Charge transport properties in liquid carbazole

The hole mobility in 9-(2-ethylhexyl)carbazole so-called liquid carbazole, in poly(N-vinylcarbazole) (PVK) and in their blends is determined by time-of-flight experiment using a phthalocyanine charge generation layer. With an applied electric field of 2.5 × 10⁵ V/cm, mobilities of 4 × 10⁻⁶ cm²/Vs and 6 × 10⁻⁷ cm²/Vs are measured in liquid carbazole and PVK, respectively. The enhancement of the charge carrier mobility in liquid carbazole is attributed to both a larger transfer integral and changes in the distribution of the excimer trapping sites. The results show the potential interest of liquid carbazole for electroactive applications in optoelectronics.