This event will be held virtually.
Speaker: Junhao Zhu, ECpE Graduate Student
Advisor: Vikram Dalal
Title: Vapor Deposited Inorganic Perovskite Solar Cells
Abstract: We report on the fabrication and material properties of completely inorganic perovskite solar cells where the organic cation has been replaced by an inorganic cation, Cs. The replacement of the organic cation by Cs results in a material that is intrinsically thermally stable, as indicated by x-ray diffraction data on the composition, for post-fabrication test temperatures up to 200 C for over 24 hours, unlike materials with organic cations that decompose at 85-125 C. The material is deposited using a deposition process using individual precursors, followed by thermal annealing at high temperature. We made heterojunction superstrate device using the structure n-CdS/perovskite/P3HT/gold on FTO substrates with a photovoltaic conversion efficiency of 11.8%. Most importantly, the solar cell performance remains stable in an extended test at test temperature of 200 C for over 24hours, unlike solar cells using organic cations where the performance degrades rapidly at 85 C. This fact indicates that the inorganic perovskite materials may be appropriate for use in tandem junction cells for use in real-life environments such as the Southwestern US, Australia, the Middle East, and India, where the ambient temperatures in the deserts approach or exceed 50 C in the summer, and cell temperatures exceed 100 C. Further engineering work has been done towards band diagram alignment to minimize the voltage loss of the solar cell device. With only Br used as the halide anion in the perovskite, ultrahigh open circuit voltage of 1.62V has been achieved using the structure of FTO/c-TiO2/perovskite/doped-P3HT/Ag, which is the highest Voc ever achieved for inorganic perovskite solar cell devices.
Bio: Junhao Zhu received his B.S. in Electronic Science and Technology from University of Electronic Science and Technology of China, Chengdu, China, and M.S. in Material Science and Engineering from University of Florida, Gainesville, United States. He is currently working on his Ph.D. at Iowa State University under the advisement of Professor Vikram Dalal. His research is focusing on inorganic perovskite solar cell devices, with high thermal and air stability, and ultrahigh open circuit voltage, using highly controllable and reproducible vapor deposition methods.
Webex Link: https://iastate.webex.com/iastate/j.php?MTID=m9dcc96357cb79247de6b95e19a41d977
Seminar Recording: https://iastate.webex.com/iastate/ldr.php?RCID=9875b3cceabd449eacfb6f8854a64ab0