| Summary: | Based on the photovoltaic properties and tandem solar cells theory, Gallium Indium Arsenide/Germanium Stannide (GaInAs/GeSn)-based double-junction (DJ) solar cells have been numerically simulated for the first time. In this study, we explore the band gap combination under lattice matching and obtain the content of In/Sn at optimal efficiency, which is expressed as Ga _0.84 In _0.16 As/Ge _0.93 Sn _0.07 DJ solar cell (1.20/0.58 eV). Afterward, it is optimized in terms of variation in the doping contents and active layer thickness. To take full advantage of the electron mobility of the material, the optimal ‘inverted doping profile’ concentration N _a(d) is 1.5(5)/5(20) × 10 ^18 cm ^−3 . In addition, the reasonable p ( n ) layer thickness could be comprised of 0.2–0.8(0.2–1)/0.5–3(1–4) μ m of the DJ solar cells with less material consumption. When the p ( n ) layer thickness is 0.30(0.25)/0.9(1.35) μ m, the tandem device can achieve an optimal efficiency of 31.00% with 28.98 mA cm ^−2 ( J _sc ), 1.25 V ( V _oc ) and 85% ( FF ). This study highlights that GeSn materials have the potential to combine with III–V materials to form low-cost and high-efficiency tandem devices.
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