Self‐Assembled Monolayers Facilitate Simultaneous Enhancements of External Quantum Efficiencies and Circularly Polarized Luminescence Dissymmetry Factors for Chiral Perovskite Red Spin‐Light Emitting Diodes

Abstract Stemming from the chirality‐induced spin‐orbit coupling (CISOC), the transfer of spin angular momenta to angular momenta of light can be realized by chiral hybrid perovskites (CHPs) for developing novel spin‐light emitting diodes (spin‐LEDs). The primary challenge lies in simultaneous enhancements for the electronic charge associated external quantum efficiencies (EQEs) and spin‐dependent dissymmetry factor of circularly polarized electroluminescence ( g EL ), which severely limits the high‐performance spin‐LEDs’ development. Herein, a self‐assembled monolayer (SAM) that acts as an interfacial layer between a nickel oxide (NiO x ) transport layer and a chiral perovskite emissive film has been adopted for red spin‐LED fabrications. An optimal EQE of 8.3% and g EL of 16.3% have been successfully achieved for the red circularly polarized electroluminescence (CPEL) at 725 nm. From the spin‐optoelectronic consideration, the well‐balanced EQE and g EL . These are attributed to remarkable fluorescence recombination lifetime improvements, ion migration suppressions, and trap density reductions. Notably, a two times greater spin lifetime (≈27.6 ps) has been obtained by comparing with a control sample (≈12.1 ps). Improved chiral‐induced spin‐orbit coupling (CISOC) strengths further elevate spin‐selective capacities, which consequently promote polarized spin current generation. This study unlocks the challenge and opens a new avenue for constructing high‐performance spin‐LEDs using the SAM nanotechnology.