Filsø M Ø, Eikeland E, Zhang J, Madsen S R, Iversen B B
Center for Materials Crystallography, Department of Inorganic Chemistry and iNANO, Aarhus University, Denmark.
Dalton Trans. 2016 Mar 7;45(9):3798-805. doi: 10.1039/c5dt04532k.
The layered semiconductor SnS2 spurs much interest for both intercalation and optoelectronic applications. Despite the wealth of research in the field of metal dichalcogenides, the structure-property relationship of this compound remains unclear. Here we present a thorough study combining single-crystal X-ray diffraction and DFT calculations on SnS2 in the pressure range 0 < p < 20 GPa. The anisotropic compression of the unit cell is clearly linked to the van der Waals interactions between the S-Sn-S sandwich layers, as the compression mainly affects the interlayer distance. This compression behavior is coincidal with the compression of other well-known layered compounds (graphite and boron nitride) but differs significantly from the compression of other MS2 compounds, making it clear that SnS2 presents a unique and interesting case in the field of metal dichalcogenides. The compression leads to a significant increase in S···S interlayer interaction which in turn results in a change in the electronic structure, documented through DFT band structure calculations. The calculated narrowing of the band gap is supported by a significant, reversible color change of the single crystal. At 20 GPa, the size of the band gap has decreased from 2.15 to 0.88 eV, and band gap closure is predicted to occur at 33 GPa.
层状半导体二硫化锡(SnS2)在插层和光电子应用方面引发了诸多关注。尽管在金属二硫属化物领域已有大量研究,但该化合物的结构-性能关系仍不明确。在此,我们对0 < p < 20 GPa压力范围内的SnS2进行了结合单晶X射线衍射和密度泛函理论(DFT)计算的深入研究。晶胞的各向异性压缩明显与S-Sn-S夹心层之间的范德华相互作用相关,因为压缩主要影响层间距离。这种压缩行为与其他著名的层状化合物(石墨和氮化硼)的压缩情况一致,但与其他MS2化合物的压缩情况有显著差异,这表明SnS2在金属二硫属化物领域呈现出独特且有趣的情况。压缩导致层间S···S相互作用显著增强,进而引起电子结构变化,这通过DFT能带结构计算得以证明。带隙的计算变窄得到了单晶显著的可逆颜色变化的支持。在20 GPa时,带隙大小从2.15 eV降至0.88 eV,预计在33 GPa时带隙将关闭。