Exciton vortices in two-dimensional hybrid perovskite monolayers

TL;DR

This paper theoretically investigates exciton Bose-Einstein condensation and vortex formation in a 2D perovskite monolayer, revealing potential room-temperature excitonic effects and electric field-induced vortex patterns.

Contribution

It combines first-principles calculations with the Keldysh model to predict high exciton binding energies and novel vortex phenomena in 2D perovskites.

Findings

Exciton binding energy approaches hundreds of meV.

Critical temperature of exciton condensation nears liquid nitrogen temperature.

Electric fields induce patterned exciton vortices.

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 (PEA)2PbI4 in a monolayer can approach hundreds 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 presence of perpendicular electric fields, the dipole-dipole interaction between excitons is found to drive the condensed excitons into patterned vortices, as the evolution time of vortex patterns is comparable to the exciton lifetime.