Origin of the low conversion efficiency in Cu2ZnSnS4 kesterite solar cells: the actual role of cation disorder
Origin of the low conversion efficiency in Cu2ZnSnS4 kesterite solar cells: the actual role of cation disorder
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DOI：
10.1039/d1ee00260k
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发表时间：
2021-04-20
影响因子：
32.5
通讯作者：
Hautier, Geoffroy
中科院分区：
文献类型：
--
作者：
Chen, Wei;Dahliah, Diana;Hautier, Geoffroy
阳离子无序在非常低的开路电压（V-OC）的Cu 2 ZnSnS 4（CZTS）锌黄锡石吸收剂的有争议的作用是通过集群扩展方法内的无序的统计处理检查。它表明，广泛的铜锌无序单独不能负责在许多CZTS太阳能电池中观察到的大Urbach尾巴。虽然带隙减小的结果形成的高斯尾附近的价带边缘，由于铜集群，带隙波动的贡献只有轻微的V-OC赤字，从而排除Cu-Zn无序作为CZTS设备的低效率的主要来源。另一方面，广泛的无序稳定了Sn-Zn反位及其缺陷复合物的形成，它们作为非辐射复合中心和少数载流子捕获中心主导了CZTS中的V-OC损失。我们的分析表明，目前的CZTS设备可能已经接近最大的转换效率（14%）的有限的生长条件和残余的阳离子无序，即使在退火后。鉴于CZTS衍生的锌黄锡矿吸收剂实现的效率提高，本工作中提出的方法提供了一种途径来理解和优化这些新兴的锌黄锡矿太阳能设备，以提高效率。
The controversial role of cation disorder in the extraordinarily low open-circuit voltage (V-OC) of the Cu2ZnSnS4 (CZTS) kesterite absorber is examined through a statistical treatment of disorder within the cluster-expansion method. It is demonstrated that the extensive Cu-Zn disorder alone cannot be responsible for the large Urbach tails observed in many CZTS solar cells. While the band gap is reduced as a result of the Gaussian tails formed near the valence-band edge due to Cu clustering, band-gap fluctuations contribute only marginally to the V-OC deficit, thereby excluding Cu-Zn disorder as the primary source of the low efficiency of CZTS devices. On the other hand, the extensive disorder stabilizes the formation of Sn-Zn antisite and its defect complexes, which as nonradiative recombination and minority carrier trapping centers dominate the V-OC loss in CZTS. Our analysis indicates that current CZTS devices might have already approached the maximum conversion efficiency (14%) given the limited growth conditions and the remnant cation disorder even after postannealing. In view of the improved efficiency achieved with CZTS-derived kesterite absorbers, the methodology presented in this work offers an avenue to understanding and optimizing these emerging kesterite solar devices towards higher efficiency.