Effect of doping and chemical ordering on the optoelectronic properties of complex oxides: Fe 2 O 3 -V 2 O 3 solid solutions and hetero-structures
The electronic and optical properties of α-(Fe V ) O at low (x = 0.04) and high (x = 0.5) doping levels are investigated using a combination of periodic and embedded cluster approaches, and time-dependent density functional theory. At low V concentrations the onset of the optical absorption is ∼0.5...
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Veröffentlicht in: | Physical chemistry chemical physics : PCCP 2017-01, Vol.19 (2), p.1097-1107 |
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Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The electronic and optical properties of α-(Fe
V
)
O
at low (x = 0.04) and high (x = 0.5) doping levels are investigated using a combination of periodic and embedded cluster approaches, and time-dependent density functional theory. At low V concentrations the onset of the optical absorption is ∼0.5 eV (i.e., nearly 1.6 eV lower than that in pure α-Fe
O
) and corresponds to the electron transitions from V 3d to Fe 3d* orbitals. At high V concentrations, optical absorption energies and intensities are sensitive to specific arrangements of Fe and V atoms and their spin configuration that determine Fe-V hybridization. The onset of the lowest inter-vanadium absorption band in the case of Fe
O
/V
O
hetero-structures is as low as ∼0.3 eV and the corresponding peak is at ∼0.7 eV. In contrast, in the case of solid solutions this peak has lower intensity and is shifted to higher energy (∼1.2 eV). Analysis of the orbital character of electronic excitation suggests that Fe
O
/V
O
hetero-structures absorb light much more effectively than random alloys, thus promoting efficient photo-induced carrier generation. These predictions can be tested in α-(Fe
V
)
O
thin films synthesized with well-controlled spatial distribution of Fe and V species. |
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ISSN: | 1463-9076 1463-9084 |
DOI: | 10.1039/C6CP06087K |