Structural and electronic properties of Fe-doped silver delafossites: AgAl1-xFexO2 and AgGa1-xFexO2 (x=1-5%)

摘要

Delafossite materials have been studied for a long time for photovoltaic and catalytic applications due to their wide band gaps and bipolar conductivities. These systems have forbidden fundamental band gaps which are much smaller than their apparent optical gaps. Making optical transitions permissible across the fundamental gap allows photocatalytic reactions to harness solar light in the visible region. Recently, it has been shown that B site doping can break the inversion symmetry of these delafossites allowing light absorption across the fundamental gap. We study structural and electronic properties of two Fe-doped delafossites, AgAl1-xFexO2 and AgGa1-xFexO2 (x = 1-5%) using high-throughput calculations. Preferable Fe dopant locations in both these systems are studied using two metrics. Based on the electronic density of states and unfolded band structures, we find that Fe impurities mainly affect the valence band edges of both these systems. New Fe states at the. point can result in lower energy optical transitions compared to the undoped delafossites. The estimated reductions in the direct band gap at the Gamma point are 1.3 eV and 0.5 eV for AgAl1-xFexO2 and AgGa1-xFexO2 respectively. Hence, Fe doped silver delafossites are possible candidates to be tested as catalysts under visible light.