Study On Reflection Characteristics Of Monocrystalline Silicon Surface Microstructure Based On FDTD Method

Monocrystalline silicon solar cells has been dominant in the solar market because of its good stability,high conversion efficiency and mature process technology.Because the refractive index of a silicon mutation is larger compared with the air,resulting in generating higher reflectance on the solar cell surface,how to improve the absorption rate has become one of the hot topics researching by many scholars.In order to improve the efficiency of photoelectric conversion efficiency,adopting finite difference time domain method,the variation rules of the sunlight reflection on monocrystalline silicon surface has been studied when it is prepared with periodic structure which has different parameters.The main content includes the following several aspects:First,a microstructure morphology has been prepared on the monocrystalline silicon surface by chemical etching method,based on the experimental data to establishe a mathematical model of pyramid-shaped microstructure,which’s reflectivity is further simulated by the FDTD theory in the range of 300~1000nm.Comparing with the reflectivity in the experiment,the result shows that the pyramid-shaped microstructures are basically equivalent in this range.The rationality and correctness of the theoretical modeling has been verified.Then,the influence of parameters such as pyramid size,surface duty ratio and inclination angle on the reflectivity has been discussed,and a set of pyramid microstructural parameters with the best antireflection effect are obtained by comparing and analyzing,as the length of the pyramid bottom is 2?m,the surface duty ratio is 1,the inclination angle is 60 o,the reflectivity is only 6.28%.In order to further reduce the surface reflectivity,on the basis of the above work,based on the equivalent medium theory,the variation rules of the equivalent refractive index of the pyramid,parabolic cone,cone gradient microstructure has been discussed,drawing a conclusion that the parabolic cone array microstructure possesses better antireflective performance.Then,the parabolic cone microstructure has been equivalent to a series of equal thickness thin film layers,based on the zero reflection formula of multilayer thin films,and the change of the surface reflectivity with parameters such as height,period and duty cycle of the parabolic cone array has been discussed by the FDTD theory,and it is concluded that the average value of the surface reflectivity is 1.3%,when the height H = 600 nm,the period T = 350 nm,the duty ratio D/T = 1.Finally,on the basis of the parabolic cone square arrangement,a new composite structure of pyramid and parabolic cone has been proposed,and the simulation result shows that the maximum reflectivity of the structure is less than 1% which has basically achieved zero reflection performance.When the incident angle changes within a wide range,it can still maintain a better antireflective performance.The research results in this paper can provide theoretical references for designing surface microstructure to reduce reflection performance and improve the photoelectric conversion efficiency of solar cell.