High‐Efficiency, Long‐Lifetime and Color‐Tunable Hybrid WOLEDs Using a Platinum Complex with Voltage‐Dependent Monomer and Aggregate Emission

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.