Abstract
Color-tunable white organic light-emitting diodes (CT-WOLEDs) have attracted widespread attention given their large color variation to meet the different daily scenarios from the perspective of circadian rhythm. However, most reported CT-WOLEDs, especially the tri-color devices, exhibit poor performances and sophisticated structures. Here, a simple structure tri-color CT-WOLED is demonstrated that simultaneously exhibits high efficiency, ultralong operation lifetime, and wide color-tunable range for dynamic sunlight emulation. The design is based on a newly developed platinum complex that can emit light efficiently in both monomer and aggregation states, providing voltage-dependent green-to-red phosphorescence emission, not only ensuring tunable colors in WOLEDs but also simplifying the device structure. Combining with a blue delayed fluorescence material, this hybrid device exhibits a wide range of tunable colors with Commission Internationale de l'Eclairage 1931 (CIE) coordinates and correlated color emperature (CCT) shifts from (0.502, 0.474) and 2628 K at 2.6 V to (0.211, 0.334) and 14860 K at 8 V, achieving good visual alignment with sunlight color throughout the day. This same device also shows high external quantum efficiencies from 28.8% at maximum to 26.2% at 5000 cd m(-2). Furthermore, an impressively long time of 21,144 h is achieved to decay to 90% of the initial luminance at 100 cd m(-2), being the longest among recorded CT-WOLEDs.