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Study Of Molybdenum Oxide As A Back Contact Buffer For Thin Film N Cds P Cdte Solar Cells
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Book Synopsis Study of Molybdenum Oxide as a Back Contact Buffer for Thin Film N-CdS/p-CdTe Solar Cells by : Hao Lin
Download or read book Study of Molybdenum Oxide as a Back Contact Buffer for Thin Film N-CdS/p-CdTe Solar Cells written by Hao Lin and published by . This book was released on 2012 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Back contact improvement is one of the most crucial issues for the realization of highly efficient n-CdS/p-CdTe solar cells. Conventional methods for making a sufficiently ohmic contact to p-CdTe usually involve a solution etching process and a Cu doping process, which are known to negatively affect the device reliability. To resolve this problem, a low-resistance back contact for n-CdS/p-CdTe solar cells has been developed, which utilizes a vapor-deposited transition metal oxide (TMO) thin film as the back contact buffer layer between p-CdTe and the back electrode. The usefulness of TMO is attributed to its unusually high work function which is needed to match that of p-type CdTe in producing a contact of low resistance. As one major representative of TMO materials, molybdenum oxide (MoOx) has been investigated as a novel buffer in this thesis. First, the processes for making low resistance contact with MoOx buffer are explored. To achieve a good ohmic contact to p-CdTe, a water rinse step is necessary in order to remove surface residues from the CdTe surface prior to MoOx deposition. In addition, different methods for depositing MoOx films have been examined, including thermal evaporation and DC sputtering methods. With MoOx as the high work function buffer, various metals can be used as the electrode to realize an ohmic back contact to p-CdTe. Other advantages of the MoOx buffer include dry application by vacuum deposition, and thus it is particularly suitable for the fabrication of ultra-thin CdTe solar cells without introducing additional shorting defects. Second, the mechanism by which MoOx improves the performance of the back contact is studied through the investigation of Ni/CdTe and Ni/MoOx/CdTe interfaces with x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Contrasting differences in the interface formation and core level structure were observed, indicating that the presence of a thin MoOx inter-layer was effective in reducing the unfavorable reaction between Ni and the native tellurium oxide at the CdTe surface. Finally, the stability of CdTe cells with MoOx buffer is studied. MoOx is found to effectively stabilize the device performance, especially the open-circuit voltage (Voc) of the CdTe solar cell during thermal stress tests. The cell with a Ni-only electrode rapidly degrades due to Ni diffusing into the CdTe film and Ni abstracting Te from CdTe. With the addition of a layer of MoOx as the buffer layer, the diffusion of Ni and the reaction between Ni and CdTe are alleviated, resulting in significantly improved device stability. To summarize, an efficient and stable back contact has been developed through the application of a high work function MoOx as the buffer for p-CdTe. As a result, n-CdS/p-CdTe solar cells with improved efficiency and stability have been realized"--Page viii-ix.
Book Synopsis Recent Advances in Thin Film Photovoltaics by : Udai P. Singh
Download or read book Recent Advances in Thin Film Photovoltaics written by Udai P. Singh and published by Springer Nature. This book was released on 2022-09-02 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides recent development in thin-film solar cells (TFSC). TFSC have proven the promising approach for terrestrial and space photovoltaics. TFSC have the potential to change the device design and produce high efficiency devices on rigid/flexible substrates with significantly low manufacturing cost. TFSC have several advantages in manufacturing compared to traditional crystalline Si-solar cells like less requirement of materials, can be prepared with earth’s abundant materials, less processing steps, easy to dispose, etc. Several universities/research institutes/industry in India and abroad are involved in the research area of thin-film solar cells. The book helps the readers to find the details about different thin-film technologies and its advancement at one place. Each chapter covers properties of materials, its suitability for PV applications, simple manufacturing processes and recent and past literature survey. The issues related to the development of high efficiency TFSC devices over large area and its commercial and future prospects are discussed.
Book Synopsis Energy Applications of 2D Nanomaterials by : Ram K. Gupta
Download or read book Energy Applications of 2D Nanomaterials written by Ram K. Gupta and published by CRC Press. This book was released on 2022-05-26 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: 2D nanomaterials have emerged as promising candidates for use in energy devices owing to their superior electrochemical properties, surface area, nanodevice integration, multifunctionality, printability, and mechanical flexibility. Energy Applications of 2D Nanomaterials covers a wide range of applications of 2D nanomaterials for energy, as well as future applications and challenges in fabricating flexible energy generation and storage devices. This book: Examines 2D nanomaterials for solar cells, fuel cells, batteries, supercapacitors, and flexible devices Details novel methods and advanced technologies Covers future applications and challenges This book is aimed at materials scientists, chemists, electrochemists, and engineers working in energy disciplines.
