Multi‐Resonance TADF Conjugated Polymers toward Highly Efficient Solution‐Processible Narrowband Green OLEDs

Abstract Due to the extended conjugation along the polymeric backbone and the scarcity of suitable multi‐resonance (MR) emitting units for polymerization, precisely adjusting the colors of MR‐thermally activated delayed fluorescence (MR‐TADF) conjugated polymers to green and red region remains to be a formidable challenge. Herein, this work develops a series of green MR‐TADF polymers for the first time by attaching MR emitting moiety as pendant to an acceptor triphenyltriazine while simultaneously embedding acceptor moiety into polycarbazole backbone. Benefitting from the enhanced intramolecular charge transfer (ICT) interaction by introducing acceptor on the para ‐carbon position of boron (B) atom of the MR unit, as well as extended conjugation along backbone, all polymers exhibit red‐shifted emissions with emission peaks of 505–517 nm and full‐width at half maximums (FWHMs) of below 48 nm compared to the pendant bluish‐green MR unit peaking at 484 nm. The solution‐processed devices based on these polymers exhibit excellent performances with maximum quantum efficiency (EQE) of 22.2%, emission peak at 511 nm and FWHM of 44 nm, which represents the state‐of‐the‐art performance among the MR‐TADF polymer‐based narrowband OLEDs.