Two-Photon Pumped Amplified Spontaneous Emission and Lasing from Formamidinium Lead Bromine Nanocrystals

Formamidinium (FA) perovskites have exhibited outstanding optoelectronic properties in solar cells and light-emitting diodes. However, their development on nanolaser application have rarely been explored, especially the up-conversion lasing performance. Here, the two-photon pumped lasing from colloidal FA-perovskite nanocrystals (NCs) is realized at room temperature, which are prepared by a ligand-assisted reprecipitation strategy. These colloidal FAPbX(3) NCs exhibit high-quality cubic phase and tunable bright emission (from 433 to 667 nm). By tuning the ratio of the surface organic ligands, the morphology of FAPbBr(3) NCs can be transferred from quantum dots to nanoplatelets, consequently the emission can be tuned in 520-542 nm. In addition, the low-threshold amplified spontaneous emission (ASE) under both two- and one-photon excitations is demonstrated benefiting from the large two-photon absorption coefficient (0.76 cm/GW) and high optical net gain (480 cm(-1)), indicating that FAPbX(3) NCs can be regarded as an excellent optical gain medium. The strong temperature-tolerent ASE action with a high characteristic temperature of 308 K indicates the weak requirements of heat management of FA-based devices. Finally, as we couple FAPbBr(3) into a hollow capillary tube, stable two photon excited whispering-gallery-mode lasing is successfully achieved with a low threshold of similar to 310 mu J/cm(2). Our findings suggest that FAPbX(3) NCs can act as excellent gain media for high-performance upconverted nanolasers toward optoelectronic application.