Donor-π-acceptor materials for robust electroluminescence performance based on hybridized local and charge-transfer state

Abstract Efficient and robust organic light-emitting diodes (OLEDs) have always been of great interest for both academia and industry. In this work, two electroluminescence donor-π-acceptor structure materials 3,6-TC and 3,6-T2C were synthesized and investigated on their excited state properties and electroluminescence performances. The non-doped and doped OLED of the two materials both exhibited high maximum external quantum efficiency (EQE) of near 5% and exciton utilizing efficiency (EUE) of over 60%. More importantly, the introduction of an extra cyano group of 3,6-T2C facilitated a fine modulation of hybridized local and charge-transfer (HLCT) excited state with a crossed dipole of CT transition and an energy favorable high-lying reverse intersystem crossing (RISC), which contributed to a more stable photoluminescence (PL) and EUE than the 3,6-TC. This work provided a novel design strategy to realize high-performance OLED device by the fine modulation in HLCT state.