During the last decade, organic photovoltaic research has attracted attention and power conversion efficiencies have shown strong growth. This growth has attracted economic and scientific interest towards organic solar cell. This attention was possible due to the introduction of new polymer materials, inorganic molecules, sophisticated methods of fabrication, and improved material technologies. Bulk-Hetero Junction solar cells achieved 7 % efficiency with the introduction of inorganic small molecules in organic polymers. Organic solar cells of 12% efficiency are targeted. However, the degradation of organic semiconductors due to the environment and the effect of cathode deposition make the organic solar cells inferior to silicon solar cells. In this thesis, the effect of cathode deposition with various deposition methods was studied.
The Dark Capacitance-Voltage characteristics and Capacitance-Frequency characteristics Of MEH PPV (Poly (p-phenylene vinylene) (PPV)) Solar cell with sputtering and thermal evaporation of the aluminum cathode are reported here. Capacitances are measured at different temperatures using cryogenic testing. Interface state densities and their time constants are calculated and analyzed. The variance of depletion width, interface state densities and time constants with two different processes is discussed here. The observations indicated that rf sputtering deposition of cathode is introduces greater interface densities compared to thermal evaporation devices