Enhanced Rashba Indirect Exciton Emission in 2D Dion–Jacobson Perovskite Microplates via Efficient Photon Recycling

Abstract 2D Dion–Jacobson perovskite (4AMP)PbI 4 (4AMP = 4‐(aminomethyl)piperidinium) (DJP) has recently attracted considerable attention due to its remarkable Rashba effect. Upon Rashba splitting in the momentum space of DJP, it is significant to identify the momentum‐indirect excitons (IXs) through photoluminescence spectroscopy and explore the photophysics influenced by the Rashba effect. In this work, a space‐confined aqueous method to synthesize single‐crystalline DJP microplates with uniform rectangular morphology is developed. Functioning as whispering‐gallery‐mode cavities, the as‐grown microplates exhibit greatly enhanced Rashba IX emission at all temperatures investigated through efficient photon recycling in the Rashba indirect gap. The efficient photon recycling can substantially extend the exciton transport length, which is conducive to light‐harvesting devices. This study not only provides a convenient method to observe Rashba states but also sheds light on the future applications of DJP in optoelectronics and optospintronics.