Enhanced color stability for white organic light-emitting diodes based on dual ultra-thin emitting layer

Highly efficient white organic light-emitting diodes (WOLEDs) with dual ultra-thin phosphorescent blue and orange emitting layers (EMLs) were achieved in this work. The 1,3-di-9-carbazolylbenzene (mCP) was selected as a carrier-exciton adjusting layer (C-EAL), then the distribution of carriers and excitons was effectively controlled. The investigation of the relationship between C-EAL thickness and spectrum was carried out, and it concluded that the additional C-EAL was beneficial for the suppressing of charge carrier trapping and the decreasing of the direct recombination. Then the improved spectra stability to voltage was also studied. Preferably, the device based on a 4 nm C-EAL exhibits stable Commission Internationale de L'Eclairage (CIE) coordinates from (0.32, 0.40) at 124 cd/m(2) to (0.30, 0.40) at 9705 cd/m(2). The device structure and production process here was simplified and compatible with industrial production. (C) 2017 Elsevier B.V. All rights reserved.