Exciton Vortices in Two-Dimensional Hybrid Perovskite Monolayers* *Supported by the National Key R&D Programme of China (Grant Nos. 2017YFA0303400 and 2016YFE0110000), the National Natural Science Foundation of China (Grant Nos. 11574303 and 11504366), the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2018148), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB28000000).

Abstract

We study theoretically the exciton Bose–Einstein condensation and exciton vortices in a two-dimensional (2D) perovskite (PEA)2PbI4 monolayer. Combining the first-principles calculations and the Keldysh model, the exciton binding energy of in a (PEA)2PbI4 monolayer can approach hundreds of meV, which make it possible to observe the excitonic effect at room temperature. Due to the large exciton binding energy, and hence the high density of excitons, we find that the critical temperature of the exciton condensation could approach the liquid nitrogen regime. In the presence of perpendicular electric fields, the dipole-dipole interaction between excitons is found to drive the condensed excitons confined in (PEA)2PbI4 monolayer flakes into patterned vortices, as the evolution time of vortex patterns is comparable to the exciton lifetime.