Effect of Wormhole-like Mesoporous Anatase TiO2 Nanofiber Prepared by Electrospinning with Ionic Liquid on Dye-Sensitized Solar Cells

A series of 1-D mesoporous anatase TiO2 nanofibers (TNFx, x = 0-3 in wt %) were synthesized via a simple electrospinning technique combined with a sol gel process which used 0-3 wt % of room-temperature ionic liquid (RTIL) as the mesopore formation template. TNF1 electrospun with 1 wt % RTIL was found to be the most favorable TNFx for application in a dye-sensitized solar cell (DSSC). The effects of TNFx as photoanode materials on the property of DSSC were further investigated using electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS), and intensity-modulated photovoltage spectroscopy (IMVS) measurements. The results indicated that the unique morphology of TNF1, being a straight, large surface, wormhole-like mesoporous anatase nanofiber with the smallest average fiber diameter, was the main reason leading to the largest improvement in its light harvesting, electron transport, and charge collection efficiencies among the series of TNFx-based photoanodes. This study demonstrated TNF1 as a promising photoanode material for DSSC; specifically, the DSSC fabricated with TNF1 showed the largest improvement (similar to 50.4%) in energy conversion efficiency (5.64%) over that with TNF0 electrospun without RTIL (3.75%).