The electronic structure of two-dimensional (2D) materials are inherently prone to environmental perturbations, which may pose significant challenges to their applications in electronic or optoelectronic devices. A 2D material couples with its environment through two mechanisms: local chemical coupling and nonlocal dielectric screening effects. The local chemical coupling is often difficult to predict or control experimentally. Nonlocal dielectric screening, on the other hand, can be tuned by choosing the substrates or layer thickness in a controllable manner. Therefore, a compelling 2D electronic material should offer band edge states that are robust against local chemical coupling effects. Here it is demonstrated that the recently synthesized MoSi₂N₄ is an ideal 2D semiconductor with robust band edge states protected from capricious environmental chemical coupling effects. Detailed many-body perturbation theory calculations are carried out to illustrate how the band edge states of MoSi₂N₄ are shielded from the direct chemical coupling effects, but its quasiparticle and excitonic properties can be modulated through the nonlocal dielectric screening effects. This unique property, together with the moderate band gap and the thermodynamic and mechanical stability of this material, paves the way for a range of applications of MoSi₂N₄ in areas including energy, 2D electronics, and optoelectronics.

二维（2D）材料的电子结构本质上容易受到环境干扰，这可能对其在电子或光电器件中的应用构成重大挑战。二维材料通过两种机制与其环境耦合：局部化学耦合和非局部介电屏蔽效应。局部化学耦合通常难以通过实验预测或控制。另一方面，可以通过以可控方式选择基板或层厚度来调整非局部介电屏蔽。因此，引人注目的二维电子材料应提供对局部化学耦合效应具有鲁棒性的能带边缘状态。这里证明了最近合成的 MoSi ₂ N ₄是一种理想的二维半导体，具有强大的带边状态，可免受反复无常的环境化学耦合效应的影响。进行了详细的多体微扰理论计算，以说明 MoSi ₂ N ₄的能带边缘状态如何屏蔽直接化学耦合效应，但其准粒子和激子性质可以通过非局部介电屏蔽效应进行调制。_{这种独特的性质，加上这种材料的适度带隙以及热力学和机械稳定性，为 MoSi 2} N ₄在能源、二维电子和光电子等领域的一系列应用铺平了道路。