Abstract: Using CASTEP module based on density functional theory in Material Studio 2017 software, the simulation of ZnO supercell (2×2×2) was established, Zn atoms in supercell were replaced by different proportions of Cu/Al (Cu-Al, 2Cu-Al and Cu-2Al) in the same case, a Zn_1－x－yCu_xAl_yO system was obtained, and the electronic structure and optical properties of pure ZnO and ZnO codoped with Cu-Al were calculated by the first-principles. The results show that the light absorption of the above-mentioned doped systems is red-shifted in the low energy zone, and the system is degenerate semiconductor. For different purposes of ZnO, the optical absorption or light transmission of the system in visible light can be improved by controlling Cu/Al doping ratio. In visible light, the light absorption of Zn_{0.812 5}Cu_0.125Al_{0.062 5}O system is the strongest, which can be used to make photoelectrode materials for solar panels. The high transmittance of the Zn_{0.812 5}Cu_{0.062 5}Al_0.125O system can be used to make high transmittance ZnO semiconductor thin films.

Key words: Cu/Al co-doped ZnO, first-principles calculations, electronic structure, optical properties