Preparation of TiO2 paste starting from organic colloidal suspension for semi-transparent DSSC photo-anode application

We investigated the effect of different formulation strategies on the preparation of TiO2 screen printable pastes starting from the same organic colloidal suspension for dye-sensitized solar cells (DSSCs) application. As first strategy, we developed TiO2 pastes starting from nano-crystalline powder dried from the synthetized suspension, with and without an additional acid treatment, obtaining non-transparent scattering sintered layers. Instead, we demonstrate that starting from the sol solution is a key factor to obtain a well nano-dispersed TiO2 paste. The novel paste process resulted in a final homogeneous and semitransparent porous layer (T>80% @450-550 nm). In order to evaluate the properties of TiO2 powders and inks we performed thermal analysis, BET and FTIR measurements. The films were screen printed on FTO (fluorinedoped tin oxide) glass and characterized after sintering via profilometry, FE-SEM analysis and UVVis spectra measurements. The photo-anode was further validated in small (2 cm2) and large (90 cm2) active area DSSCs, giving an average photovoltaic efficiency respectively of 5,22% and 2,39%, comparable with commercially available TiO2 paste with similar composition.