Preparation Of SnO₂ Based Thin Films And Photoelectric And Photocatalytic Properties

Fluorine-doped SnO₂?FTO?thin film and SnO₂/FTO composite film are two kinds of semiconductor thin film materials composed of SnO₂,which could be applied to solar cells and photocatalytic materials,respectively.In order to study the relationship between defects and photoelectric properties in FTO films and the photocatalytic mechanism of SnO₂/FTO composite films.The prepared FTO films with different F/Sn ratio prepared by AACVD method were investigated by XRD,SEM,Raman,XPS,TEM and photoluminescence?PL?spectroscopy.The effect of F/Sn ratio on the structural,optical and electrical properties of FTO films was prepared by aerosol-assisted chemical vapor deposition,and the defect behavior in FTO films was discussed.On the basis of FTO thin film,the degradation mechanism of pollutant degradation dye Rhodamine B by SnO₂/FTO composite film prepared by hydrothermal method was studied using ultraviolet light irradiation.The results shown that:FTO film consists of polycrystalline cassiterite tetragonal particles with a particle size ranging from 20³7 nm,showing a preferential orientation of the?200?plane.As the F/Sn ratio increases,the texture coefficient of?110?plane increases.When the current F/Sn ratio is 40 at.%,F content in the FTO film is 1.69 at.%,the optical energy gap?Eg?is 4.06 eV and FTO films possess the optimum photoelectric properties with the transmittance of 76.98%,the highest carrier concentration of 1.031×10²¹ cm^-3,the lowest resistivity of 3.42×10^-4?·cm,and the highest quality factor of 13.54×10^-3?^-1.This is due to the existence of three oxygen vacancies(_OV⁰,_OV⁺,_OV⁺⁺)defects in the FTO film and the conductivity of FTO films is related to the oxygen chemical states.Under UV light irradiation,SnO₂/FTO composite film has good photocatalytic activity and high catalytic stability for Rhodamine B.After 120 min of UV irradiation,the photocatalytic degradation rate of Rhodamine B can reach 97%.After 5 cycles,the degradation rate of SnO₂/FTO composite film catalyst of 95%.Under UV irradiation,the electrons generated by the nano-sheet-like SnO₂ film with a large specific surface area of69 m²·g^-1 can be efficiently transferred to the conductive FTO film,which can effectively suppress the photo-generated electron-hole recombination and improve the photocatalytic activity of SnO₂/FTO composite film.The photocatalytic reactive species are superoxide radicals?·O₂^-?,which are the main factors affecting the photocatalytic performance.