Electrical transport properties of thermally evaporated phthalocyanine (H2Pc) thin films

Abstract

Thin films of H 2 Pc of various thicknesses have been deposited onto glass substrates using thermal evaporation technique at room temperature. The dark electrical resistivity measurements were carried out at different temperatures in the range 298-473 K. An estimation of mean free path (l o ) of charge carriers in H 2 Pc thin films was attempted. Measurements of thermoelectric power confirm that H 2 Pc thin films behave as a p-type semiconductor. The current density-voltage characteristics of Au/H 2 Pc/Au at room temperature showed ohmic conduction mechanism at low voltages. At higher voltages the space-charge-limited conduction (SCLC) accompanied by an exponential trap distribution was dominant. The temperature dependence of current density allows the determination of some essential parameters such as the hole mobility (μ h ), the total trap concentration (N t ), the characteristic temperature (T t ) and the trap density P(E). © 2005 Elsevier B.V. All rights reserved.