Dataset of "Electronic structure and defect states in bismuth and antimony sulphides identified by energy-resolved electrochemical impedance spectroscopy"

Understanding the nature of the defects in the absorber materials, namely point defects, their formation mechanism and the contribution to the properties is essential for the photovoltaic device performance improvement. They are one the reasons why chalcogenide-based solar cells do not yet meet expected high power conversion efficiencies. Here we identify and present energy distribution of defects in Bi2S3 and Sb2S3, and their (SbxBi(100-x))2S3 alloys (with x = 0, 10, 33, 50, 67, 90, 100 at% Sb content) chalcogenides, being explored for emerging photovoltaic applications as they are earth-abundant and highly absorbing in the visible light range. We show that their density of states (DOS) and related parameters can be obtained experimentally by energy-resolved electrochemical impedance spectroscopy (ER-EIS) in a technically simple and quick way, where ER-EIS data are well correlated with theoretical DFT calculations. ER-EIS reveals that in Bi2S3 there are only shallow defects at CBM. In Sb2S3, ER-EIS reveals also midgap states which can be the cause of low electrical conductivity of Sb2S3. We also explain the discrepancy in the reported values of ionisation potentials and the bandgaps of the Bi- and Sb-chalcogenides. Dominant sulphur vacancy defect was identified in Bi- and Sb-chalcogenides whereas in ternary (SbxBi(100-x))2S3 system, merely 10 at.% of Bi transforms the midgap sulphur defects to shallow ones. This provides novel strategy for healing the midgap defects in Sb2S3, which is crucial for boosting the PV performance and tuning the electrical conductivity in Sb2S3.阐明吸收层材料中点缺陷的本质、形成机制及其对材料性能的贡献，对提升光伏器件的性能至关重要。硫系基太阳能电池尚未达到预期的高功率转换效率，这类缺陷正是其核心诱因之一。本研究针对可应用于新兴光伏领域的硫化铋（Bi₂S₃）、硫化锑（Sb₂S₃）以及(SbₓBi_(100−ₓ))₂S₃三元合金（Sb含量分别为0、10、33、50、67、90、100原子百分比）展开分析，这类硫系化合物因地球储量丰富且对可见光具有极强吸收能力而受到广泛关注。我们证实，可通过技术流程简便快捷的能量分辨电化学阻抗谱（energy-resolved electrochemical impedance spectroscopy, ER-EIS）实验获取其态密度（Density of States, DOS）及相关参数，且ER-EIS实验数据与密度泛函理论（Density Functional Theory, DFT）计算结果具有良好的相关性。ER-EIS分析结果显示，硫化铋（Bi₂S₃）仅在导带最小值（Conduction Band Minimum, CBM）处存在浅能级缺陷；而硫化锑（Sb₂S₃）中则存在中间带隙态，这可能是导致其电导率偏低的原因。此外，我们还解释了此前文献中报道的铋基与锑基硫系化合物电离能及带隙数值存在差异的根源。研究在铋基与锑基硫系化合物中均识别出占主导地位的硫空位缺陷；而在(SbₓBi_(100−ₓ))₂S₃三元体系中，仅需掺入10原子百分比的铋，即可将中间带隙的硫缺陷转化为浅能级缺陷。这一发现为修复硫化锑（Sb₂S₃）中的中间带隙缺陷提供了全新策略，而该策略对于提升锑基硫系化合物的光伏性能、调控其电导率均具有关键意义。