ENHANCING PHOSPHORESCENCE LIFETIME OF CsPbBr₃ THROUGH ORGANIC CATION DOPING WITH BENZIMIDAZOLIUM SALTS

Abstract

All CsPbBr₃ perovskites exhibit exceptional photophysical properties yet suffer from rapid non-radiative recombination, severely limiting their phosphorescence efficiency and lifetime. In this work, we report the molecular doping of CsPbBr₃ supercrystals with two benzimidazolium salts to mitigate defect-mediated quenching and extend emission persistence. Pristine CsPbBr₃ exhibited a sharp decay in luminescence, with rapid quenching within the first 20 seconds due to dominant trap-assisted recombination pathways. In contrast, benzimidazolium-doped samples demonstrated both delayed emission decay and enhanced phosphorescence intensity, indicating effective passivation of defect states and stabilization of excitonic populations. Notably, one doped system exhibited prolonged emission with moderate peak intensity, while the second achieved both high initial radiative efficiency and sustained persistence, reflecting distinct dopant–lattice interactions. The π-conjugated benzimidazolium framework likely interacts with halide vacancies and surface states through electrostatic and hydrogen-bonding mechanisms, thereby reducing trap density and enhancing radiative pathways. These findings establish benzimidazolium doping as a robust molecular engineering strategy for controlling recombination dynamics in CsPbBr₃, with direct implications for the design of persistent luminescent perovskites in light-emitting, photonic, and optoelectronic applications.