连续激光辐照对三结砷化镓电池散射光谱的特性影响

Effect of Continuous Laser Irradiation on Scattering Spectrum Characteristics of GaAs Cells

太阳能电池作为一种高效的光电转化器,被广泛地应用于光伏发电系统中。激光作为一种高亮度光源辐照电池时,会导致其出现损伤,可利用电池的表面散射光谱特性,对其损伤程度进行判别。通过目标表面散射光谱测量系统,对激光辐照后的三结砷化镓电池散射光谱进行测量,并计算双向反射分布函数(BRDF)。其中测量系统主要由FX 2000和NIR 17型光纤光谱仪组成,针对电池表面的强镜反射特性,在实验中采用了入射角和反射角为30°的测量几何模型。原始三结砷化镓太阳能电池的结构主要包括减反射膜DAR层、顶电池GaInP层、中电池GaAs层和底电池Ge层,其散射光谱特征包括可见光谱段(500~900 nm)的吸收特性及近红外谱段(900~1 200 nm)的类周期振荡特性,在对连续激光辐照损伤后电池的光谱特性进行实验测量后,得到了损伤电池光谱BRDF的变化,并结合基于薄膜干涉理论的电池散射光谱模型,对各膜层损伤后的特征进行了分析。结果表明:DAR层的主要作用是降低光谱反射能量,对光谱曲线的特性影响较小;Ge层对光谱曲线形状基本无影响;电池散射光谱吸收和干涉等特征主要由GaInP层和GaAs层所引起,其中,GaInP层主要影响可见光谱段的吸收特性,并对近红外谱段内的干涉特性起到调制作用,而GaAs层主要影响近红外谱段的干涉特性,当其损伤到一定程度后,会导致可见光谱段内出现干涉特性。最后,在实验结果分析的基础上,通过模型研究了电池各层对散射光谱特性的影响,并讨论了基于散射光谱特性的电池损伤程度判别,研究结果可为电池激光损伤判别提供参考。

Solar cells are widely used as an efficient photo-converter in photovoltaic power generation systems.Laser,as a kind of high light source,will cause damage to the battery.The surface scattering spectrum characteristics of the battery can be used to determine the damage degree.This paper used the target surface scattering spectrum measurement system to measure the scattering spectrum of three junction GaAs cells irradiated by laser,and the bidirectional reflection distribution function(BRDF)was calculated.The measurement system comprised an FX 2000 and NIR 17 optical fiber spectrometer.Based on the strong mirror reflection characteristics of the battery surface,a geometric model of incident and reflection angle of 30°was adopted in the experiment.The structure of the original GaAs solar cells mainly consists of the antireflection film DAR layer,the top cell GalnP layer,the middle cell GaAs layer and the bottom cell Ge layer.The scattering spectrum characteristics of GaAs solar cells include absorption characteristics in the visible spectrum(500~900 nm)and period-like oscillation characteristics in the near-infrared spectrum(900~1200 nm).When the cell was damaged by continuous laser irradiation,the change of the spectral BRDF of the damaged ones was obtained.The characteristics of the damaged film layer were analyzed.The results showed that the function of the DAR layer was to reduce the spectral reflection energy,and it had little effect on the characteristics of the spectral curve.The Ge layer had little effect on the change of the spectral curve,too.The scattering spectrum characteristics of the battery were mainly caused by the GalnP and GaAs layer.The GalnP layer mainly affected the absorption characteristics of the visible spectrum and modulated the interference characteristics of the near-infrared spectrum,while the GaAs layer mainly affected the interference characteristics of the near-infrared spectrum.As the damage of the GalnP layer reached a certain extent,it would lead tothe interference characteristics in the visible spectrum.Finally,based on the analysis of the experimental results,the influence of each layer of the battery on the scattering spectrum characteristics was studied according to the provided model,and the analysis of the battery damage based on the characteristics was discussed.The results can provide the basis for the damage degree determination of the battery.