Bimodal hole transport in bulk BiVO4 from computation

Taifeng Liu, Viswanath Pasumarthi, Christine Laporte, Zhaochi Feng, Qiuye Li, Jianjun Yang, Can Li, Michel Dupuis

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We report first principles and mesoscale kinetic simulations of intrinsic electron and hole transport in stoichiometric monoclinic BiVO4 (BVO). A main finding is that hole transport is bimodal: there are fast hole hops within VO4 tetrahedra that are not 'transport-efficient' and slower hole hops across VO4 tetrahedra that are 'transport-efficient'. This bimodality in hole transport may explain the slow transport/high recombination characteristics of BVO. In this work, polaron hops were described via the two-state Marcus/Holstein model of VV-VIV and OI-OII interchanges for electron and hole polarons respectively. The relevant parameters in the theory were obtained using the density functional theory DFT+U method. Hopping activation energies were combined with Einstein diffusion theory to yield mobility as well as with kinetic Monte Carlo (KMC) modeling. All unique nearest neighbor electron and hole hopping processes were characterized. For V-to-V hops of electron polarons, we obtained activation energies of ∼0.37 eV that compare well with the experimental activation energy of ∼0.30 eV for drift mobility. Electron polarons remain localized on single sites along the hopping pathways before hopping via tunneling, suggestive of small non-adiabatic coupling and a diabatic character consistent with V-to-V electron transfer through space (no bridge linkers). These simulations yield a small electron transport anisotropy, with transport in the (a,b) plane being faster than along the c direction by a factor of ∼2. For hole polarons our calculations support the character of small polarons localized on O atoms as well. Some nearest neighbor hole hops have a diabatic character, while other nearest neighbor hops are adiabatic and phonon-assisted with an Arrhenius thermal dependence. Hops through O-V-O bridges and through space have low activation barriers (∼0.17 eV and ∼0.25 eV) while hops through O-Bi-O bridges have higher activation barriers (∼0.37 eV and higher). The mobility is gated by the slower transport across VO4 tetrahedra through O-Bi-O bridges owing to the underlying BVO lattice network. Hole mobility is determined to be about one order of magnitude larger than electron mobility consistent with THz spectroscopy measurements. This work sets the foundation to address facet selectivity of charge carriers in shape and size-tailored crystals.

Original languageEnglish
Pages (from-to)3714-3723
Number of pages10
JournalJournal of Materials Chemistry A
Volume6
Issue number8
DOIs
Publication statusPublished - Jan 1 2018

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Polarons
Electrons
Activation energy
Chemical activation
Gene Conversion
Kinetics
Hole mobility
Electron mobility
Interchanges
Charge carriers
Discrete Fourier transforms
Density functional theory
bismuth vanadium tetraoxide
Anisotropy
Spectroscopy
Atoms
Crystals

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Liu, T., Pasumarthi, V., Laporte, C., Feng, Z., Li, Q., Yang, J., ... Dupuis, M. (2018). Bimodal hole transport in bulk BiVO4 from computation. Journal of Materials Chemistry A, 6(8), 3714-3723. https://doi.org/10.1039/c7ta10170h

Bimodal hole transport in bulk BiVO4 from computation. / Liu, Taifeng; Pasumarthi, Viswanath; Laporte, Christine; Feng, Zhaochi; Li, Qiuye; Yang, Jianjun; Li, Can; Dupuis, Michel.

In: Journal of Materials Chemistry A, Vol. 6, No. 8, 01.01.2018, p. 3714-3723.

Research output: Contribution to journalArticle

Liu, T, Pasumarthi, V, Laporte, C, Feng, Z, Li, Q, Yang, J, Li, C & Dupuis, M 2018, 'Bimodal hole transport in bulk BiVO4 from computation', Journal of Materials Chemistry A, vol. 6, no. 8, pp. 3714-3723. https://doi.org/10.1039/c7ta10170h
Liu T, Pasumarthi V, Laporte C, Feng Z, Li Q, Yang J et al. Bimodal hole transport in bulk BiVO4 from computation. Journal of Materials Chemistry A. 2018 Jan 1;6(8):3714-3723. https://doi.org/10.1039/c7ta10170h
Liu, Taifeng ; Pasumarthi, Viswanath ; Laporte, Christine ; Feng, Zhaochi ; Li, Qiuye ; Yang, Jianjun ; Li, Can ; Dupuis, Michel. / Bimodal hole transport in bulk BiVO4 from computation. In: Journal of Materials Chemistry A. 2018 ; Vol. 6, No. 8. pp. 3714-3723.
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