Jeffrey DuBose

Chemistry and Biochemistry

Faculty Advisor: Prashant Kamat

Understanding How Phase Segregation Occurs in Mixed Halide Perovskite Solar Cells

Solar cells utilizing a perovskite as the light absorbing material are the next generation of high performing and lightweight solar panels. The state-of-the-art perovskites contain a mixture of different halide atoms in the crystal structure – typically bromine and iodine. In a solar cell utilizing these mixed halide perovskites (MHPs), the MHP is in contact with a charge extraction layer which pulls electrons out of the cell. This project will investigate how one of the most common electron transport layers – titanium dioxide (TiO2) –– can induce a phase change in MHPs under operating conditions. Specifically, it will investigate how electron transfer out of the perovskite can cause the MHP to segregate into regions that are more iodine-rich and bromine-rich, due to a build-up of holes (positive charges). Understanding the role of hole accumulation in phase segregation is crucial, as segregation drastically lowers the performance of a solar cell[1]. Developing a better understanding of phase segregation will allow scientists to develop strategies to mitigate the process and stabilize these materials.

[1]: Samu et al., ACS Energy Lett. 2017