Ultrastrong circularly polarized electroluminescence achieved by chiral co-assembly of a liquid crystal-functionalized carbazole derivative

Abstract

Circularly polarized organic light-emitting diodes (CP-OLEDs) exhibiting circularly polarized electroluminescence (CP-EL) properties hold significant promise for future display technologies. However, enhancing the electroluminescence dissymmetry factor (g_EL) remains a substantial challenge. Herein, ultrastrong CP-EL emissions are achieved using a liquid crystal (LC)-functionalization strategy under the regulation of chiral co-assembly. The LC molecule 3CzPCH containing carbazole and mesogenic units could be readily synthesized using Suzuki coupling reactions. When doping chiral inducers R/S-D into 3CzPCH, the chiral co-assemblies formed helical nanofibers upon 120 °C annealing treatment and emitted strong deep-blue circularly polarized luminescence (CPL) with |g_lum| of 0.13 (λ_em = 422 nm, Φ_FL = 34%). Most importantly, these chiral co-assemblies served as the emitting layers (EMLs) of CP-OLEDs, reaching an ultrastrong deep-blue CP-EL with a |g_EL| value up to 0.47 (λ_EL = 440 nm). The corresponding Q-factor (EQE × |g_EL|) of 1.12 × 10⁻² represents one of the highest values reported for CP-OLEDs. This study demonstrates that the LC-functionalization strategy effectively enables intense CP-EL, paving the way for high-performance CP-OLEDs.