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

Thin films of H2Pc 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 (lo) of charge carriers in H2Pc thin films was attempted. Measurements of thermoelectric power confirm that H2Pc thin films behave as a p-type semiconductor. The current density-voltage characteristics of Au/H2Pc/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 (μh), the total trap concentration (Nt), the characteristic temperature (Tt) and the trap density P(E).