类石墨烯材料（即二维原子晶体）受到广泛关注，其能带调控对其电子器件和光电器件极其重要。人们付出了很多努力调控其带隙，但是获得的带隙范围仍然有限（对于石墨烯，Eg<0.4eV）。这里我们首次提出二维原子晶体能带连续调控的一种新方法，即合金化。该方法基于在原子水平上杂化晶格结构相近但带隙不同的单组分材料，获得带隙能在单组分材料带隙之间连续可调的合金材料。合金在三维块体材料的能带工程中已广泛应用，但还没有在二维材料中实现。我们将选择过渡金属二硫族化物体系（其种类丰富、结构相近、带隙不一），可控制备多个二维原子合金系列（如阳离子型合金：Mo1-xWxS2，Mo1-xWxSe2等，阴离子型合金：MoSexTe2-x等）,实现带隙从0.8-2.0eV的连续调控，并制备近红外发光器件和近红外光探测器件。该课题将解决二维体系中合金生长的结构控制、合金电子结构与原子排布和组成的关联关系等关键性问题。

Since the discovery of graphene in 2004, atomically thin two-dimensional (2D) atomic crystals have attracted intense interest in recent years. Band gap engineering of 2D materials is the key to their applications in nano-electronic, optoelectronics and photonics. Many efforts have been made to exfoliate new 2D atomic crystals and also to tune the band gap using many approaches, such as electrical gating, straining and functionalization. But still, only limited band gap range has been achieved. Here we propose a new approach to achieve 2D atomic crystals with tunable band gaps. The approach is alloying, which is widely used in band gap engineering of bulk semiconductors and could provide a general way to engineer band gap of 2D atomic crystals in a wide range. We will focus on 2D transition-metal dichalcogenide atomic alloys because of various choices of transition-metal dichalcogenides with minimal lattice mismatch but versatile electronic properties. We will synthesize several series of 2D atomic alloys, such as cation type alloys Mo1-xWxS2, Mo1-xWxSe2 and anionic type alloys MoSexTe2-x, and then achieve tunable band gap from 0.8 to 2.0 eV. NIR emission devices and NIR light detection devices will be demonstrated based on the synthesized 2D atomic alloys. At last, this proposal is aimed to solve key problems in structure-controlled growth of 2D atomic alloys and understand structure-property relationship in 2D atomic alloys.