Real time monitoring of ultrafast sensitization for Dye-Sensitized Solar Cell photoanodes

In this paper, the real time monitoring of a microfluidic based ultrafast sensitization process is proposed for two different nanostructured semiconducting oxides (transparent TiO2 and sponge-like ZnO) to be employed as photoanodes in Dye-Sensitized Solar Cells (DSSCs). A home-made set-up has been appositely developed in which the semiconducting oxide film is sandwiched into a microfluidic cell architecture connected to a pumping system. This innovative housing system allows impregnation of the photoanodes under continuous flow regime, thus ensuring a considerable reduction in the loading time and in the employed dye amount. This improvement is of particular interest in view of the device production at industrial scale. The effect of the dye concentration on the sensitization process is analyzed through dye adsorption analysis, obtained both by real time absorption monitoring and traditional desorption methods. The dye-impregnated TiO2 and ZnO photoanodes have been used for DSSCs fabrication, using the same customized microfluidic architecture. The results are thoroughly discussed and correlated to the obtained DSSCs electrical performances such as photovoltaic conversion efficiencies and Incident Photon-to-electron Conversion Efficiency (IPCE) spectra.