Test of Different Sensitizing Dyes in Dye-Sensitized Solar Cells Based on Nb2O5 Photoanodes

High-performance dyes routinely employed in TiO2-based dye-sensitized solar cells (DSSCs) were tested in cells assembled using Nb2O5 nanostructure-based photoanodes. The sensitizers were chosen among both metal-complex (two Ru-based, N749 and C106, and one Zn-based dye, DNF12) and metal-free organic dyes (DNF01, DNF11 and DNF15). Two different sensitization processes were performed: the one commonly used for TiO2 photoanodes, and a new process relying on high pressure by autoclavation. The assembled cells were characterized by current density-voltage (J-V) curves under air mass (AM) 1.5 G illumination and in the dark, incident photon-to-current efficiency (IPCE) measurements, and electrochemical impedance spectroscopy. The tested cells show different proportional efficiencies of the dyes under investigation for Nb2O5 and TiO2-based devices. Furthermore, the results were compared with those obtained in our previous work using N719 anchored on Nb2O5. A remarkable efficiency value of 4.4% under 1 sun illumination was achieved by coupling the C106 dye with a nonvolatile electrolyte. This value is higher than the one attained under the same conditions by using N719.