High Optical Gain of Solution-Processed Mixed-Cation CsPbBr3 Thin Films towards Enhanced Amplified Spontaneous Emission

A solution-processed thin film made of all-inorganic CsPbBr3 perovskite is a promising candidate for low-cost and flexible green-color lasers. However, the amplified spontaneous emission (ASE) of solution-processed CsPbBr3 films still experiences a high threshold owing to poor morphology and insufficient optical gain. Here, a multiple-cation doping strategy is demonstrated to develop compact, smooth thin films of Cs-0.87(FAMA)(0.13)PbBr3/(NMA)(2)PbBr4 (FA: formamidinium; MA: methylammonium; NMA: naphthylmethylammonium) with a record high net modal optical gain of approximate to 3030 cm(-1) and low propagation loss of 1.0 cm(-1). The FA and MA cations improve the crystallization kinetics to form continuous films, and the NMA cations reduce the grain dimension, increase film dispersibility/uniformity, and enhance spatial confinement to promote optical gain. Room-temperature ASE is demonstrated under a low threshold of approximate to 3.8 mu J cm(-2) without degradation after four months of storage in glove box or excitation by 3 x 10(7) laser pulses. These findings provide insights into enhancing the optical gain and lowering the threshold of perovskite lasers in terms of molecular synthesis and microstructure engineering.

Automated summary

By utilizing a multiple-cation doping strategy, compact and smooth CsPbBr3 thin films with high net modal optical gain and low propagation loss have been developed, demonstrating a lower threshold for lasers and enhanced optical gain capabilities.