Unraveling the Defect-Dominated Broadband Emission Mechanisms in (001)-Preferred Two-Dimensional Layered Antimony-Halide Perovskite Film

By adding molar-controlled SbCl3 in a Cs3Sb2Cl9 precursor, we employed a low-temperature solution-processed approach to prepare high-quality (001)-preferred Cs3Sb2Cl9 thin film, which demonstrates a stable defect-dominated broadband emission at room temperature. Density functional theory calculations reveal that the defect emission originates from the donor-acceptor pair (DAP) recombination between chlorine vacancy (VCl) and cesium vacancy (VCs). Furthermore, VCl + VCs DAP is more stable on the (001) surface. The improved film quality and the more stable VCl + VCs DAP increase the activation energy related to defect states, resulting in an enhancement of the defect emission for the high-quality (001)-preferred film. This work provides deep insight into the key role of the (001) surface in defect emission and a feasible strategy to enhance the defect emission in 2D halide perovskites A3B2X9 (A = CH3NH3, Cs, Rb; B = Bi, Sb; X = Cl, Br, I) by control of the thin film preferred orientation.

Automated summary

By using a low-temperature solution-processed method, we successfully prepared high-quality Cs3Sb2Cl9 thin films and found that defect emission is more stable on the (001) surface. By controlling the preferred orientation of thin films, the defect emission in 2D halide perovskites can be enhanced.