Study On Photovotaic Performance Of SiNWs/BFO Heterojunction

The rapid development of society leads to the rapid growth of energy demand,and non-renewable energy will limit the development of human society.Therefore,the research and application of new energy are imminent.Solar energy is widely used because of its inexhaustible,clean,and safe characteristics.People use solar panels to achieve the conversion of light energy into electrical energy.At present,the most studied and widely used solar panels are crystalline silicon solar cells,but such cells have high incident light reflectivity,resulting in low solar utilization.The study found that the preparation of silicon nanowire arrays on the surface of crystalline silicon can greatly reduce the reflectivity of incident light,so that almost all visible light is absorbed.However,the micro-nano structure will significantly increase the surface area of the silicon wafer,causing serious recombination of photo-generated carriers,resulting in a decrease in the photoelectric conversion efficiency of solar cells.The strip-shaped electric domains inside the ferroelectric material are arranged neatly and regularly,and the adjacent electric domains have different polarities,which is the reason for their spontaneous polarization.When light irradiates ferroelectric materials,the obtained photovoltaic voltage is significantly higher than its own band gap width.The photovoltaic effect generated by the polarized electric field of ferroelectric materials can effectively separate photo-generated carriers,which provides new ideas for breaking the limit of solar cell efficiency.Bismuth ferrite?BFO?,as a single-phase multiferroic material,is ferroelectric and ferromagnetic at room temperature,and its open circuit voltage is not limited by the width of the forbidden band.Therefore,the preparation of high-quality BiFeO₃ thin films on silicon?Si?substrates,the combination of semiconductors and ferroelectric oxides,has potential for the design and development of new photovoltaic devices.However,due to factors such as lattice mismatch and interfacial interdiffusion,it is difficult to directly prepare ferroelectric single-phase BiFeO₃ thin films on Si substrates.Different buffer layers are added between the Si surface and the BiFeO₃ film to reduce lattice mismatch and interdiffusion.Starting from another direction,this thesis prepared silicon nanowire arrays on P-type conductive Si substrates by metal-catalyzed chemical etching,and grown BiFeO₃ films by sol-gel method.1.Using a two-step method to achieve metal-catalyzed chemical etching to prepare Ag nanoparticles,and etch silicon nanowire arrays on the silicon surface to form a micro-nano structure.The effects of AgNO₃ concentration,deposition time and annealing temperature on the deposited Ag nanoparticles were studied.It was found that when the AgNO₃ concentration was 0.01 mol/L,the Ag nanoparticles deposited on the Si sheet for 30 s had no dendrite formation,uniform distribution,and relatively morphological Good;further,studies was carried out on the influence of experimental parameters such as HF concentration,H₂O₂ concentration,reaction temperature,etching time,silicon crystal orientation,silicon wafer type on SiNWs.The optimal reaction temperature determined by experiment is 20 ?C.When the concentration of HF is 5 mol/L,the concentration of H₂O₂ is 0.2 mol/L,and the etching time is 10 mins,the prepared nanowires have good uprightness and regularity;2.The effect of different etching time on the reflectivity of silicon nanowires was studied.It was found that the reflectivity of the silicon wafers at different etching times was less than 10 %,indicating that the preparation of silicon nanowires greatly reduced the reflectivity of the silicon wafers;the phase structure of the silicon nanowires was studied,and the experiment found that the etching process did not change Lattice structure of silicon wafer;3.Using the sol-gel method to prepare BFO thin films on SiNWs to form a SiNWs/BFO heterostructure.The growth morphology of heterostructures under different experimental conditions was studied,and the effect of polarized electric field on the photovoltaic characteristics of heterostructures was explored.Based on this,a theoretical model was proposed and its principles were explained to further optimize device performance.