Two-Photon Lasing from Two-Dimensional Homologous Ruddlesden-Popper Perovskite with Giant Nonlinear Absorption and Natural Microcavities

Two-dimensional Ruddlesden-Popper perovskites (RPPs) with multiple quantum well-like structures, strong excitonic quantum confinement, and high stability are promising optical gain media. However, the lasing from such material with a small number of inorganic well layers is difficult to achieve. Herein, we demonstrate the low-threshold upconversion lasing from the homologous RPP (PEA)(2)(MA)(n-1)PbnI3n-1 (n = 2 and 3) microflakes with wavelength varies from .598 to 637 nm under 800 nm laser excitation at low temperature (<= 153 K). Using the micro Z-scan technique, we discovered that the RPP flakes have a giant two-photon absorption coefficient beta as high as 3.6 x 10(3) cm GW(-1), resulting in the effective upconversion transition under two-photon excitation. Furthermore, the self-formation of Fabry-Perot microcavities provides the support for lasing emission from the n >= 2 RPP flakes. Calculation results and microscopic transient absorption measurements reveal that low-threshold lasing is due to the high differential gain coefficient and the suppressed non-radiative Auger recombination rate inside the quantum confinement structures. These properties enable RPPs as potential gain media for developing upconversion microcavity lasers.