Design And Fabrication Of Anti-reflection Coatings For Four-junction GaAs Solar Cells

With the reduction of traditional energy sources and the pollution caused to the environment,solar energy has become a clean and environment-friendly energy source required by human society.Solar cells are the most direct and effective way to utilize solar energy.Among them,multiple-junction tandem solar cells based on GaAs have become a leader in thin film solar cells other than Si-based cells because of their wide spectral absorption.In order to further improve its photoelectric conversion efficiency,in addition to optimizing the battery structure,but also by designing the solar cell anti-reflection coating and increase the absorption of light.In this paper,the TFCale software was used to optimize the ZnS/MgF₂/nano-SiO₂trilayer anti-reflection coating system on GaInP/GaAs/InGaAs/InGaAs of four-junction solar cells and the coating was completed by magnetron sputtering equipment.The specific research contents are as follows:（1）The TFCale optical simulation software was used to simulate and design the three-layer anti-reflection coatings of the four-junction GaAs solar cell in the wavelength of 350nm to 1800nm.By studying the effects of different film thickness,light incident angle and refractive index on the antireflection effect of the film,ZnS/MgF₂/nano-SiO₂ three-layer anti-reflection coating with the lowest effective reflectivity of 3.23%was obtained;（2）The magnetron sputtering technique is used to prepare the anti-reflection coating materials for each layer,and the material with satisfactory performance can be obtained.The optimum process conditions at this time are:the sputtering power of ZnS is 70W,sputtering gas pressure is 0.5Pa,the sputtering time is 20 minutes;the sputtering power of MgF₂ is 70W,the sputtering gas pressure is 0.3Pa,and the sputtering time is 13 minutes;the sputtering power of nano-SiO₂ is 100W,the sputtering gas pressure is 0.8Pa,and the sputtering time is 105 minutes;（3）The ZnS/MgF₂/nano-SiO₂ three-layer anti-reflection coatings were prepared on GaAs substrates with an average reflectance of 10.08%measured in the wavelength range from 350 nm to 1800 nm,The average reflectance simulated by theory was 7.12%;The actual average reflectance measured in the range of 350 nm to650 nm was 13.97%with a theoretical value of 12.83%;In 650nm to 880nm,the measured value was 9.64%,the theoretical value was 8.71%;In 880nm to 1240nm,the measured value was 8.12%,the theoretical value was 5.66%;In 1240 nm to 1800nm,the observed value was 7.31%,the theoretical value was 4.46%.