Optoelectronic properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Ta</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:math>: A joint theoretical and experimental study

Morbec, Juliana M.; Narkeviciute, Ieva; Jaramillo, Thomas F.; Galli, Giulia

doi:10.1103/physrevb.90.155204

Cited by 67 publications

(49 citation statements)

References 54 publications

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“…5(a)) with a band gap energy of 3.1 eV. The lowest-energy band gap of this material originates from the direct O 2p 6 -Bi 6p 0 orbital transitions. For Bi 4 Ti 3 O 12 , the electronic analysis reveals that valence-band states in a wide energy range below the Fermi level are dominated by O 2p orbitals with negligible contributions from Bi 6s orbitals, whereas the conduction-band states primarily consist of empty Ti 3d orbitals (Fig.…”

Section: A Structural Propertiesmentioning

confidence: 99%

“…[1][2][3][4][5] This is particularly relevant in the case of semiconductor materials for solar applications, [6][7][8][9][10] where the capability of the semiconductor to use effectively solar light depends on combination of a series of properties. 2 Thus, the efforts devoted to the accurate theoretical and experimental characterization of a large variety of semiconductor materials aimed to elucidate fundamental properties, such as band gap, optical absorption coefficient, dielectric constant, and charge carrier effective masses.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

Lardhi

Noureldine

Harb

et al. 2016

The Journal of Chemical Physics

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Density functional theory calculation was conducted to determine the optoelectronic properties of bismuth titanate sillenite (Bi12TiO20) and perovskite-like (Bi4Ti3O12) structures. The lattice parameters were experimentally obtained from Rietveld analysis. The density functional perturbation theory approach was used with the standard Perdew–Burke–Ernzerhof functional and screened Coulomb hybrid Heyd–Scuseria–Ernzerhof functional to investigate the electronic structure and absorption coefficient. Both compounds have good carrier transport properties, low effective hole and electron masses, high dielectric constant, and low exciton binding energy.

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Section: A Structural Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

Lardhi

Noureldine

Harb

et al. 2016

The Journal of Chemical Physics

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“…We considered (i) uniaxial strain along a, b and c directions (see band minimum (CBM) located at Y point. 8 We found that hydrostatic strains between −1.5% and 1.5% induce small changes in the band gap, less than 1.5% (see Fig. S5 (c)), while uniaxial strain along the b direction induces changes up 5.6% (Fig.…”

Section: Resultsmentioning

confidence: 73%

“…3 However, recent experiments have reported low photocurrent and poor overall performance of Ta 3 N 5 photoanodes for water oxidation, 4,5 which is likely caused by poor charge transport properties [6][7][8] as well as by rapid photodegradation of the samples in water.…”

Section: Introductionmentioning

confidence: 99%

Charge transport properties of bulkTa3N5from first principles

Morbec

Galli

2016

Phys. Rev. B

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Tantalum nitride is considered a promising material for photoelectrochemical water splitting, however its charge transport properties remain poorly understood. We investigated polaronic and band transport in Ta 3 N 5 using first-principles calculations. We first studied the formation of small polarons using density-functional theory (DFT) including DFT+U and hybrid functionals. We found that electron small polarons may occur but hole polarons are not energetically favorable.The estimated polaronic mobility for electrons is at least three orders of magnitude smaller than that measured in Ta 3 N 5 films, suggesting that the main transport mechanism for both electrons and holes is band-like. Since band transport is strongly affected by the carrier effective masses, and Ta 3 N 5 in known to have large electron and hole effective masses, we also investigated whether substitutional impurities or strain may help lower the effective masses. We found significant reduction in both electron and hole effective masses (up to 17% for electron and 39% for hole) under applied strain, which may lead to substantial improvement (up to 30% for electron and 15% for hole) in the carrier mobilities.

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“…This observation agrees well with similar effective masses for electrons and holes theoretically estimated for Ta3N5. 57,58 The ultrafast quenching of holes at the Ta3N5 phase is consistent with its poor OER performance (provided that trapped holes are not energetically suitable to promote OER after trapping). From THz characterization, we cannot conclude whether the hole traps are present in the surface or in the bulk phase.…”

Section: Figure 1 (A) Time Courses Of Photocatalytic Oermentioning

confidence: 77%

Enhanced Kinetics of Hole Transfer and Electrocatalysis during Photocatalytic Oxygen Evolution by Cocatalyst Tuning

et al. 2016

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Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report a substantial enhancement by a factor of 3 in photocatalytic efficiency for the oxygen evolution reaction (OER) by adding trace amounts (~0.05 wt%) of noble metals (Rh or Ru) to a 2 wt% cobalt oxide-modified Ta3N5 photocatalyst particulate. The optimized system exhibited high quantum efficiencies (QEs) of up to 28 and 8.4% at 500 and 600 nm in 0.1 M Na2S2O8 at pH 14. By isolating the electrochemical components to generate doped cobalt oxide electrodes, the electrocatalytic activity of cobalt oxide when doped with Ru or Rh was improved compared with cobalt oxide, as evidenced by the onset shift for electrochemical OER. Density functional theory (DFT) calculation shows that the effects of a second metal addition perturbs the electronic structure and redox properties in such a way that both hole transfer kinetics and electrocatalytic rates improve. Time resolved terahertz spectroscopy (TRTS) measurement provides evidence of long-lived electron populations (>1 ns; with mobilities μe ~0.1-3 cm 2 V -1 s -1 ), which are not perturbed by the addition of CoOx-related phases. Furthermore, we find that Ta3N5 phases alone suffer ultrafast hole trapping (within 10 ps); the CoOx and M-CoOx decorations most likely induce a kinetic competition between hole transfer toward the CoOx-related phases and trapping in the Ta3N5 phase, which is consistent with the improved OER rates. The present work not only provides a novel way to improve electrocatalytic and photocatalytic performance but also gives additional tools and insight to understand the characteristics of photocatalysts that can be used in a suspension system.

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Optoelectronic properties ofTa3N5: A joint theoretical and experimental study

Cited by 67 publications

References 54 publications

Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

Charge transport properties of bulkTa3N5from first principles

Enhanced Kinetics of Hole Transfer and Electrocatalysis during Photocatalytic Oxygen Evolution by Cocatalyst Tuning

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