The Role of Sodium as a Surfactant and Suppressor of Non-Radiative Recombination at Internal Surfaces in Cu2ZnSnS4
The Role of Sodium as a Surfactant and Suppressor of Non-Radiative Recombination at Internal Surfaces in Cu2ZnSnS4
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DOI：
10.1002/aenm.201400849
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发表时间：
2015-01-21
影响因子：
27.8
通讯作者：
Guha, Supratik
中科院分区：
文献类型：
--
作者：
Gershon, Talia;Shin, Byungha;Guha, Supratik
众所周知，钠可以提高 Cu2ZnSnS4 (CZTS) 器件的性能，但其增强机制仍不完全清楚。这项工作的目的是对 CZTS 中的晶界、这些边界处的钠含量、非辐射复合以及产生大的微观结构变化的表面活性剂效应之间的关系提出统一的解释。使用与温度相关的光致发光测量，证明当薄膜中存在足够的钠时，含有显着不同晶粒尺寸的样品表现出相同的辐射和非辐射衰减特性。还表明，有效钝化非辐射缺陷所需的钠浓度明显低于获得微米尺寸的 CZTS 晶粒所需的量。最后，在 CZTS 薄膜中观察到的高密度供体-受体对似乎位于晶粒本身内，而不是晶界处。
It is well-known that sodium improves the performance of Cu2ZnSnS4 (CZTS) devices, yet the mechanism of the enhancement is still not fully understood. This work aims to present a unified account of the relationships between grain boundaries in CZTS, sodium content at these boundaries, non-radiative recombination, and surfactant effects that produce large microstructural changes. Using temperature-dependent photoluminescence measurements, it is demonstrated that samples containing dramatically different grain sizes display identical radiative and non-radiative decay characteristics when sufficient sodium is present in the film. It is also shown that the sodium concentration needed to efficiently passivate non-radiative defects is significantly less that the quantity needed to obtain micrometer-sized CZTS grains. Finally, the high densities of donor-acceptor pairs that are observed in CZTS films appear to reside within the grains themselves, rather than at grain boundaries.