利用光学膜系设计软件(TFCalc),设计出空间用GaInP/(In)GaAs/Ge 三结太阳电池的分布式布拉格反射器(DBR)。实验结果表明由15对Al_0.2Ga_0.8As/Al_0.9Ga_0.1As组成的DBR在中心波长850 nm处的反射率高达96%,使800~900 nm波段内红外光被有效反射后又被二次吸收,提高了GaInAs中间电池的抗辐照能力。基于细致平衡原理,结合p-n结形成机理,对原电池结构和包含DBR的新电池结构进行厚度优化。通过对比中电池厚度为2.93 μm的原电池结构和中电池厚度为1.2,1.6,2.0 μm的新电池结构的辐照前外量子效率(EQE),发现新电池结构基本弥补了基区减薄对短路电流的影响。通过分析两种结构电池辐照前后的电学性能,发现DBR结构的存在明显改善了辐照后电池电流的衰减,并且中电池厚度为1.6 μm的新电池结构辐照后效率高达24.87%,较原电池结构提升了近2%,基本接近中电池厚度为2.0 μm的新电池结构,且明显高于1.2 μm中电池厚度的新电池结构。

A distributed Bragg reflector (DBR) for space GaInP/(In)GaAs/Ge triple-junction solar cell is designed by the optical film design software (TFCalc). The experimental results show that the reflectivity of 15-pair Al0.2Ga0.8As/Al0.9Ga0.1As DBR is 96% at the center wavelength of 850 nm. The light in the spectral range of 800-900 nm is reflected and then absorbed twice, which enhances the anti-radiation ability of the middle subcell. According to the detailed balance principle and p-n junction formation mechanism, the thicknesses of the original cell structure and the new cell structure containing the DBR are optimized. By comparing the external quantum efficiency (EQE) of the original cell structure with middle subcell thickness of 2.93 μm and the new cell structure with middle subcell thickness of 1.2, 1.6 and 2.0 μm, we conclude that the influence of the battery current attenuation by thinning base can be almost made up by the new structure. By analyzing the electrical properties of the two types of solar cell structures before and after irradiation, we find that the DBR structure significantly improves the decay of the current after irradiation. The efficiency of the new structure with the middle subcell thickness of 1.6 μm is up to 24.87%, which is increased by nearly 2% than that of the original structure,close to that of the new structure with the middle subcell thickness of 2.0 μm, and significantly higher than that of the new cell structure with middle subcell thickness of 1.2 μm.