Solution‐Processable Epitaxial Metallic Delafossite Oxide Films

Metallic delafossites ABO 2 , as the new benchmark of ultra‐high conductive oxides, have recently attracted great interest. The harsh processing conditions and dimensional sizes obviously limit the fundamental sciences and technological applications. Here, a low‐cost and facile solution approach is realized to synthesize epitaxial metallic ABO 2 thin films including PtCoO 2 , PdCoO 2 , and PdCrO 2 with a dimension up to two‐inches in diameter, showing ultra‐high room temperature conductivity. The electrical properties, growth mechanisms, and potential technical applications including transparent conducting films and hydrogen evolution reaction activity are unveiled. The achievements of epitaxial metallic delafossites ABO 2 thin films through solution methods will pave the route to producing wafer‐scaled ultra‐high conductive metallic delafossites.