Effect Of External Electric Field Research Articles

Comparative study of external electric field and potential effects on liquid water ions

Molecular dynamics simulations were used extensively in the last decades to study the influence of an external electric field on many physical processes in water, including mobility of ions, field-induced vaporisation, and electrowetting. In most of these studies, the electric field was applied as an external force to all atoms in the simulation. While such an approach is intuitive and straightforward, it neither captures the shielding of the electric field by water nor any interfacial effect. The Constant Electrode Potential Method (CPM) allows for an external electric field to be applied on a system level, resembling experimental settings and accounting for shielding effects by water. In this work, the CPM method has been implemented to study the influence of an external electric field on the surface tension of water and to compare that to the conventional method, in addition to computing the interfacial mobilities of Na+ and Cl− ions at a liquid–vapor interface. The two approaches yield a similar trend of surface tension variation with the electric field. The CPM method predicts a weaker variation in the surface tension in comparison to that of the conventional method, with the maximum reported difference being 36% of the surface tension value.

Corrugation effect, Dirac cone splitting, and plasmon properties of biased twisted bilayer graphene

The unconventional behaviors observed in twisted bilayer graphene (TBG) at special ``magic angles'' characterized by the vanishing Fermi velocity make TBG an intriguing platform for the study of correlated phenomena. Here, on the basis of an effective continuum model, we propose an analytic expression of the Fermi velocity based on which we demonstrate that the first magic angle of TBG is independent of the corrugation effect. We also correlate analytically the Dirac cone splitting of the biased TBG to the external electric field, twist angle, and corrugation effect. The biased TBGs exhibit unusual plasmonic responses. In the long-wavelength limit, the plasmon frequency is nearly independent of the carrier density but can be tuned by the bias voltage.

Electronic properties and tunable Schottky barrier of non-Janus MoSSe/graphene heterostructures

We investigate the stability and electronic properties of van der Waals junctions composed with graphene and non-Janus MoSSe in comparison with graphene/Janus MoSSe configuration, and furthermore explore its Schottky barrier as well as the effect of external electric field. Based on first-principles calculations, we compare the interlayer distance and binding energy between them. It is found that with the adhesion of graphene, the less-stable Janus MoSSe becomes the most stable configuration. The graphene/non-Janus MoSSe configuration has the minimum interlayer distance, and the weak vdW interactions indicates the preservation of unique electronic properties in both two materials. An n-type Schottky contact with the Schottky barrier height (SBH) of 0.38 eV is formed at the equilibrium state for graphene/non-Janus MoSSe, while the n-type SBH for two configurations of graphene/Janus MoSSe is 0.67 and 0.10 eV, respectively. With the application of an external electric field perpendicularly to the surface, not only the Schottky barrier height but also the transition of n-type and p-type Schottky contacts as well as Ohmic contacts can be modulated within a relatively small electric field strength. This property distinguishes graphene/non-Janus MoSSe from graphene/Janus MoSSe configuration, and provides great potential for applications in optoelectronic and nanoelectronic and devices.

Effect of external direct current electric field on the inhibition behavior of Zn-MOFs for Cu in 0.5 mol/L NaCl solution

The effect of an external DC electric field on the inhibition behavior of Zn-MOFs in 0.5 mol/L NaCl solution for copper was investigated via electrochemical measurements and various characterization techniques. Results indicated that the corrosion inhibition efficiency of the Zn-MOFs decreased under strong electric field intensities, which went from 94.2% to 61.7%. The corrosion inhibition efficiency of the materials decreased with increasing electric field duration when maintained at a certain electric field intensity. When the electric field duration time was 6 h, 12 h, 18 h and 24 h, the corresponding efficiency was 90.4%, 86.8%, 78.2% and 61.7% respectively. The effect of an electric field on the corrosion inhibition performance of the Zn-MOFs could essentially be attributed to changes in the structure of the material framework.

Effect of External Electric Field on Tetrel Bonding Interactions in (FTF3···FH) Complexes (T = C, Si, Ge, and Sn).

A quantum chemical study was accomplished on the σ-hole interactions of the barely explored group IV elements, for the first time, in the absence and presence of the positively and negatively directed external electric field (EEF). The analyses of molecular electrostatic potential addressed the occurrence of the σ-hole on all the inspected tetrel atoms, confirming their salient versatility to engage in σ-hole interactions. MP2 energetic findings disclosed the occurrence of favorable σ-hole interactions within the tetrel bonding complexes. The tetrel bonding interactions became stronger in the order of C < Si < Ge < Sn for F–T–F3···FH complexes with the largest interaction energy amounting to −19.43 kcal/mol for the optimized F–Sn–F3···FH complex under the influence of +0.020 au EEF. The interaction energy conspicuously evolved by boosting the magnitude of the positively directed EEF value and declining the negatively directed EEF one. The decomposition analysis for the interaction energies was also executed in terms of symmetry-adapted perturbation theory, illuminating the dominant electrostatic contribution to all the studied complexes’ interactions except carbon-based interactions controlled by dispersion forces. The outcomes that emerged from the current work reported significantly how the direction and strength of the EEF affect the tetrel-bonding interactions, leading to further improvements in the forthcoming studies of supramolecular chemistry and materials science.

