About the seminar:

Compared to conventional, dopable semiconductors, halide perovskite
semiconductors are uniquely defect tolerant and maintain their optoelectronic properties
despite hosting intrinsic high equilibrium defect concentrations. Optical bandgap and
conductivity in iodide-based semiconductors are largely driven by the dominant, low energy
iodide vacancy defect. The disruption in iodide bonding introduced by these imperfections
in the crystal structure leads to electronic states that may lie within the bandgap of the
material. The distance of these defect states from band edges is acutely sensitive to iodide
chemical potentials during and after synthesis and is directly related to conductivity
changes through defect mediated electronic equilibria. Thus, changes in structural
composition and external environment can strongly influence the prevalence of iodide
vacancies and related defects. Herein, emphasis is placed on the unique oƯ-gassing
equilibrium that halide semiconductors can undergo at modest temperatures.
Understanding the nature of this halogen gas exchange is necessary to improve stability and
performance of halide semiconductors.