Dye-sensitized solar cells based on Cr-doped TiO2 nanotube photoanodes

The effect of chromium doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated. Cr-doped TiO2 nanotubes (CrTNs) with different amounts of chromium were obtained by anodizing of titanium foils in a single-step process using potassium chromate as the chromium source. Film features were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and ultraviolet-visible (UV-Vis) spectroscopy. It is clearly seen that highly ordered TiO2 nanotubes are formed in an anodizing solution free of potassium chromate, and with a gradual increase in the potassium chromate concentration, these nanotube structures change to nanoporous and compact films without porosity. The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent-voltage (I-V) curves. It is found that the photovoltaic efficiency of DSSCs with CrTNs1 sample is improved by more than three times compared to that of DSSCs with undoped TNs. The energy conversion efficiency increases from 1.05 % to 3.89 % by doping of chromium.