Design Of Fishnet Metal Structure And Its Plasmonic Light Trapping In Thin Film Solar Cells

With the growth of global energy demand,it is necessary to develop photovoltaic systems.To develop the thin film solar cells technology is a good way to reduce material costs.However,as the thickness of the absorbed layer decreases,the absorption naturally decreases,which is a particularly important issue for thin film solar cells.Therefore,we need to improve the efficiency of thin film solar cells and trap light more effectively.One way to achieve light trapping in thin film solar cells is to use surface plasmon metal nanostructures.By appropriately designing these metal nanostructures,light can be concentrated and ’folded’ on a thinner semiconductor layer to enhance absorption.The research in this paper is the fishnet metal structure,which is a kind of plasmon structure connected on the circuit.This paper optimizes its geometric structure to achieve its absorption enhancement in the a-Si layer of thin film solar cells at a specific target wavelength.This paper uses rigorous coupled-wave analysis(RCWA)and finite-difference timedomain(FDTD)simulations,by changing the line width,thickness,angle and other parameters of the fishnet metal structure,and calculating the fishnet structure under different parameter conditions.Transmittance,reflectance,absorptivity,scattering spectrum,absorption spectrum,extinction spectrum,light intensity distribution,etc.Are used to optimize the fishnet metal structure to obtain a more ideal battery structure.The results are as follows:First of all,through the simulation and optimization of the mesh metal structure,it is obtained that the included angle has the optimal value of absorption near 20°,30° and 90°,corresponding to three different wave bands,and for the different angles of the mesh metal structure,The band corresponding to its extinction peak is also different.As the angle increases,the absorption peak gradually blue-shifts,the extinction peak also blueshifts,and the peak value gradually decreases,that is,the smaller the angle,the more obvious the resonance.The thickness has the optimal value of absorption near 3,4,and 5nm.As the thickness increases,the absorption peak wavelength blue-shifts,and the extinction peak also gradually blue-shifts,and both peaks remain roughly unchanged,that is,1-15nm The height within the range has little effect on the resonance amplitude.The line width has the optimal value of absorption near 50-150nm.With the increase of the line width,the absorption peak wavelength has a red-shifts,and the extinction peak also has an obvious red-shifts,and the peak value gradually decreases,that is,the smaller the line width,the more obvious the resonance.The period has an optimal value of absorption near 500nm,and there are absorption peaks at different wavelengths near 800nm.With the increase of the period,the absorption peak gradually decreases,the wavelength of the absorption peak is blue-shifts,and the extinction peak is also gradually blue-shifts,except In addition,with the increase of the period in the early stage,the extinction peak peak value gradually increased,and when it increased to about 800nm,the extinction peak peak value gradually decreased,that is,the resonance was most obvious at about 800nm,and gradually decreased to both sides.Secondly,applying the above structure to thin film batteries can be obtained:in the amorphous silicon battery,the parameters suitable for the response spectrum band optimized in Chapter 3 are used to obtain the photoelectric conversion efficiency of 8.21%when the thickness of the amorphous silicon layer is only 100nm.Increased to 9.61%,the photocurrent of amorphous silicon cell calculated by quantum efficiency is increased from JscflatH100=-187.945 A/m2 to JscAg fishnet H=100=-219.962 A/m2.Also in the crystalline silicon cell using the optimized parameters,the photoelectric conversion efficiency can be increased from 6.67%to 8.25%when the thickness of the crystalline silicon layer is only 2 μm,and the photocurrent of the crystalline silicon cell calculated by quantum efficiency is increased from Jscflat=-128.472 A/m2 increased to JscAg fishnet=148.818 A/m2.