Dye-sensitized photovoltaic properties of hydrothermally prepared TiO2 nanotubes

Abstract

Hydrothermal synthesis utilizing aqueous alkaline reaction conditions was employed for the preparation of TiO2 nanotubes. The ultimate material morphology was found to be extremely sensitive to the nature of the reaction conditions including the chemical nature of the reactor itself—well-defined TiO2 nanotubes were obtained only when the reaction was carried out in a Teflon reactor/autoclave assembly, as ascertained by electron microscopy imaging. In addition, it was shown that the nanomaterial morphology heavily impacted the performance of dye-sensitized photovoltaic devices based on these materials; devices assembled from well-defined TiO2 nanotubes exhibited marked overall improvement in the power conversion efficiency. Several individual experimental parameters including hydrothermal synthesis temperature, film thickness, TiO2 paste composition, and sintering temperature were shown to affect the photovoltaic properties of the resultant solar cells. Upon sensitization with Ru(dcbpyH2)2(NCS)2, optimized devices showed an average power conversion efficiency of 3.76 ± 0.25% under AM1.5G one sun illumination, seemingly limited by low dye surface coverages.