Book Synopsis Study of Back Contact Formation on CdTe/CdS Thin Film Solar Cells by : Jian Tang
Download or read book Study of Back Contact Formation on CdTe/CdS Thin Film Solar Cells written by Jian Tang and published by . This book was released on 1998 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Processing of CdTe- and CuIn[subscript 1-x]Ga[subscript x]Se2-Based Solar Cells: Final Technical Report, 26 May 1998-22 December 2001 by : Don Louis Morel
Download or read book Advanced Processing of CdTe- and CuIn[subscript 1-x]Ga[subscript x]Se2-Based Solar Cells: Final Technical Report, 26 May 1998-22 December 2001 written by Don Louis Morel and published by DIANE Publishing. This book was released on 2003 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Back Contacts for CdTe Thin Films Solar Cells by : Fadhil Khalaf Dahash Alfadhili
Download or read book Development of Back Contacts for CdTe Thin Films Solar Cells written by Fadhil Khalaf Dahash Alfadhili and published by . This book was released on 2020 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film solar cells based on polycrystalline p-type cadmium telluride (CdTe) represent one of these the most promising photovoltaic (PV) device due to high efficiency and low-cost production. Currently, CdTe solar cells provide the lowest cost electricity generation in utility-scale applications, which is a cost-competitive with the traditional power source, fossil fuel. CdTe thin film PV has attained 22.1 % of power conversion efficiency for small area scale and 18.6 % for modules scale. However, the high efficiency of CdTe devices has been achieved by increasing the photo-generated current by changing the traditional window layer (CdS) of CdTe to a wider bandgap material with better band alignment. The open-circuit voltage (VOC) remains below the theoretical limit due to a barrier at the back of the device due to the deep valence band edge of CdTe (-5.9 eV). Voc can be increased by adding a buffer layer between CdTe and the back electrode to decrease band banding and reducing carrier recombination at the back interface. In this thesis, several materials were investigated as a back-buffer layer, such as single-wall carbon nanotube (SWCNT), zinc telluride (ZnTe), tellurium (Te), and cadmium zinc telluride (CZT) to minimize the bend bending at CdTe/back-buffer layer interface. An alternative method to reduce the carrier recombination at the rear surface, the use of aluminum oxide (Al2O3) layer as a passivation layer was also demonstrated. Finally, an effective method of CdCl2 treatment for CZT thin film was investigated. This method shows that zinc (Zn) can be maintained during the heat treatment.
Book Synopsis Back Contact Buffer Layer for Thin-film Solar Cells by :
Download or read book Back Contact Buffer Layer for Thin-film Solar Cells written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.
Book Synopsis Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells by : Poonam Rani Kharangarh
Download or read book Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells written by Poonam Rani Kharangarh and published by . This book was released on 2013 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe solar cell performance, the effect of processing on defect states, and simple and effective characterization techniques must be investigated and identified. In this research the thin film n+-CdS/p-CdTe solar cells made with evaporated Cu as a primary back contact, are characterized by using the temperature dependence of the reverse bias diode current (J-V-T) to determine the energy levels of deep defects. The results of the J-V-T measurements on solar cells made at NJIT show that while modest amounts of Cu enhance cell performance, an excessive high temperature annealing step degrades device quality and reduces efficiency. This work addresses the error that can be introduced during defect energy level estimation if the temperature dependence of the carrier capture cross-section is neglected. Therefore, the location of traps is derived using a Shockley-Read-Hall recombination model with modified assumptions. A Cu-related deep level defect with activation energy of 0.57eV is observed for Cu evaporated back contact cells and an intrinsic defect with activation energy 0.89eV is found. Frequency dispersion in Capacitance-Voltage measurements confirms the presence of Cu-related deep level traps for cells with a Cu evaporated back contact, whereas no such defects are observed in carbon paste contact. The behavior is believed to be due to diffusion of excess Cu from the contact. It is further observed that majority carrier deep level traps (Cu-related or intrinsic) contribute differently to the degradation of electronic properties of the CdTe solar cells. A simple and effective characterization technique based on temperature dependent capacitance spectroscopy (TDCS) is used to identify majority carrier trapping defects in thin film n+-CdS/p-CdTe solar cell, made with evaporated Cu as a primary back contact. The distinct deep level traps, observed by TDCS seem to be due to the ionization of impurity centers located in the depletion region of n+-CdS/p-CdTe junction.
