Epitaxial growth of MoO3 polymorphs and impacts of Li-ion electrochemical reactions on their structural and electronic properties

Two polymorphs of MoO3 (orthorhombic alpha and monoclinic beta phases) were epitaxially grown on the (100) plane of cubic perovskites by using pulsed-laser deposition. The electrochemical cells were implemented for investigating the impacts of Li-ion intercalation on each phase. Despite the most stable phase, alpha-MoO3 films were transformed to an amorphous phase after a single electrochemical cycle. In contrast, the beta-MoO3 films indicated reversible cyclic voltammogram against repeated electrochemical cycles of intercalation and subsequent deintercalation, and remained in forms of the crystalline Li x MoO3. Systematic evolutions of electronic, optical, and structural properties of Li x MoO3 films across insulator-to-metal transition are reported.