▎ 摘　　要

First-principle calculations are used to study the electronic structures, electronic and optical properties of pure, phosphorus-doped, aluminum-doped, and co-doped graphene with phosphorus and aluminum. The results show that the band gap of graphene can be effectively opened as the carbon atoms were replaced by P and Al atoms, and a large band gap of 0.45 eV could be opened when the P and Al atoms co-replaced carbon atoms. In addition, the band gap could be also reached 0.40 eV when an Al atom replaces a carbon atom. When P is doped into graphene, the band gap value is only 0.12 eV. For co-doped graphene with phosphorus and aluminum, the lost number of the electrons which are around the aluminum (2.10 e) is smaller than that of the Al-doping graphene (2.27 e). However, the phosphorus atom loses less electrons (0.43 e) than that in P-doping graphene (1.40 e). Furthermore, the optical parameters of pure graphene and several other doped graphene systems were studied, including refractive index, dielectric function and absorption coefficient have been also calculated. These crucial results confirm existence of P, Al and P-Al doping induced in graphene is an effective method in band gap engineering. Our research provides the theoretical foundation of using the chemical doping with heteroatoms approach to improve the electronic and optical performances of graphene, expected to benefit the practical application of graphene in tunable optoelectronic devices.