Study of how photoelectrodes modified by TiO2/Ag nanofibers in various structures enhance the efficiency of dye-sensitized solar cells under low illumination

Abstract

Dye-sensitized solar cells (DSSCs) are low-cost solar cells belonging to the thin-film photovoltaic cell type. In this study, we studied the photovoltaic performances of DSSCs based on titanium dioxide (TiO2) nanofibers (NFs) containing silver (Ag) nanoparticles (NPs) under low illumination. We used the sol-gel method with the electrospinning technique to prepare the TiO2 NFs containing Ag NPs. Herein, we used two ways to add TiO2/Ag NFs to modify the photoelectrode successfully and enhance the performance of DSSCs. One way was that the TiO2/Ag NFs were mixed with pristine TiO2; the other way was that the TiO2/Ag NFs were seeded beside the TiO2 colloid layer as an additional layer on the photoelectrode of the DSSC. According to this experiment, the photovoltaic conversion efficiency of the DSSC which had TiO2/Ag NF seeded as an additional layer on the photoelectrode (5.13%) was increased by 28% compared to the DSSC without the photoelectrode modification (3.99%). This was due to the suppression of electron recombination and the more effective utilization of the light radiation by adding the TiO2/Ag NFs. Because of the good conductivity of Ag, the electrons were quickly transported and electron recombination was reduced. In addition, the photovoltaic conversion efficiency of the DSSC which had TiO2/Ag NF seeded as an additional layer on the photoelectrode increased from 5.13% to 6.23% during the decrease in illumination from 100 mW/cm2 to 30 mW/cm2; however, its photovoltaic conversion efficiency decreased to 5.31% when the illumination was lowered to 10 mW/cm2.