Enhanced power conversion efficiency in dye-sensitized solar cells with TiO2 aggregates/nanocrystallites mixed photoelectrodes

Photoelectrodes of mixed microsized TiO2 aggregates and individually dispersed TiO2 nanocrystallites with different ratios were fabricated and studied for improved power conversion efficiency in dye-sensitized solar cells (DSCs). TiO2 aggregates/nanocrystallites composites possess several advantages for high performance of DSCs, including the light scattering by the microsized TiO2 aggregates and the high surface area of nanocrystallites both in aggregates and individually dispersed. A high power conversion efficiency of 7.59% was achieved with mixed TiO2 aggregates/nanocrystallites photoelectrode using conventional dye N3, without applying anti-reflection coating, back-scattering layer, or chemical treatment. The electron transport properties of DSCs with mixed photoelectrodes were investigated by electrochemical impedance spectra, and the results showed that such a photoelectrode with mixed aggregates and nanocrystallites possess better connectivity for efficient electron transport. Published by Elsevier Ltd.