Optoelectronic properties of Cr-substituted II–VI semiconductors

Materials with an isolated partially filled intermediate band are of great interest as new materials for high-efficiency solar cells because of the properties of this band. This intermediate band is only present in some compounds. The study presented in this work is based on X32Zn31Cr materials where X = S and Te. The electronic properties, atomic and orbital composition of these materials, population analysis and optical properties have been calculated and analyzed. The absorption coefficients show an increase in the absorption sub-gap as a consequence of the optical transitions between the valence band and this partially filled intermediate band, and with lower importance, due to the transitions between the intermediate and the conduction band. These transitions could lead to an increase in solar conversion efficiency.