Extremely simplified, high-performance, and doping-free white organic light-emitting diodes based on a single thermally activated delayed fluorescent emitter

Abstract

For the first time, extremely simplified yet high-performance thermally activated delayed fluorescent (TADF) white organic light-emitting diodes (WOLEDs) have been demonstrated. Unlike previous concepts, only a single molecular emitter is required for high-quality white emissions, where an intrinsic TADF emitter is sandwiched between p-type and n-type layers, forming a doping-free p-i-n WOLED. The WOLED exhibits a color rendering index (CRI) of 91, the first WOLED that overtakes its counterparts (single-emitter white polymer/inorganic LEDs). The maximum total external quantum efficiency (28.4%) and power efficiency (68.5 lm W–1) are comparable to those of state-of-the-art doped TADF WOLEDs and doping-free phosphorescent WOLEDs and higher than those of TADF WOLEDs with ultrahigh CRIs (≥90) and high-quality single-emitter white LEDs. Significantly, this is the first TADF WOLED possessing ultrahigh CRIs at high luminance, and 18 796 cd m–2 is 370% higher than that of the previous best-performing one. Moreover, the proposed WOLED is the simplest TADF WOLED.