Inverted and Amplified CP-EL Behavior Promoted by AIE-Active Chiral Co-Assembled Helical Nanofibers.

Abstract

It is well-known that high-performance circularly polarized organic light-emitting diodes (CP-OLEDs) remain a formidable challenge to the future application of circularly polarized luminescent (CPL)-active materials. Herein, the design of a pair of AIE-active chiral enantiomers (L/D-HP) is described to construct chiral co-assemblies with an achiral naphthalimide dye (NTi). The resulting co-assemblies emit an inverted CPL signal compared with that from the L/D-HP enantiomers. After thermal annealing at 120°C, the inverted CPL signal of this kind of L/D-HP-NTi with a 1:1 molar ratio shows regular and ordered helical nanofibers arranged through intermolecularly ordered layered packing and is accompanied with a further amplified effect (|gem |= 0.032, λem = 535nm). Significantly, non-doped CP-OLEDs based on a device emitting layer (EML) of L/D-HP-NTi exhibits a low turn-on voltage (Von ) of 4.7V, a high maximum brightness (Lmax ) of 2001cdm-2 , and moderate maximum external quantum efficiency (EQEmax ) of 2.3%, as well as excellent circularly polarized electroluminescence (CP-EL) (|gEL |= 0.023, λem = 533nm).