Spectroscopic indications of room-temperature electron-hole droplets in optically excited CH3NH3PbBr3 single crystals

Abstract

An electron-hole droplet is a unique form of matter that occurs as a metallic phase in semiconductors, and its formation has been almost exclusively linked to cryogenic condensation of long-lived excitons. Creating room-temperature electron-hole droplets in semiconductors has remained an outstanding challenge. Here, we report plausible spectroscopic indications of a cloud of room-temperature electron-hole droplets in optically excited CH 3 NH 3 PbBr 3 single crystals. Droplet characters shown by the excitation threshold and optical hysteresis are demonstrated. The observed two-stage photoluminescence decaying histogram indicates rapid thermal dissociation of room-temperature excitons into hot electron-hole plasma vapor and subsequent droplet nucleation toward a metastable size. Our study sheds light on the vapor-to-liquid phase evolution in optically excited crystal bulk of direct band gap semiconductors and paves the way for further exploration toward intriguing optoelectronic and valleytronic applications. • Absorption decoupling by means of established functions is provided • Excitation threshold and optical hysteresis show droplet characters • Two-stage photoluminescence decaying histogram indicates excited phase evolution • Droplets and plasmas coexist in optically excited CH 3 NH 3 PbBr 3 single crystals Wang et al. report the occurrence of a cloud of droplets in optically excited CH 3 NH 3 PbBr 3 single crystals. Droplet characters shown by excitation threshold and optical hysteresis are demonstrated. Two-stage photoluminescence decaying histogram indicates rapid thermal dissociation of excitons and subsequent droplet nucleation toward a metastable size.