Research On Dye-sensitized Solar Cells Based On Three-dimensional Porous Structure Photoanode

Dye sensitized solar cells (DSSCs) attracted much more attentions because of their low cost and high efficiency. The DSSCs which used perovskite as dye have reached an efficiency of15%. The photoanode is a key component in DSSCs which acts as the carrier for the photogenerated electrons from the excited dyes to conductive glass layer. Nanoparticulate TiO2films are usually incorporated in highly efficient DSSCs due to their large specific surface areas, facilitating high dye absorption. However, there are two major intrinsic problems in nanoparticle-based films which limited the further improvements of the efficiency of DSSCs. The first problem involves the numerous grain boundaries between the nanoparticles. Electron transport is random in nanoparticle films, greatly lengthening the path of the electrons traveling to the conductive glass layer and facilitating electron loss via recombination. The second one is the poor redox I-/I3-diffusion caused by the narrow transport channels in the nanoparticle film. Furthermore, poor redox I-/I3-diffusion also suppresses electron transport at the particle interface.In this paper, we introduce the method called Photopolymerization induced phase separation to prepare a film with a three-dimensional interconnected network structure (TIS). The TiO2skeleton in the TIS film is continuously interwoven, providing uninterrupted pathways for electron transport. Numerous interconnected macropores and mesopores of varying sizes are embedded in the film. These macropores form large3D channels that might promote I-/I3-ion diffusion throughout the film. Meanwhile, the amount of pores may increase the specific surface area, allowing higher dye loadings. A same thickness film is adopted to assemble the DSSCs, generating an increase in efficiency relative a P25film. Then, many methods such as adding an blocking layer, TiCl4surface treatment, surface coating, composite coating and add surface plasmon were used to optimize the DSSCs. The mechanism of these methods were studied either. Adding a block layer on the FTO conducting glass can increase the adhesion of the film and suppress the recombination of electrons by releasing the interfaces of the film and condcting glass. Treating the film with TiCl4solution would improve the connection of skeleton and enlarge the specific surface area. These improvements could promote the transport of electrons and the absorption of the dye. Metal oxide(Al2O3,MgO) coating would build an energy barrier. This barrier could hinder the reverse transport of the electrons and suppress the recombination. Because of the existance of this barrier, the electron collection higher.Adding Au particles on the surface of the film would cause local surface Plasmon enhancement and this phenomenon could improve the absrption of the visible light. And the increase of the light absrption could lead in a obvious enhancment in short-circle current and photoelectric converation eddiciency.