Development of multiple resonance effect-based TADF materials

Abstract

Multiple resonance (MR) effect of boron and nitrogen/oxygen atoms induces the localization of the HOMO and LUMO on different atoms and minimizes their bonding/anti-bonding character; the resulting non-bonding molecular orbitals minimize the vibronic coupling and vibrational relaxation in the material, allowing the realization of an extremely sharp emission band and high PLQY. Moreover, the significant localization of the HOMO and LUMO reduces the energy gap between the S1 and T1 states, promoting the reverse intersystem crossing and thermally activated delayed fluorescence (TADF). Here, we present recent achievements in MR-TADF materials, construction of new core structures, and device applications.