Studies On The Microstructure And Photoelectric Properties Of FTO-graphene Composite Film Prepared By Spray Pyrolysis

In this paper,surface modification for graphene（G）was carried out with polyvinylpyrrolidone（PVP）,the tin source and fluorine source of the precursor was butyltin trichloride（MBTC）and ammonium fluoride（NH₄F）respectively,FTO-G composite film were prepared on the glass substrate by the spray pyrolysis method.The structure,morphology and optical properties for these FTO-G composite films were analyzed by using X ray diffractometer（XRD）,field-emission scanning electron microscopy（SEM）,Raman spectroscopy（Raman）,ultraviolet photoelectron spectroscopy（UPS）,Uv-vis spectrophotometer,four-point probe method and Haze meter.The dispersion of graphene was studies,the micromechanical properties and microstructure and photoelectrical properties of FTO-G composite films varied with graphene concentration,substrate temperature,and film thickness were studied too.Also the formation mechanism of micronano flower cluster structure on film surface and the Microstructure and photoelectric properties of FTO-G composite films change with the graphene concentration,substrate temperature and film thickness were studied and the formation mechanism of the flower cluster structure on the surface of composite film were explained,also the contact characteristics between graphene and SnO₂ particles in FTO-G composite films were discussed.The main results are as follows:Polyvinylpyrrolidone（PVP）has good dispersing effect on graphene,it is proved that PVP did little effect on the properties of the composite film.The surface modification for graphene was with PVP and the addition of PVP that does not affect the photoelectrical properties and structure of the composite film should be less than 1 wt.%of MBTC.There are double texture morphology on the surface of FTO-G composite film as pyramid SnO₂ particles and flower cluster structure.The wrinkle of graphene provides a similar"rough substrate"for the SnO₂ particles,making it able to grow on the fold graphene to form a flower cluster structure,and finally show the basement feature of graphene’s folds and traces.The size of flower clusters is related to graphene size and the film thickness.This morphology is favorable for improving the haze and the highest haze value is 36.08%at 530℃.The contact characteristics show that there is schottky contact between graphene and FTO thin films.The work function of FTO film was only 0.05 eV differ with FTO-2.5G film,indicating that there was good contact between the graphene and SnO₂ particles in the composite film.The microstrain for FTO-G composite films change due to the introduction of graphene.With the change of the substrate temperature,there is a competitive relationship between the thermal strain from the films and the tensile strain caused by graphene,and there is tensile strain at 470-530℃,which increases first and then decreases with the increasing of the substrate temperature.And with the increasing of film thickness,the effective strain of the composite film changes from compressive to tensile strain.