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

In this paper,one-dimensional ZnO nanorods array was prepared by the hydrothermal approach based on the ZnO seed layer grown on the conductive glass FTO.Then the secondary ZnO seed layer was coated onto the ZnO nanorods by soaking and calcination.ZnO hierarchical nanostructure with many short nanorods grown in the ZnO nanorods array was formed through a secondary hydrothermal growth.At the same time,another ZnO hierarchical nanostructure with many sheets grown in the ZnO nanorods array was prepared though a secondary hydrothermal growth in the precursor solution with sodium citrate as additive.Field emission scanning electron microscope(FESEM)and X-ray diffraction(XRD)were used to characterize the two kinds of the ZnO hierarchical structures.The growth process was also studied.Cd S nanocrystals were deposited into the ZnO hierarchical nanostructures.The light absorption and transient current were tested to investigate the photoelectric properties of the Cd S/ZnO composite structure.The results showed that the photoelectric properties of ZnO hierarchical structure is better than that of the ZnO nanorod array and the photoelectric properties of ZnO hierarchical structure based on the secondary nanorods is superior to that with the secondary sheets.The traditional deposition method of the Cd S nanocrystals,successive ionic layer absorption and reaction(SILAR),was improved by the spin-coating assisted successive ionic layer reaction(S-SILR)method.The Cd S nanocrystals were deposited into the ZnO hierarchical nanostructure by the above two menthods.Different analysis methods,SEM,XRD,UV-vis and the transit photocurrent measurement,were conducted 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 the Cd S nanocrystals photosensitive layers could be totally coated onto the ZnO nanorod arrays more easily by the improved S-SILR method.The light absorption properties and the photoelectric conversion performance of the electrodes prepared by the improved S-SILR method were more excellent compared with those electrodes prepared by the traditional SILAR method in the visible region.In order to improve the charge transport performance of the hybrid solar cells,Different methods were adopted to modify the interface of the ZnO hierarchical nanostructure and the Cd S layers:dip coating the Ti O₂layers onto the ZnO hierarchical nanostructures;spin-coating the glutathione(G)onto the interface and depositing the Ag nanoparticles onto the interface by SILAR method.Hybrid solar cells were assembled by spin-coating the p-type polymer semiconductor of P3HT and the hole transport layer of PEDOT:PSS onto the Cd S/ZnO composite hierarchical nanostructures after the above interface modification.Field emission scanning electron microscope(FESEM),ultraviolet-visible diffuse reflection spectroscopy(UV-vis DRS),fluorescence spectrometer and photovoltaic performance were conducted to characterize and analyze the samples.Experimental investigation shows that,after modification by the three above mentioned methods,the energy conversion efficiencies of the solar cells based on the Cd S/ZnO composite hierarchical nanostructures were improved obviously.The energy conversion efficiencies were up to 0.577%,0.729% and 1.033%,respectively.