Carrier Transport in van der Waals Solid: 1,3-Diphenyl-5-(p-chlorophenyl)-2-pyrazoline in Single Crystalline State, Glassy State and in Supercooled Liquid State

The hole drift mobilities in the title compound were measured in the single crystalline state (mp. 130°C), the glassy state (Tg, 16.5°C) and the supercooled liquid state up to 50°C by a time-of-flight method. The mobility (μh) in a single crystal was about 10−2 cm2/V.sec and its activation energies were 0.103 eV below 12°C and 0.037 eV above this temperature. A weakly endothermic solid phase transition was observed in a single crystal corresponding to this temperature. In the glassy state, μh was about 10−5 cm2/V.sec. In the supercooled liquid state, μh was also of the order of 10−5 cm2/V/sec and showed a maximum value at around 35°C, which appeared reproducibly and depended on the heating and cooling rate showing hysteresis phenomena. The Scher Montroll transport theory for non-crystalline solids could be applied to our material but in a rather limited temperature range.