Download or read book Microscopic Properties of Grain Boundaries in Cu In Ga Se2 and CuInS2 Thin film Solar Cells Studied by Transmission Electron Microscopy written by and published by . This book was released on 2011 with total page 156 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 The Study of Grain Boundaries in Polycrystalline Thin film Solar Cells written by Bingrui Joel Li and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon is one of the most studied semiconductor materials with techniques to control and manipulate its properties well established by the integrated circuit (IC) industry. While silicon wafer-based technology constitutes about 85% of the photovoltaics (PV) market, there are compelling reasons to develop thin-film solar cells. These include potential material cost and energy savings achievable with thin absorber layers of direct band-gap thin film materials, and the potential for incorporation of thin film PV onto inexpensive, flexible, or building material substrates, which opens up the possibility of new applications. Given the success of silicon wafer-based solar cells in the PV market, crystalline silicon on glass is a natural choice for thin-film PV technology. However, the efficiency of this technology is still too low to compete in the PV market. In fact, its record efficiency is only 10.5% which was achieved by CSG Solar. In order to boost the efficiency of this technology, we explore the use of ion-beam assisted deposition (IBAD) to create biaxially-textured silicon films which can potentially have less defects at the grain boundaries. Experimentally, we have fabricated an operational biaxially-textured silicon solar cell whose Voc is likely to have been affected by intra-grain defects as shown by our transmission electron microscopy (TEM) image. In order to investigate the interplay between grain boundary and intra-grain defects on solar cell performance and determine the potential benefits of developing biaxially-textured film solar cells, I used Synopsys' two-dimensional technology computer-aided design (TCAD) Sentaurus simulation tool. In general, the simulations found that biaxially-textured silicon solar cells improve solar cell efficiencies but there is small improvement for devices that have both large grains and low intra-grain carrier lifetime. Among the various thin-film technologies, CdTe and Cu(In, Ga)(S, Se)2 (CIGSSe), dominate the thin-film PV market. However in recent years, the photovoltaic community has seen growing interest in CZTS-based thin-film solar cells which include Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe) and Cu2ZnSn(S, Se)4 (CZTSSe) solar cells. This is driven by their potential to replace Cu(In, Ga)Se2 (CIGSe) and CdTe solar cells which face material scarcity, toxicity and market acceptance issues. In polycrystalline CIGSe-based (CIGSe, CISe, CuGaSe2 (CGSe)) and CdTe solar cells, grain boundaries do not seem to affect solar cell efficiency as much. In fact, some studies have identified grain boundaries as the source of high efficiency in polycrystalline CIGSe-based and CdTe solar cells. CIGSe-based and CZTS-based films are similar in terms of growth methods, optoelectronic and crystallographic properties. Because of these similarities and the benign nature of grain boundaries in CIGSe-based and CdTe films, it would be useful to examine the properties of grain boundaries in these materials. Using scanning Kelvin probe microscopy (SKPM) and conductive atomic force microscopy (C-AFM) techniques, I investigated the electronic properties of grain boundaries in CIGSe, CZTS and CZTSSe solar cells. SKPM measurements carried out in this work reveal a higher positive surface potential at the grain boundaries as compared to the grain while C-AFM measurements show higher current flow in the vicinity of the grain boundaries. These two measurement results are similar to those obtained for high quality CIGSe and CdTe and together they demonstrate the enhanced minority carrier collection taking place at the grain boundaries of CZTS and CZTSSe. Although SKPM measurement are susceptible to topographical and geometric effects, we believe that this effect is not dominating in our measurements as topography and surface potential profile lines are not exact mirror images of one another and regions of similar height have different potentials and vice versa. Nonetheless, I used a technique that involves photoreduction of AgNO3 to provide convincing evidence that our SKPM result is not a result of experimental artifacts but is truly indicative of the higher positive potential at the grain boundary. Having benign or beneficial grain boundaries have been found to be essential for achieving high efficiencies in polycrystalline CIGSe and CdTe solar cells. In my investigation, I found that high efficiency CZTS and CZTSSe solar cells have similar grain boundary electronic properties as high efficiency CIGSe and CdTe solar cells. As such, it might be possible for CZTS and CZTSSe solar cells to achieve similar high efficiencies as CIGSe and CdTe solar cells if other defects (intra-grain, surface and interfacial) are not limiting efficiencies.

Download or read book Thin Film Compound Semiconductor Photovoltaics 2007 Volume 1012 written by Timothy Gessert and published by . This book was released on 2007-11-14 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film compound semiconductor photovoltaic solar cells have demonstrated efficiencies of nearly 20% and are leading candidates to provide lower-cost energy due to potential advantages in manufacturing and materials costs. To fulfill the promise, a number of technical issues are being addressed, including a lack of fundamental understanding of these unique materials, devices and processes for large-area deposition. This book focuses on advances in the materials science, chemistry, processing and device issues of thin-film compound semiconductor materials that are used, or have potential use, in photovoltaic solar cells and related applications. Topics include: growth and performance of compound thin-film solar cells; novel materials and processes; defects and impurities; industrial perspectives; contacts and interfaces; grain boundaries and inhomogeneities; and structural, optical and electronic characterization.

Download or read book Electronic Grain Boundary Properties in Polycrystalline Cu In Ga Se 1tn2 Semiconductors for Thin Film Solar Cells written by Robert Baier and published by . This book was released on 2012 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AFM Based Microelectrical Characterization of Grain Boundaries in Cu In Ga Se2 Thin Films written by R. Noufi and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In, Ga)Se2 thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy both in air and in ultra-high vacuum. The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs, and the GB is positively charged. The role of the built-in potential in device performance was further examined and found to be positive, by tuning Ga content or bandgap of the film. With increasing Ga content, the potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage Cu(In, Ga)Se2 device.

