First-principles Studies On The Structure Stabilities And Electronic Structures Of Graphyne Derivatives

Two dimensional carbon material is one of the most active research direction in polymer material science,synthesis and separation of new and different dimension of carbon allotrope is the focus over the past twenty or thirty years.2010,Andre Gaim and Konstantin Novoselov was awarded the Nobel prize in physics because of the graphene groundbreaking research,the study of carbon materials has entered a new stage,inspired scientists to study the new type of carbon allotrope.In recent years a new two-dimensional material graphyne has aroused wide concern.Due to its special electronic structure and pore structure,graphyne has a important application prospects in the information technology,electronics,energy,catalysis and optoelectronics field.In this paper,we use the first-principle calculations based on density functional theory(DFT)to investigate the energetic stabilities and electronic structures of two graphyne derivatives(y-N and g-N).The studied y-Ns consist of hexagon carbon rings connected by one dimensional carbon chains with various numbers of carbon atoms N=1-6.The results show that the parity of number of carbon atoms on the carbon chains has a great influence on the structural stability and electronic properties of the system.?-Ns with odd-numbered carbon chains possess continuous C—C double bonds,energetically less stable than those with even-numbered carbon chains have alternating single and triple C—C bonds.The electronic structures indicate that y-Ns can be either metallic(odd N)or direct band gap semiconductor(even N).The existence of direct band gap can promote the efficient conversion of photoelectric energy,which indicates the advantage of y-graphyne in optoelectronic devices.g-N has a similar structure of y-N,except that the carbon chain is present only in one direction and the number of carbon atoms on the carbon chain is N = 1-8.The results show that,unlike ?-Ns,the parity of number of carbon atoms on the carbon chains has little effect on the structural stability and electronic properties of g-Ns,and they all show metallic from band structure.Our first-principle studies indicate that introducing carbon chains between the hexagon carbon rings of graphene gives us a method to switch between metallic and semiconductor electronic structures by tuning the number of carbon atoms on the chains and provides a theoretical basis for the design and preparation of tunable s—p hybridized two-dimensional materials and nanoelectronic devices based on carbon atoms.