Study On Hybrid Solar Cell Prepared By The Noble Metal Ag Nanoparticles Modified TiO₂-ZnO Hierarchical Nanostructures

The growth of hierarchical nanostructures based on 1D nanoarrays can not only keep the advantage of rapid charge transportation benefited from the 1D nanoarray materials,but also possess much larger interfacial area to adsorp or deposit more photosensitizer and then improve the light absorption and photoelectric performance of the electrode.In this thesis,two different TiO₂-ZnO hierarchical nanostructures were prepared through two-step hydrothermal processes.First,Ti O₂nanorod array was grown on the FTO conductive glass substrate by hydrothermal process.Then,Zn O sol was coated onto the TiO₂ nanorods through dip-coating method and inverted to Zn O seed layer by sintering.Finally,the secondary ZnO nanorods were grown onto the Ti O₂nanorods by the sencond hydrothermal process to form the designed TiO₂-ZnO nanorod hierarchical structure.At the same time,Zn O nanosheets were grown in the Ti O₂nanorods array without Zn O seedlayers by another hydrothermal process in the precursor solution with sodium citrateas as inhibitor to form the Ti O₂-Zn O nanorod-nanosheet hierarchical structure.SEM,TEM and XRD were employed to characterize the morphologies and structures of all the samples.A spin-coating assisted successive ionic layer reaction method（S-SILR）was used to deposit the Cd S nanocrystals into the TiO₂nanorod array,Ti O₂-Zn O nanorod hierarchical structure and TiO₂-ZnO nanorod hierarchical structure to form the Cd S/Ti O₂,Cd S/Ti O₂-Zn O nanorod-nanosheet and Cd S/TiO₂-ZnO nanorod nanocomposite films.Different analysis methods,such as SEM,TEM,XRD,EDS,contact angle test,UV-Vis and transient photocurrent,were utilized to characterize the morphologies,structures of the samples and investigate the light absorption properties,the photoelectric conversion performance of the electrodes.The results indicated that more Cd S photosensitizer could be deposited into the TiO₂-ZnO hierarchical structure compared with the pure Ti O₂nanorods array,which resulted in the enhanced light absorption ability and more excellent photoelectric property.Moreover,the photoelectrical property of the Ti O₂-Zn O nanorod hierarchical structure was superior to the Ti O₂-Zn O nanorod-nanosheet hierarchical structure after sensitiaed by the Cd S nanocrystals.Local surface plasmon resonance（LSPR）effect of the noble metal nanoparticles can induce a strong scattering of incident light on the surface of the metal nanoparticles.The energy of the scattering light confined to the surface of the metal particles can be transmitted to the semiconductor around the noble metal,resulting in the improved light absorption and photoelectric property.In this thesis,The noble metal of Ag nanoparticles were introduced between the semiconductor of Zn O and Cd S by a successive ionic layer reaction（SILR）method.The successful deposition of the Ag nanoparticles in the composite films was confirmed by TEM characterization.The p-type ploymer semiconductor of P3HT and the hole transport layer of PEDOT:PSS were spun-coating onto the surface of the composite nanostructures modified by the Ag nanoparticles to assemble organic-inorganic hybrid solar cell.The photovoltaic performance of the solar cells was tesed.The results showed that the introduction of the Ag nanoparticles could obviousely improve the energy conversion efficiency of the hybrid solar cell up to 1.06%.