Multi‐Resonance Induced Thermally Activated Delayed Fluorophores for Narrowband Green OLEDs

Abstract High‐color‐purity emissions with small a full‐width at half‐maximum (FWHM) are an ongoing pursuit for high‐resolution displays. Though the flourishment of narrow‐band emissive materials with multi‐resonance induced thermally activated delayed fluorescence (MR‐TADF) in the blue region, such materials have not validated their potential in other color regions. By amplifying the influence of skeleton and peripheral units, a series of highly efficient green‐emitting MR‐TADF materials are firstly reported. Peripheral units with electron‐deficit properties can significantly narrow the energy gap for bathochromic emission without compromising the color fidelity. MR‐TADF emitters with photo‐luminance quantum yields of above 90 % with FWHMs of ≤25 nm are developed. The corresponding organic light‐emitting diodes show maximum external quantum efficiency/ power efficiency of 22.02 %/ 69.82 lm W −1 with excellent long‐term stability.