Design And Regulation Of Composite Photoanode For Dye-sensitized Solar Cell

Resource shortage and environmental pollution have gradually become a stumbling block to the development of various countries and regions.As a renewable and clean energy,solar energy has attracted more and more attention due to its advantages such as huge reserves,environmental protection and small geographical restriction.The essence of using solar energy is to convert light energy into electric energy and heat energy that can be used by people.Among them,solar cells can directly convert light energy into electric energy through physical and chemical methods.With the deepening of research on solar cells,a series of systems have been formed,including silicon solar cells,compound thin film solar cells,organic solar cells,perovskite solar cells and nanocrystalline solar cells.Among them,dye-sensitized solar cells（DSSCs）are expected to be widely used in the future due to their features of non-pollution,low cost,good performance and easy fabrication.In this thesis,the photoelectric properties of dye-sensitized solar cells（DSSCs）photoanode are studied.As an important component of DSSCs,photoanode film can absorb dye molecules,inhibit the combination of electrons and holes and construct photon scattering paths and electron conduction channels,which directly determines the photoelectric performance of DSSCs.It is very important to regulate the type and structure of photoanode film materials to improve the photoelectric performance of DSSCs.Among many photoanode film materials,TiO₂ has suitable band gap width,good photoelectric properties and good stability,large storage,non-toxic and other natural advantages,and is widely used in DSSCs photoanode.However,photogenerated electrons are easy to be compounded away during the transmission of photoanode film,thus affecting the photoelectric performance of DSSCs.In order to improve the photoelectric properties of DSSCs and photoelectric conversion efficiency,and to explore the compound materials and new morphology of photoanode film,this paper designs SnO₂@Air@TiO₂ hierarchical urchin-like double-hollow nanospheres and hollow TiO₂ urchin-like polyhedrons with ZIF-8 templates.These two microstructures can improve the photoelectric performance by optimizing the composite materials and morphology of photoanode film,thus improving the photoelectric conversion efficiency（PCE）of DSSCs:（1）SnO₂@Air@TiO₂ hierarchical urchin-like double-hollow nanospheres（SATS）are designed and used as photoanode film materials.And the idea of layer by layer coating is used to prepare the microspheres.First,hollow SnO₂ spheres are synthesized by hydrothermal method,then SiO₂ is coated by sol-gel method,and TiO₂ nanorods are coated and grown on the surface of the microspheres by hydrothermal method.Finally,the intermediate layer of SiO₂ is washed away with strong alkali to form the double-hollow urchin-like structure.DSSCs based on SATS obtain the short-circuit current density of13.72mA/cm² at the highest,and the corresponding PCE reaches 6.87%,which is 1.35times of pure P25 DSSCs.This unique structure increases the adsorption amount of dye,promotes the effective capture of photons,and is conducive to the rapid transmission of electrons,which has a certain guiding role in the application of DSSCs.（2）The metal-organic frameworks（MOF）are used as the templates to cover and grow TiO₂ nano-sheets,and hollow TiO₂ urchin-like polyhedrons are formed after calcining.The polyhedron has a special morphology and a high degree of crystallinity,showing good photon reflectivity and electron diffusion efficiency,therefore,the PCE of DSSC has reached 6.94%,with great market potential.