Fabrication of TiO2 compact layer precursor at various reaction times for dye sensitized solar cells

A compact layer is used to increase the photoelectric conversion efficiency on DSSCs due to it can improve the transparent conduction oxides (TCOs) surface and prevent the electrolyte from directly contacting the ITO (Indium Tin Oxide) substrate. In this study, DSSCs with compact layer reacting for three hours are compared to those without compact layer, where the short-circuit current and solar energy conversion efficiency are improved by 22%, and 26%, respectively. Based on electrochemical impedance spectra (EIS) measurements, we clarify that the compact layer can decrease the charge interfacial resistance and the leakage current due to the fact that the dense TiO2 nanoparticles can effectively prevent charge transport from the photoanode to the ITO substrate. We compared different reacting times for the formation of the compact layer, and showed that the quantum efficiency of DSSC is higher when a 3 h reacting time is adopted with respect to a 24 h processing time. A study of the various molar ratios of the precursor solution has been done. The data showed that the 1 M is the optimal molar ratio. We also studies the compact layer formation on FTO with respect to ITO, showing that the FTO substrate has higher photoelectric conversion efficiency.