Intrinsically Spin‐Flip‐Induced Circularly Polarized Electroluminescence: A Strategy Spanning Deep Blue to Deep Red With Achiral MR and Perovskite Emitters

Abstract

ABSTRACT Integrating circularly polarized electroluminescence (CPEL) into light‐emitting diodes (LEDs) is crucial for advanced optical applications. However, its application is impeded by a longstanding trilemma involving a sufficient electroluminescence asymmetry factor (g EL ), high external quantum efficiency (EQE), and narrow emission bandwidth. Here, a new strategy is proposed for generating CPEL in both circularly polarized organic light‐emitting diodes (CP‐OLEDs) and circularly polarized LEDs (CP‐LEDs) by incorporating a chiral additive into the PEDOT:PSS ((3, 4‐ethylenedioxythiophene):poly(styrene sulfonate)) hole‐injection layer (HIL) to induce a spin‐flipping. Consequently, solution‐processable CP‐OLEDs based on common achiral emitters achieve advantages of high g EL , high EQE, and excellent color purity. Comparing the original PEDOT:PSS based devices, improved maximum external quantum efficiency (EQE max ) of 17.2%, 20.3%, 12.0%, and 23.0% were obtained, with |g EL | of 2 × 10 −2 , 6 × 10 −3 , 1 × 10 −2 , and 1 × 10 −3 , for blue multi‐resonance emitter, green phosphorescent emitter, and green multi‐resonance emitters, respectively. This strategy enables deep‐red perovskite‐based CP‐LEDs to deliver not only pronounced CPEL but also several‐fold enhancements in performance. Angle‐dependent CPEL measurements confirm the observed CPEL originating from spin‐flip induction rather than polarization effects. This chiral additive HIL strategy establishes a universal platform for efficient CPEL across a wide range of achiral emitters and is applicable to both OLED and LED technologies.