Accurate and efficient band-offset calculations from density functional theory

Weston, Leigh; Tailor, Hiral D.; Krishnaswamy, Karthik; Bjaalie, Lars; Walle, Chris G. Van de

doi:10.1016/j.commatsci.2018.05.002

Cited by 69 publications

(57 citation statements)

References 49 publications

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“…TiO 2 anatase (001) slabs display computed band gaps usually 0.5–0.6 eV lower than that of anatase (101) surface, because of the presence of surface states due to exposed O atoms in the surface layer . In our case, these surface states are 0.42 eV above the VBM.…”

Section: Resultsmentioning

confidence: 59%

“…TiO 2 anatase (001) slabs display computed band gaps usually 0.5-0.6 eV lower than that of anatase (101) surface, because of the presence of surface states due to exposed O atoms in the surface layer. [81] In our case, these surface states are 0.42 eV above the VBM. Therefore, we have computed the band gap of TiO 2 (001) as resulting from the Density of States projected on the inner layers, since the band gap of TiO 2 is a bulk property, regardless the specific features of the surface that is exposed.…”

Section: Modelling Of the Tio 2 /Zns Compositementioning

confidence: 48%

“…We now proceed to the analysis of the electronic properties. In Figure , the calculated plane‐averaged electrostatic potential is reported against the non‐crystallographic direction c , showing the alignment of the band edges of each component in the heterojunction . When looking at fully independent surfaces, the Valence Band Offset (VBO) can be simply calculated as the difference between the Valence Band Maximum (VBM) of the units.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure 3, the calculated plane-averaged electrostatic potential is reported against the non-crystallographic direction c, showing the alignment of the band edges of each component in the heterojunction. [25,49,[78][79][80][81] the same reference quantity, as for instance the stationary points of the electrostatic potential calculated in the fully independent slabs (E TOP ) and in the heterojunction system (E TOP ,Het ), in a spatial region that does not correspond to the interface. [25,78,82,83]…”

Section: Modelling Of the Tio 2 /Zns Compositementioning

confidence: 99%

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Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

2020

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Composite materials whose band alignment induces a favorable separation of photogenerated electrons and holes often reveal a stronger photocatalytic activity compared to their separate components. As shown by experiments, titania composites display a heterojunction between the anatase (101)‐(001) surfaces, where the former stabilizes electrons and the latter the holes. In principle, an even more efficient carriers separation is achieved if a third component with high hole‐stabilizing capability, ZnS(110), is growth on anatase (001). However, even though this ternary TiO2/TiO2/ZnS composite material displays good photoactivity, it does not overperform the TiO2/TiO2 one. In this paper an explanation of this evidence is provided by means of periodic hybrid DFT calculations, showing how Coulomb forces play a role against the separation of charge carriers predicted based on the relative energy of the band edges. This highlights the necessity to explicitly account for structural and electronic junction's effects, as well as charge carriers’ localization.

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Section: Resultsmentioning

confidence: 59%

Section: Modelling Of the Tio 2 /Zns Compositementioning

confidence: 48%

Section: Resultsmentioning

confidence: 99%

Section: Modelling Of the Tio 2 /Zns Compositementioning

confidence: 99%

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Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

2020

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“…In a recent study, Weston et al [35], proposed an accurate and computationally efficient methodology for calculating band alignment at semiconductor interfaces. According to Weston et al [35], values of ΔV obtained from semi-local functional are in a very good agreement with those obtained from HSE functional. Therefore, while E v CBTSe and E v CdS are obtained from bulk band-structure calculations using HSE functional, ΔV can be safely obtained from supercell calculations using PBE functional.…”

Section: Band Alignments Based On Average Electrostatic Potentialmentioning

confidence: 99%

On efficiency of earth-abundant chalcogenide photovoltaic materials buffered with CdS: the limiting effect of band alignment

Ghorbani

2020

J. Phys. Energy

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Earth-abundant and environmentally-friendly Cu 2 -II-IV-VI 4 (II=Sr, Ba; IV=Ge, Sn; VI=S,Se) are considered materials for the absorber layers in thin film solar cells. Attempts to understand and improve optoelectronic properties of these newly emerged absorbers resulted in an efficiency of 5.2% in less than two years. However, the energy band alignment at the buffer/absorber interface has not been studied yet; an information which is of crucial importance for designing high performance devices. Therefore, current study focuses on the band offsets between these materials and the CdS buffer. Using first-principles calculations, band discontinuities are calculated at the buffer/absorber interface. The results yield a type-II band alignment between all Cu 2 -II-IV-VI 4 absorbers and CdS, hence a negative DE c . Adoption of a negative DE c (cliff-like conduction band offset) at the buffer/ absorber interface, however, gives rise to low open circuit voltage and high interface-related recombinations. Therefore, it is necessary to search for an alternative buffer material that forms a type-I band alignment with these absorbers, where the conduction band minimum and the valence band maximum are both localized on the absorber side.

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Nature and Role of Surface Junctions in BiOIO₃ Photocatalysts

Liberto

Tosoni

Pacchioni

2021

Adv Funct Materials

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BiOIO3 photocatalysts exposing (010) and (100) surfaces show high efficiency in photocatalytic experiments thanks to an efficient charge separation: photogenerated electrons migrate to the (010) face, and holes move to the (100) one (F. Chen, et al.). However, if one considers the band alignment of the two thermodynamically most stable terminations of the (010) and (100) surfaces as derived from high‐level density functional theory calculations, the band alignment is opposite to the experiment even if the formation of an explicit (010)/(100) junction is considered. To reconcile theory with experiment, one has to invoke the formation of a junction between a less stable (010) surface termination with the most stable (100) one. New chemical bonds at the interface result in a thermodynamically stable system and a significant charge transfer. This junction not only provides the correct band alignment, but also a position of the energy levels that is fully consistent with the experiment. This shows that in order to rationalize the behavior of semiconducting materials where charge separation helps the photoactivity, one has to describe the formation of explicit interfaces with atomistic precision, and to take into account the overall thermodynamic stability of the system.

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Accurate and efficient band-offset calculations from density functional theory

Cited by 69 publications

References 49 publications

Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

On efficiency of earth-abundant chalcogenide photovoltaic materials buffered with CdS: the limiting effect of band alignment

Nature and Role of Surface Junctions in BiOIO₃ Photocatalysts

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Accurate and efficient band-offset calculations from density functional theory

Cited by 69 publications

References 49 publications

Charge Carriers Cascade in a Ternary TiO2/TiO2/ZnS Heterojunction: A DFT Study

Charge Carriers Cascade in a Ternary TiO2/TiO2/ZnS Heterojunction: A DFT Study

On efficiency of earth-abundant chalcogenide photovoltaic materials buffered with CdS: the limiting effect of band alignment

Nature and Role of Surface Junctions in BiOIO3 Photocatalysts

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Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

Nature and Role of Surface Junctions in BiOIO₃ Photocatalysts