Exploring Orbit-Orbit Interaction in Relationship to Photoluminescence Quantum Efficiency in Perovskite Quantum Dots through Rashba Effect.

This study demonstrates the influence of the orbit-orbit interaction on the photoluminescence quantum efficiency (PLQE) of metal halide perovskite quantum dots (QDs) through the Rashba effect. The orbit-orbit interaction between excitons was characterized by using the minimal excitation intensity required to generate a photoluminescence difference (ΔPL) between linearly and circularly polarized photoexcitations. It was observed that changing the surface functionalization from PFOA-OA to PFSH-OAm and OA can largely increase the minimal excitation intensity for generating ΔPL. This indicates that the orbit-orbit interaction is essentially decreased in CsPbBr1I2 QDs with surface functionalization. Simultaneously, the PLQE is increased from 39% to 59 and 72% in CsPbBr1I2 QDs upon surface functionalization. Furthermore, the PL lifetime is decreased with increasing the PLQE in CsPbBr1I2 QDs upon surface functionalization. This phenomenon implies that decreasing the orbit-orbit interaction can essentially weaken the Rashba effect and consequently reduce the disallowed transitions, leading to an enhancement in the PLQE in perovskite QDs.