The influences of electric field intensity and driving force on the slip behaviour of water flow in a nanochannel.

In the present work, non-equilibrium molecular dynamics (MD) simulations are used to investigate the flow of liquid water between two metallic solid atomistic smooth walls. The present work focuses on the combined effect of external electric field and driving force on the slip behaviour and structure of liquid water at the solid-water interface. The upper wall of the set model is positively charged, and the lower wall of the model is negatively charged. The simulation results show that as the driving force increases, the slip length also increases. At a given driving force, no matter how the electric field intensity changes, there is almost no change in the slip length, so the slip length is independent of the electric field strength. In addition, the results found that there is a linear relationship between the slip length and the normalised main peak of the static structure factor under different driving forces.

Effect of electric fields on the electronic and thermoelectric properties of zigzag buckling silicene nanoribbons

We investigate the electronic structure and the thermoelectric transport properties of zigzag buckling silicene nanoribbons (BSiNRs) under the effect of external electric fields by means of atomistic simulations. The obtained results show that thanks to the buckling feature, zigzag BSiNRs have a stronger response to a vertical electric field compared to its flat form structure and also single-layer and bi-layer graphene nanoribbons with zigzag edges (GNRs & BGNRs). An inverse is observed in the case of a transverse electric field. Interestingly, the mutual effect when applying simultaneously the vertical and transverse fields induces a larger bandgap compared to individual ones. The mutual effect observed with zigzag BSiNRs is much more pronounced compared to that in zigzag BGNRs since the vertical field has a modest effect on zigzag BGNRs stemming from weak van der Waals interactions between graphene layers. Thermoelectric performance of zigzag BSiNRs is enhanced remarkably with electric fields in which the figure of merit ZT can be tuned to exceed 1. Interestingly, although the mutual impact of two external fields induces the largest Seebeck coefficient, it unveils that the vertical electric field is overall more efficient in enhancing the thermoelectric performance of zigzag BSiNRs. In addition, the enhancement of ZT is demonstrated to stem mainly from a dramatical degradation of the electron thermal conductance around the Fermi level. This study shows that zigzag BSiNRs in combination with external electric fields have favourable advantages for different electronic and thermoelectric applications.

Photoluminescence of P3HT:PCBM bulk heterojunction thin films and effect of external electric field

AbstractSteady‐state and time‐resolved photoluminescence (PL) and electrophotoluminescence (E‐PL) have been recorded for bulk heterojunction samples of thin films of regio‐regular poly(3‐hexylthiophene) (P3HT) and methyl [6,6]‐phenyl‐C61‐butanoate (PCBM). The PL spectra of the bulk heterojunction samples showed a monotonic decrease of PL quantum yield with increased PCBM content in the film. The PL decay was measured with both a femtosecond up‐conversion technique and a time‐correlated single‐photon‐counting technique. The mechanism of PL quenching deviated from a simple Stern‐Volmer equation, explained in terms of an apparent static quenching with a sphere‐of‐action model and dynamic quenching. With increased content of PCBM, the static quenching played a dominant role. Upon application of an electric field, the E‐PL spectra of both P3HT and bulk heterojunction samples showed an enhanced quantum yield and incremented lifetime of PL of P3HT. The long‐range electron transfer from P3HT to PCBM was retarded upon application of an electric field; the field‐induced change increased with increasing PCBM content.

Effect of external electric field on photo-responsivity of CdS/ZnSe multiple quantum well photodetector

