EFFECT OF OXIDE THICKNESS ON THE PROPERTIES OF METAL-INSULATOR-ORGANIC SEMICONDUCTOR PHOTOVOLTAIC CELLS

The dependence of the dark and photovoltaic characteristics of metal-insulator-semiconductor (MIS) devices of the structure Al/Al-oxide/TPP/Au (TPP = tetraphenylporphyrin) on the thickness of the interfacial oxide layer is described. Iodine-doped MgTPP devices show a variation of open-circuit photovoltage, short-circuit photocurrent, fill factor, power conversion efficiency, and capacitance with Al-oxide thickness, in a manner similar to inorganic MIS structures. An optimum oxide thickness of around 2 nm is observed for highest photovoltaic efficiency. The properties of oxygen/water vapor-doped ZnTPP and H2TPP cells appear dependent upon the extent of oxide growth on the aluminum electrode during the doping process.