10-Dibenzothiophenyl-9,9-diphenylacridane-based multiple resonance emitters for high-efficiency narrowband green OLEDs with CIE y > 0.7 at high doping concentrations

Abstract

Multiple resonance emitters are attractive for high-color-purity organic light-emitting diodes (OLEDs) because of their unique narrowband emissions; however, they are typically used at low doping concentrations (≤15 wt%) due to aggregation-caused quenching and spectral broadening induced by planar molecular skeletons. Here, we report two multiple resonance emitters (BThPAc-1 and BThPAc-2) consisting of a 10-dibenzothiophenyl-9,9-diphenylacridane segment for efficient narrowband green emission at high doping concentrations. The dibenzothiophenyl-9,9-diphenylacridane segment contains two carbon-bridged phenyl rings as steric groups to inhibit intermolecular aggregation and a dibenzothiophene unit to extend conjugation and red-shift the emission to the green region. The resultant emitters exhibit narrowband emissions that peaked at 509–510 nm with a full width at half-maximum (FWHM) of 32 nm in 1 wt% doping films, which are maintained at less than 35 nm even in neat films. Remarkably, OLEDs employing the emitters reveal pure-green electroluminescence with a maximum external quantum efficiency of 20.3% and CIE coordinates of (0.18, 0.72) at 30 wt% doping concentration, which represents the best color coordinates for green multiple resonance OLEDs at high doping concentrations.