Double perovskite Ba_2BiTaO_6 as a promising p-type transparent conductive oxide: A first-principles defect study

摘要

The realization of p-type transparent conductive oxides (TCOs) is a long-standing difficulty because of their generally large hole effective mass and low doping limit ascribed to the strong electronegativity of oxygen. By introducing a Bi atom with a lone-pair s orbital on the B site, double perovskite Ba_2BiTaO_6 could exhibit a dispersive upper valence band and a small hole effective mass due to the strong sp anti-bonding coupling. In contrast to n-type TCOs, i.e., ZnO and In_2O_3, first-principles studies on the intrinsic defects of Ba_2BiTaO_6 show that it is able to exhibit a good p-type property or stay intrinsic instead of being n-type by tuning the chemical potentials and its dominated defects (V_(Ba), V_(Bi), Ba_(Bi), and Bi_(Ta)) are shallow acceptors, indicating that Ba_2BiTaO_6 is able to be a promising p-type TCO. This work shows that perovskites could be a class of potential p-type TCOs by introducing strong sp coupling with lone-pair-s-orbital elements.