) is lowered from 0.17 eV for BCz-BN to 0.06 eV, thereby promoting more efficient reverse intersystem crossing (RISC) and improved exciton harvesting. As a result, the corresponding OLED device based on DBX-BCz-BN exhibits an external quantum efficiency (EQE) of 22.2%, while maintaining the same emission color. These results demonstrate that rigid-core engineering via DBX incorporation is an effective strategy for achieving narrowband, efficient, and color-pure sky-blue TADF emitters.
Viswanathan et al. (Tue,) studied this question.