Ultra-long photoluminescence lifetime in an inorganic halide perovskite thin film

Abstract

Reducing non-radiative recombination and decreasing the harmful defects are significant to achieve remarkable performance, and regarded as hallmarks of long photoluminescence (PL) lifetimes in inorganic halide perovskite films. Herein, we obtained an ultra-long PL lifetime of more than 2500 ns in inorganic halide perovskite films of polymer-cladding CsPbI₂Br (CPI2); this is the longest PL lifetime measured to date for inorganic halide perovskites. This enhanced lifetime was realized by introducing polyvinyl pyrrolidone (PVP) with two modifications: chemical passivation of trap states on the grain surface, mainly owing to the interactions of the O–Pb covalent-like bond, and improvement of crystallinity, resulting in the reduction of internal defects inside the grain. The PVP simultaneously caused a substantial enhancement in the steady-state PL intensity and quantum efficiency. The approach for chemical passivation would be utilized to enhance the physical properties of functional materials.