23.3: Distinguished Paper: High‐Efficiency Tandem Blue OLEDs

Tandem blue OLEDs using different fluorescent dopants have achieved 20 cd/A (CIEx,y = 0.14, 0.18) and 38 cd/A (CIEx,y = 0.15, 0.42) with external quantum efficiencies higher than 11%. The tandem blue OLEDs include two electroluminescent units that are connected in series with an organic intermediate connector. At an initial brightness of 1,000 cd/m2, the drive voltage of the devices can be less than 6.5 V, and the operational lifetime (T 50) of the devices is estimated to be greater than 10,000 h. We also demonstrate that the selection of electron-transporting material and an intermediate connector have significant impact on the electroluminescence performance of the tandem blue OLEDs.