We show the enhancement of photo-responsivity through applied external electric field F of CdS/ZnSe multiple quantum well (MQW) photo-detector for the detection of mid infrared wavelengths. The subband energy levels E n are calculated using the Schrödinger equation via finite difference method by incorporating exchange-correlation potential and Hartree potential caused by doping in the well layer. We note that by increasing F , E n and the corresponding optical transition energies decreases. It is observed that dipole matrix element M 21 reduces for higher F and we obtain approximately 38 % lower value of M 21 at F = 40 kV/cm. Moreover, absorption coefficient decreases with F due to the strong dependence on M 21 . We obtain current density of 0.03 A/cm 2 and responsivity of 0.012 A/W at wavelength λ = 2.73 μm for M (number of wells) = 20, well width L w = 2 nm at F = 20 kV/cm. We show that the responsivity is enhanced by increasing M, L w as well as doping concentration N D in the well. We also achieved higher photo-responsivity in CdS/ZnSe MQW using our proposed model as compared to the earlier reported results for GaAs/AlGaAs QWIP . • We achieved enhancement of photo-responsivity in CdS/ZnSe QWIP as a function of electric field ( F ). • The Photocurrent ( J ) and Responsivity ( R ) are more significant at higher F . • Enhnacement of J and R with F is due to the reduction in dipole matrix element. • Increasing doping concentrations, number of wells and well widths of QWIP enhances responsivity.

External electric field effect and impact of encapsulating matrix on optical and electronic properties within CdSe/ZnSe core/shell QDs

In this study, we have carried out a theoretical investigation of CdSe/ZnSe core/shell spherical quantum dot (CSQD) embedded in different dielectric matrix. The effect of surrounding matrix and the external electric field on the linear and third-order nonlinear real and imaginary parts of the dielectric function have been simulated numerically using the effective mass approximation and taking into account the compact density matrix approach. The electronic band structure and corresponding wave functions were calculated by solving the Schrödinger equation in the framework evoked previously. The study revealed a significant blue shift of the transition energies under electric field offering the possibility of adjusting them. In addition, by varying the dielectric matrices enveloping our main structure, it was also found that the choice of the pattern of the matrix is fundamental for the manipulation of the resonance peak energies of the dielectric function.

A novel approach for evaluating the effect of external electric field on charged particles based on the Lagrangian particle tracking method

This paper develops a novel approach for evaluating charged particles' collision probability in the external electric field of a regular two-stage electrostatic precipitator based on Lagrangian particle tracking method, which overcomes itself difficulties and that of the Eulerian method. The numerical simulation aims to obtain the particles' accumulated displacement which is a parameter to reflect the efficiency of particle collision. The effect factors of frequency, gas velocity, plate spacing and applied voltage are also considered. Results indicate that the external electric field of R-AC is more beneficial to particle collision compared to the other waveforms of AC. Besides, frequency and plate spacing are not found to have obvious or regular effect on collision probability, but the promotion effect of applied voltage on it was obtained. The dimensionless coefficient analysis provides extremely useful information for the optimization of working conditions in different types of the external electric field.

Intensity-dependent nonlinear optical properties in an asymmetric Gaussian potential quantum well-modulated by external fields

In this paper, the effects of external electric, magnetic and non-resonant intense laser fields on the nonlinear optical rectification (NOR), second-harmonic (SH), and third harmonic (TH) generation in a GaAs quantum well with asymmetrical Gaussian potential are theoretically investigated. Firstly, the energy eigenvalues and eigenfunctions of a single electron confined in the structure are obtained by using the diagonalization method within the framework of the effective-mass and parabolic band approaches. Then, using these energy eigenvalues and eigenfunctions, expressions derived within the compact density matrix approximation have been employed to calculate the coefficients of the nonlinear optical response in the structure. The obtained simulation results show that the influence of the external fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation in the system. As a result, it has been seen that the amplitude and position of the peaks of nonlinear optical rectification, second and third harmonic coefficients can be controlled by changing the applied external fields.

Sequestration of Carbon Dioxide with Frustrated Lewis Pairs Based on N-Heterocycles with Silane/Germane Groups.

Frustrated Lewis pairs (FLPs) based on nitrogen heterocycles (pyridine, pyrazole, and imidazole) with a silane or germane group in the α-position of a nitrogen atom have been considered as potential molecules to sequestrate carbon dioxide. Three stationary points have been characterized in the reaction profile: a pre-reactive complex, an adduct minimum, and the transition state connecting them. The effect of external (solvent) or internal (hydroxyl group) electric fields in the reaction profile has been considered. In both cases, it is possible to improve the kinetics and thermodynamics of the complexation of CO2 by the FLP and favor the formation of adducts.

Structural and physical properties of trichloroethylene under an external electric field

AbstractStudy on a series of physical and chemical changes of molecules under an external electric field (EEF) can deeply understand the properties of molecules. Trichloroethylene is widely used in industrial solvents, extractants, fungicides, refrigerants, dry cleaning, and other fields. In this work, the structural and physical characteristics of trichloroethylene under EEF were investigated on the basis of density functional theory within the B3LYP/def2‐TZVP level. Calculated results show that the bond lengths, bond angles, total energy, dipole moment, charge, and Raman spectra change under EEF. Under the effect of EEF, the Raman spectra show vibrational stark effect, which causes a redshift or blueshift of the wavenumbers. These results help to understand the effect of EEF on structures and physical properties and provide effective guidance for various applications.

