Preparation And Reflection Property Of The Silicon Nanowires Array And Its Carbon Composite

Solar cells are one of the important ways to solve energy demand and maintain sustainable development.The absorption efficiency of sunlight plays a key role in silicon-based solar systems.In order to improve the absorption efficiency of incident sunlight,various antireflection measures are generally used.Silicon nanowires(SiNWs)have attracted widespread attention because of their unique optical,electrical,and thermal properties,which is considered promising nanostructured materials for high efficiency batteries.The two-step metal-assisted chemical etching(MACE)method is an important way to prepare SiNWs.One of the current research focuses is the further assembly of one-dimensional nanostructures into two-dimensional or three-dimensional nanostructures to achieve a change in morphology and better performance.Among them,carbon materials exhibit excellent performance in all aspects and attract the attention of researchers.In order to study the relationship between the structure and reflection performance of SiNWs and its composites,in this work,we studied the main factors influencing SiNWs,and SiNWs/carbon nanospheres,SiNWs/carbon nanotubes(CNT)composites prepared by hydrothermal method and chemical vapor deposition(CVD)method,respectively.The main research contents of this study are presented as follows:(1)The controllable growth and smooth surface of SiNWs were prepared by MACE method.By changing the concentration of H2O2,Ag NO3,etching time,etching temperature and other parameters,the best parameters for the preparation of SiNWs were obtained.Combined with SEM images,the mechanism and surface morphology of the chemical etching method were analyzed.(2)The composites was further prepared.Firstly,the carbon nanospheres were coated on the surface of SiNWs by hydrothermal method using glucose aqueous solution,the characterization of this composites revealed that the nanospheres were evenly distributed on the nanowires,which increased the surface area of SiNWs and changed the internal structure of SiNWs;Secondly,SiNWs/CNT composites were prepared by CVD using xylene and ferrocene as catalysts.It was found that the prepared composites maintains excellent orientation,the structure growth direction is highly ordered,the morphology of SiNWs is uniform and stable,with relatively few forms and defects.(3)The infrared-visible spectrum was used to test the variable angle reflection characteristics of the SiNWs and its composites.It was found that the SiNWs and itscomposites have a good anti-reflection effect.We studied the influence of various parameters and carbon nanospheres and CNT on reflectivity and diffusivity.It was found that the reflectivity decreases with the increase of the length,increases with the surface agglomeration,and increases with the decrease of the regularity of the structure.The appropriate porosity can improve the anti-reflection performance of the SiNWs.In general,the average reflectance of SiNWs in the wavelength range of 500-1100 nm is less than about 1%.While the arrays exhibits excellent angle and wavelength dependence,there is also have good anisotropy,and this property is expected to have a good application in the photovoltaic industry.