Highly flexible TiO2/C nanofibrous film for flexible dye-sensitized solar cells as a platinum- and transparent conducting oxide-free flexible counter electrode

In this study, highly flexible TiO 2 /C nanofibrous film was fabricated via electrospinning followed by thermostabilization and carbonizaiton. These nanofibers (NFs) composed of carbon and TiO 2 nanoparticles (NPs) with incorporation of TiO 2 NPs into carbon matrix. The content of polyvinylpyrrolidone (PVP) and titanium (IV) isopropoxide (TiP) were adjusted to optimize the performance of the TiO 2 /C nanofibrous film. The results show that the average diameter of TiO 2 /C NFs and the content of carbon in NFs decreased as the proportion of PVP increased. With addition of PVP, TiO 2 NPs distributed more uniformly. With increase of TiP, the average diameter and content of TiO 2 increased. As a result, the conductivity decreased with the increase of PVP and TiP. While, the flexibility increased, reaching a best value before decreasing as the PVP and TiP increased. The TiO 2 /C nanofibrous film presented best flexibility with the content of PVP and TiP of 50% and 0.7   g. Notably, the flexible TiO 2 /C nanofibrous film showed pleasurable catalytic activity. Therefore, the TiO 2 /C nanofibrous film served as platinum (Pt)- and transparent conducting oxide (TCO)-free counter electrode (CE) for flexible dye-sensitized solar cells (FDSSCs). Besides, the TiO 2 /C nanofibrous film CE withstood large deformation of bending and exhibited excellent bending stability.