35.2: Improved Efficiency and Lifetime by Tailoring the Charge Carrier Supply in OLEDs

The electron and hole supply into the recombination zone of an OLED is of crucial importance to achieve optimum performance. By adjusting the energetic levels of the transport and the blocking layers we optimize lifetime and power efficiency of blue and red fluorescent PIN OLEDs. for a red OLED, we achieve 100 cd/m2 below 2 V. By deliberately introducing barriers in the electron supply of red fluorescent OLEDs, we can “switch on” triplet‐triplet annihilation, leading to a significant boost in efficiency — up to 12 % external quantum efficiency were measured in an integrating sphere.