Thermal stability of sputtered Mo/polyimide films and formation of MoSe<sub>2sub> and MoS<sub>2sub> layers for application in flexible Cu(In,Ga)(Se,S)<sub>2sub> based solar cells
摘要
Molybdenum (Mo) films with a thickness of about 800 nm were room temperature sputtered onto flexible polymeric substrates. Upilex庐 films were chosen as substrates on the basis of their high thermal endurance and reduced coefficient of thermal expansion. Thermal stability of Mo films has been proved by heat treatment of the Mo/Upilex庐 structures at a temperature comparable to that used in the preparation of the Cu(In,Ga)(Se,S)<sub>2sub> absorber layer. A combination of high optical reflectance (maximum values of 75-80%), low electrical resistivity (about 30 渭惟 cm) and a smooth surface free of cracks for heated films highlights their good thermal stability. The formation of MoSe<sub>2sub> and MoS<sub>2sub> layers, after selenization/sulfurization of the Mo/Upilex庐 structures, has been further investigated in view of their application as back contact layers in flexible CIGS based solar cells.