Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool , Liverpool L69 7ZF, U.K.
Department of Chemistry, University College London , Christopher Ingold Building, London WC1H 0AJ, U.K.
ACS Appl Mater Interfaces. 2017 Dec 6;9(48):41916-41926. doi: 10.1021/acsami.7b14208. Epub 2017 Nov 21.
The earth-abundant material CuSbS (CAS) has shown good optical properties as a photovoltaic solar absorber material, but has seen relatively poor solar cell performance. To investigate the reason for this anomaly, the core levels of the constituent elements, surface contaminants, ionization potential, and valence-band spectra are studied by X-ray photoemission spectroscopy. The ionization potential and electron affinity for this material (4.98 and 3.43 eV) are lower than those for other common absorbers, including CuInGaSe (CIGS). Experimentally corroborated density functional theory (DFT) calculations show that the valence band maximum is raised by the lone pair electrons from the antimony cations contributing additional states when compared with indium or gallium cations in CIGS. The resulting conduction band misalignment with CdS is a reason for the poor performance of cells incorporating a CAS/CdS heterojunction, supporting the idea that using a cell design analogous to CIGS is unhelpful. These findings underline the critical importance of considering the electronic structure when selecting cell architectures that optimize open-circuit voltages and cell efficiencies.
地球丰富的材料 CuSbS（CAS）作为光伏太阳能吸收材料具有良好的光学性能，但太阳能电池性能相对较差。为了研究这种异常的原因，通过 X 射线光电子能谱研究了组成元素的芯能级、表面污染物、电离势和价带谱。该材料的电离势和电子亲和势（4.98 和 3.43 eV）低于其他常见吸收剂，包括铜铟镓硒（CIGS）。实验证实的密度泛函理论（DFT）计算表明，与 CIGS 中的铟或镓阳离子相比，来自锑阳离子的孤对电子将价带最大值升高，从而在价带中增加了额外的态。与 CdS 的能带失配是包含 CAS/CdS 异质结的电池性能不佳的原因，这支持了使用类似于 CIGS 的电池设计没有帮助的观点。这些发现强调了在选择优化开路电压和电池效率的电池结构时，考虑电子结构的重要性。
