Thermodynamics, Electronic Structure, and Vibrational Properties of Snn(S1-xSex)m Solid Solutions for Energy Applications
Thermodynamics, Electronic Structure, and Vibrational Properties of Snn(S1-xSex)m Solid Solutions for Energy Applications
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DOI：
10.1021/acs.chemmater.9b00362
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发表时间：
2019-05-28
影响因子：
8.6
通讯作者：
Parker, Stephen C.
中科院分区：
文献类型：
--
作者：
Gunn, David S. D.;Skelton, Jonathan M.;Parker, Stephen C.
硫化锡和硒化物具有广泛的应用，从光伏和热电到光催化剂和光电探测器。然而，广泛应用仍面临重大挑战，包括SnS和器件接触材料之间的电气和化学不相容性以及硒的环境毒性。同结构硫化物和硒化物相的固溶体可以为优化可持续性要求的物理性质提供空间，但这还没有得到全面的探讨。本文对Pnma和岩盐Sn（S1-xSex）、Sn(S1-xSex)(2)和Sn-2(S1-xSex)(3)固溶体进行了详细的建模研究。这四种岩石盐在所有组成中都表现出能量有利且均匀的混合，但岩盐Sn（S1-xSex）和Sn-2(S1-xSex)(3)只有在一定的合成条件下才能达到亚稳态。合金化导致带隙、态密度和光学性质随组成的可预测变化，允许SnS2“调低”到理想的1.34 eV的Shockley-Queisser带隙。还研究了形成固溶体对晶格动力学的影响，为热电应用中Sn（S1-xSex）固溶体的增强性能提供了见解。这些结果表明，合金对电子、光学和振动特性提供了方便和精确的控制，允许光电子应用的材料性能在各种实际考虑的同时得到优化。
The tin sulfides and selenides have a range of applications spanning photovoltaics and thermoelectrics to photocatalysts and photodetectors. However, significant challenges remain to widespread use, including electrical and chemical incompatibilities between SnS and device contact materials and the environmental toxicity of selenium. Solid solutions of isostructural sulfide and selenide phases could provide scope for optimizing physical properties against sustainability requirements, but this has not been comprehensively explored. This work presents a detailed modeling study of the Pnma and rocksalt Sn(S1-xSex), Sn(S1-xSex)(2), and Sn-2(S1-xSex)(3) solid solutions. All four show an energetically favorable and homogenous mixing at all compositions, but rocksalt Sn(S1-xSex) and Sn-2(S1-xSex)(3) are predicted to be metastable and accessible only under certain synthesis conditions. Alloying leads to a predictable variation of the bandgap, density of states, and optical properties with composition, allowing SnS2 to be "tuned down" to the ideal Shockley-Queisser bandgap of 1.34 eV. The impact of forming the solid solutions on the lattice dynamics is also investigated, providing insight into the enhanced performance of Sn(S1-xSex) solid solutions for thermoelectric applications. These results demonstrate that alloying affords facile and precise control over the electronic, optical, and vibrational properties, allowing material performance for optoelectronic applications to be optimized alongside a variety of practical considerations.