We here present a planarized solid-state chemical reaction that can produce transition metal monochalcogenide (TMMC) 2D crystals with large lateral extent and finely controllable thickness down to individual layers. The enhanced lateral diffusion of a gaseous reactant at the interface between a solid precursor and graphene was found to provide a universal route towards layered TMMCs of different compositions. A unique layer-by-layer growth mechanism yields atomically abrupt crystal interfaces and kinetically controllable thickness down to a single TMMC layer. Our approach stabilizes 2D crystals with commonly unattainable thermodynamic phases, such as β-Cu₂S and γ-CuSe, and spectroscopic characterization reveals ultra-large phase transition depression and interesting electronic properties. The presented ability to produce large-scale 2D crystals with high environmental stability was applied to highly sensitive and fast optoelectronic sensors. Our approach extends the morphological, compositional, and thermodynamic complexity of 2D materials.

我们在这里提出了一种平面化的固态化学反应，该反应可以产生大横向范围和可精确控制厚度的过渡金属单硫属元素化物（TMMC）2D晶体，直至单个层。发现气态反应物在固体前体和石墨烯之间的界面处的增强的侧向扩散提供了通向不同组成的层状TMMC的通用途径。独特的逐层生长机制可产生原子突变的晶体界面，并且可动力学控制厚度直至单个TMMC层。我们的方法用稳定通常达不到热力学相2D晶体，如β-Cu系₂S和γ-CuSe的光谱表征显示出超大的相变抑制和有趣的电子性质。所产生的具有高环境稳定性的大规模2D晶体的生产能力已应用于高度灵敏且快速的光电传感器。我们的方法扩展了2D材料的形态，成分和热力学复杂性。