Dimethyl-dihydroindenocarbazole-anthracene-phenanthroimidazole based hybridized local and charge-transfer molecules as efficient nondoped deep-blue emitters for highly efficient fluorescent organic light-emitting diodes

Abstract

The pursuit of hybridized local and charge transfer (HLCT) excited state-based emitters is a promising strategy to achieve high external quantum efficiency in blue organic light-emitting diodes (OLEDs). Two isomeric dimethyl-dihydroindenocarbazole-anthracene-phenanthroimidazole-based emissive molecules (PhAnsIn and PhAnoIn) were designed and explored based on the HLCT scheme. All molecules possessed the HLCT excited-state characters, according to the photophysical investigation and density functional theory calculations. Consequently, PhAnsIn and PhAnoIn showed good blue emission with peaks at 457 and 464 nm and photoluminescence quantum yield of 80.6% and 56.5% in neat films, respectively. The fabricated blue OLEDs with PhAnsIn and PhAnoIn as emitters also realized the corresponding blue emission with electroluminescence peaks at 458 and 457 nm, respectively. The nondoped devices based on PhAnsIn and PhAnoIn exhibited maximum external quantum efficiencies of 8.2% and 8.5% with CIE coordinates of (0.14, 0.12) and (0.14, 0.11), respectively.