Efficient Circularly Polarized Electroluminescence Enabled by Low-Dimensional Bichiral Perovskite Nanocrystals.

Li, Zejian; Wang, Jiaqi; Chi, Shurui; Lin, Kebin; Zhang, Wenchao; He, Chenlu · ACS Nano · 2024

basic_science · Level V

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Abstract

Chiral organic-inorganic hybrid perovskite nanocrystals have gained attention as promising materials for circularly polarized luminescence emission, owing to their high photoluminescence efficiency and superior charge-carrier mobility. However, achieving circularly polarized electroluminescence (CPEL) from mixed-phase perovskite nanocrystals remains a significant challenge. We present bichiral formamidinium lead bromide (FAPbBr<sub>3</sub>) nanocrystals that achieve room-temperature circularly polarized light-emitting diodes (LEDs) via a synergistic effect between a chiral interior spacer (methylbenzylamine cation, MBA<sup>+</sup>) and a chiral surface ligand (camphorsulfonic acid, CSA). The incorporation of MBA<sup>+</sup> induces chiral crystal lattices, while CSA ligands, featuring sulfonate groups, effectively passivate defects, suppress exciton spin-flip, and enhance conductivity. The resulting circularly polarized LEDs exhibit an enhanced electroluminescence asymmetry factor (<i>g</i><sub>EL</sub>) of ∼2 × 10<sup>-3</sup>, along with an external quantum efficiency (EQE) of 3.1%. These bichiral nanocrystals represent a significant advancement in luminescence efficiency and enantioselectivity, indicating their potential for next-generation chiroptoelectronic applications.