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201808 https://hdl.handle.net/2286/R.2.N.201808 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 2027-08-01T10:21:30 168 pages Doctoral Dissertation Academic theses en Duan, Xiaomeng Yan, Feng Li, Lin Yang, Sui Zhuang, Houlong Arizona State University Partial requirement for: Ph.D., Arizona State University, 2025 Field of study: Materials Science and Engineering Cadmium Telluride (CdTe) is a direct bandgap semiconductor with a bandgap of 1.5 eV. According to the Shockley-Queisser limit, the theoretical efficiency of CdTe solar cells is 33%. Currently, the highest laboratory-recorded power conversion efficiency for CdTe solar cells reaches 23.1%. While the short-circuit current (JSC) is optimized, the open-circuit voltage (VOC) and fill factor (FF) have less utilization. Doping is an important strategy to enhance VOC. Additionally, due to the high electron affinity of CdTe, implementing a back contact between CdTe and the electrode is necessary to enhance the fill factor.Using an AsCl3 vapor annealing doping approach, arsenic-doped CdSeTe devices have achieved approximately 18% efficiency, much higher than CdSeTe devices fabricated without vapor annealing. Besides the significant enhancements of efficiency, this vapor annealing approach led to a longer carrier lifetime of over 72 ns and VOC of 850 mV. The As2Te3 and As2Se3 solutions were synthesized using DI water and ammonium sulfide as solvents at room temperature. Subsequent experiments and characterizations show that these arsenic chalcogenides can serve as dopants and back contacts. In the case of the As2Te3 solution, the formation of tellurium promotes hole transport. Compared to the As2Ses doped CdSeTe device, the fill factor (FF) of the CdSeTe device doped with As2Te3 increased from 70.44% to 73.09%. Antimony chalcogenides can potentially serve as dopants. Initially, Sb2S3 films were synthesized, and the impact of precursor processing ambient on crystal growth behavior was investigated. This project demonstrates the feasibility of synthesizing antimony chalcogenides, which can be used as dopants and back contacts in CdSeTe solar cells. In the next section of the chapter, Sb2Se3 and Sb2Te3 solutions, using en and edtH2 as solvents, will be synthesized and can be applied to the CdSeTe substrate. In addition to their role as dopants, Sb2Se3/Sb2Te3 could also work as back contacts. However, compared to Sb2Se3, the conduction band offset between CdTe and Sb2Te3 is larger, which leads to electron transport to the back contact and results in electron-hole recombination at the back contact. The FF increased from 67.68% to 70.70% when switching from Sb2Te3 to Sb2Se3 as the dopant sources. Energy Materials Science Engineering CdSeTe Solar Cells Group V Doping Thin Film Group V Diffusion Doping in CdSeTe Thin Film Solar Cells