Component Engineering to Tailor the Structure and Optical Properties of Sb-Doped Indium-Based Halides

Controlling the structure of halide perovskites through component engineering, and thus revealing the changes in luminescence properties caused by the conversion of crystal structure, is of great significance. Herein, we report a controllable synthetic strategy of three-dimensional (3D) Cs₂KInCl₆ and zero-dimensional (0D) (Cs/K)₂InCl₅(H₂O) halide perovskites by changing the Cs/K feed ratio. 3D Cs₂KInCl₆ double perovskites are obtained at the Cs/K feed ratio of 1:1, while 0D (Cs/K)₂InCl₅(H₂O) perovskites are formed at the Cs/K feed ratio of 2:1. Further, a reversible crystal structure transformation between 3D Cs₂KInCl₆ double perovskites and 0D (Cs/K)₂InCl₅(H₂O) perovskites can be achieved by subsequent addition of metal-salt precursors. In addition, the emission efficiency of two perovskite structures can be greatly boosted by breaking the forbidden transition through Sb doping, and as a result, a novel green/yellow reversible emission switch is generated. Meanwhile, the relationship between perovskite structure and luminescence mechanism has been systematically revealed. These environmentally stable halide perovskites have great potential to be applied in optoelectronic devices.