Preparation And Photoelectric Properties Study Of TiO₂ Nanorod Arrays Photoanode Based On TiO₂ Compact Layer

The research content of this subject is the TiO₂photoanode material for dye-sensitized solar cells(DSSCs),which aims to highlight the role of TiO₂compact layer(TCL)in photoanode,in order to better achieve the directional crystal growth of TiO₂nanorod and improve the crystal perfection.Meanwhile,it is also to reduce the current loss in the TiO₂photoanode and improve the photocurrent intensity.Therefore,the comprehensive influence of the TCL on the growth,morphology,structure and photoelectric properties of TiO₂nanorod array(TNA)were mainly investigated,with the aim of obtaining TiO₂photoanode films with good performance.The research results indicated that:1.The hydrothermal reaction after two times effectively promoted the oriented growth of TiO₂nanorods along the normal direction of(002)plane,forming a TNA film with good microstructure.After two cycles of growth,the light absorption of TNA film was significantly enhanced.In addition,the optical absorption band edge of TNA film had a redshift.Although the displacement was small,it indicated that increasing the reaction number can make the absorption band edge move toward the direction of long wave,thus enhancing the absorption of visible light of the film.2.While TCL not only improved the compactness of the film,but also played the role of TiO₂seed layer,which effectively reduced the lattice mismatch between FTO substrate and TiO₂crystal,so as to better realize the oriented growth of TiO₂crystal on the basis of TiO₂seed layer.TNA film based on TCL increased the use of visible light and reduced the defects in TiO₂crystal,so that the charge recombination center caused by defects also decreased,electrons and holes were effectively separated,the charge recombination rate decreased,and the transient photocurrent significantly increased.On the basis of TCL,proper increase of hydrothermal reaction time can effectively improve the crystallization characteristics of TiO₂and promote better oriented crystal growth,while the reduction of band-gap(E_g)can significantly enhance the utilization efficiency of sunlight.The transient photocurrent of the TNA film was maximized by the good charge transfer performance.3.Subsequently,the TCLs with different thickness were prepared on the FTO substrate by a two-step method,and then a TNA film was successfully grown on the TCLs.The results showed that TCL with proper thickness could effectively improve the structure and photoelectric properties of TNA film.Through the comparative analysis of TNA films based on TCLs with different thickness,it was found that TNA film grown on TCL₂₀showed relatively better comprehensive photoelectric performance,and the DSSCs made by it also obtained a photoelectric conversion efficiency(PCE)of 3.3%.4.In a large number of literature studies,researchers mostly only introduced TCL,but lacked of further research on TCL.Therefore,on the basis of the previous study,the Ni-doped TCLs with different thickness were studied accordingly.The results showed that the overall performance of TNA films grown on Ni-doped TCLs was significantly improved.Among them,the TNA film based on Ni:TCL20 showed the best morphology,structure and photoelectric performance,and the DSSCs made by this TiO₂photoanode film also showed better photovoltaic performance,which not only improved the PCE to 4.42%,but also improved the time stability of the solar cell.