Multi-core cable-like TiO₂ nanofibrous membranes for dye-sensitized solar cells

Multi-core cable-like TiO₂ nanofibres were fabricated by calcination of composite polyvinyl acetate (PVAc)/titania nanofibres with a hot pressing pre-treatment. This resultant novel fibre structure was composed of sheaths of 200 nm in diameter and 25 nm in wall thickness, and cores filled with 24 nm thick TiO₂ fibrils. The formation of multi-core cable-like structures of fibres is considered to be due to the enhanced phase separation of PVAc-rich and TiO₂-rich phases during the hot pressing process. The BET results showed that the specific surface area of pressed TiO₂ membranes was much higher than that of unpressed TiO₂ membranes. In this study, the novel multi-core cable-like TiO₂ fibrous membranes were used as electrode materials for dye-sensitized solar cells (DSSCs). It was observed that the photocurrent and conversion efficiency of the electrodes increased concurrently with increasing applied pressure and average membrane thickness in the range of 1-9 μm. The maximum short circuit photocurrent and energy conversion efficiency were 16.09 mA cm^-2 and 5.77% when the membrane had an average thickness of 9.21 μm and 8 MPa applied pressure.