In this paper, several donor–acceptor compounds using pyrazine and triphenylamine as building units have been synthesized and fully characterized. The physical properties and theoretical calculations were also investigated. In addition, the OLED devices using these compounds as active elements have been fabricated and all devices display very good performance. Specifically, the maximum EQE for 2 is 7.37%, which is higher than the theoretical limit for fluorescent emitters (5%), indicating that the mechanism for compound 2 is different from traditional fluorescent dyes. Our results suggest that D–A molecules could be a good approach to improve the performance of OLED devices.