Download or read book Alternative Buffer Layers Device Modeling and Characterization of Copper indium diselenide based Thin film Solar Cells written by Chia-Hua Huang and published by . This book was released on 2002 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical and Electronic Characterization of Copper Indium Gallium Diselenide Thin Film Solar Cells and Correlation of These Characteristics to Solar Cell Operation written by Michael Justin Hetzer and published by . This book was released on 2009 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This dissertation embodies solid state physics research to understand the basic physical mechanisms underlying the movement of charge inside solar cells, in particular, the high efficiency copper indium gallium diselenide (CIGS) solar cell. The fundamental physics of the operation of these complex polycrystalline alloys remains incompletely understood. CIGS based solar cells have obtained conversion efficiencies of nearly 20%. Solar cells based on this material have been examined in this work using high resolution, atomic scale techniques to better understand the fundamental operation of these solar cells as well as correlating these basic properties to the operation of the finished full solar cell devices. Auger Electron Spectroscopy (AES) measurements of the chemical composition taken with nanometer resolution in an ultra high vacuum secondary electron microscope show evidence for compositional changes at the grain boundaries of the CIGS layer. These findings support theoretical calculations that predict higher solar cell performance as a result. Additionally, measurements have been taken with cathodoluminescence spectroscopy (CLS) studying the band structure locally within the CIGS layers. Significant variation is present in the resulting spectra, even within single grains indicating improved uniformity could be a path to better solar cell operation. Attempts to correlate the chemical composition and the energy band structure using AES and CLS measurements have yielded some interesting initial results but more work remains to be done to obtain a deeper understanding of the physics involved in these solar cells. Correlations have been observed between the energy band structure and the performance parameters of the solar cell, such as efficiency. These results indicate the possibility of alloying between the different layers of the solar cell and also that this intermixing is detrimental to the performance of the solar cell. This work has revealed important fundamental characteristics of these materials regarding changes in the atomic composition and energy band structure and how these changes influence the performance of the CIGS layer.

Download or read book Preparation and Characterization of Copper Indium Gallium Diselenide Films Used in the Absorber Layers of Thin film Solar Cells written by 陳富珊 and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Photocurrent and Voltage Limitations of Copper indium Gallium selenide Thin film Polycrystalline Solar Cells written by Christopher P. Thompson and published by ProQuest. This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film polycrystalline CdS/Cu(In, Ga)(Se, S) 2 solar cells have great potential as a candidate for high efficiency, high throughput, low cost production. Cu(In, Ga)Se 2 devices have laboratory efficiencies approaching 20% and module efficiencies around 11%. However, most progress in device optimization has been the result of empirical studies; little is known about the device defect structure, and even less is known about the control of defects within the Cu(In, Ga)(Se, S) 2 absorber. Despite years of study, the complex nature of the Cu(In, Ga)(Se, S) 2 system has made progress towards a fundamental understanding of device behavior, and limiting defects a slow affair. The goal of this work is to shed further light on the nature of the limitations on photocurrent and voltage. The main topics covered in this thesis are: (1) fitting quantum efficiency curves calculated from an analytical model to measured quantum efficiency curves, and (2) Open circuit voltage temperature measurements. For the first section, series of devices with varying absorber layers will be analyzed, using the minority carrier diffusion length as the only fitting parameter. All other variables within the model will be supplied from direct and indirect measurements. We show that by using quantum efficiency, capacitance-voltage, and current-voltage measurements, we can generate excellent fits using only diffusion length as a fitting parameter. It is found that for Cu(In, Ga)Se 2 devices with E G [approximate]1.2eV, L=1000-1500nm.; for wide bandgap devices, with E G [approximate]1.4eV, L=10-400nm; for devices with E G [approximate]1.2eV, deposited with a low substrate temperature, L=650nm. Wide bandgap devices long wavelength collection is limited by minority carrier diffusion. For the second section, V OC (T) measurements are taken on devices with a wide range of absorbers, including some previously un-measured devices; absorbers grown with a Na deficiency. Analysis will focus on the activation energy of the dominant recombination mechanism, as well as low temperature saturation of V OC . Both of these parameters shed light on the limiting properties of devices. Cu(In, Ga)Se 2 with bandgap ranging from 1.2eV-1.4eV are limited by Shockley Read Hall recombination, and have a ratio of saturation voltage to bandgap of 80%. Lowering the electrical quality of the absorber by depositing the Cu(In, Ga)Se 2 layer at lower substrate temperature decreases the ratio of saturation voltage to bandgap to 64%, as a result of increased bandtail defect states. CuInS 2 devices and Cu(In, Ga)Se 2 devices with low or no Na are limited by hetero-interface recombination, and have a saturation voltage to bandgap ratio of ~60%.

