Two-dimensional materials provide new opportunities for the next generation of effective and ultrathin photovoltaic solar cells. Herein, we propose Janus monolayers of Tin monochalcogenides, especially Janus Sn₂SSe (type TA) and SnGeS₂ (type TB) nanosheets, as strong absorber candidates for solar energy conversion, referring to their excellent electronic and optical properties. Interestingly, based on the first-principles computations, both Janus Sn₂SSe and SnGeS₂ monolayers possess semiconductor character with indirect and moderate band gaps of $1.60$ and $1.61eV$, respectively. Accordingly, the considered systems, Sn₂SSe and SnGeS₂ single-layers, have high absorption coefficient, reaching up to $49.7$ and $62.5\mu m^{-1}$, high optical conductivity of about $4513$ and $3559{\Omega }^{-1}c{m}^{-1}$, as well as low reflectivity never exceed $34.6$ and $38.5\text{\%}$ in visible region, respectively. Additionally, the maximum photovoltaic efficiency of single-junction solar cells based on SnGeS₂ and Sn₂SSe nanosheets can reach as high as $27.47\%$ and $28.12\%$, respectively. The present outstanding results would motivate both theoretical and experimental researchers to deepen the study of the potential applications of two-dimensional Janus materials based on Tin monochalcogenides in solar cell technology.

二维材料为下一代高效超薄光伏太阳能电池提供了新的机遇。在此，我们建议将 Janus 单层锡单硫族化合物，尤其是 Janus Sn ₂ SSe（TA 型）和 SnGeS ₂ （TB 型）纳米片作为太阳能转换的强吸收剂候选者，因为它们具有优异的电子和光学性能。有趣的是，基于第一性原理计算，Janus Sn ₂ SSe 和 SnGeS ₂单层都具有半导体特性，其间接和中等带隙为$1.60$ 和 $1.61\mathrm{电子}伏$， 分别。因此，所考虑的系统，Sn ₂ SSe 和 SnGeS ₂单层，具有高吸收系数，可达$49.7$ 和 $62.5\mu {米}^{-1}$, 高光导率约 $4513$ 和 $3559{\Omega }^{-1}C{米}^{-1}$，以及低反射率永远不会超过 $34.6$ 和 $38.5\text{\%}$分别在可见光区。此外，基于 SnGeS ₂和 Sn ₂ SSe 纳米片的单结太阳能电池的最大光伏效率可高达$27.47\%$ 和 $28.12\%$， 分别。目前的杰出成果将激励理论和实验研究人员深入研究基于锡单硫属元素化物的二维 Janus 材料在太阳能电池技术中的潜在应用。