First-principles investigation of the electronic and optical properties of Al-doped FeS2 pyrite for photovoltaic applications

In this study, we use density functional theory with the generalized gradient approximation proposed by Perdew–Burke–Ernzerhof (GGA-PBE) to investigate the effect of Al-doping on the structural, electronic and optical properties of the pyrite FeS2 structure. It shows an indirect band gap of 1.07 eV, which is in reasonable agreement with the experimental data. When Al atom occupies the Fe site, one of the most effects occurred in the electronic structure is to create shallow donor states partially occupied at the bottom of the conduction band, which could be considered as the primary induced origin of the electrical conductivity in the Al doped FeS2 system. Then, the injection of free electrons into the conduction band could be carried out only from the low excitation energies as well as the photon absorptions could be enhanced in the visible range. Therefore, all these features may be making of Al-doped FeS2 a useful material for cell photovoltaic applications with a reasonable cost.