Certain example embodiments relate to a transparent conductor film stack with cadmium stannate used as a front contact layer and/or a buffer layer in a photovoltaic device or the like. The cadmium stannate-based layers may be provided between the front glass substrate and the semiconductor absorber film in a photovoltaic device (e.g., a CdS and/or CdTe based photovoltaic device). In certain example embodiments, the buffer layer based on cadmium stannate may have a higher resistivity than the transparent conductive oxide layer based on cadmium stannate. In certain example embodiments, one or more index matching layer(s) may be provided between the glass substrate and the layer(s) comprising cadmium stannate, e.g., to help overcome the optical mismatch between the glass substrate and the CdSnOx.