Investigation on excited-state properties and electroluminescence performance of Donor−Acceptor materials based on quinoxaline derivatives.

The reverse intersystem crossing (RISC) process plays a decisive role in next-generation organic light-emitting diodes (OLEDs), which depends on the energy gap and spin-orbit coupling (SOC) between singlet state and triplet state. To investigate the excited state structure-property relationship and the SOC effect in electro-fluorescent donor-acceptor (D-A) materials, herein, we constructed four quinoxaline derivatives based donor-acceptor (D-A) materials and investigated their excited state properties with a theoretical combined experimental research. The four materials are of different hybridized local and charge-transfer (HLCT) characters. Among them, the most hybridized TPA-DPPZ achieved a higher quantum efficiency over 90% for the effective suppression of non-radiative transition, and it exhibited a higher exciton utilization of 42.8% in non-doped OLED due to a "hot-exciton" channel facilitated with sizeable SOC. Image 1 • Quinoxaline acceptors with boosted SOC are adopt for electroflurescence material. • Restricted non-emissive transition rates are realized in HLCT material TPA-DPPZ. • TPA-DPPZ achieved an exceeding exciton utilization of 43% in non-doped OLED. • "Hot-exciton" channel facilitated with large SOC helps high exciton utilization. [ABSTRACT FROM AUTHOR]