Efficiency enhancement by adding SnS powder during selenization for Cu2ZnSn(S,Se)4 thin film solar cells
Efficiency enhancement by adding SnS powder during selenization for Cu2ZnSn(S,Se)4 thin film solar cells
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DOI：
10.1016/j.solmat.2015.10.037
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发表时间：
2016-02
影响因子：
6.9
通讯作者：
C. Cai;Shih-yuan Wei;Wei-Chih Huang;Je-Wei Lin;T. Yeh;C. Lai
中科院分区：
文献类型：
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作者：
C. Cai;Shih-yuan Wei;Wei-Chih Huang;Je-Wei Lin;T. Yeh;C. Lai
具有堆叠前体的后退火的两步法已被广泛用于Cu 2 ZnSn（S，Se）4（CZTSSe）吸收体。然而，目前没有简单的方法可用于同时调节S/（S+Se）比并避免CZTSSe膜中的锡损失问题，这是实现高效率的关键因素。在这项工作中，我们证明，通过简单地添加SnS粉末在硒化过程中，我们可以消除锡损失，也控制S/（S+Se）的比例。此外，我们可以抑制在硒化过程中形成的Mo（S，Se）2。基于热力学计算，我们提出了SnS粉末与硒反应形成SnSe，并在硒化过程中释放硫蒸气。含Sn蒸气避免锡从CZTSSe蒸发。通过改变SnS粉末的量，可以调节硫与硒的分压比，因此，可以改变CZTSSe的膜组成和能带bap。硫分压的存在也显著降低了硒化过程中Mo（S，Se）2的形成。通过在硒化过程中加入SnS粉末，将效率从3.97%大幅提高到7.35%。我们的方法实现了一步磺硒化，提供了一个通用的调谐旋钮的CZTSSe吸收剂的组成控制，它照亮了各种工艺发展的CZTSSe吸收剂退火后真空或溶液制造的前体。
A two-step process with post-annealing of stacked precursors has been widely used for Cu2ZnSn(S,Se)4(CZTSSe) absorbers. However, no simple approach is currently available for simultaneously tuning the S/(S+Se) ratio and avoiding tin loss issue in CZTSSe films, which are critical factors to achieve high efficiency. In this work, we demonstrate by simply adding SnS powder during selenization, we can eliminate the tin loss and also control the S/(S+Se) ratio. Furthermore, we can suppress the formation of Mo(S,Se)2during selenization. Based on thermodynamic calculations, we propose SnS powder reacts with selenium to form SnSe and releases sulfur vapor during selenization. The Sn-contained vapor avoids tin evaporation from CZTSSe. By varying the amount of SnS powder, the partial pressure ratio of sulfur to selenium can be tuned; therefore, the film composition and band bap of CZTSSe can be changed. The presence of sulfur partial pressure also dramatically decreases the formation of Mo(S,Se)2during selenization. The efficiency is substantially boosted from 3.97% to 7.35% by adding SnS powder during selenization. Our approach realizes one-step sulfo-selenization, providing a general tuning knob for compositional control of CZTSSe absorbers, which shines light on various process developments of CZTSSe absorbers by post-annealing vacuum- or solution-fabricated precursors.