Light-Induced Charge Transfer in Two-Dimensional Hybrid Lead Halide Perovskites

Abstract

2D hybrid perovskites consisting of layers of lead halide octahedra separated by long organic linker cations have great potential for functional material design toward tailored optical and electronic properties. Here, we report the first direct observation of light-induced charge transfer (CT) in a series of novel 2D perovskites incorporating conjugated linkers based on the carbazole molecule. Dedicated electron paramagnetic resonance experiments and supporting quantum-chemical calculations reveal that excitons generated in the lead halide layer undergo CT at the organic-inorganic interface, resulting in a positive polaron delocalized over several carbazole moieties and a partner electron residing in the inorganic layer. The occurrence of such CT processes in these materials not only offers interesting new perspectives for the functionalization of future 2D perovskites but could also lead to a better understanding of the unusual broadband emission reported for this material class, which has been directly related to polaronic effects.