TiO2 doping has been widely used in photocatalysis and photovoltaic cells to improve the performance of this semiconductor. This paper studies the use of copper as a dopant in TiO2 in dye-sensitized solar cells (DSSC), analysing the effect on the photovoltaic properties of the cells of different concentrations of copper incorporated into the semiconductor. The copper-doped TiO2 semiconductor was characterized with several instrumental techniques, including X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning transmission electron microscopy (STEM), and UV–Vis spectroscopy in order to know its structure, composition and band gap energies with different concentrations of the dopant. An analysis was also performed of the variations in open-circuit voltage depending on the concentration of copper. This showed that the presence of copper in DSSCs made with a standard configuration – using a ruthenium complex (N3) as a dye and the redox pair as the electrolyte with 3-methoxypropionitrile as a solvent – leads to improvements of up to 10% in the open-circuit voltage of DSSCs.