Download or read book Determination of Grain Boundary Charging in Cu In Ga Se2 Thin Films written by and published by . This book was released on 2012 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface potential mapping of Cu(In, Ga)Se2 (CIGS) thin films using scanning Kelvin probe force microscopy (SKPFM) aims to understand the minority-carrier recombination at the grain boundaries (GBs) of this polycrystalline material by examining GB charging, which has resulted in a number of publications. However, the reported results are highly inconsistent. In this paper, we report on the potential mapping by measuring wide-bandgap or high-Ga-content films and by using a complementary atomic force microscopy-based electrical technique of scanning capacitance microscopy (SCM). The results demonstrate consistent, positively charged GBs on our high-quality films with minimal surface defects/charges.

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 Local Built in Potential on Grain Boundary of Cu In Ga Se2 Thin Films written by R. Noufi and published by . This book was released on 2005 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In, Ga)Se2 (CIGS) thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy (SKPM). The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs and that the GB is positively charged. The role of the built-in potential in device performance was further examined by tuning Ga content or band gap of the film. With increasing Ga content, the GB potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage CIGS device.

Download or read book II IV Compound Semiconductor Photovoltaic Materials Volume 668 written by Robert Birkmire and published by . This book was released on 2001-10-15 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on materials issues related to Cu(In,Ga)(Se,S)2 and CdTe-based polycrystalline thin-film photovoltaic solar cells and related oxides and chalcogenides. Phase equilibrium and thermochemical kinetic aspects of the absorber layer formation of CdTe and Cu(In,Ga)(Se,S)2 are emphasized and several papers on micro-analytical analysis report on detailed structural properties of thin films. The use of flexible plastic or metal foil substrates as an alternative to glass is addressed in terms of solar-cell performance and limitations imposed by the nature of the substrates. Properties of defects and interfaces in CdTe and CIGSS are highlighted using electrical, optical, and micro-analytical tools. While film properties are correlated to device physics, controversy still exists on the detailed operation of both CdTe and CIGSS devices. Topics include: materials and synthesis; thin films on alternate substrates; defects; growth and junction formation; surfaces and interfaces and film and device characterization.

Download or read book Microscopic Characterisation of Solar Cells written by and published by . This book was released on 2013 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Investigation of the Microstructure of Cu In Ga Se2 Thin Films Used in High Efficiency Devices Preprint written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This conference paper describes the microstructure of Cu(In,Ga)Se2 (CIGS) films, as it transitioned from Cu-rich to In-rich composition, by transmission electron microscopy, and energy-dispersive X-ray spectroscopy. We find that the Cu-rich samples have larger grains than the In-rich samples, and they contain two structurally different forms of the CuxSe secondary phase. These samples also showsub-interfaces about 0.2 ..mu..m below the surface. The In-rich samples were almost void of these sub-interfaces.

Download or read book New Deposition Process of Cu In Ga Se2 Thin Films for Solar Cell Applications written by Himal Khatri and published by . This book was released on 2009 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molybdenum (Mo) is currently the most common material used for Cu(In, Ga)Se2 solar cell back contacts. The first objective of this study is to utilize in-situ and ex-situ characterization techniques to investigate the growth, as well as the physical and chemical properties, of Mo thin films deposited by RF magnetron sputtering onto soda-lime glass (SLG) substrates. The effects of the deposition pressure on the nucleation and growth mechanisms that ultimately influence morphology and grain structure have been studied. Correspondence between real time spectroscopic ellipsometry (RTSE), X-ray diffraction (XRD), atomic force microscopy (AFM), and four-point probe resistivity measurements indicate that increasing deposition pressure leads to smaller average grain sizes and higher oxygen content in the Mo thin films. Changes of the material properties were also evaluated by changing RF power. It is observed that higher RF power, results in higher conductivity films. The second and overall objective of this work is to focus on the deposition and characterization of the Cu(In, Ga)Se2 absorber layer using the hybrid co-sputtering and evaporation process, which has potential for commercial PV. Solar cells were completed with a range of elemental compositions in the absorber layer, keeping a constant profile of Ga and varying Cu concentrations. The slightly Cu deficient Cu(In, Ga)Se2 films of band gap ~1.15 eV fabricated by this process consist of a single chalcopyrite phase and device efficiencies up to 12.4% were achieved for the composition ratios (x, y) = (0.30, 0.88). Correspondence between energy dispersive X-ray spectroscopy (EDS), X-ray diffraction, transmission and reflection (T & R), four-point probe resistivity, and current density-voltage (J-V) measurements indicate that increased Cu concentration leads to the incorporation of a secondary phase Cu2-xSe compound in the Cu(In, Ga)Se2 films, which is detrimental to cell performance. The third objective of this work is to evaluate the Cu2-xSe material properties by employing in-situ RTSE, as well as ex-situ SE and various other characterization techniques. SE revealed that the dielectric function spectra of Cu2-xSe evolve with temperature, providing insights into the evolution of transport properties and critical point structures. At room temperature, semi-metallic behavior of Cu2-xSe thin films was revealed by SE and Hall Effect measurements. These characteristics serve as key inputs for optical modeling of complex layer structures of Cu(In, Ga)Se2 films grown by 2- and 3-step processes.

Download or read book Investigation of Structure property Relationships of Cu In Ga Se2 and Ag Cu In Ga Se2 Thin Film Solar Cells written by Sinju Thomas and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Microstructural Defects in Cu In Ga Se2 Thin Films by Scanning Transmission Electron Microscopy written by Ekin Şimşek Sanlı and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: