Non-doped white organic light-emitting diodes with superior efficiency/color stability by employing ultra-thin phosphorescent emitters

Abstract

Using a simple method employing ultra-thin phosphorescent emitters into bis(3-(9,9-dimethyl-9,10-dihydroacridine)phenyl)sulfone (mSOAD) based on zig-zag acridine/sulfone derivative, high efficiency and high color stability of non-doped white organic light-emitting diodes (WOLEDs) are realized. After optimization of the location and quantity of the ultra-thin emitters, maximum current efficiency, power efficiency and external quantum efficiency (EQE) of the WOLEDs of 31.9 cd A⁻¹, 30.4 lm W⁻¹ and 17.3%, respectively, are achieved. The stable white spectra are also obtained with the Commission Internationale de I’Eclairage (CIE) coordinates of (0.469 ± 0.008, 0.382 ± 0.004) from 4 V to 8 V. We find that efficient confinement to carriers and excitons has a key role; the location and quantity of ultra-thin emitters also have a large effect on device performance.