Ab Initio Design of Pb2+-based Ternary Oxides for Phase Stable and Hole Dopable p-type Oxides

Recent work on searching for high mobility p-type oxides have led to the identification of several promising p-type oxide candidates. Among them, post-transition metal cations, including Sn2+, Pb2+, Sb3+, Tl1+, and Bi3+ are good materials space for high performance p-type oxides design due to their occupied lone-pair s orbitals hybridizing with the O-2p orbital at the valence band edge. However, few of them have been experimentally proven applicable until now, due to their weak phase stability such as SnO or limited p-type dopability like Ba2BiTaO6. In this work, we focus on Pb2+ chemistry which has not been previously investigated, to design phase stable and hole dopable p-type oxides. It is found that the atomic orbital energy level of Pb-6s in Pb2+-based oxides is deep and thus guarantees a stable Pb2+ valence stability as well as compound phase stability. While monoxide PbO has spontaneous formation of oxygen vacancy limiting its p-type dopability, Pb2+ ternary compounds Pb2+–O–X containing a third element X show high hole dopability as well as other good p-type oxide performances including wide band gap, high hole mobility, and robust phase stability. Several promising candidates, including K2Pb2O3, TiPbO3, As2PbO6, and Sb2PbO6 are identified. These results broaden the current p-type oxide materials design space and provide guidance to the experimental realization of phase stable and hole dopable high-performance p-type oxides.