Research On Modification And Application Of Photoanode Of Quantum Dot Sensitized Solar Cell

In recent years,human society has made great progress,the scientific technology have developed quickly,but the energy problem has become more and more seriously.To deal with this problem,it is of great significance to research and develop new energy sources.As one of the most promising energy sources,solar energy has been developed rapidly.With the widespread application of photovoltaic power generation,this low-cost and clean solar energy have gradually entered our lives.Quantum dot-sensitized solar cells（QDSSCs）,which is one of the third-generation solar cells,have attracted the attention of scientific researchers due to their low preparation and cost constraints,high photoelectric conversion efficiency,and great develop potential.Although it has extremely high photoelectric conversion efficiency in theory and has attracted much attention,the actual efficiency of QDSSCs is unstable and much lower than the theoretical conversion efficiency due to the limitation of materials and interface structure.The photoanode of different materials has a non-negligible effect on the photoelectric conversion efficiency of the QDSSCs.The traditional TiO₂transparent layer has a small particle size,which is not conducive to light scattering.In this paper,by introducing a sub-micron structure of light scattering material to form a double-layer structure with the transparent layer,the interface structure of the photoanode is improved,and the visible light absorption range of the device is effectively increased.Designing and studying the effects of different composite electrode films on QDSSCs,the light scattering ability of photoanode was increased,so that QDSSCs conversion efficiency is improved.The research work is as follows:（1）Using ethanol/water as the reaction solvent and SnCl₂·2H₂O as the precursor,the SnO₂hierarchical microsphere structure was synthesized by the one-step hydrothermal method.By adjusting the hydrothermal temperature,the SnO₂hollow sphere sub-micron particles have better crystallinity,and the hollow sub-micron spheres are formed densely without agglomeration,which promotes the hollow sub-micron structure through its larger specific surface area and low density to increase the light capture efficiency,and it is widely used in photoanode materials.The quantum dot sensitizer is Zn Cu In Se,Cu₂S is used as the counter electrode,and the photoanode is used to form a solar cell.The SnO₂material is prepared as the scattering layer using different hydrothermal temperatures,and the TiO₂transparent layer is prepared by P25 particles.The effect of the photoanode on the performance of QDSSCs is explored.The morphology,structure and composition of the composite photoanode were characterized by SEM,TEM,Mapping,XRD,etc.The influence of different hydrothermal temperature on the morphology of SnO₂hollow sphere submicron particles and the influence of the thickness of the scattering layer on the performance of QDSSCs were explored.The results show that the QDSSCs based on the SnO₂thin film prepared by hydrothermal at 200℃have the best performance,reaching 7.34%,which is an increase of 19%compared with the pure TiO₂photoanode.Through the film thickness comparison experiment,when the SnO₂scattering layer film thickness is 9μm,the cell efficiency is the highest.Compared with the commercial TiO₂scattering layer under the same film thickness,the PCE is increased by 13%.It shows that using SnO₂as the scattering layer and P25 nanoparticles to prepare optimized photoanodes is suitable for QDSSCs and provides a new way for the improvement of photoanode films.（2）The special structure of CeO₂is synthesized by the hydrothermal method,and the synthesized CeO₂ball-core structure is used as the scattering layer to be coated on the titanium dioxide film to construct the photoanode device of the composite structure film.By preparing Zn Cu In Se quantum dots,Zn S as a passivation layer,and Cu₂S is used as a counter electrode with the photoanode to form QDSSCs.Use SEM,XRD,TEM,HRTEM,XPS,etc.to characterize morphology,structure and other characteristics.The effective adsorption of quantum dots is increased by adjusting the film thickness of the scattering layer,and the specificity of the ball-core structure is utilized to cause the visible light to scatter in the optical path during the propagation process,which effectively enhances the absorption of sunlight.After conducting electrochemical tests of the QDSSCs,it is found that the photoelectric conversion efficiency of the photoanode adopts the method of combining a TiO₂transparent layer and a CeO₂scattering layer is improved compared with the previous simple TiO₂QDSSCs without a scattering layer.The results show that the photoelectric conversion efficiency reaches the highest（7.46%）when the film thickness of the scattering layer is 10±1μm,which is 20%higher than that of pure TiO₂.It shows that the composite photoanode composed of CeO₂with ball-core structure as the scattering layer has important reference value for the development of photoanode materials.