Modulation of the band gap of tungsten oxide thin films through mixing with cadmium telluride towards photovoltaic applications

Tungsten oxide (WO₃) is a wide band gap semiconductor that has received extensive interest in optoelectronic applications. However, its band gap is too large for applications based on the absorption of visible light. To that end, we have modulated the band gap of WO₃ thin films through mixing it with cadmium telluride (CdTe). The films were prepared by thermal evaporation of WO₃ containing controlled concentrations of CdTe (0–25%). The obtained films showed a continuous reduction in the band gap from 3.30 eV (0% CdTe) to 2.47 eV (25% CdTe). Photocurrent response increased significantly with the increase of CdTe concentration due to the enhancement of the light absorption in the long wavelength region. The results obtained support the potential of these alloyed films for photovoltaic applications.