Download or read book Advances in Thin Film Solar Cells written by I. M. Dharmadasa and published by CRC Press. This book was released on 2018-09-05 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy conversion plays a very important role in the rapid introduction of renewable energy, which is essential to meet future energy demands without further polluting the environment, but current solar panels based on silicon are expensive due to the cost of raw materials and high energy consumption during production. The way forward is to move towards thin-film solar cells using alternative materials and low-cost manufacturing methods. The photovoltaic community is actively researching thin-film solar cells based on amorphous silicon, cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and dye-sensitised and organic materials. However, progress has been slow due to a lack of proper understanding of the physics behind these devices. This book concentrates on the latest developments and attempts to improve our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. The author extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multi-layer 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 combine "impact ionisation" and "impurity photovoltaic" effects. The improved device understanding presented in this book should impact and guide future photovoltaic device development and low-cost thin-film solar panel manufacture. This new edition features an additional chapter besides exercises and their solutions, which will be useful for academics teaching in this field.

Download or read book Fundamental Materials Research and Advanced Process Development for Thin film CIS based Photovoltaics written by and published by . This book was released on 2006 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical and Photovoltaic Properties of Copper Indium gallium Diselenide Materials and Solar Cells written by Puruswottam Aryal and published by . This book was released on 2014 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for clean and renewable energy sources in recent years has motivated research on the development of low cost, thin film photovoltaic devices. As a consequence, tools for the investigation and characterization of thin film photovoltaic component materials and devices, which can be implemented in real time as well as under in-line and off-line measurement conditions, are becoming increasingly important. Real time spectroscopic ellipsometry (RTSE) and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization tools suitable for applications in the optimization of device performance and the evaluation of thin film photovoltaics technology scale-up from dot cell sizes in research laboratories to full module sizes in factories. These non-destructive optical probes implement multichannel spectroscopic detection for achieving high measurement speed, while simultaneously yielding high precision light-matter interaction parameters. The interaction parameters can be analyzed to obtain layer thicknesses as well as their optical properties from which material properties such as composition can be determined. The layer thicknesses and their optical properties in turn provide insights into the fraction of incident light absorbed in the active layer of the solar cell and also provide a basis for short-circuit current optimization through optical simulations. In this dissertation research, Cu(In, Ga)Se2 films with different Ga contents have been prepared by a one stage co-evaporation process. These films have been studied by spectroscopic ellipsometry (RTSE) in real time during their deposition, which has been performed at high temperature (570oC). After cooling the films to room temperature, in-situ SE measurements were undertaken in order to extract the dielectric functions of the thin film materials. An extended parameterization was established through the fitting of these dielectric functions to analytical functions, followed by the development of expressions in the free parameters that describe these analytical functions versus the Ga content. As a result of this parameterization, dielectric function spectra can be predicted for any desired composition. This capability was applied for the structural and compositional mapping of CIGS thin films and solar cells deposited over 10 cm × 10 cm substrate areas. Correlations of the deduced structural and compositional parameters with the corresponding device performance characteristics have yielded important insights with the potential to assist in the optimization of solar cell devices incorporating thin CIGS layers. In addition, a methodology of external quantum efficiency simulation (EQE) has been developed that relies on ex-situ spectroscopic ellipsometry analysis of complete thin film solar cells and so does not require free parameters. The simulations have been applied to CIGS and a-Si:H solar cells, based on the assumption that all photo-generated carriers within the active layers of these cells are collected without any recombination losses. Thus, it should be noted the predicted EQE is the maximum that the solar cell having the given structure can generate, and the difference between the predicted and measured EQE for the same device can provide insights into recombination losses in the device. Because the predicted EQE is based on specular interfaces, it can also be lower than the measured values due to light trapping caused by rough surfaces and interfaces. In another research area of interest for CIGS materials and solar cells, the role of the stage II/III substrate temperature (540oC - 640oC) in the deposition of the films by the three stage process has been studied, as has its effect on device performance, sodium diffusion, and grain size. Since standard soda-lime glass does not tolerate temperatures above 570oC due to glass softening, specially engineered high temperature soda-lime glass produced by Nippon Electric Glass Co., Japan was used as the substrate material in this study. It was found that the average device performance improves up to 620oC as a consequence of reduced shunting and improved diode quality factor which affect the fill factor of the device. At 640oC, however, these parameters have exhibited a wider distribution, and thus have yielded a lower average efficiency for the cells. SEM micrographs of these devices showed that the grain size first increased with increasing temperature up to 620oC, and then showed a bimodal distribution at 640oC. Finally, ex-situ mapping ellipsometry has been applied in the study of silver nanoparticle thin films prepared by the drop casting method. These films are important because of the plasmonic effects they exhibit. Such effects can be exploited by integrating the nanoparticle layers into solar cells in order to promote light trapping, and hence, increase the overall efficiency of the cells. A study of these films with mapping spectroscopic ellipsometry provides a means of determining thickness uniformity over large areas that is critical for scale-up of the deposition processes. The uniformity of other parameters of the films such as the plasmon resonance energy and its broadening are equally important to ensure maximum coupling of light into the solar cell absorber layer.

