CH_3NH_3PbI_3薄膜中放大自发辐射效应的研究

Studies on the Amplified Spontaneous Emission in CH_3NH_3PbI_3 Thin Films

利用光谱学手段研究了CH3NH3PbI3薄膜中的放大自发辐射效应。首先,从随温度变化的光致发光(Photoluminescence,PL)光谱中观察到了CH3NH3PbI3从正交相到四方相的相变。在低于相变温度时,PL过程优先发生在四方相上。在较高的激发光强下,正交相的PL峰由于四方相上激子浓度的饱和而逐渐显现,导致了放大自发辐射现象。然而,放置15天后的CH3NH3PbI3薄膜中激光效应却出现在了四方相上,表明CH3NH3PbI3薄膜中的缺陷态能够自发湮灭,从而增强了四方相在低温下的光辐射能力。

In order to further explore the photophysical processes and luminescence mechanisms in perovskite materials,the amplified spontaneous emission in CH3NH3PbI3 films was studied.Firstly,the phase transition of CH3NH3PbI3 from the orthorhombic phase to the tetragonal phase was observed from the temperature-dependent photoluminescence（PL）spectra.Below the phase transition temperature,the PL process occurred preferentially on the tetragonal phase.At the higher excitation light intensity,the PL peak of the orthorhombic phase gradually appeared due to the saturation of the exciton concentration on the tetragonal phase,resulting in the amplification of the spontaneous emission.However,the laser effect in the CH3NH3PbI3 thin film after storage for 15 days appeared in the tetragonal phase,indicating that the defect state in the CH3NH3PbI3 thin film can be spontaneously quenched,thereby enhancing the light radiation ability of the tetragonal phase at low temperature.