Models of Polaron Transport in Inorganic and Hybrid Organic-Inorganic Titanium Oxides

16 February 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Polarons are a type of localized excess charge in materials and often form in transition metal oxides. The large effective mass and confined nature of polarons make them of fundamental interest for photochemical and electrochemical reactions. The most studied polaronic system is rutile TiO2 where electron addition results in small polaron formation through the reduction of Ti(IV) d0 to Ti(III) d1 centers. Using this model system, we perform a systematic analysis of the potential energy surface based on semi-classical Marcus theory parameterized from the first-principles potential energy landscape. We show that F-doped TiO2 only binds polaron weakly with effective dielectric screening after the second nearest neighbor. To tailor the polaron transport, we compare TiO2 to two metal-organic frameworks: MIL-125 and ACM-1. The choice of ligands and connectivity of the TiO6 octahedra largely vary the shape of the diabatic potential energy surface and the polaron mobility. Our models are applicable to other polaronic materials.


metal-organic frameworks
Marcus model

Supplementary materials

Supporting Information: Models of Polaron Transport in Inorganic and Hybrid Organic-Inorganic Titanium Oxides
Details on TiO6 geometry, potential energy surface, and matrix control method


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