High performance multijunction solar cells based on polycrystalline thin films will require a wide bandgap top cell with at least 15% efficiency. With the bottom cell being CIGS which have already demonstrated the required efficiencies, this work aims to study the complete fabrication and performance of Cd1-xZnxTe solar cells with a bandgap of 1.7eV on glass and flexible polyimide substrates. Cd1-xZnxTe films were deposited by RF magnetron co-sputtering with CdTe and ZnTe sources. By varying the composition of Cd1-xZnxTe being deposited the required bandgap of 1.7eV was achieved. The optical and structural properties of the films were studied with optical transmission, SEM and XRD measurements. The films exhibited high optical transmission and pinhole free grain structure. CZT solar cells were fabricated on glass and flexible polyimide substrate and were analyzed by J-V and spectral response measurements. The effect of post deposition treatments and the effect of N2 during sputtering on CZT device performance were studied.