Electronic charge transfer during metal/SiO2 contact: Insight from density functional theory

Antony, Andrew C.; Thelen, D.; Zhelev, Nikolay; Adib, Kaveh; Manley, Robert G.

doi:10.1063/5.0038302

Cited by 15 publications

(9 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Charge density difference plots are commonly used when applying DFT to study triboelectric charging [ 18 , 36 , 37 ]. Typically, they are employed to examine the redistribution of charges in molecules that are chemically bonded to a surface.…”

Section: Resultsmentioning

confidence: 99%

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations

Middleton,

Ghadiri,

Scott

2024

Pharmaceutics

View full text Add to dashboard Cite

Triboelectrification is a ubiquitous and poorly understood phenomenon in powder processing, particularly for pharmaceutical powders. Charged particles can adhere to vessel walls, causing sheeting; they can also cause agglomeration, threatening the stability of powder formulations, and in extreme cases electrostatic discharges, which present a serious fire and explosion hazard. Triboelectrification is highly sensitive to environmental and material conditions, which makes it very difficult to compare experimental results from different publications. In this work, density functional theory (DFT) is used to investigate the charge transfer characteristics of several functional groups of paracetamol in order to better understand the mechanisms of charging at the nanoscale and the influence of the environmental and material properties on charge transfer. This is achieved by studying the structure and electronic properties at the molecule–substrate interface. Using this molecule–substrate approach, the charging contributions of individual functional groups are explored by examining the Hirschfeld charges, the charge density difference between the molecule and substrate, the density of states, and the location of the frontier orbitals (HOMO and LUMO) of a paracetamol molecule. Charge density difference calculations indicate a significant transfer of charge from the molecule to the surface. Observable regions of electron density enrichment and depletion are evident around the electron-donating and -withdrawing groups, respectively. The density of states for the paracetamol molecule evolves as it approaches the surface, and the band gap disappears upon contact with the substrate. Hirshfeld charge analysis reveals asymmetry in the charge redistribution around the molecule, highlighting the varying charging tendencies of different atoms.

show abstract

Section: Resultsmentioning

confidence: 99%

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations

Middleton,

Ghadiri,

Scott

2024

Pharmaceutics

View full text Add to dashboard Cite

show abstract

“…When the system is in equilibrium, the dielectric surface states will be filled as high as the Fermi energy level and the charge on the dielectric can be molded as seen in eq . Likewise, the average surface state density can be modeled as seen in eq , where E 0 is the surface work function of the dielectric and N s ( E ) is the surface density of state. From eqs and , the total energy range of the filled surface state can be modeled as seen in eq …”

Section: Resultsmentioning

confidence: 99%

Mechanism of In-Plane and Out-of-Plane Tribovoltaic Direct-Current Transport with a Metal/Oxide/Metal Dynamic Heterojunction

Benner

Yang

Lin

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Interfacial layer engineering has been demonstrated as an effective strategy for boosting power output in semiconductor-based dynamic direct-current (DC) generators, although the underlying mechanism of power enhancement remains obscure. Here, such ambiguity has been elucidated by comparing fundamental tribovoltaic DC output characteristics of prototypical metal–oxide–metal heterojunctions prepared by atomic-layer deposition (ALD) with a vertical (out-of-plane carrier transport through the interfacial layer) and a horizontal (in-plane carrier transport along the interfacial layer) configuration such that the influences from nonequilibrium electronic excitation and interfacial capacitive amplification can be individually tuned and investigated. It is found in the case of Al/TiO2/Ti vertical configurations that the open-circuit voltage (V OC) increases linearly from −0.03 to −0.52 V as the thickness of titanium oxide (t TiO2 ) increases from 0 to 200 nm with a linear amplification coefficient of −2.31 mV nm–1, which is validated by a parallel-capacitor theoretical model with tribovoltaic electronic excitation. In contrast, the V OC output with the horizontal configuration is ∼55 mV, where the potential difference is merely associated with the accumulation of surface charges and the subsequent charge rearrangement in the depletion region. Meanwhile, it is measured that the short-circuit current density (J SC) shows an initial increasing trend when t TiO2 increases, reaches its peak value at 0.21 A m–2 at t TiO2 = 20 nm, and then decreases as t TiO2 increases further. From current–voltage (I–V) characterization, it is proposed that such DC output variation with an optimal interfacial layer thickness stems from the competition of amplified voltage and increased resistance with increasing interfacial layer thickness, with the main charge transport mechanism switching from quantum tunneling to thermionic emission/trap-assisted transport. In contrast, tribovoltaic excitation is proven to be significantly weaker when a wide band-gap insulator (Al2O3) is involved. The elucidation of the fundamental mechanism of power enhancement by the interfacial layer in this work is of great significance in providing instructional direction for the development and optimization of high-performance DC nanogenerators.

show abstract

“…In addition to the kinetic processes that dictate the hydroxylation of a glass surface, the electronic states at the surface of the glass are of considerable interest in the context of triboelectric nanogenerators (TENGs) and, more generally, the phenomena of contact electrification (CE). − Surface state theory , has been proposed as a way to understand the electrostatic charge transfer between insulating silicate surfaces and metals − based on the alignment of Fermi energy levels of the contacting surfaces and their electronic energy states. For insulating materials with a band-gap energy ( E g ) on the order of 7–10 eV, the density of electronic surface mid-gap states within the apparent insulating band gap has been hypothesized to play a significant role in both the magnitude and direction of charge transfer.…”

Section: Introductionmentioning

confidence: 99%

Passivation of Mid-Gap Electronic States at Calcium Aluminosilicate Glass Surfaces upon Water Exposure: An Ab Initio Study

et al. 2022

Self Cite

View full text Add to dashboard Cite

When a clean glass surface is exposed to humid air, a thin water layer forms on the hydrophilic surface. Using ab initio molecular dynamics, we simulate the changes in the electronic structure of a CaO–Al2O3–SiO2 glass model upon vacuum fracture and subsequent exposure to H2O. When the glass is fractured, dangling bonds form, which lower the band gap of the surface by ∼1.8 eV compared to the bulk value due to mid-gap surface states. When H2O adsorbs onto the vacuum-fractured surface, the band gap increases to a value closer to that of the bulk band gap. Using two different hydroxylation methods, we find that the calculated band gap of the glass surface depends on the hydroxylation state. Surfaces with ∼4.5 OH/nm2 have smaller band gaps due to unfilled surface states, and surfaces with ∼2.5 OH/nm2 have larger band gaps with no apparent unfilled surface states. The resulting changes in the electronic structure, quantified by electron affinity and work function values, are hypothesized to play an important role in the electrostatic charge transfer based on the principles of surface state theory, which posit that the density of electronic surface states determines the amount of electronic charge transfer to or from material surfaces.

show abstract

Electronic charge transfer during metal/SiO2 contact: Insight from density functional theory

Cited by 15 publications

References 60 publications

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations

Mechanism of In-Plane and Out-of-Plane Tribovoltaic Direct-Current Transport with a Metal/Oxide/Metal Dynamic Heterojunction

Passivation of Mid-Gap Electronic States at Calcium Aluminosilicate Glass Surfaces upon Water Exposure: An Ab Initio Study

Contact Info

Product

Resources

About