Dissymmetric interface design of SnO₂/TiO₂ side-by-side bi-component nanofibers as photoanodes for dye sensitized solar cells: Facilitated electron transport and enhanced carrier separation

SnO₂/TiO₂ type II heterojunctions are often introduced to enhance the separation efficiency of photogenerated carriers in photoelectrochemical electrodes, while most of these heterojunctions are of core–shell structure, which often limits the synergistic effect from the two components. In this work, dissymmetric SnO₂/TiO₂ side-by-side bi-component nanofibers (SBNFs) with tunable composition ratios have been prepared by a novel needleless electrospinning technique with two V-shape connected conductive channels (V-channel electrospinning). Results show that this V-channel electrospinning technique is more stable, controllable and tunable for the large-scale preparation of SBNF materials compared to the traditional electrospinning using two side-by-side metal needles. And these SnO₂/TiO₂ SBNFs are dissymmetric and comprised of a tiny SnO₂ NF (tunable diameter within 20–80 nm) and a Sn-doped TiO₂ NF (diameter of ~ 250 nm) with a side-by-side structure. Moreover, the dye-sensitized solar cells (DSSCs) based these dissymmetric SnO₂/TiO₂ SBNFs show the maximum power conversion efficiency (PCE) of 8.3%, which is 2.59 times that of the ones based on the TiO₂ NFs. Series of analyses indicate that the enhancements in PCE could mainly be due to the improved electron transport via SnO₂ NFs and the enhanced carrier separation via dissymmetric SnO₂/TiO₂ heterojunction interface. This research will give some new insight in the preparation of SBNFs for high-performance photoelectrochemical devices.