Solution-processing has been a very successful fabrication route for Cu₂ZnSn(S, Se)₄ (CZTSSe) absorbers: since 2010, every world record for CZTSSe-based solar cells has been achieved by this approach. The solution formulation in terms of both cation oxidation states and choice of counterion varies between laboratories. Here, we investigate the influence of various counter anions on the element loss mechanisms, absorber formation path and the resulting PV properties. A Cu²⁺–Sn²⁺ system was used due to its advantages in terms of fabrication in ambient conditions. We found that solutions containing excess amounts of Cl⁻ anions result in pronounced Sn loss, as the Sn(DMSO)₂Cl₄ complex decomposes into volatile products at elevated temperatures. Fabricating a Sn-rich solution to accommodate for Sn loss is not a viable strategy, because it leads to SnSe₂ formation. Accumulation of SnSe₂ causes local PV performance degradation, which prevents the fabrication of uniform samples. By partially substituting OAc⁻ for Cl⁻ ions, Sn loss was mitigated, and PV performance uniformity improved. The highest efficiency achieved was 11.8% (12.5% active area). These results show the importance of precursor salt choice to mitigate Sn loss and enhance uniformity, which is a crucial aspect in view of future scale up of solution-processed CZTSSe devices.

中文翻译：

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通过 Cu2ZnSn（S， Se）4 太阳能电池 Cu2+–Sn2+ 前驱体系统中的阴离子取代来减轻 Sn 损失


固溶处理一直是 Cu₂ZnSn（S， Se）₄ （CZTSSe） 吸收材料的一种非常成功的制造途径：自 2010 年以来，基于 CZTSSe 的太阳能电池的所有世界纪录都是通过这种方法实现的。阳离子氧化态和反离子选择的溶液配方因实验室而异。在这里，我们研究了各种反阴离子对元素损失机制、吸收器形成路径和由此产生的 PV 特性的影响。使用 Cu²⁺–Sn²⁺ 系统是因为它在环境条件下的制造方面具有优势。我们发现，含有过量 Cl⁻ 阴离子的溶液会导致明显的 Sn 损失，因为 Sn（DMSO）₂Cl₄ 络合物在高温下分解成挥发性产物。制造富含 Sn 的解决方案来适应 Sn 损失不是一个可行的策略，因为它会导致 SnSe₂ 的形成。SnSe₂ 的积累会导致局部 PV 性能下降，从而阻止制造均匀的样品。通过部分用 OAc⁻ 代替 Cl⁻ 离子，减少了 Sn 损失，并提高了 PV 性能均匀性。实现的最高效率为 11.8%（12.5% 有效面积）。这些结果表明，前驱体盐的选择对于减轻 Sn 损失和增强均匀性非常重要，这是鉴于未来溶液处理 CZTSSe 设备规模扩大的一个关键方面。