Deep red to near‐infrared thermally activated delayed fluorescence conjugated polymers toward highly efficient solution‐processible deep red and near‐infrared organic light‐emitting diodes

Abstract

As governed by the energy gap law, developing highly efficient deep red (DR) and near‐infrared (NIR) thermally activated delayed fluorescence (TADF) polymers with emission peaks of over 670 nm presents a significant challenge. Herein, by employing the strategy of embedding acceptor into backbone and attaching donor as pendant, a batch of DR and NIR TADF conjugated polymers are developed, with emission wavelengths encompassing from 675 to 733 nm. Using solution‐processing method, the organic light‐emitting diodes (OLEDs) based on these polymers exhibit leading DR emission, with maximum external quantum efficiency (EQE _max ) up to 6.4%, intense luminance up to 4254 cd m ⁻² , and Commission Internationate de I’Eclairage (CIE) coordinates of (0.61, 0.38), peaking at 678 nm. Impressively, a NIR device achieves EQE _max as high as 2.5%, with CIE coordinates of (0.65, 0.34) and an emission wavelength at 706 nm. In addition, even a luminance of 788 cd m ⁻² and high radiance of 20.5 W Sr ⁻¹  m ⁻² are also achieved. These results represent the first demonstration of DR and NIR OLEDs using TADF polymers with emission peaks of over 670 nm. This work serves as a valuable framework for researchers aiming to develop DR and NIR TADF conjugated polymers in the future.