High Stability and Ultralow Threshold Amplified Spontaneous Emission from Formamidinium Lead Halide Perovskite Films

The opportunity of lasing from organolead halide perovskite materials has recently attracted extensive attention in order to realize electrically driven lasers. So far, for devices with planar structure, most reports focus on CH3NH3PbI3 (MAPbI3) films, which are unstable when in operation due to phase transitions and elemental redistribution. Herein, we demonstrate highly stable amplified spontaneous emission (ASE) with ultralow threshold from formamidinium-based perovskite CH(NH2)2PbI3 (FAPbI3) films. ASE from MABr-stabilized FAPbI3 films was also achieved, with an ultralow threshold of about 1.6 μJ/cm2. More importantly, upon continuous operation under pulsed laser for several hours, the ASE intensity in the MAPbI3 film decreased to 9% of the initial value, while it was maintained above 90% in the FAPbI3 film. The low trap density, smooth film morphology, high thermal stability, and the excitonic emission in nature of the FAPbI3 film are expected to contribute to its low lasing threshold and high stability, demonstrating a strong potential for applications in continuous-wave pumped lasers and electrically driven lasers.