Construction of High-Performance Carbene–Metal–Amide-Like TADF Materials: A Theoretical Study

Thermally activated delayed fluorescence (TADF) molecules based on carbene–metal–amides (CMAs) have attracted tremendous attention, but it remains a great challenge for the rational design of such materials due to the lack of reliable molecular construction guidelines. In this work, we perform a computational investigation to design CMA-based TADF materials by elucidating how the location (α, β) and number of nitrogen atoms in carbolines affect the TADF properties. Four promising CMA-based TADF molecules with both small splitting energy and large fluorescence oscillator strength were successfully designed. Moreover, it was found that β-position with one and two N atoms are promising in achieving improved TADF performance in light of their small geometric relaxations, low energy barriers for electron injection, small singlet–triplet splitting energies, facile intersystem crossing, and efficient fluorescence radiative rates. These theoretical understandings could give an in-depth physical insight into the structure–performance relationship of CMA-based luminescent materials, providing important guidance for the exploration of high-performance TADF molecules.