Band gap modulation and type transition in all-carbon Dirac material α-graphyne by heterostructure engineering

α-graphyne (α-GY), an all-carbon two-dimensional material, has triggered enormous interest due to its predicted flexible properties, including electronic, optical, mechanical, and field emission properties. Nevertheless, the zero band gap imposes restrictions on its applicability. Here, utilizing the first-principles calculations based on density functional theory, we focus on the electronic properties of α-GY through engineering heterostructures with the substrate of molybdenum disulfide (MoS₂). Interestingly, the band gap opening with 106.8 meV can be obtained, which is ascribed to the sublattice symmetry breaking brought by the charge redistribution. Furthermore, by adjusting the interlayer distance, the band gap can be successfully changed. Besides, a direct–indirect transition of the band gap occurs with the decreasing interlayer distance. It can be explained that the varying interlayer distances could induce different coupling effects, which in turn have an important impact on the band structure of the heterostructures. Our work provides insights into achieving a significant band gap of α-GY and further makes it a promising candidate for application in electronic devices.