ultra-thin CIGS solar cells with Mo back contacts, optical properties and multilayer structural data are deduced via spectroscopic ellipsometry analysis and used to predict the QE spectra and maximum obtainable Jsc values upon thinning the absorber. Moreover, SE-guided optical design of ultra-thin CIGS solar cells has been demonstrated. In the case of solar cells fabricated on Mo, thinning the absorber in a CIGS solar cell is associated with significant optical losses in the Mo containing back contact layers. This is due in part to the poor optical reflectance of Mo. Such optical losses may be reduced by employing a back contact design with improved reflectance. Thus, alternative novel solar cell structures with ultra-thin absorbers and improved back contact reflectance have been designed and investigated using SE and the optical modeling methods. In addition to optical losses, electronic losses in the ultra-thin solar cells have been evaluated. By separating the absorber layer into sub-layer regions (for example, near-junction, bulk, and near-back-contact) and varying carrier collection probability in these regions, the contribution of each region to the current can be estimated. Based on this separation, the origin of the electronic losses has been identified as near the back contact.

Download or read book Development of Cu In Ga Se2 Superstrate Thin Film Solar Cells written by Franz-Josef Haug and published by . This book was released on 2001 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Cu In Ga Se2 Solar Cell on Stainless Steel Substrate written by Chantana Jakapan and published by LAP Lambert Academic Publishing. This book was released on 2015-07-03 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electricity power is normally generated by burning fossil fuels, having detrimental impacts on the environment and will be depleted. One of the most appropriate ways to solve the foreseeable world's energy crisis is to utilize the power of the sun. Solar cells, using photovoltaic effect, are of wide interest as they can convert solar energy to electricity. Chalcopyrite based thin-film solar cell is considered as the low-cost and high-efficiency solar cells. One of the most important chalcopyrite compounds for photovoltaic application is Cu(In, Ga)Se2. Fabricating the solar cells on flexible substrates is intriguing, as it can be applied to the roll-to-roll process with the ability to reduce production cost of the solar cells. Consequently, the purpose of the book is to provide the overview for accomplishing the good physical properties and suitable double [Ga]/([Ga]+[In])-grading profiles of Cu(In, Ga)Se2 absorbers on flexible stainless steel substrates for the thin-film solar cells with high conversion efficiency (>15%

Download or read book Enhancement of Cu In Ga Se2 Solar Cells and Materials Via the Incorporation of Silver written by Scott A. Little and published by . This book was released on 2012 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Cu(In, Ga)Se2 (CIGS) technology has proven itself to be a worthy solar cell technology, research efforts have redoubled to explore ways to enrich the already mature technology or create spin-offs of the technology with specific goals for manufacturing in mind. CIGS technology is now at an efficiency and production level that is competitive with other second generation solar cell devices and c-Si. Further research in CIGS allows for a toolbox of new ideas to try in the technology. This work aims at that goal by generating and presenting many ideas on how that may be possible. Primarily, this work contains information concerning the improvement of the manufacturing process using a hybrid sputter deposition chamber for scaling up and allowing for easy in situ monitoring using ellipsometry. It also explores the possibility of the addition of Ag to enhance and control device behavior and properties, and investigates the concept of a two-stage process with a co-sputtering deposition chamber. Monitoring of Ag in situ and in real time was explored to possibly improve the back contact of solar cells that use Ag as a back contact (not necessarily CIGS) and as a potential precursor for nanocrystals.time was explored to possibly improve the back contact of solar cells that use Ag as a back contact (not necessarily CIGS) and as a potential precursor for nanocrystals.

Download or read book Growing Cu In Ga Se2 Thin Film Solar Cells with High Efficiency and Low Production Costs written by Shihang Yang and published by . This book was released on 2012 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two major approaches are performed to improve solar cell performances. Light trapping by etching AZO top contact for creating pyramid-structures to enhance light scattering. Efficiency is increased by more than 1.5% for solar cells with etched AZO surfaces. Solar cells with efficiency larger than 13% can be grown by using AZO etching. Another approach is by using suitable Ga content in absorber layer. Solar cells with efficiency as high as 14.17% are grown which makes thinner CIGS solar cells very competitive.