Effect of protons on polaron mobility in transition metal oxides

Understanding polaron mobility in transition metal oxides is essential for advancing materials in proton-based electrochemical random access memory (ECRAM) neuromorphic devices. Using first-principles calculations, the authors quantify how protons affect polaron migration barriers in promising ECRAM channel materials WO${}_{3}$, V${}_{2}$O${}_{5}$, and MoO${}_{3}$. Beyond electrostatic attraction, which promotes proton-polaron pairing and increases migration barriers, protons also influence polaron transport directionality. By forming hydrogen bonds that distort metal-oxygen-metal linkages, they affect orbital overlap between metal sites and modulate migration barriers along these pathways. These results highlight a nontrivial role of protons in polaron transport and provide guidance for designing energy-efficient electrochemical devices.