Book Synopsis Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells by : Hehong Zhao
Download or read book Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells written by Hehong Zhao and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: CdTe/CdS thin film solar cells are the most promising cost-effective solar cells. The goal of this project is to improve the performance for CdS/CdTe devices by improving the open circuit voltage V[subscript]oc and current density J[subscript]sc. Efforts focused on increasing the V[subscript]oc, which include increasing the doping concentration by introducing Phosphorus and Antimony, finding and testing new back contact materials, and varying the ambient of CSS CdTe. In addition, the effect of Zn2SnO4 on the cells' performance was also studied. Electrical characterization of the thin films and completed devices were carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V), and Spectral Response (SR) measurements. Structural/chemical characterization was done by SEM, XRD and EDS analysis. The ambient of CSS CdTe affects the growth rate, the grain size and electronic properties of CdTe. The N2/O2 mixture with varied ratio (N2/O2=9/1, 7/3, 5/5 and 1/9) was used in this study. The cells' performance and the net carrier concentration were studied as a function of the N2/O2 ratio. The net carrier concentration increases with the increasing O2 concentration. The extrinsic impurities (P and Sb) were incorporated into CdTe layer. Phosphorus was directly introduced into CSS CdTe source. The Sb was incorporated into CdTe by a diffusion process. The effects of the annealing parameters, the excess Sb on CdTe surface, the CdCl2 treatment and the depth of Sb in CdTe were studied. Higher doping concentration up to 1016 cm−3 has been achieved, however, V[subscript]oc is still in the range of 830 mV.
Book Synopsis Molybdenum as a Back Contact for Cucl Treated Cds/cdte Solar Cells by : Matheshkumar Jayabal
Download or read book Molybdenum as a Back Contact for Cucl Treated Cds/cdte Solar Cells written by Matheshkumar Jayabal and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: CdTe is one of the most promising absorbers for use in inexpensive semiconductor solar cells having achieved a high efficiency of 16.4% in small area cells [1]. One of the most important technological problems in obtaining high efficiencies is to have a good ohmic contact on the CdTe, which is characterized by a very high work function [2]. Cu is used as a dopant in CdTe at the contact to promote quantum mechanical tunneling [3]. But the oversupply of Cu causes the diffusion of Cu through CdTe to the underlying CdS layer resulting in the degradation of the cell performance. It has been reported that Cu was segregated near the CdS/CdTe junction. To avoid the Cu segregation at the junction, Cu supply should be minimized while the ohmic characteristics of p-CdTe contact are maintained [4]. In this thesis, the main objective is to understand the role of Cu at the CdS/CdTe interface. Here the Cu is added at the CdS/CdTe interface and is avoided at the back contact.
Book Synopsis From Front Contact to Back Contact in CdTe/CdS Solar Cells by : Yann Roussillon
Download or read book From Front Contact to Back Contact in CdTe/CdS Solar Cells written by Yann Roussillon and published by . This book was released on 2004 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of a Front Buffer Layer on the Performance of Flexible CdS/CdTe Solar Cells by : Hasitha Padmika Mahabaduge
Download or read book Influence of a Front Buffer Layer on the Performance of Flexible CdS/CdTe Solar Cells written by Hasitha Padmika Mahabaduge and published by . This book was released on 2013 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium telluride (CdTe) solar cells have been developing as a promising candidate for large-scale application of photovoltaic energy conversion and have become the most commercially successful polycrystalline thin-film solar module material. In scaling up from small cells to large-area modules, inevitably non-uniformities across the large area will limit the performance of the large cell or module. The effects of these non-uniformities can be reduced by introducing a thin, high-resistivity transparent buffer layer between the conductive electrodes and the semiconductor diode. ZnO is explored in this dissertation as a high-resistivity transparent buffer layer for sputtered CdTe solar cells and efficiencies over 15% have been achieved on commercially available Pilkington TEC15M glass substrates. The highest open-circuit voltage of 0.858V achieved using the optimized ZnO buffer layer is among the best reported in the literature. The properties of ZnO:Al as a buffer are also investigated. We have shown that ZnO:Al can serve both as a transparent conducting oxide layer as well as a high-resistivity transparent layer for CdTe solar cells. ZnO:Al reactively sputtered with oxygen can give the necessary resistivities that allow it to be used as a high-resistivity transparent layer. Glass is the most common choice as the substrate for solar cells fabricated in the superstrate configuration due to its transparency and mechanical rigidity. However flexible substrates offer the advantages of light weight, high flexibility, ease of integrability and higher throughput through roll-to-roll processing over glass. This dissertation presents significant improvements made to flexible CdTe solar cells reporting an efficiency of 14% on clear Kapton® flexible polyimide substrates. Our efficiency of 14% is, to our knowledge, the best for any flexible CdTe cell reported in literature.
