Abstract Homogeneous element distribution of absorber, as well as high crystallinity, is very critical for the highly efficient Cu2ZnSnS4 (CZTS) thin-film solar cell. However, it is more difficult to prepare high quality CZTS absorber layer by post sulfurization of sputtered metallic stack precursors. Herein, we report a simple process, i.e., the optimization for heating rate during the sulfurization, to effectively improve both the uniformity of Sn element distribution and crystallinity of CZTS absorber. CZTS films are prepared by sulfurizing sputtered metallic stack precursors under S and SnS mixed atmosphere. The effects of heating rates on phase structure, morphology, composition distribution of CZTS films and resultant solar cells performance have been comprehensively investigated. CZTS film, sulfurized with a heating rate of 15 °C/min, demonstrates the uniformity of composition distribution, especially for Sn element, besides good crystallinity. Consequently, the series resistance of CZTS solar cells is reduced and the performance of solar cells is improved remarkably. A CZTS solar cell with efficiency of 7.02% (active area efficiency 7.69%) without MgF2 anti-reflection coating is obtained. The optimization for the heterojunction interface is expected to further improve efficiency.

中文翻译：

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通过促进Sn元素的均匀分布来提高Cu2ZnSnS4太阳能电池的效率

摘要 吸收体的均匀元素分布以及高结晶度对于高效的Cu2ZnSnS4（CZTS）薄膜太阳能电池至关重要。然而，通过溅射金属叠层前驱体的后硫化来制备高质量的 CZTS 吸收层更加困难。在这里，我们报告了一个简单的过程，即硫化过程中加热速率的优化，以有效提高锡元素分布的均匀性和 CZTS 吸收剂的结晶度。CZTS 薄膜是通过在 S 和 SnS 混合气氛下硫化溅射的金属叠层前体来制备的。已经全面研究了加热速率对 CZTS 薄膜的相结构、形态、成分分布和所得太阳能电池性能的影响。CZTS薄膜，以15℃/min的升温速率硫化，除了良好的结晶度外，还展示了成分分布的均匀性，特别是对于 Sn 元素。从而降低了CZTS太阳能电池的串联电阻，显着提高了太阳能电池的性能。获得效率为7.02%（有效面积效率7.69%）的CZTS太阳能电池，没有MgF2抗反射涂层。异质结界面的优化有望进一步提高效率。