硫铁矿FeS <sub>2中的</sub>硫空位聚集及其对电子性能的影响<sub></sub>,Chemistry of Materials

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硫铁矿FeS _2中的硫空位聚集及其对电子性能的影响
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-05-05 , DOI: 10.1021/acs.chemmater.0c01669
Debmalya Ray ₁ , Bryan Voigt ₂ , Michael Manno ₂ , Chris Leighton ₂ , Eray S. Aydil _{2,

3} , Laura Gagliardi ₁

Affiliation

最近已经通过实验将硫空位相关的缺陷鉴定为黄铁矿FeS _2中的无意n型掺杂的来源，黄铁矿FeS ₂是一种潜在的富含地球，无毒，超低成本的薄膜太阳能电池吸收剂。但是，从历史上看，理论上不支持这种可能性，因为简单的S单空位具有较高的形成能，以及与实验不一致的供体态能量。在这里，我们使用密度泛函理论对黄铁矿中的S空位进行详细而系统的研究，不仅要考虑单空位，还要考虑多种形式的空位簇。我们首先确认S单空位确实产生了一个离导带最小值太远的供体态，无法解释最近的实验。然后研究了S双空位的四种构型，从而发现S–S二聚体空位会在缺口中部附近诱导供体状态升高。重要的是，对于该缺陷和反式都发生了明显的结合能，以进行缺陷聚类。-S双空位，在一个共同的Fe协调中心具有两个单空位。然后，我们将这些缺陷结合起来，构建一个四空位复合物，计算出一个低于导带最小值的0.41 eV的深供体态，从而以0.23 eV的实验值获得了迄今为止的最佳协议。与该四价空位相关的结合能更大，这表明黄铁矿中可能进一步空位聚集。然后，我们概述了如何通过黄铁矿晶体生长过程中受表面生成的空位的热平衡或动力学陷阱支配的途径，发生初始空位掺入（作为聚类的来源）。本研究从而前进š空位簇作为用于可能负责缺陷Ñ在黄铁矿FeS _2中观察到的X型掺杂效应，促进了对这种有前途的光伏材料中掺杂的理解。

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Sulfur Vacancy Clustering and Its Impact on Electronic Properties in Pyrite FeS2

A sulfur vacancy-related defect has been recently experimentally identified as the source of unintentional n-type doping in pyrite FeS₂, a potential earth-abundant, nontoxic, ultralow-cost absorber for thin film solar cells. Historically, however, theory has not supported this possibility, as simple S mono-vacancies have high formation energies, as well as donor state energies inconsistent with experiment. Here, we use density functional theory to perform a detailed and systematic study of S vacancies in pyrite, considering not only mono-vacancies but also multiple forms of vacancy clusters. We first confirm that the S mono-vacancy indeed produces a donor state too far from the conduction band minimum to explain recent experiments. Four configurations of S di-vacancies are then investigated, leading to the finding that S–S dimer vacancies induce an elevated donor state near the middle of the gap. Importantly, significant binding energy for defect clustering occurs for both this defect and a trans-S di-vacancy, which features two mono-vacancies across a common Fe coordination center. We then combine these defects to construct a tetra-vacancy complex, calculating a deep donor state 0.41 eV below the conduction band minimum, thus achieving the best agreement to date with the experimental value of 0.23 eV. There is a yet more sizable binding energy associated with this tetra-vacancy, suggesting that further vacancy clustering is likely in pyrite. We then outline how initial vacancy incorporation, as a source for clustering, could occur, via routes governed by either thermal equilibrium or kinetic trapping of surface-created vacancies during pyrite crystal growth. This study thus advances S vacancy clusters as the defects likely responsible for the n-type doping effects observed in pyrite FeS₂, advancing the understanding of doping in this promising photovoltaic material.

更新日期：2020-05-05

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