Enhanced power conversion efficiency in dye-sensitized solar cells with TiO_2 aggregatesanocrystallites mixed photoelectrodes

摘要

Photoelectrodes of mixed microsized TiO_2 aggregates and individually dispersed TiO_2 nanocrystallites with different ratios were fabricated and studied for improved power conversion efficiency in dye-sensitized solar cells (DSCs). TiO_2 aggregatesanocrystallites composites possess several advantages for high performance of DSCs, including the light scattering by the microsized TiO_2 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 TiO_2 aggregatesanocrystallites 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.