Room temperature two-photon-pumped random lasers in FAPbBr₃/polyethylene oxide (PEO) composite perovskite thin film

Solution-processed organic-inorganic halide lead perovskites have attracted increasing attention due to their great potential in low-cost, effective, and versatile light emission applications and large-scale portable optoelectronic devices. In this paper, formamidinium lead tribromide perovskite thin films composited with polyethylene oxide (PEO) were fabricated by a solution processing method. Great enhancement of photoluminescence was observed and more attractively, two-photon-pumped random lasing action could be achieved at room temperature when pumped by a nanosecond pulse laser with excitation wavelength centered at 1064 nm. Evident transition from spontaneous upconversion emission to random lasing action was investigated by monitoring the log-log light emission slope and peak width at half height. The lasing threshold is at around 1.1 mJ cm^-2, which is comparable to that of other two-photon upconversion random lasers. The efficient random lasing emission originates from the multiple random scattering provided by the micrometer-scale rugged morphology and polycrystalline grain boundaries. Compared with conventional lasers that normally serve as a coherent light source, the perovskite random lasers show promise in fabricating low-cost thin-film lasing devices for flexible and speckle-free imaging applications.