Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States.
ACS Nano. 2015 Jan 27;9(1):555-63. doi: 10.1021/nn505809d. Epub 2015 Jan 13.
Transition metal dichalcogenides monolayers and black phosphorus thin crystals are emerging two-dimensional materials that demonstrated extraordinary optoelectronic properties. Exotic properties and physics may arise when atomic layers of different materials are stacked together to form van der Waals solids. Understanding the important interlayer couplings in such heterostructures could provide avenues for control and creation of characteristics in these artificial stacks. Here we systematically investigate the optical and optoelectronic properties of artificial stacks of molybdenum disulfide, tungsten disulfide, and black phosphorus atomic layers. An anomalous photoluminescence quenching was observed in tungsten disulfide-molybdenum disulfide stacks. This was attributed to a direct to indirect band gap transition of tungsten disulfide in such stacks while molybdenum disulfide maintains its monolayer properties by first-principles calculations. On the other hand, due to the strong build-in electric fields in tungsten disulfide-black phosphorus or molybdenum disulfide-black phosphorus stacks, the excitons can be efficiently splitted despite both the component layers having a direct band gap in these stacks. We further examine optoelectronic properties of tungsten disulfide-molybdenum disulfide artificial stacks and demonstrate their great potentials in future optoelectronic applications.
过渡金属二卤化物单层和黑磷薄膜是新兴的二维材料，具有非凡的光电性能。当不同材料的原子层堆叠在一起形成范德华固体时，可能会出现奇异的性质和物理现象。了解这些异质结构中的重要层间耦合，可以为控制和创造这些人工堆叠中的特性提供途径。在这里，我们系统地研究了二硫化钼、二硫化钨和黑磷原子层人工堆叠的光学和光电性质。在二硫化钨-二硫化钼堆叠中观察到异常的光致发光猝灭。这归因于二硫化钨在这种堆叠中的直接到间接带隙跃迁，而二硫化钼通过第一性原理计算保持其单层性质。另一方面，由于二硫化钨-黑磷或二硫化钼-黑磷堆叠中存在很强的内置电场，激子可以有效地分裂，尽管在这些堆叠中，组成层都具有直接带隙。我们进一步研究了二硫化钨-二硫化钼人工堆叠的光电性质，并证明了它们在未来光电应用中的巨大潜力。
