Effect Of Oxide Quantum Dots Modified TiO₂ Photoanode On The Photoelectric Performance Of DSSCs

Today,the worldwide consumption of fossil fuels is increasing year by year,and the fossil fuels once spent are not renewable,so the whole globe is attempting to explore new energy.Dye-sensitized solar cells（DSSCs）offer excellent photoelectric conversion efficiency and good practical application possibility,they become the research hotspot.The bottleneck of DSSCs commercialization is still the large gap between the actual conversion efficiency and the theoretical efficiency due to problems such as the interface and structure of the photoanode.In this dissertation,the photoanode of DSSCs was taken as the research object,and the quantum dots of Zn S and Cd S were loaded on porous TiO₂films by successive ion adsorption reaction（SILAR）.Zn O quantum dots（Zn O-QDs）and Cd O quantum dots（Cd O-QDs）are obtained by oxidation sintering.The surface and interface structure ofnano TiO₂were optimized and improved to enhance the photoelectric performance of DSSCs.The research content of this dissertation is as follows:TiO₂nanoparticle film（NP）was prepared by sol-gel-hydrothermal method and electrohydrodynamic（EHD）technology,Zn O-QDs/TiO₂（NP）and Cd O-QDs/TiO₂（NP）films were prepared by SILAR and oxidation sintering method which regulated the impregnation time of precursor solution.XRD,SEM and TEM analysis show that Zn O-QDs and Cd O-QDs of about 3-5nm are successfully loaded on the surface of TiO₂（NP）film.The UV-vis spectra shows that Zn O-QDs and Cd O-QDs can decrease the band gap and enhance the absorbance of the photoanode film.Zn O-QDs/TiO₂（NP）photoanode,Cd O-QDs/TiO₂（NP）photoanode,dye,electrolyte and Pt were assembled into DSSCs respectively for photoelectric performance test.The results show that Zn O-QDs modified TiO₂（NP）films can enhance the electron transfer and effectively inhibit the electron recombination on the surface of TiO₂films.When the impregnation time in the precursor solution is 50 s,the photoconversion efficiency of the prepared DSSCs of Zn O-QDs/TiO₂（NP）composite photoanode is 6.59%.The modification of Cd O-QDs can effectively improve the surface defects of TiO₂（NP）and reduce the electron hole recombination.The composite photoanode assembly cell prepared with immersion time of 50 s can obtain 5.60%photoelectric conversion efficiency,which is about 18.14%higher than that ofpure TiO₂（NP）.TiO₂nanorods（NR）were synthesized by hydrothermal method,porous TiO₂（NR）films were constructed on the conductive glass of TiO₂compact layer by EHD technology,and Zn O-QDs/TiO₂（NR）and Cd O-QDs/TiO₂（NR）composite films were prepared by SILAR and oxidation sintering methods,respectively.The DSSCs device was assembled for testing.It founds that Zn O-QDs modified TiO₂（NR）photoanode can also increase the photoelectric conversion efficiency of the DSSCs,reduce the electron hole recombination,one-dimensional TiO₂（NR）has a higher electron transport efficiency,when the impregnation time is 50 s,the photoconversion efficiency of the DSSCs constructed by Zn O-QDs/TiO₂（NR）photoanode is 6.92%,which is 5%higher than that of Zn O-QDs/TiO₂（NP）.For the introduction of Cd O-QDs to reduce the surface defects of TiO₂nanorods,the photoelectric conversion efficiency of DSSCs assembled by the photoanode obtained by the immersion time of 50 s reached the highest value of 7.40%,and the efficiency increased by 32%.