Solvent‐Modulated Photophysics and Maximum Exciton Utilization Via “Hot‐Exciton Pathway” in Efficient Donor–π–Acceptor HLCT Emitters Suitable for Non‐Doped and Doped OLEDs

Abstract Hybridized local and charge transfer (HLCT) emitters are gaining attention as a promising class of high‐efficiency emitters for organic light‐emitting diodes (OLEDs) due to their efficient hot‐exciton utilization and tuneable emission properties. However, a comprehensive understanding of the excited‐state dynamics remains limited. To replenish this lacuna, three donor‐π‐acceptor (D‐π‐A) molecules having moderate twist angles (θ), with acronyms, TSBP, TBPS, and 2TBPS, comprising a triphenylamine (TPA) donor and a thiophene‐modified benzophenone acceptor, are designed. These emitters exhibit high photoluminescence quantum yields (PLQYs) in solution and solid states, with TSBP achieving an exceptionally high PLQY of 94% in toluene, 40% in neat film, and 85% in polymethyl methacrylate (PMMA) film. Solvent‐dependent photophysics, femtosecond transient absorption spectroscopy and theoretical investigations confirm the formation of the HLCT states in low and moderately polar environment. Utilizing a simple solution‐processable method, OLED devices are fabricated with emitters exhibiting green and cyan‐blue emission in non‐doped and doped conditions respectively. Among them, TSBP delivers an outstanding device performance, achieving an external quantum efficiency (EQE _max ) of 4.1% in a non‐doped device (CIE: 0.28, 0.62) and a higher EQE _max of 5.6% (CIE: 0.20, 0.55) (CIE = Commission Internationale de l'Éclairage) in a CBP‐doped device. These findings underscore the potential of HLCT‐based emitters for developing efficient and cost‐effective OLEDs.