TiO₂ Paper-Inserted Sinter-Free Electrode for Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have become an important solar energy conversion system. The development of DSSC structures that use lightweight and flexible plastic substrates is very important for their actual use as solar energy conversion devices in urban life. The greatest obstacle to the application of lightweight flexible substrates to DSSC is the preparation of mechanically robust TiO₂-based nanoporous working electrode layers without a sintering process. This paper presents a novel nanofiber/nanoparticle composite structured TiO₂ working electrode fabricated without a sintering process; instead, TiO₂ paper, consisting of TiO₂ nanofibers, is inserted into the TiO₂ nanoparticle-based electrode. TiO₂ nanofiber paper was prepared by direct electrospinning from TiO₂ sol solution without polymer additives, followed by redispersion, filtering, and heat treatment to yield well-crystallized and mechanically flexible paper. Insertion of TiO₂ nanofiber paper into the electrode prevented cracking of the TiO₂ nanoparticle-based sinter-free electrode like composite materials toughened by fibers. At the same time, well-sintered TiO₂ nanofibers improved energy conversion efficiency compared to conventional TiO₂ nanoparticle sinter-free electrodes.