Green SpinLight-Emitting Diodes Enabled by PerovskiteNanocrystals <i>in Situ</i> Modified with Chiral Ligands

Spin-polarized light-emitting diodes (spin-LEDs) hold promise for next-generation technologies across optical communication, biological imaging, and quantum information processing. Chiral metal halide perovskites, which combine advantageous optoelectronic properties with chirality, are promising materials for high-performance spin-LEDs. However, such spin-LEDs still suffer from low efficiency and limited brightness, as they often rely on low-dimensional chiral perovskites with rather inferior charge-transport properties as spin filter layers. Herein, we demonstrate bright and efficient green spin-LEDs based on chiral perovskite nanocrystals as emitters. We employed an <i>in situ</i> chiral ligand modification using R-/S-1-(4-bromophenyl)-ethylammonium bromide to imprint chirality onto CsPbBr₃ nanocrystals, which exhibited both a high photoluminescence quantum yield of 89% and improved spin relaxation lifetime. A remarkable spin-polarization of 88% was observed for the CsPbBr₃ nanocrystal films. Consequently, our spin-LEDs without a commonly used spin filter layer simultaneously achieved a maximum brightness of 12,800 cd m^–2, a record-high peak external quantum efficiency of 15.4%, and a circularly polarized electroluminescence with a dissymmetry factor of 2.16 × 10^–3 at room temperature, setting new benchmarks for perovskite-based spin-LEDs.