Hole transports in molecularly doped triphenylamine derivative

Hole mobilities of N′,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD), TPD doped with 5, 6, 11, 12-tetraphenylnathacene (rubrene), and TPD doped with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryle) 4H-pyran (DCM1) were measured by a time-of-flight (TOF) technique between 200 and 300 K. Pristine TPD has a hole mobility of about 2×10−3 cm2 V−1 s−1 at room temperature. The corresponding TOF time transients were non-dispersive. Upon doping, the hole mobility decreased slightly for rubrene-doped TPD, and sharply for DCM1-doped TPD. The TOF time transients remain non-dispersive for both kind of doped samples. The dependence of the mobility on electric field and temperature for undoped and doped TPD was investigated.