Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Quaternary Cu2ZnSn(S,Se)4 Absorber Materials for Photovoltaic Applications" By Shukai Yao Purdue MSE Preliminary Exam Advisor: Professor Peilin Liao ABSTRACT Cu2ZnSn(S,Se)4 (CZTSSe) has drawn wide interest in the photovoltaic (PV) community for the last decade as the material components are environmental friendly and abundant on earth, and it has tunability in terms of band gap ranging from 1.0 to 1.5 eV. However, the CZTSSe-based solar cell needs to be improved with respect to energy conversion efficiency (~12%). The inherent elements complexity of quaternary CZTSSe system has raised difficulties in fabricating samples with a high quality. The underlying origin of the difficulties is manifested by two main factors: (i) secondary phases and (ii) point defects. Suppressing their formation will decrease the band alignment fluctuations and the carrier recombination, enhancing the PV performance. Combining the current experimental and computational studies, this review discussed the crystal structure, electronic structure, secondary phases and points defects of CZTSSe, exploring the possible future work on optimizing this PV material. Date: Wednesday, December 11, 2019 Time: 8:30 A.M. Place: ARMS B071