Color tuning of di-boron derived TADF emitters: molecular design and property prediction

Abstract

A class of thermally activated delayed fluorescence (TADF) molecules with electron-deficient diboron-derived units have been investigated by means of quantum chemical calculations. The modification of the electron acceptor by the fixation of 9,10-diboraanthracene (DBA) and its adjacent benzene rings and extension of the π-conjugation of DBA could effectively tune the electron-withdrawing ability, thus achieving the fluorescence emission in a visible spectrum color range. The reverse intersystem crossing (RISC) and radiative process of the investigated boron-containing compounds are analyzed in detail to reveal the TADF mechanism. The calculated results indicate that the RISC process of the emitter might be promoted by either the assistance of the non-adiabatic coupling effect or the dynamical molecular conformation changes activated at room temperature. This work provides an in-depth understanding of the TADF performance of organoboron compounds and establishes the structure–property relationship to screen highly efficient boron-based TADF materials.