Application Of The Optical Structures In Silicon-based Solar Cell

Traditional solar cells are faced with two problems,one is to reduce the cost and the other is to improve the photoelectric conversion efficiency of solar cells.The thickness of traditional silicon solar cells is roughly in 180nm-300 nm,but the thickness of the film solar cells is thinner.So a lot of Si can be saved.But reducing the thickness of Si will decease the photoelectric conversion efficiency of solar cells.In order to improve photoelectric conversion efficiency of solar cells.In this aitical we design several different optical structure and simulate the above structures for influence the photoelectric conversion efficiency of the solar cells.In order to study the the solar cells,using finite element method is to analyze the characteristics and optimize the structure parameters of the solar cell.First we design an antireflection layer(60nmSiO2)on the surface of solar cell which thickness is 450 nm.Compared with the signal solar cell(450nmSi),the light absorption increased by 50.5% and the spectral response increased by 43.3%.On this basis,we design shortwave DBR which band gap range is 350nm-650 nm,longwave DBR which band gap range is 650nm-1200 nm,and composite DBR(six period)which band gap range is 350nm-1200 nm.When we choose composite DBR(six period)as back reflector of the thin film solar cells,compared with the reference solar cell(450nm Si+60nm SiO2)the light absorption increased by 41.7.% and the spectral response increased by 53.4%.But consider the material factor,we also can choose composite DBR(four period)as back reflector of the thin film solar cells,the corresponding light absorption and spectral response respectively increased by 38.8%,51.1%,the material decreased by 33.3%.Based on the study of the DBR to enhance property of the thin film solar cells.We futher design two different grating which are rectangle grating and triangle grating on the surface of DBR.The grating material is make up of Si and SiO2.In fact the size of grating will directly effect the modulation of light,so it also can influence the light absorption of the solar cells.Therefore,according to four different incident wavelength(1107nm,800 nm,600nm,400nm),we design the size of rectangle grating.The results show that the combination structures which are rectangle grating designed by the 800 nm incident wavelength and DBR(six period)can most increase the property of solar cells.Compared with the solar cell which only has DBR(six period composite DBR)the light absorption will increased by 13.6% and the spectral response will increased by 20.0%.Compared with the reference solar cell the light absorption will increased by 61.6% and the spectral response will increased by 85.4%.In addition,we design triangle grating which sizes are as same as the rectangle grating.The results of 1107 nm triangle grating and 800 nm triangle grating are samely.But we consider the 1107 nm is the absorption limit of silicon.So we choose 800 nm wavelength to design the size of grating.Lastly,in the view of semiconductor technology,the triangle grating can be maked easily.In addition,the nanoscale metal can provide surface plasmons,so it will provide better light absorption for solar cells.In this article,we use finite element method to analyze the extinction characteristics of three different shapes of Ag.We analyze the different radius and period length of silver column to effect the property of solar cells.The simulations show that the silver column which radiu is 50 nm and the period length is 500 nm,the light absorption increased by 54 %.Compare three different mental which are gold,silver,copper,found that silver can most enhance the property of solar cell.