New Jersey Institute of Technology Digital Commons @ NJIT Dissertations Electronic Theses and Dissertations Summer 8-31-2016 Processing of CdS/CdTe solar cell and the growth model of CdTe thin film Guogen Liu New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/dissertations Part of the Chemical Engineering Commons Recommended Citation Liu, Guogen, "Processing of CdS/CdTe solar cell and the growth model of CdTe thin film" (2016). Dissertations. 88. https://digitalcommons.njit.edu/dissertations/88 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Dissertations by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. 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Please Note: The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation Printing note: If you do not wish to print this page, then select “Pages from: first page # to: last page #” on the print dialog screen The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty. ABSTRACT PROCESSING OF CDS/CDTE SOLAR CELL AND THE GROWTH MODEL OF CDTE THIN FILM by Guogen Liu Cadmium telluride is the only thin film photovoltaic (PV) technology to surpass crystalline silicon PV in the cost. The most common CdTe solar cells consist of a simple p-n heterojunction structure containing a p-doped CdTe layer and n-doped cadmium sulfide (CdS) layer, which acts as a window layer. Cadmium Sulfide (CdS) thin films are often deposited on glass substrates coated with TCO layers by the close-spaced sublimation (CSS) or sputter techniques in industrial because of in-line production integration. It is seldom reported that CdS is deposited by the chemical bath deposition (CBD) batch process. The bottleneck of CBD for commercial application is its low production rate and waste water treatment. This dissertation reports how to produce different thickness large area (100cm2) CdS thin film by CBD. The influence of the solution temperature and concentration on the thickness of CdS is investigated. This dissertation also reports a growth model for CdTe deposition including diffusion limited and sublimation limited. The model was consistent with experimental observations and showed very good agreement over a range of operating conditions. PROCESSING OF CDS/CDTE SOLAR CELL AND THE GROWTH MODEL OF CDTE THIN FILM By Guogen Liu A Dissertation Submitted to the Faculty of New Jersey Institute of Technology in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering August 2016 Copyright © 2016 by Guogen Liu ALL RIGHTS RESERVED . APPROVAL PAGE PROCESSING OF CDS/CDTE SOLAR CELL AND THE GROWTH MODEL OF CDTE THIN FILM Guogen Liu Dr. Ken K. Chin, Dissertation Advisor Date Professor of Physics, Director of CNBM Photovoltaic Material Research Center, NJIT Dr. Laurent.Simon, Dissertation Advisor Date Associate Professor of Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering Dr. Alan E. Delahoy, Committee Member Date Research Professor of Physics, NJIT Dr. Reginald P Tomkins, Committee Member Date Professor of Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering Dr. Xiaoyang Xu, Committee Member Date Assistant Professor of Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering Dr. George E. Georgiou, Committee Member Date University Lecturer of Physics, NJIT BIOGRAPHICAL SKETCH Author: Guogen Liu Degree: Doctor of Philosophy Date: August 2016 Undergraduate and Graduate Education: • Doctor of Philosophy in Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ, 2016 • Master of Chemical Engineering, Beijing University of Chemical Engineering, Beijing, P. R. China, 2007 • Bachelor of Chemical Engineering, Nanchang University, Jiangxi, P. R. China, 2004 Major: Chemical Engineering Presentations and Publications: Guogen Liu, Zimeng Chen, George E. Georgiou, Ken K. Chin, “The Growth Model of CdTe Thin Film by Close Spaced Sublimation,” at 42th IEEE Photovoltaic Conference, (June 2015). Zimeng Cheng, Alan E. Delahoy, Guogen Liu, Shou Peng, Congxiao Wang, Jingong Pan, Xin Cao and Ken K. Chin, “Modelling of The Nonstoichiometric Composition Shift In Physical Vapor Deposition