Zero-Dimensional Perovskite Open Cavities for Low-Threshold Stimulated Emissions

Zero-dimensional perovskites exhibit exotic optoelectronic responses, but stimulated emissions from such media remain elusive and challenging thus far. Here, we demonstrate for the first time the capability of zero-dimensional perovskite Cs4PbBr6 open systems to trigger low-threshold single- and two-photon pumped mirrorless lasing entitled "random lasing". Amplified spontaneous emission occurred at a threshold of ∼370 μJ/cm2 under optical pumping with a 490 nm picosecond laser. On the other hand, sharp-spiked lasing, characteristic of coherent random lasing, was achieved under optical pumping with a femtosecond laser at 400 and 800 nm, respectively. The threshold is ∼25.98 μJ/cm2 when pumped at 400 nm, while 800 nm pumping upconverted lasing began to emerge at a threshold of ∼719 μJ/cm2. The pump threshold of the single-photon pumped lasing is even ∼2–17 times lower than those of well-confined Cs4PbBr6 cavities, suggesting the superior performance of Cs4PbBr6 ceramics. A strategy based on stimulated emission properties has been proposed and experimentally demonstrated to verify that the green photoluminescence is intrinsic to Cs4PbBr6. This work is expected to shed more light on fundamental physics and pave the way for developing random photonics in the field of low-dimensional perovskites.