Enhanced optical absorption of rutile TiO2 through (Sm, C) codoping: a first-principles study

In this Paper, we employ the density functional theory to investigate the electronic and optical properties of rutile TiO2, Sm doped and (Sm, C) co-doped TiO2 materials. We use the Tran-Blaha modified Beck Johnson (TB-mBJ) potential. This functional can estimate the band gap of these compounds with more accuracy compared to the generalized gradient approximation (GGA). The obtained electronic band gap of the pristine TiO2 is Eg=2.76 eV, which is close to the experimental value Eg=3.0 eV. We report also that Sm doped and (Sm, C) co-doped TiO2 are stable in ferromagnetic state. The magnetic moment of samarium is consistent with other literature works. Furthermore, adding samarium atom with 4f states and carbon atom with activated 2p states improve appreciably the optical properties in the visible light range. The corresponding obtained optical band gap value of the (Sm,C) co-doped TiO2 is an optimal one which evidences that the materials is capable of showing high power conversion efficiency. Additionally, the enhancement of optical absorption under the visible-light of these materials, especially the co-doped one can find suitable applications in optoelectronic devices.