AI 中文总结
该研究结合第一性原理密度泛函理论与机器学习，揭示 pnictogen chalcohalide 固溶体的带边位置可通过组成和晶面调控，识别出适配多种（光）电化学半反应的组成，明确其与光伏接触材料的匹配特性。
AI 中文摘要
pnictogen chalcohalide（MChX；M=Bi、Sb；Ch=S、Se；X=I、Br）固溶体结合了地球丰度高的组分、可调带隙（1.2-2.1 eV）和强光学吸收，使其在太阳能转换领域极具吸引力。然而，其庞大的组成空间迄今阻碍了对带边位置如何随化学计量比和表面终止变化的系统评估。在此，我们将第一性原理密度泛函理论与机器学习相结合，预测 BiₓSb₁₋ₓSᵧSe₁₋ᵧI_zBr₁₋z 固溶体在两种最稳定表面（010）和（011）的全组成范围内的价带和导带边位置。我们发现，仅通过组成就能将价带顶和导带底调控超过 1 eV，且对于相同组成，两种表面终止之间的位移可达 0.6 eV，尽管它们的形成能几乎简并，这确立了晶面选择是与化学取代同等重要的设计参数。基于这些结果，我们确定了能够驱动氢、氨、甲烷、过氧化氢和氧的（光）电化学半反应的特定组成，并表明光伏器件中常用的几种电子和空穴传输接触材料仅作为空穴选择接触与 MChX 固溶体匹配。
英文摘要
Pnictogen chalcohalide (MChX; M=Bi,Sb; Ch=S,Se; X=I,Br) solid solutions combine earth-abundant constituents, tunable band gaps ($1.2$-$2.1$ eV), and strong optical absorption, making them attractive for solar energy conversion. Yet their vast compositional space has so far prevented a systematic assessment of how band-edge positions vary with stoichiometry and surface termination. Here, we combine first-principles density functional theory with machine learning to predict the valence and conduction band-edge positions of $\mathrm{Bi}_x\mathrm{Sb}_{1-x}\mathrm{S}_y\mathrm{Se}_{1-y}\mathrm{I}_z\mathrm{Br}_{1-z}$ solid solutions across their full compositional range on the two most stable surfaces, (010) and (011). We find that the valence-band maximum and conduction-band minimum can be tuned by more than $1$ eV through composition alone, and shift by up to $0.6$ eV between the two surface terminations for a same composition despite their nearly degenerate formation energies, establishing facet selection as a design parameter on par with chemical substitution. Guided by these results, we identify specific compositions capable of driving hydrogen, ammonia, methane, hydrogen peroxide, and oxygen (photo)electrochemical half-reactions, and show that several electron- and hole-transport contact materials commonly used in photovoltaic devices align with MChX solid solutions only as hole-selective contacts.
