The impacts of dopants on the small polaron mobility and conductivity in hematite – the role of disorder

Abstract

Hematite (α-Fe2O3) is a promising transition metal oxide for various energy conversion and storage applications due to advantages of low cost, high abundance, and good chemical stability. However, its low...

High-throughput parallel testing of ten photoelectrochemical cells for water splitting: case study on the effects of temperature in hematite photoanodes

“…The conduction of electrons in transition metal oxides like a-Fe 2 O 3 is governed by small polaron hopping. 81,82 Small polarons are electrons that are self-trapped in a single-site local lattice distortion, which for Tidoped hematite is predicted to be nearby a Fe 3+ ion, reducing it to Fe 2+ . 83 To hop from one site to the next, small polarons require a phonon and the process has an activation energy which follows an Arrhenius-type temperature dependence (under the assumption of adiabatic regime).…”

Dual modification on hematite to minimize small polaron effects and charge recombination for sustainable solar water splitting

“…In metal oxides, the charge carrier can locally deform the lattice due to the carrier-phonon coupling, inducing a potential dwell that acts as a carrier trap called a small polaron. 11 Solid solution dopants with stronger correlated electrons than the 3d electrons of Fe are potential candidates for minimizing polaron effects, but their effects are limited in concentration by the formation of multipole clusters. 12 At the same time, polycrystalline structures, such as those derived from the polymeric precursor, show a greater magnitude of isolated electron polaron adsorption, implying a key role of interface defects in the carrier conduction.…”

Towards sustainable photoelectrodes for solar to hydrogen conversion through the combination of earth-abundant elements

“…In metal oxides, the charge carrier can locally deform the lattice due to the carrier-phonon coupling, inducing a potential dwell that acts as a carrier trap called a small polaron. 13 Solid solution dopants with stronger correlated electrons than the 3d electrons of Fe are potential candidates for minimizing polaron effects, but their effects are limited in concentration by the formation of multipole clusters. 14 At the same time, polycrystalline structures, such as those derived from the polymeric precursor, show a greater magnitude of isolated electron polaron adsorption, implying a key role of interface defects on the carrier conduction.…”