The relation between TiO2 nano-pastes rheology and dye sensitized solar cell photoanode efficiency

TiO2 nanpparticle pastes for screen printed semiconductive photoanodes of dye sensitized solar cells were prepared with different content (from 0 to 9 wt%) of ethyl cellulose and evaluated by rheology measurements. The effect of ethyl cellulose content in the paste is crucial for printed and sintered TiO2 photoanode properties as thickness, roughness and amount of adsorbed dye, measured by profilometry, atomic force microscopy, IR and UV-Vis spectroscopy. Moreover, the expressive correlation among paste rheology, layer properties and the final dye sensitized solar cell efficiency depending on the initial ethyl cellulose content was found, including correlations of the properties local maxima positions. The highest efficiency was achieved for the TiO2 paste with 6.5 wt% of ethyl cellulose, where initial paste viscosity and thixotropy, printed layer thickness, roughness and amount of adsorbed dye achieved the local maxima (similar to 40 Pa.s, 4.5 mu m, 24 nm, 1.92 x 10(-8) mol/cm(2), respectively) that indicates the optimal structure of the oxide photoanode layer. The results confirm the importance of controlled ethyl cellulose concentration and rheological properties of applied pastes for higher DSSC efficiency achievement. (C) 2014 Elsevier Ltd. All rights reserved.