Pressure-modulated triplet-state switching in zero-dimensional Sb-based hybrid perovskites

Abstract

Zero-dimensional (0D) hybrid metal halide perovskites have emerged as promising candidates for optoelectronic applications, owing to their strong exciton confinement and high structural tunability. However, modulation of triplet-state emission pathways remains a key challenge. Here, we report pressure-induced emission switching in the Sb-based 0D hybrid perovskite (TPP)2SbBr5. Under ambient conditions, the material exhibits broadband red emission (∼735 nm) arising from self-trapped excitons (STEs) associated with a low-energy triplet state. Upon increasing pressure to 0.97 GPa, lattice symmetry breaking and enhanced Sb 5s2–Br 4p orbital hybridization induce splitting of the triplet state, activating a new high-energy emission band at 638 nm. Further compression beyond 3.0 GPa completely suppresses the low-energy channel, resulting in dominant recombination via the high-energy STE channel. A combination of in situ photoluminescence, Raman spectroscopy, synchrotron x-ray diffraction, and femtosecond transient absorption reveals that exciton localization, orbital coupling, and lattice distortion collectively govern the emission channel transition. Our findings establish a pressure-responsive triplet-state reconfiguration mechanism in 0D perovskites and offer a strategy for designing stimuli-adaptive optoelectronic materials.