• color rendering index;
  • roll-off;
  • spacer layer;
  • ultra-thin;
  • WOLEDs


High efficiency performance and color rendering index (CRI) are two main requirements for the applications of white organic light-emitting diodes (WOLEDs). We report successful fabrication of efficient and high-color-rendering phosphorescent WOLED by employing ultra-thin red emitter – spacer layer – ultra-thin green emitter architecture. By fine-tuning the thicknesses of emitting layers and spacer layer, we have obtained WOLED with a high CRI of 80 and high luminance efficiency (LE) of 29.2 cd A−1 which only rolls off to 22.8 cd A−1 at 1000 cd m−2. A typical WOLED for comparison exhibits a CRI below 40 and maximum LE of 15.8 cd A−1 which decreases to 11.4 cd A−1 at 1000 cd m−2. The superiority of ultra-thin device compared with typical device demonstrates utilizing ultra-thin emitting layer is a promising technique to achieve high performance organic light-emitting diode (OLED).