What's happening?

Title: Unified thermodynamic theory for light-induced phase separation in mixed halide perovskites

Speaker: Zehua Chen (TU/e, Computational Materials Physics Group)
Time: Oct. 29, 2020, 10:00–11:00
Location: Online (MS Teams)

Abstract | Under illumination, mixed halide perovskites that are thermodynamically stable in the dark can demix due to a free energy lowering of photocarriers that funnel to a nucleated phase with different halide composition and lower band gap than the parent phase. This is problematic for applying mixed halide perovskites in solar cells. I will present in this seminar a unified thermodynamic theory for this light-induced phase separation and apply it to five mixed iodine-bromine perovskites. The spinodals separating metastable and unstable regions in the composition-temperature phase diagrams shift upward in temperature under illumination, while new light-induced binodals separating stable and metastable regions appear that signal nucleation of a low-band gap iodine-rich phase. The threshold photocarrier density for phase separation is mainly governed by the band gap difference of the parent and iodine-rich phase. Partial replacement of organic cations by cesium reduces this difference and therefore has a stabilizing effect.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you would like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it. so as to receive the MS Teams meeting link.