of CdTe Thin Films Based on Experimental Results,” EUPVSEC, (2015). Guogen Liu, Zimeng Chen, Ken K. Chin, Robert B. Barat, George E. Georgiou, Alan E. Delahoy, “CdS Thin Film Grown by Aerosol-Assisted Deposition Method,” at 38th IEEE Photovoltaic Conference, (June 2012). Guogen Liu, Zimeng Chen, Ken K. Chin, Robert B. Barat, Alan E. Delahoy, George E. Georgiou, “Preparation and characterization of high efficiency CdS/CdTe solar cell, ” at VIII th Annual Graduate Student Research Day, NJIT, Newark, NJ, (Nov 2012). iv Poonam Kharangarh, Durgamadhab Misra, George E. Georgiou, Alan E. Delahoy, Zimeng Cheng, Guogen Liu, Halina Opyrchall, Timothy Gessert and Ken K. Chin, “Investigation of Defects in n+CdS/p-CdTe Solar Cells,” Proc. of 38th PVSC, Austin, TX USA , p. 1286, Jun 2012. Guogen Liu, Zimeng Chen, Ken K. Chin, Robert B. Barat, George E. Georgiou, “Large Area CdS Thin Film Grown By Chemical Bath Deposition,” In proceedings of 37th IEEE Photovoltaic Conference, June 2011. Guogen Liu, Zimeng Chen, Ken K. Chin, Robert B. Barat, George E. Georgiou, “Preparation and characterization of CdS/CdTe solar cell,” at VIth Annual Graduate Student Research Day, NJIT, Newark, NJ, Nov 2010. v To my family: Fuliang Liu, Aimei Xu, Qiaozhen Liu vi ACKNOWLEDGMENT I would like to express my deep gratitude and sincere appreciation to my advisors, Prof. Ken K. Chin and Prof. Laurent Simon, for their constant support and guidance throughout this work. Their valued advice, encouragement, and constructive criticism have been a great source of inspiration in the fulfillment of this thesis. I would also like to express my gratitude and thanks to all my committee members Dr. Reginald P. Tomkins, Dr. George E. Georgiou, Dr. Alan E. Delahoy and Dr. Xiaoyang Xu for their interest, useful suggestions, and support in this study. The valuable discussions and constructive suggestions from Tim Gessert and Jim Sites are greatly acknowledged. Many thanks to Chemical Engineering and CNBM for their funding support. Finally, I would also like to thank all my colleagues for their help and support in my work. vii TABLE OF CONTENTS Chapter Page 1 INTRODUCTION……............ ................………………..…………………………. 1 1.1 Why Renewable Energy? …………….…………………………..…….………. 1 1.1.1 Fossil Fuels................................................................................................. 2 1.1.2 Renewable Energy...................................................................................... 3 1.2 Why Solar Energy? ……….…..…………………..…………...….…………..... 6 1.3 Why CdTe Thin Film Solar Cell? ……………………….…………………...... 14 1.4 Structure of Cds/CdTe Solar Cell…..…………...………….………………....... 21 1.5 Pilot Line for Cds/CdTe Modules….…………………………..……………...... 27 2 DEPOSITION OF HIGH EFFICIENT CDTE SOLAR CELL................................... 36 2.1 Introduction ……….………………………………………………………….... 36 2.2 Preparation Of CdS/CdTe Solar Cell.................……. ….. ………………….…. 37 2.2.1 TCO Deposition.......................................................................................... 37 2.2.2 CdS Deposition........................................................................................... 38 2.2.3 CdTe Deposition…..................................................................................... 43 2.2.4 CdCl2 Treatment........................................................................................ 49 2.2.5 Back Contact.............................................................................................. 56 2.3 CdTe Solar Cell Efficiency................................................................................... 59 3 LARGE AREA CDS THIN FILM GROWN BY CBD……………………….……. 64 3.1 Introduction ……………….………………………..………………………...… 64 3.2 Preparation of CdS by CBD....…………….………………………………….… 66 viii TABLE OF CONTENTS (Continued) Chapter Page 3.3 Mechanism of CBD.............……………………………………………..…....… 68 3.4 Results and Discussion……………….……………………………………….... 70 3.4.2 Photoelectric Microscope Measurement....................................................