Solution process feasible highly efficient white organic light emitting diode

Solution-processed, highly efficient white organic light-emitting diodes (White OLEDs) are emerging as the most encouraging technology for the next-generation flat panel display and solid-state lighting applications. High efficiency is essential for being energy saving and long lifespan, while solution-process sustainability enables low-cost roll-to-roll fabrication of large area-size devices. We demonstrate here a highly-efficient white OLED with a solution-processed single emissive layer consisting of two white light complementary colors. The best performing white OLED displays outstanding electroluminescence performance with a forward-viewing power efficiency of 44.5 lm W−1, current efficiency of 52.9 cd A−1 and external quantum efficiency of 32.7% at 100 cd m−2, which are 39.8 lm W−1, 53.7 cd A−1 and 23.4% at 1000 cd m−2, respectively. They are the highest among the reported single emission layer white OLED fabricated via wet-process. The marked high-efficiency may be attributed to the device being composed of the balanced hole and electron injection layers, designed device architectures enabling efficiency-effective host-to-guest energy transfer and high hole mobility of employed molecular hole transporting material. This study opens up a possibility of comprehending cost-effective wet-process feasible highly efficient white OLED via balancing the injection of carriers into the desired recombination zone with commercially obtainable resources and restricted choices in device structure design.