NOVELTY - Forming solar cell (200) device, comprises: forming a first transparent conductive oxide layer over a first surface of a substrate, where the first transparent conductive oxide layer contains tin and oxygen, and the substrate contains a glass material having an iron concentration less than 0.03 wt.%; forming a conductive contact layer disposed on the first transparent conductive oxide layer, where the resistivity of the first transparent conductive oxide layer and conductive contact layer is less than 10 Ohms/square; and forming a first p-i-n junction (116) on the conductive contact layer.    USE - The method is useful for making a solar cell device.    ADVANTAGE - The method provides: thin-film solar cells with broadest possible absorption characteristics to increase overall cell conversion efficiency; and smaller bandgap films which have a low defect density and high current generation.    DETAILED DESCRIPTION - Forming a solar cell (200) device, comprises: forming a first transparent conductive oxide layer over a first surface of a substrate, where the first transparent conductive oxide layer contains tin and oxygen, and the substrate contains a glass material having an iron concentration less than 0.03 wt.%; forming a conductive contact layer disposed on the first transparent conductive oxide layer, where the resistivity of the first transparent conductive oxide layer and conductive contact layer is less than 10 Ohms/square; and forming a first p-i-n junction (116) on the conductive contact layer. The step of forming the first p-i-n junction comprises: forming a p-doped amorphous silicon layer on the conductive contact layer; forming an intrinsic type amorphous silicon layer over the p-type amorphous silicon layer; and forming an n-type microcrystalline silicon layer on the conductive contact layer or intrinsic type amorphous silicon layer.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic side-view of a tandem junction thin-film solar cell.    First p-i-n junction (116)    Conductive index matching layer (118)    Amorphous silicon layer (n-type) (134)    Second p-i-n junction (136)    Solar cell (200)