Dye-sensitized solar cells (DSSCs) have been more systematically studied for many years. All kinds of innovative design of photoanode materials have paved the way to improve the photoelectric conversion efficiency (eta) of DSSCs. New technological advancements, like preparation of nano-TiO2 and surface modification, have had a positive effect on improving eta of DSSCs in recent years. The low-cost TiO2 become promising photoanode materials due to its strong adsorption capacity, not anti-light corrosion, good acid and alkali resistance and excellent biocompatibility. Excited dye molecules transfer electrons to the conduction band of the TiO2 and then to the external circuit through the TiO2 substrates. The photoelectron production, transfer, and output are related to TiO2, the dye/TiO2 interface and electrolyte/TiO2 interface. Among them, the loss of electrons is mainly due to I-3(-) trapping electrons on the dye/TiO2 interface and electrolyte/TiO2 interface. Therefore, it is a very effective method for modifying the surface of TiO2 to reduce the loss of electrons during the process, thereby improving eta of DSSCs. This review studies the preparation of nano-TiO2 and surface modification, which have an effect on improving eta of DSSCs. At the same time, according to the development situation of DSSCs based on TiO2 photoanode, the common TiO2 modification methods are summarized to analyze the effects of different modification methods on DSSCs.
