Direct observation of anisotropic small-hole polarons in an orthorhombic structure of BiVO₄ films
Author(s)
Chaudhuri, A.; Mandal, L.; Chi, X.; Yang, M.; Scott, M. C.; Motapothula, M.; Yu, X. J.; Yang, P.; Venkatesan, T.; Wee, A. T. S.; Rusydi, A.; Shao-Horn, Yang; ... Show more Show less
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Here, we report an anisotropic small-hole polaron in an orthorhombic structure of BiVO₄ films grown by pulsed-laser deposition on yttrium-doped zirconium oxide substrate. The polaronic state and electronic structure of BiVO₄ films are revealed using a combination of polarization-dependent x-ray absorption spectroscopy at VL[subscript 3,2] edges, spectroscopic ellipsometry, x-ray photoemission spectroscopies, and high-resolution x-ray diffraction with the support of first-principles calculations. We find that in the orthorhombic phase, which is slightly different from the conventional pucherite structure, the unoccupied V 3d orbitals and charge inhomogeneities lead to an anisotropic small-hole polaron state. Our result shows the importance of the interplay of charge and lattice for the formation of a hole polaronic state, which has a significant impact in the electrical conductivity of BiVO₄, hence its potential use as a photoanode for water splitting.
Date issued
2018-05Department
Massachusetts Institute of Technology. Department of Mechanical EngineeringJournal
Physical Review B
Publisher
American Physical Society
Citation
Chaudhuri, A. et al. "Direct observation of anisotropic small-hole polarons in an orthorhombic structure of BiVO₄ films." Physical Review B 97, 19 (May 2018): 195150 © 2018 American Physical Society
Version: Final published version
ISSN
2469-9950
2469-9969