Anatase mesoporous TiO2 nanofibers with high surface area for solid-state dye-sensitized solar cells

Mesoporous nanofibers (NFs) with a high surface area of 112 m2/g have been prepared by electrospinning technique. The structures of mesoporous NFs and regular NFs are characterized and compared through scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies. Using mesoporous TiO2 NFs as the photoelectrode, solid-state dye-sensitized solar cells (SDSCs) have been fabricated employing D131 as the sensitizer and P3HT as the hole transporting material to yield an energy conversion efficiency (η) of 1.82%. A Jsc of 3.979 mA cm−2 is obtained for mesoporous NF-based devices, which is 3-fold higher than that (0.973 mA cm−2) for regular NF-based devices fabricated under the same condition (η = 0.42%). Incident photon-to-current conversion efficiency (IPCE) and dye-desorption test demonstrate that the increase in Jsc is mainly due to greatly improved dye adsorption for mesoporous NFs as compared to that for regular NFs. In addition, intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) measurements indicate that the mesopores on NF surface have very minor effects on charge transport and collection. Initial aging test proves good stability of the fabricated devices, which indicates the promise of mesoporous NFs as photoelectrode for low-cost SDSCs