The Hole Transport Characteristics of 1, 4, 5, 8, 9 and 11-Hexaazatriphenylene-Hexacarbonitrile by Blending**Supported by the National Natural Science Foundation of China under Grant Nos 51333007, 91433201 and 61204059, the National Basic Research Program of China under Grant No 2013CB834805, the Foundation of Jilin Research Council under Grant Nos 2012ZDGG001 and 20130206003GX, and the Key Research Program of the Chinese

Abstract

The hole transport characteristics of molecule blends of 1, 4, 5, 8, 9 and 11-hexaazatriphenylene-hexacarbonitrile (HAT-CN): N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB) and HAT-CN: 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC) with various NPB and TAPC mixing concentrations (5–90 wt%) are studied. When the concentration is in the range of 5–80 wt%, it is found that the hole conductions in the two blends are space-charge-limited current (SCLC) with free trap distributions. The current–voltage characteristics of the two blends show SCLC with exponential trap distributions at the concentration of 90 wt%. The hole mobilities of the two blends are very close (10−4–10−3 cm2V−1s−1), the dependence of electric field and temperature can be described by the modified Poole–Frenkel model. The hole mobility and activation energy of the two blends depending on concentration are similar.