Amplified spontaneous emission properties of solution processed CsPbBr3 perovskite thin films doped with large-group ammonium cations

Inorganic solution processed CsPbBr₃ perovskite thin films are highly promising optoelectronic materials and have been applied in solar cells, light emitting diodes, and photodetectors. They show good electroluminescence properties combined with high thermal stability. In this work, CsPbBr₃ perovskite thin films doped with a series of organic cations of various chain lengths, namely, methylammonium (MA), ethylammonium (EA), butylammonium (BA) and octylammonium (OA) at optimized molar ratios of (organic cations: Cs⁺), were fabricated with a two-step solution process. The crystalline structure, surface morphology and photophysical properties of the films were characterized in detail. The surface morphology of the films was improved with reduced surface roughness, accompanying by doping with the organic cations. The amplified spontaneous emissions (ASE) were observed from all of the different CsPbBr₃ films at room temperature. The gain coefficients for the doped CsPbBr₃ films were higher than the pristine films, due to much reduced bulk defects, reduced non-radiative recombination in the films, as well as improved surface quality of the films. This work provides a simple method of preparing organic cations modified CsPbBr₃ laser gain media of high performance.