Influence of iodine on the electrical and photoelectrical properties of zinc phthalocyanine thin film devices

The electrical and photovoltaic properties of the zinc phthalocyanine (ZnPc) and I2 doped ZnPc thin films, sandwiched between indium tin oxide (ITO) and Al electrodes, were investigated. Doping with iodine brings adequate changes in the characteristics of the device. The devices constitute a metal-insulator-semiconductor (MIS) structure, in which depletion layer is formed in ZnPc, near Al-Al2O3/ZnPc. The depletion layer width and potential barrier height decrease with I2 doping. The charge transport phenomenon at higher voltage range appears to be space charge limited conduction (SCLC), in the presence of the discrete trapping level. The position of Fermi level shifts toward the valence band edge, which indicates that I2 doping increases the P-type conductivity. Various electrical and photovoltaic parameters were determined from the J-V and C-V analysis. The influence of the I2 doping has been discussed in detail.