Download or read book Preparation and Characterization of Copper Indium Gallium Diselenide Powders and Films Used in the Absorber Layer of Thin film Solar Cells written by 吳忠憲 and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 2002 with total page 776 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 Preparation and Characterization of Copper Indium Diselenide based Solar Cells with a Thin Zinc Selenide Intermediate Layer written by Ji-Beom Yoo and published by . This book was released on 1989 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Growth Characterization and Thermodynamic Modeling of Absorber and Transparent Conducting Oxides for Copper Indium Diselenide Based Thin Film Solar Cells written by Lei L. Kerr and published by . This book was released on 2004 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solution Processing for Copper Indium Sulfide Solar Cells written by Stephen Thacker Connor and published by Stanford University. This book was released on 2011 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the field of photovoltaics has become increasingly important due to rising energy demand and climate change. While most solar cells are currently composed of crystalline silicon, devices with thinner films of inorganic absorber materials might allow production at a greater scale due to their lower materials cost. In particular, thin films of CuInS2 are promising solar absorber materials due to their high efficiencies and low required thicknesses. However, the fabrication of thin film solar cells currently requires expensive vacuum techniques. As an alternative, solution-based deposition techniques have been proposed as a route to low-cost and high-throughput electronic device fabrication. I have studied how film growth depends on solutuion deposited precursor film quality, with the goal of producing large grained films of CuInS2 through solution processing. In the first approach, we used solvothermal decomposition of organometallic precursors at moderate temperatures to produce nanoparticles of CuInS2. Thin films of these nanoparticles were cast onto molybdenum coated glass and further processed to create CuInS2 solar cells. We found that performance was dependent on film porosity, grain size, and stoichiometry of the nanoparticles. Films with grain sizes of ~200nm were attained, from which 1.3% efficient solar cells were made. In addition, we showed that this synthesis could be extended to produce CuInS2 nanoparticles with partial substitution of Fe, Zn, and Ga. In the second approach, we synthesized an air-stable hybrid organometallic/nanoparticle ink at room temperature in ambient conditions through a vulcanization reaction. This ink could be coated onto substrates in smooth layers, and further reactive annealing formed large grained CuInS2 films. This process was characterized, and a correlation between residual carbon and grain growth was found. Additionally, the chemical transformation between precursor layers and final sulfide thin film was analyzed, with an emphasis on the difference between sulfurization and selenization. We demonstrated that the sulfurization process was producing morphological defects due to its nucleation limited growth mechanism. However, it was modified to more closely resemble the diffusion limited selenization mechanism, thus producing flat films of CuInS2 with grain sizes of ~500nm.

Download or read book Preparation and Characterization of Copper Indium Gallium Diselenide and Copper Zinc Tin Sulfide Powders Used as the Absorber of Thin film Solar Cells written by 林詣軒 and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of the Optoelectronic Properties of Copper Indium Gallium Diselenide Solar Cells Using Measurements on Bifacial Devices and Device Modeling written by David Berney Needleman and published by . This book was released on 2007 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book TMS 2011 140th Annual Meeting and Exhibition Materials Fabrication Properties Characterization and Modeling written by The Minerals, Metals & Materials Society (TMS) and published by John Wiley & Sons. This book was released on 2011-04-12 with total page 987 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents the most up-to-date information on the state of Materials Fabrication, Properties, Characterization, and Modeling. It's a great mix of practical applied technology and hard science, which is of invaluable benefit to the global industry.

Download or read book Investigation of Excess Carrier Lifetimes and Buffer Layer Processing in Copper Indium Diselenide CIS Thin Film Solar Cells by Dual Beam Optical Modulation Technique written by Chia-Hua Huang and published by . This book was released on 1997 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: