Time-Resolved Opportunities at the APS and Beyond: Upgraded Capabilities and Compact X-ray FEL Visions (WK#3 | 2026 APS/CNM user meeting)

Ultrafast lattice dynamics of metal halide double perovskites by time-resolved X-ray probes

May 6, 2026, 9:05 AM

25m

Building 402 Lecture Hall

Speaker

Peijun Guo (Yale)

Description

Developing light-emitting semiconductors with high photoluminescence quantum yield (PLQY) is important for
energy-efficient solid-state lighting applications. A subset of solution-processed metal halide perovskites has
been shown to exhibit intrinsic, broadband white-light emission with high PLQY from 10% to 90%. The
intrinsic white-light emission is attributed to self-trapped excitons (STEs), where photo-excited electron-hole
pairs are strongly coupled to local lattice deformations. I will discuss our efforts on understanding light-induced
lattice dynamics underpinning STEs in a prototypical metal halide double perovskite using optical pump-probe
spectroscopy, time-resolved photoluminescence spectroscopy, and optical-pump X-ray diffraction probe
experiments. I will show that charge carrier recombination is asynchronous with lattice dynamics and recovery,
and our hypothesis of a long-lived metastable structure with a recovery time of milliseconds. Additionally, I will
present our recent work on using synchrotron x-ray micro-diffraction to discern the microstructural evolution of
a newly observed spherulite phases from chiral 2D metal halide perovskites.