Design Principles for the Enhanced Transparency Range of Correlated Transparent Conductors

Correlated transparent conductors (TCs) have attracted great attention because they can overcome the limitations of conventional TCs owing to their high visible transmittance and low sheet resistance. However, the most widely studied TC 3d¹ SrVO₃ exhibits low ultraviolet transmittance, and the recently investigated TC 4d² SrMoO₃ has low infrared transmittance. Here, it is proposed that the wide transparency range of correlated TCs arises from both high correlation strength and high transition energy from the O-2p to the transition metal d orbitals. Applying this comprehensive design principle to single-crystalline correlated metals, it is confirmed that correlated 4d¹ SrNbO₃ exhibits enhanced ultraviolet–visible–infrared transmittance, with low sheet resistance at room temperature, compared to 3d¹ SrVO₃ and 4d² SrMoO₃. Spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and density functional theory calculations reveal that the advantageous properties of 4d¹ SrNbO₃ can be attributed to high p–d transition energy and moderate correlation effect. The design principle can aid the discovery of additional high-performance TC materials and further development of correlated TCs.