Research On Dielectric Metasurface Light Trapping Structure Of Silicon Thin Film Solar Cells

At present,the cost of commercial silicon solar cells is 2-3 times that of traditional hydropower and thermal power,which is mainly due to the high cost of silicon materials.Therefore,it is the most effective method to reduce the thickness of the silicon absorbing layer to reduce the cost,and silicon thin film solar cell is thus produced.However,the absorption coefficient of silicon materials in near infrared band is very low,which leads to serious photocurrent loss of thin film silicon solar cells.The light trapping structure can increase the light coupling effect and enhance the light trapping ability in near infrared band of thin film silicon cells,increase the absorption of solar energy by silicon absorption layer,then improve the photoelectric conversion efficiency of thin film silicon solar cells.This thesis innovatively proposes a new silicon-based dielectric metasurface trapping structure,and the structure was designed,fabricated and studied.The main research contents are as follows:Firstly,dielectric metasurface trapping structures were designed on 2?m and 100?m silicon respectively.The optimal structure parameters were obtained by FDTD method.The optical and electrical properties of dielectric metasurface trapping structures were simulated.The results of optical calculation show that the absorption enhancement effect and angle response of the dielectric metasurface trapping structures are better than that of the inverted pyramid on 2?m,100?m silicon.The results of electrical calculation show that the J_sc of dielectric metasurface trapping structure solar cells is 22.07 mA/cm²on 2?m thin film silicon cells,which is 20%higher than that of the inverted pyramid solar cells.The photoelectric conversion efficiency of dielectric metasurface trapping structure solar cells is 9.53%,while the efficiency of inverted pyramid structure solar cells is only 8.69%.The J_sc of 100?m thick dielectric metasurface trapping structure solar cell is 24.90 mA/cm²,which is 0.52 mA/cm² higher than that of the inverted pyramid structure case.The photoelectric conversion efficiency of dielectric metasurface trapping structure is 11.72%better than inverted pyramid 11.48%.Secondly,dielectric metasurface trapping structures were fabricated on 200?m thick silicon wafer surface by photolithography combined with wet etching.Then,the silicon wafers with dielectric metasurface trapping structures were thinned to 100?m by chemical etching and physical polishing,respectively.The reflection spectrum of the dielectric metasurface trapping structures were measured at incident angles of 0,10 and20 degrees and compared with the reflection spectrum of inverted pyramid structure.Finally,dielectric metasurface structure,inverted pyramid structure and planar Si/PEDOT:PSS hybrid solar cells were prepared,and their J-V curves were measured.The results show that the J_sc of dielectric metasurface structure Si/PEDOT:PSS hybrid solar cell is 5%higher than that of inverted pyramid hybrid case,and the J_sc of dielectric metasurface structure Si/PEDOT:PSS hybrid solar cell is about 1.3 times of that of planar hybrid cell device.The efficiency of the dielectric metasurface structure cell device was 10.1%,which was higher than 9.72%of the inverted pyramid and 8.73%of the bare panel.The J_sc and efficiencies indicate that the dielectric metasurface structure is more effective in improving solar cell performance than inverted pyramid.