Improved color stability of complementary WOLED with symmetrical doped phosphors in single host: experimental verification and mechanism analysis

Abstract

In this work, by symmetrically doping blue and orange phosphors in a single host, a complementary all-phosphor white organic light-emitting diode (WOLED) was demonstrated. Compared with the reference white device with blue-orange sequential cascade dopants in a single host, the proposed WOLED with (blue-orange-blue) symmetrical arranged dopants shows an improved spectra stability with a change in Commission Internationale de L'Eclairage (CIE) coordinates of less than (±0.020, ±0.010) as the driving voltage increases from 4 V to 9 V, corresponding to the luminance increasing from 100 cd m⁻² to about 15 000 cd m⁻². The improvement of color stability should be ascribed to the symmetric dopants in the multi-doped single host being able to effectively offset the spectral change caused by the shift of carrier recombination zone with the increase of driving voltage. This is confirmed by systematic probe devices, where the shift of carrier recombination zone was observed to give a more detailed analysis.