An efficient hole-transporting blue fluorophore 3,6-dipyrenyl-9-ethylcarbazole for undoped organic light-emitting devices

A new blue-emitting carbazole derivative, 3,6-dipyrenyl-9-ethylcarbazole (DPEC), has been designed and synthesized for applications in organic light-emitting devices (OLEDs). Undoped DPEC-based OLEDs give a saturated blue electroluminescence with Commission Internationale de L’Eclairage 1931 coordinates of (0.15, 0.18), and possess high luminous efficiency of 4.75 cd A−1. On the other hand, DPEC can also function as a hole-transporting layer (HTL). In particular, by replacing N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) as HTL, a simplified bilayer device demonstrated good performance, comparable to that of the trilayer device. This good device performance illustrates that DPEC is a promising candidate as a blue hole-transporting emitter.