Roles of low temperature sputtered indium tin oxide for solar photovoltaic technology

Abstract

Different functionalities of materials based on indium tin oxide and fabricated at soft conditions were investigated with the goal of being used in a next generation of solar photovoltaic devices. These thin films were fabricated in a commercial UNIVEX 450B magnetron sputtering. The first studied functionality consisted of an effective n-type doped layer in an n-p heterojunction based on p-type crystalline silicon. At this point, the impact of the ITO film thickness (varied from 45 to 140 nm) and the substrate temperature (varied from room temperature to 250◦ C) on the heterojunction parameters was evaluated separately. To avoid possible damages in the heterojunction interface, the applied ITO power was purposely set as low as 25 W; and to minimize the energy consumption, no heat treatment process was used. The second functionality consisted of indium-saving transparent conductive multicomponent materials for full spectrum applications. This was carried out by the doping of the ITO matrix with transition metals, as titanium and zinc. This action can reduce the production cost without sacrificing the optoelectronic film properties. The morphology, chemical, structural nature and optoelectronic properties were evaluated as function of the doping concentrations. The results revealed low manufactured and suitable films used successfully as conventional emitter, and near-infrared extended transparent conductive materials with superior performance that conventional ones, useful for full spectrum applications. Both can open interesting choices for cost-effective photovoltaic technologies.