Chiral Ionic Liquids Enable High-Performance Room Temperature Single Junction Spin-Light Emitting Diodes

Abstract

Room temperature and solution-processible spin-light emitting diodes (spin-LEDs) are of practical importance since electronic spins act as information carriers for circularly polarized electroluminescence (CP-EL) generation. The recent boost of quasi-2D chiral hybrid perovskites (CHPs) has gained unprecedented attention because of the possible spin manipulation via innate chiral-induced spin-orbit coupling (CISOC) without involving cumbersome spin injection from ferromagnets. Herein, a unique method is developed using chiral ionic liquids (CILs) as antisolvents for fabricating highly reproducible and stable lead-bromide thin films based single junction spin-LEDs. With this, the chirality is successfully transferred into the perovskites with outstanding chiroptical properties and improved film crystallinities. More than 75% photoluminescent quantum yields (PLQY) and 13% CP-EL have been achieved. The existence of chiral-induced spin selectivity (CISS) is proved and a large degree of polarized spin current (${\mathit{P}}_{\mathbf{spin}}$) of ≈80% with a long spin lifetime exceeding 1.0 ns is attained. Further their magneto-chiroptical effects are explored through magnetic circular dichroism (MCD) and magneto-photoluminescence (MPL). The method opens a new avenue for the development of CHPs and high-performance single junction spin-LEDs.