Book Synopsis Coatings and Thin-Film Technologies by : Jaime Andres Perez Taborda
Download or read book Coatings and Thin-Film Technologies written by Jaime Andres Perez Taborda and published by BoD – Books on Demand. This book was released on 2019-01-03 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of coatings and thin-film technologies is rapidly advancing to keep up with new uses for semiconductor, optical, tribological, thermoelectric, solar, security, and smart sensing applications, among others. In this sense, thin-film coatings and structures are increasingly sophisticated with more specific properties, new geometries, large areas, the use of heterogeneous materials and flexible and rigid coating substrates to produce thin-film structures with improved performance and properties in response to new challenges that the industry presents. This book aims to provide the reader with a complete overview of the current state of applications and developments in thin-film technology, discussing applications, health and safety in thin films, and presenting reviews and experimental results of recognized experts in the area of coatings and thin-film technologies.
Book Synopsis Study Of Cu Free Back Contacts to Thin Film CdTe Solar Cells by : Vijay Viswanathan
Download or read book Study Of Cu Free Back Contacts to Thin Film CdTe Solar Cells written by Vijay Viswanathan and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The effect of etching ambient, pressure, plasma power and etch time on contact performance will be studied.
Book Synopsis CdTe and Related Compounds; Physics, Defects, Hetero- and Nano-structures, Crystal Growth, Surfaces and Applications by :
Download or read book CdTe and Related Compounds; Physics, Defects, Hetero- and Nano-structures, Crystal Growth, Surfaces and Applications written by and published by Elsevier. This book was released on 2009-11-11 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost thirty years after the remarkable monograph of K. Zanio and the numerous conferences and articles dedicated since that time to CdTe and CdZnTe, after all the significant progresses in that field and the increasing interest in these materials for several extremely attractive industrial applications, such as nuclear detectors and solar cells, the edition of a new enriched and updated monograph dedicated to these two very topical II-VI semiconductor compounds, covering all their most prominent, modern and fundamental aspects, seemed very relevant and useful. - Detailed coverage of the main topics associated with the very topical II-VI semiconductor compound CdTe and its alloy CZT - Review of the CdTe recent developments - Fundamental background of many topics clearly introduced and exposed
Book Synopsis Indium Oxide as a High Resistivity Buffer Layer for CdTe/CdS Thin Film Solar Cells by : Umamaheswari Balasubramanian
Download or read book Indium Oxide as a High Resistivity Buffer Layer for CdTe/CdS Thin Film Solar Cells written by Umamaheswari Balasubramanian and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: ITO films with resistivity as low as 1.9X10-4 ohm-cm, mobility 32 cm2V-1s-1 and average transmission %7E 90% in the visible region were obtained for carrier concentration in the order of 1.1XE21cm-3.
Book Synopsis Stability Studies of CdTe/CdS Thin Film Solar Cells by : Bhaskar Reddy Tetali
Download or read book Stability Studies of CdTe/CdS Thin Film Solar Cells written by Bhaskar Reddy Tetali and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusion of Cui+ ions from the back contact along CdTe grain boundaries had been previously reported [16]. An increase in light/dark J-V crossover and bulk Rs with stress time and temperature was observed. A slow degradation component attributed to Cu-related substitutional defect [23] formation/diffusion to the junction and CdS is proposed. This should compensate the CdS over time and increase its photoconductivity/resistivity. An improvement in the current collection and FF within 100 hours of LS was observed. This is possibly due to the enhancement of Cui+ diffusion into the junction and CdS during LS as previously reported [16]. A reduction in light/dark J-V crossover was observed, possibly due to an increase in CdS doping and reduction in the CdS/SnO2 front contact barrier. However, a fast decrease in Voc and increase in recombination current was also observed in the first 1000 hours of LS.
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