Impact of titanium and copper buffer layers on the structure and I-V characteristics of TiO2/CuxO thin film solar cells

TiO2/CuxO thin-film solar cells are deposited using reactive direct-current magnetron sputtering. This study introduces a novel approach by employing titanium and copper as buffer layers to study their influence on the crystal structure and electrical properties of TiO2/CuxO solar cells. Cell manufacturing process was carried out for TiO2 and CuxO layers with similar process parameters and different configurations of Ti and Cu buffer layers. The structural and morphological characterization of the TiO2/CuxO solar cells were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the optical properties and current-voltage characteristics were studied. Basic morphological characterizations, like thickness, mechanism of growth, and average grain sizes, were analyzed via scanning electron microscopy. From the XRD study, thin films were observed in CuO, Cu2O, TiO2 , Ti4O7 and Ti3O5 phases. The I-V study confirms the photovoltaic behavior of TiO2/CuO thin-film solar cells. The open-circuit voltage (Voc) and short-circuit current (Isc) values of the photovoltaic devices ranged from 29 to 21mV and from 1 to 22µA, respectively. It was shown that the samples with a Cu buffer layer and Ti/Cu buffer layer have a bimolecular recombination with a differential slope DS≈1.5, which is typical for the solar cells structures with double injection.