Benzotri(Triazole)‐Based HLCT Host Molecular Engineering for Highly Efficient Solution‐Processable OLED

ABSTRACT

Realizing high efficiency solution processable organic light‐emitting diode (OLED) by a ‘hot exciton’ channel is still a challenge. In this study, we pioneer the use of a benzotri(triazole) acceptor fragment to construct novel hybridized local and charge‐transfer (HLCT) molecules, successfully realizing a ‘hot exciton’ channel for light generation. Three molecules, named TPT‐TPA‐R (R = H, OMe, tBu), were prepared and characterized, which employed the benzotri(triazole) as the acceptor and triphenylamine derivative as the donor. These emitters display intense blue emission in the range of 440–490 nm in toluene, accompanied by excellent photoluminescence quantum yields ranging from 89% to 99%. Theoretical and experimental evidence confirms that all emitters exhibit prominent HLCT characteristics, which facilitate efficient reverse intersystem crossing from upper‐triplet states to the singlet manifold, thereby harvesting both singlet and triplet excitons. Employing the HLCT molecule as dopant, the solution‐processed OLED achieved a promising maximum external quantum efficiency (EQE _max ) of 5.3%. Moreover, the solution processable phosphorescent device utilizing TPT‐TPA‐H as a host demonstrates a remarkable EQE _max of 24.5%. This work validates the benzotri(triazole) core as a powerful building block for HLCT emitters and provides an effective strategy for HLCT‐based host engineering in solution‐processed OLEDs.