Electronic structures of halogen-doped Cu20 based on DFT calculationsElectronic structures of halogen-doped Cu20 based on DFT calculationsElectronic structures of halogen-doped Cu20 based on DFT calculations

In order to construct p-n homojunction of Cu20-based thin film solar cells that may increase its conversion efficiency, to synthesize n-type Cu20 with high conductivity is extremely crucial, and considered as a challenge in the near future. The doping effects of halogen on electronic structure of Cu20 have been investigated by density function theory calculations in the present work. Halogen dopants form donor levels below the bottom of conduction band through gaining or losing electrons, suggesting that halogen doping could make Cu20 have n-type conductivity. The lattice distortion, the impurity formation energy, the position, and the band width of donor level of Cu201-xHx （H = F, C1, Br, I） increase with the halogen atomic number. Based on the calculated results, chlorine doping is an effective n-type dopant for Cu20, owing to the lower impurity formation energy and suitable donor level.