Cu(II)-Doped TiO₂ Nanoparticles as Photoelectrode in Dye-Sensitized Solar Cells: Improvement of Open-Circuit Voltage and a Light Scattering Effect

Cu-doped TiO₂ nanoparticles were synthesized for use as photoanodes in dye-sensitized solar cells (DSSCs). The nanoparticles were characterized by using inductively coupled plasma atomic emission spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning transmission electron microscopy and UV-Vis spectroscopy. Cu-doped TiO₂ nanoparticles showed a low band gap energy. Normally, using these nanoparticles in photovoltaic devices leads to an increase in the open-circuit voltage (V _OC), caused by a negative displacement of the flat band voltage (V _FB), with a simultaneous decrease in the short-circuit current density (J _sc). This study presents a way of resolving this problem by using a second deposition of nanoparticles in the electrode of the cells. This produces a light scattering effect that makes it possible to minimize the decrease in J _sc produced by the cells. The distribution of these types of nanoparticles was confirmed using scanning transmission electron microscopy.