Highly efficient deep-blue organic light-emitting devices (OLEDs) have been fabricated using 2,7-di(2,2':6',2″-terpyridin-4-yl)-9,9-dioctyl-9H-fluorene (DTPF) as the emitter, which has a wide energy gap, high emission quantum yield (Φf = 0.88), and high electron transporting property to improve the charge balance. A high efficiency of 2.55 cd/A and 2.67 lm/W are obtained in OLED. The device also exhibits a low turn-on voltage of 3.0 V and Commission Internationale de l'Éclairage (CIE) coordinates of (0.16, 0.09).