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

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 (FAPbBr₃) nanocrystals that achieve room-temperature circularly polarized light-emitting diodes (LEDs) via a synergistic effect between a chiral interior spacer (methylbenzylamine cation, MBA⁺) and a chiral surface ligand (camphorsulfonic acid, CSA). The incorporation of MBA⁺ 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 (g_EL) of ∼2 × 10^-3, 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.