Efficient circularly polarized thermally activated delayed fluorescence hetero-[4]helicene with carbonyl-/sulfone-bridged triarylamine structures

Abstract

This work presents the first circularly polarized thermally activated delayed fluorescence hetero-[4]helicene with a carbonyl-/sulfone-bridged triarylamine structure (QPO-PhCz), demonstrating circularly polarized light emission through effective intramolecular steric hindrance and intramolecular space charge transfer. The new molecular architecture displays a good quantum yield (0.51) and clearly circularly polarized luminescence with an absolute luminescence dissymmetry factor of 1.2 × 10⁻³ in dichloromethane solution. Moreover, for their racemates, characterization of the electroluminescence device shows a sky-blue emission (488 nm) and a maximum external quantum efficiency of 10.6%. Finally, the circularly polarized organic light-emitting diodes exhibit circularly polarized electroluminescence signals with an electroluminescence dissymmetry factor of +1.6 × 10⁻³ and −1.1 × 10⁻³ for (M)-QPO-PhCz and (P)-QPO-PhCz, respectively.