Based on first-principles calculations, we investigate the structural, electronic and optical properties of few-layer two-dimensional (2D) (110)-oriented BN nanosheets in relation to the layer number (n). After structural optimization, for n =1 and n=2, the buckling 2D BN nanosheets are reconstructed into planar sheets. With an increasing layer number n ≥ 3, the original bulk c-BN structures are energetically favorable to being maintained, and their properties tend to stabilize. It is demonstrated that the minimum number of layers that can satisfy the cubic phase structure of the (110) surface is 3; the thickness is approximately 5 Å. What is more interesting is that there are characteristics of the electronic and optical properties that are distinct from those of bulk c-BN material; the band gap and static refractive index values decrease to nearly half of those of the bulk material when the dimension changes from 3D to 2D. The development of novel structures in BN material fields is of great significance for both basic science and practical industrial applications.

基于第一性原理计算，我们研究了相对于层数（n）的几层二维（2D）（110）取向BN纳米片的结构，电子和光学性质。在结构优化之后，对于n = 1和n = 2，将屈曲的2D BN纳米片重建为平面片。随着层数n≥如图3所示，原始的大块c-BN结构在能量上有利于保持，并且它们的性质趋于稳定。结果表明，可以满足（110）表面立方相结构的最小层数是3；厚度约为5Å。更有趣的是，电子和光学特性的特征与块状c-bn材料不同。当尺寸从3D更改为2D时，带隙和静态折射率值减小到块状材料的几乎一半。BN材料领域新型结构的发展对于基础科学和实际工业应用都具有重要意义。