Mechanism of Charge Transport in Mixed-Valence 2D Layered Hybrid Bronze Materials

TL;DR

This study uses advanced computational methods to uncover the molecular mechanisms behind charge transport in mixed-valence 2D hybrid bronze materials, explaining why certain variants exhibit much higher electrical conductivity.

Contribution

It provides detailed mechanistic insights into charge transport pathways in hybrid bronze materials using first-principles calculations and machine learning simulations, guiding future material design.

Findings

EV variant has ~3 orders of magnitude higher conductivity than MV.

Structural and electronic factors influencing conductivity differences are identified.

Insights aid in designing materials with improved electrical properties.

Abstract

Two-dimensional layered bronze (HB) materials are a new class of mixed-valence hybrid organic-inorganic metal oxides that demonstrate great potential as advanced functional materials for next-generation electronics. Recently, new hybrid vanadium bronze materials, (EV)V8O20 and (MV)V8O20, EV = ethyl viologen and MV = methyl viologen, have been introduced, with EV having ~3 orders of magnitude higher electrical conductivity than the MV system. Given their identical inorganic V-O layers and similar reduction potentials, the observed large difference in electrical conductivities is puzzling. Here, through accurate first-principles calculations coupled with MACE machine learning molecular dynamics (MD) simulations validated by accurate ab initio MD simulations, we provide mechanistic molecular-level insights into dominant charge transport and electrical conductivity pathways in these materials. Our detailed structural and electronic properties data identifies factors contributing to this significant difference in electrical conductivities of these materials. Our findings in this work offer clues and provide valuable insights into improving the electrical conductivity of hybrid bronze and similar materials in order to guide the design of next-generation materials with enhanced properties for future electronic and thermoelectric applications.