Hot-Exciton Mechanism with Diphenyl Anthracene Core Unit: A Detailed Theoretical Study

Hot-exciton materials, among all kinds of organic light-emitting diode (OLED) emitters, have better exciton utilization efficiency and efficiency roll-off, making them possible for their practical applications. We studied the photophysical properties of a few hot-exciton molecules based on an anthracene core unit to efficiently harvest all triplet excitons to the lowest excited singlet state. The conversion of triplet exciton to singlet exciton utilizing hRISC can be enhanced due to the ¹ππ*←³nπ* transition channel. The energy gap between the excited singlet and triplet excited states, spin-orbit coupling interaction, nature of excited states, rate constants of reverse intersystem crossing, and radiative process were calculated and analyzed to gain more insights into the hot-exciton mechanism. Additionally, we extended our study by substituting groups in the diphenyl anthracene core unit to find improved performance. We found that the combinations of triphenylamine (TPA) or 9-phenyl-9H-carbazole (CZP) acting as the electron donor, benzophenone as the acceptor, and the anthracene as the π-bridge is the most efficient hot-exciton emitter for improved OLED lighting application technology.