International Iberian Nanotechnology Laboratory (INL) , 4715-330 Braga, Portugal.
Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) , 14109 Berlin, Germany.
ACS Appl Mater Interfaces. 2017 Dec 20;9(50):44173-44180. doi: 10.1021/acsami.7b12448. Epub 2017 Dec 11.
We report on the initial stages of CdS buffer layer formation on Cu(In,Ga)Se (CIGSe) thin-film solar cell absorbers subjected to rubidium fluoride (RbF) postdeposition treatment (PDT). A detailed characterization of the CIGSe/CdS interface for different chemical bath deposition (CBD) times of the CdS layer is obtained from spatially resolved atomic and Kelvin probe force microscopy and laterally integrating X-ray spectroscopies. The observed spatial inhomogeneity in the interface's structural, chemical, and electronic properties of samples undergoing up to 3 min of CBD treatments is indicative of a complex interface formation including an incomplete coverage and/or nonuniform composition of the buffer layer. It is expected that this result impacts solar cell performance, in particular when reducing the CdS layer thickness (e.g., in an attempt to increase the collection in the ultraviolet wavelength region). Our work provides important findings on the absorber/buffer interface formation and reveals the underlying mechanism for limitations in the reduction of the CdS thickness, even when an alkali PDT is applied to the CIGSe absorber.
我们报告了在铷氟化物（RbF）后沉积处理（PDT）下，Cu(In,Ga)Se（CIGSe）薄膜太阳能电池吸收体上 CdS 缓冲层形成的初始阶段。通过空间分辨原子力显微镜和开尔文探针力显微镜以及横向积分 X 射线光谱学，对不同化学浴沉积（CBD）时间的 CIGSe/CdS 界面进行了详细的表征。在 CBD 处理时间长达 3 分钟的情况下，观察到样品界面的结构、化学和电子特性的空间不均匀性，表明缓冲层的覆盖不完全和/或组成不均匀。预计这一结果会影响太阳能电池的性能，特别是在减少 CdS 层厚度时（例如，试图增加紫外波长区域的收集）。我们的工作提供了关于吸收体/缓冲层界面形成的重要发现，并揭示了即使在将碱 PDT 应用于 CIGSe 吸收体的情况下，CdS 厚度减少的限制的潜在机制。
