Blue TADF Conjugated Polymers with Multi‐Resonance Feature toward Solution‐Processable Narrowband Blue OLEDs

Abstract The development of thermally activated delayed fluorescence (TADF) polymers with narrowband emission, particularly in the blue region, remains a formidable challenge. Herein, a new approach is demonstrated for blue TADF conjugated polymers by integrating multiresonance TADF moiety into the conjugated backbone. All the new polymers exhibit TADF characteristics with narrowband blue emission with full‐width at half‐maximums (FWHMs) of 23 nm. The solution‐processed OLEDs based on these polymers achieve a maximum external quantum efficiency (EQE max ) of 17.9% with the emission peak at 479 nm and FWHM of 28 nm. The main‐chain type MR‐TADF polymer shed light on the development of narrowband emissive TADF conjugated polymers.