摘要
Highly photoluminescent, lead-free perovskites are of interest for displays and solid-state light-emitting devices. In this report, streak camera-based time-resolved emission and transient absorption spanning visible to deep-ultraviolet (UV) wavelengths are utilized to study self-trapped and free exciton dynamics in vacuum-deposited cesium copper halide thin films of CsCu 2 I 3 and Cs 3 Cu 2 I 5 . Self-trapped exciton emission of CsCu 2 I 3 exhibits more noticeable changes with time in the peak position and width than Cs 3 Cu 2 I 5 . UV-to-blue emission is detectable for both compositions, where free exciton emission is distinct for CsCu 2 I 3 . Transient absorption shows loss of ground-state bleach signals at early time delays for both, and the bleach signal shifts toward higher energy as time delay increases, likely due to strains induced by the newly created self-trapped excitons. Global analysis performed on the transient absorption results yields time constants in these materials that build an overall dynamic scheme. This work aids in building a complete picture regarding light emission in these promising materials.