Ohmic and space-charge-limited conduction in lead phthalocyanine thin films

Article abstract of DOI:10.1002/pssa.2211230119

The electrical characteristics of thermally evaporated triclinic lead phthalocyanine thin films are studied. A number of parameters is evaluated on the basis of the theory of space-charge-limited conduction and the following values are obtained: permittivity ε = 3.16 × 10^-11 F m^-1; hole mobility μ ≈ 6.05 × 10^-10 m² V^-1 s^-1; room temperature hole concentration p_o ≈ 1.60 × 10¹⁸ m^-3; concentration of traps per unit energy range at the valence band edge P_o ≈ 2.79 × 10⁴³ J^-1 m^-3; temperature parameter of trapping distribution T_t ≈ 770 K; total trap concentration N_t ≈ 2.97 × 10²³ m^-3. The room temperature electrical conductivity σ = 1.55 × 10^-10 S m^-1. C-U measurements confirm that the Au-PbPc interface does not form a Schottky barrier. At low temperatures the capacitance of Au-PbPc-Au devices is temperature insensitive, increasing rapidly above 300 K and saturating at about 400 K. Measurements of thermoelectric power confirm that semiconduction is p-type.