Space-charge-limited conductivity in evaporated α-form metal-free phthalocyanine thin films

摘要: Abstract The electrical properties of thermally evaporated thin films metal-free phthalocyanine (H2Pc), having gold electrodes, have been investigated. Capacitance measurements as a function film thickness at standard frequency 1 kHz showed the usual geometric dependence, with relative permittivity value er = 2.9. Room temperature dc current density-voltage (J-V) linear ohmic dependence low voltages, followed by power-law exponent 4, higher voltage levels. These results confirm that acts an contact to H2Pc, and indicate space-charge-limited conductivity (SCLC) voltages. Measurements density inverse constant applied yielded hole mobility μ 6.25 × 10−7 m2 V−1 s−1. In conjunction room J-V data this gave p0 8 1018 m−3 for concentration. SCLC voltages was dominated exponential distribution traps, P(E) P0exp(−E/KTt, where P0 1.29 1046 J−1 m−3, Tt 900 K total trap concentration Nt 1.6 1026 m−3. suggested desorption oxygen, regrowth appearance crystal defects during heat treatment.