▎ 摘　　要

Relying on the density functional theory(DFT), the structural stability and field emission performance of Cs/graphene compound with different Cs coverage were investigated. The results indicated that the adsorption of single Cs atom on the center site of hexatomic ring is energetically favorable. With the increase of Cs coverage, the adsorption interaction between Cs and graphene are gradually enhanced, (4x4)R 0 degrees and (2x2)R 0 degrees structures are stable. Due to the modification effect of Cs metals, the work function of Cs/graphene system decreases obviously, and it is continuously reduced with increasing of Cs coverage. The computational results of the density of states (DOSs) identified that the reduction of the work function is mainly related to the electron transfer between Cs and graphene. With increasing of Cs coverage, the electronic states will shift to a lower energy position, leading to the increase of Fermi energy and the reduction of work function.