Electrical properties of iron phthalocyanine thin film device using gold and aluminium electrodes

The electrical conductivity of FePc thin film sandwich structures using gold and aluminium electrodes has been investigated for the freshly prepared devices and device after exposure to oxygen for 30 days. Current density-voltage characteristics of the devices in the forward bias showed an ohmic conduction in lower voltages and a space charge limited conduction (SCLC) controlled by a single and an exponential trapping levels at two different ranges of applied voltages. The hole concentrations are obtained as P _o = 3.92 × 10¹⁶ m⁻³ with a hole mobility μ = 5.81 × 10⁻⁶ m⁻¹ V⁻¹ s⁻¹. In the SCLC region a discrete trap level of 1.88 × 10²¹ m⁻³ is found at 0.66 eV followed by an exponential trap distribution of P _e = 4.63 × 10⁴⁶ J ⁻¹ m⁻³ at N _t(e) = 2.23 × 10²⁶ m⁻³. From the current limitations in the reverse bias, the conduction is identified as an electrode limited Schottky type of conduction. In the oxygen-doped samples, both in the forward and reverse bias the order of currents are much enhanced and a transition from the ohmic conduction to a space charged conduction is observed.