Towards red thermally activated delayed fluorescence emitter: Molecular design and property prediction of phenothiazine-triphenyltriazine derivative

Abstract

A series of thermally activated delayed fluorescence (TADF) molecules with the linkage of the electron-donating group (phenothiazine, PTZ) and electron-withdrawing groups (2,4,6-triphenyl-1,3,5-triazine type, TRZ) have been designed and investigated for efficient red TADF emitters by means of quantum chemical calculations. The geometrical and electronic structures, absorption and emission properties, reverse intersystem crossing (RISC), radiative and nonradiative decay processes of the PTZ-TRZ-based molecules were analyzed. The calculated results indicate that the designed molecules possess the relatively large RISC rates (>105 s−1) and exhibit the red emission, indicating that they have the potential to be an efficient red emitting TADF material. Furthermore, the position of N atom in the TRZ acceptor group have significant effects on RISC process and emission color. This work provides in-depth understanding of the structure–property relationship of PTZ-TRZ-based TADF molecules, and offers the guideline for the screening of the efficient pure red TADF emitters.