ITO/BiFeO₃ Composite Film Optimizes Black Silicon Solar Cell

In modern society,the demand for energy is growing,and non-renewable energy will become a major limitation of human economic and social development.Therefore,research and application of new energy sources is imperative.Solar energy is the source of all energy on earth.It is abundant,clean and safe.People have used solar cells to convert light energy into electrical energy.At present,crystalline silicon solar cells is widely used in researches and applications.However,this type of cells has a high reflectance of the incident light,and their solar energy utilization efficiency is low.After pyramid texturing,further processing of the surface of the silicon wafer can significantly improve the absorption of incident light.But the surface area of the crystalline silicon increased and the carrier recombination intensified at the same time.In order to solve the problems above,this paper studied the preparation of black silicon and new ITO/BFO composite thin film,and discussed the optimization performance of the composite films on the black silicon cells.For the traditional crystalline silicon solar cells,the reflectivity of the incident light is still very high after the pyramid processing,this study has put forward a micro-nano black silicon structure.The preparation method of black silicon is the Ag-assisted chemical etching method,it is simple and low cost.The black silicon prepared has excellent absorption of incident light.The effects of AgNO3 concentration,H2O2 concentration,Ag nanoparticles deposition time and HF/H2O2 etching time on the black silicon nanostructure and incident light reflectance were discussed respectively.Optimal preparation parameters were obtained: put silicon wafer into 0.03 mol/L Ag NO3 solution for 5-10 s to deposite a layer of Ag on the surface,then the deposited silicon wafer was etched in a 10% HF and 6% H2O2 solution for 2 min.The obtained black silicon has a micro-nano structure,and the reflectance of incident light is less than 5%.Because of the micro-nano structures,a large number of carrier recombination centers were introduced.To solve this problem,a optimization scheme of the ITO/BFO composite thin film applied to the surface of the black silicon is proposed.The ITO/BFO thin films were deposited on the black silicon surface by magnetron sputtering.The effects of sputtering pressure,sputtering time and oxygen pressure on the surface morphology,crystal structure and ferroelectric properties of the composite films were investigated by means of scanning electron microscopy(SEM),XRD,Raman scattering analysis and ferroelectric analysis.The optimum process parameters obtained are as follows: 100 W RF power,1.5 Pa sputtering pressure,1:4Ar/O2(28),sputtering 90 min at room temperature.The obtained BFO thin film has pure phase and high residual polarization.The UV test and the I-V test were used to study the optimal performance of the composite film for black silicon solar cell.The results show that the composite film has a certain passivation effect on the black silicon surface.