Quasi 2D perovskite single-mode vertical-cavity lasers through large-area film transfer

Quasi two-dimensional (2D) perovskites are a new class of laser gain medium; however, the thickness of the solution-processed perovskite layer is usually too thin to support an optical mode due to the low solubilities of precursors. Here, we report a flexible large-area film transfer method to lengthen the cavity according to the resonant condition. Then a single-mode vertical-cavity quasi 2D (PEA)(2)Csn-1PbnX3n+1 (X:Br, Cl) perovskite pure green laser is demonstrated, which has a low threshold of 39.3 mu J/cm(-2), a high-quality factor of 1159, and a highly linear polarization degree of 92.5% under nanosecond pulsed optical pumping. This is a significant step toward low-cost practical perovskite lasers.