Blue organic light-emitting diodes with hybridized local and charge-transfer excited state realizing high external quantum efficiency

Abstract

Donor–spacer–acceptor (D–π–A) materials CAPI and CCAPI, with hybridized local and charge transfer (HLCT) emissive states, have been synthesized. The twisting D–π–A architecture promotes the partial separation of HOMO and LUMO, leading to an enhanced % CT component, and the anthracene moiety in CAPI and CCAPI increases the conjugation length, leading to an enhanced % LE component. The non-doped device with CCAPI^b shows the blue emission (450 nm) with maximum current efficiency (η_c), power efficiency (η_p), and external quantum efficiency (η_ex) of 16.83 cd A⁻¹, 15.32 lm W⁻¹, and 12.0%, respectively, as well as exciton utilization efficiency (EUE) of 95% with a luminance of 32 546 cd m⁻² and a roll-off efficiency of 0.53%. The new design strategy has great potential for developing high-performance blue electroluminescent materials.