Incorporating hydrangea-like titanium dioxide light scatterer with high dye-loading on the photoanode for dye-sensitized solar cells

• Hydrangea-like TiO2 (HTiO2) and coral-like TiO2 (CTiO2) are self-synthesized.
• HTiO2 and CTiO2 act as the light scattering layer in the photoanode of DSSCs.
• An HTiO2-based DSSC got a light-to-electricity conversion efficiency (η) of 7.5%.
• The DSSC without a light scattering layer presented the smallest η of 6.41%.
• Better dye adsorption and light scattering ability make the better performance.

The light scattering layer is significant for dye-sensitized solar cells (DSSCs) to harvest incident light more efficiently and excite larger amounts of electrons. Hydrangea-like TiO2 (HTiO2) and coral-like TiO2 (CTiO2) nanostructures are synthesized via a hydrothermal method without using templates. Both of the nanostructures are applied as the light scattering layer for DSSCs with the commercial P90 TiO2 nanoparticles as the dye-adsorbed underlayer in the photoanodes. The DSSC with HTiO2 as the light scattering layer achieves a higher light-to-electricity conversion efficiency (η) of 7.50% than those of 6.70% and 6.61% for the cells with CTiO2 and commercial TiO2 as the light scattering layer, and of 6.41% for the DSSC without a light scattering layer in its photoanode, mainly due to the enhanced photocurrent density through the abundant dye adsorption coupled with the inherent light scattering ability for the former case. The results indicate that not only the importance of the light scattering layer in the photoanode but the morphology of the nanostructure composed of the light scattering layer plays great roles on the light scattering and the dye-adsorbing capabilities. The incident photon-to-current efficiency the electrochemical impedance spectroscopy measurements are also applied to analyze the electrochemical performance of the resulting DSSCs.

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