Bismuth doped lead-free two-dimensional tin based halide perovskite single crystals

Heterovalent-metal doping is an efficient tool to tune the optoelectronic properties of the famous halide perovskites. Previous studies have focused on the heterovalent-doping in three-dimensional (3D) halide perovskites. However, there is a lack of such doping in two-dimensional perovskites which possess unique optoelectronic properties and improved chemical stability as compared to 3D analogues. Here, we present successful doping of Bismuth into the lattice of lead-free, two-dimensional perovskite PEA2SnBr4 single crystals. Structural characterizations demonstrate that the doped crystals possess identical crystal structure and layered morphology with the pristine one. Intriguingly, we find the PL peak and spectral shape can be tailored by tuning the concentration of Bi dopants. Femtosecond transient absorption spectroscopy is performed to understand the underlying mechanism related to tunable PL behaviors, and a clear picture of the Bismuth-doping impact is provided.