Controllable Preparation Of TiO₂ Nanomaterials And Their Applications In Dye-sensitized Solar Cell

During the past decade, dye sensitized solar cell(DSSC) has drawn intense attention as a potentially clean and low cost energy resource, due to their low cost of fabrication and relatively high power conversion efficiency. The improvement of conversion efficiency of DSSCs is limited by the photoanode materials. In general, desirable properties for a well performing photoanode are high specific surface area, fast electron transport and a large light scattering effect. However, the conventional semiconductor photoanode composed of small Ti O2 nanoparticles with size of 10-30 nm made by hydrothermal method, which can provide large surface area for dye absorption, resulting in low-intensity Rayleigh back-scattering giving low solar light capture by dye molecules. To solve this issue, depositing a layer of relatively large particles on the nanocrystalline photoanode to fabricate the bilayer structure with a scattering layer consisting of relatively big size particles as the overlayer has recently been proposed.In this paper, the flower-like Ti O2 nanomaterials and Ti O2 mesoporous microspheres materials preparation has been studied to obtain optimal conditions, as well as the structural characterization of the morphology and photoelectric propertie of the materials. The results showed that prepared flower-like Ti O2 nanomaterials were rutile phase, composed of straight nanowires. The length of nanowire was about 400 nm, diameter was about 24 nm. The prepared mesoporous Ti O2 microspheres presents anatase phase, an average particle diameter was about 2.5 μm. Ti O2 microspheres coated with a plurality of interconnected square-shaped nanosheets, forming a mosaic structure, exposure to anatase(001) plane.The photoelectrochemical properties of the two Ti O2 materials have been studied. 10% flower-shaped Ti O2 nanomaterials mixed with 25 nm P25 nanocrystalline particles as scattering centers, the DSSC conversion efficiency can be achieved as 7.28%. The DSSCs based on photoelectrodes with Ti O2 nanoparticles as the underlayer and anatase Ti O2 microspheres as the scattering layer demonstrated much better light harvesting capability, longer electron lifetimes and higher photoelectrical conversion efficiency of 6.49%, noticeably improved compared with photoelectrodes based on pure Ti O2 nanoparticles or pure anatase Ti O2 microspheres.