Research On Design And Fabrication Of New Solar Cell Absorbing Layer With Wide-band And Wide-angle

In recent years,the application of thin-film solar cells has become the focus of attention.The absorption layer is the core of the whole thin-film solar cells,which is the main place to generate electron hole pairs.Copper zinc tin sulfur(CZTS)is an ideal candidate material for absorption layer because of its rich resources,high optical absorption coefficient and moderate band gap.However,optical absorption and carrier recombination in thin-film structure may lead to an increase in electron loss.In order to realize that light and current can be transmitted along different paths,improve the absorption efficiency of the absorption layer and save the cost of fabrication.Therefore,this paper proposes the introduction of radial PN junction nanostructure in thin film solar cells,which combines low-cost,high-yield nanosphere mask etching technology with CZTS thin film preparation process.While maintaining the film quality,high specific area nanostructures can provide a more direct charge transfer channel,which is conducive to charge collection efficiency and absorption efficiency,thus obtaining high-performance nanowire structure CZTS absorption layer.In this paper,the structure of nanowire arrays is simulated and designed by finite-difference time-domain method(FDTD).By optimizing the duty cycle,column height and other parameters,the diameter and height of nanowire arrays are set at 400 nm and 2 um,and the reflectivity of nanowire arrays in 300-2000 nm wide band is reduced.In the case of oblique incidence,the light absorption characteristic increases as the incident angle increases,achieving an extension of the incident angle of 0°-60°.The mask is prepared by a self-assembly technique using a pulling method,The monolayer polystyrene microsphere mask with regular arrangement is obtained by determining the ratio of water to ethanol 1:2,the concentration of surfactant 4 wt%,the static balance 2 minutes after pulling,and plus nanospheres with plastic dropper suspension.By inductively coupled plasma etching(ICP),the size-controllable array of Silica nanorods can be prepared by changing the etching time and other conditions on the mask plate,and the planar substrate can be replaced by nanowire substrate.Then CZTS prefabricated film is prepared by magnetron sputtering.The film is compact under the conditions of sputtering pressure 3mTorr,sputtering power 120 W and substrate temperature 300°C.The chemical element ratio of the films is about 2:1:1:4.After vulcanization heat treatment,it is determined that a single phase CZTS film will be formed at 550°C.The CZTS absorption layer with nanowire arrays has a relatively high absorption rate in the visible region,and the optical absorption in the wide band is higher than that of the planar thin film,which improves the optical performance of solar cell devices.