Managing Charge and Exciton Transporting Behavior in White Organic Light-Emitting Devices for High Power Efficiency and Superior Color Stability

An advanced device structure using doped blue dual emitting layers (EMLs) and an undoped orange EML is developed for achieving white organic light-emitting diodes. The optimized device using a single emitting species for both blue and orange emission shows a peak power efficiency of 60 lm W⁻¹ and high color stability over the entire operation process due to the aligned energy levels for facilitated charge transport. Quantitative analysis of the device working mechanism is performed to provide an explanation for the high performance of the device. It is found that both the charge and exciton transporting behavior can be finely tuned between different emitting regions, and therefore the efficiency and spectrum of the device are improved systematically.