Band Alignment in Monolayer Boron Phosphide with Janus MoSSe Heterobilayers under Strain and Electric Field

Recent studies have revealed that Janus structures and heterobilayers made from them might have properties superior to those of two-dimensional (2D) materials. We construct 2D monolayer boron phosphide (MBP)/$\mathrm{Mo}\mathrm{S}\mathrm{Se}$ and $\mathrm{Mo}\mathrm{S}\mathrm{Se}$/MBP heterobilayers and describe comprehensively their optoelectronic properties in the presence of biaxial in-plane and uniaxial out-of-plane strain and the effects of electric fields using first-principles methods. The electronic bands of both MBP/$\mathrm{Mo}\mathrm{S}\mathrm{Se}$ and $\mathrm{Mo}\mathrm{S}\mathrm{Se}$/MBP heterobilayers display a peculiarity in the direct gap, with different band-gap values in the pristine forms. Remarkably, it is shown that different varieties of band alignments are induced for different orders of the van der Waals (vdW) heterobilayers. Electric fields and in-plane and out-of-plane strain give rise to important changes in the electronic and optical properties. The band alignments can transform from type I to type II under the influence of an electric field and strain. The main absorption peaks of pristine forms of both heterobilayers have in the visible region (approximately 2.67 eV), while in the presence of biaxial strain are redshifted. Since the absorption peaks of the pristine forms of the heterobilayers are in the visible region, the heterobilayers recommended here can be used in photovoltaic applications, and the presence of effects of external electric fields and strain promises functional optoelectronic devices.

Effects of external electric field on adsorption behavior of organic molecules on stanene: Highly sensitive sensor devices

Motivated by the recent advances in stanene based devices for potential application such as superior gas sensors and electronic devices, we systematically investigated the structural configurations, adsorption energies and charge transfer of organic molecules (OM) on stanene sensors using first-principles calculations. The results show that aniline (C6H7N) and chlorobenzene (C6H5Cl) act as charge acceptors and are chemisorbed on stanene with sizable adsorption energies for the most stable OM/stanene systems. In particular, C6H7N/stanene and C6H5Cl/stanene systems can open the band gaps with 114.3 and 5.0 meV, respectively. Moreover, adsorption energies, charge transfer and band gaps of OM/stanene systems under external electric field can change dramatically, which indicates that external factors on stanene are highly preferred. Our results provide a theoretical basis for the application of stanene in highly sensitive sensor devices.

Electric field induced magnetism decline in organic ferromagnets

With an Anderson-like model including electron-electron interaction and electron-lattice interaction, the effect of external electric field on the electric and magnetic properties of quasi-one-dimensional organic ferromagnets is investigated theoretically. The results demonstrate a field-induced magnetism decline of the organic ferromagnet, which manifests a continuous decrease of the total molecular spin and suppression of the spin density wave after a critical field. The analysis of energy band evolution under the field indicates that the field-induced energy levels crossover of the spin-split flat bands is responsible for the magnetism decline. A companied charge polarization and charge transfer between spin radicals and main chain in the OF are observed. Different strength of the internal interactions including electron-electron interaction, hopping integral between radicals and main chain, and electron-lattice interaction is discussed. This work is helpful to understand the property of organic ferromagnets under external field in the situation of organic-ferromagnetic devices.

Theoretical Prediction of the Structural and Electronic Properties of a Single Layer Graphene-like Two-dimensional Janus GaInSTe

This paper constructs a new type of two-dimensional graphene-like Janus GaInSTe monolayer and systematically investigates its structural and electronic properties as well as the effect of external electric field using first-principles calculations. In the ground state, Janus GaInSTe monolayer is dynamically stable with no imaginary frequencies in its phonon spectrum and possesses a direct band gap semiconductor. The band gap of Janus GaInSTe monolayer can be tuned by applying an electric field, which leads the different transitions from semiconductor to metal, and from indirect to direct band gap. These findings show a great potential application of Janus GaInSTe material for designing next-generation devices.

Effect of external electric field on the formation of colloidal Ag–Au alloy nanoparticles through laser post-irradiation

We report the synthesis of Ag–Au alloy nanoparticles (NPs) by post-irradiation of mixed colloidal Ag and Au NPs by a nanosecond pulse laser in the presence of an external electric field (EEF). In our study, size, optical, and plasmonic properties of colloidal Ag–Au alloy NPs were investigated. A colloid of individual Ag and Au NPs were separately prepared by nanosecond pulsed laser ablation in distilled water. An appropriate volume of these colloidal NPs samples was mixed and post-irradiated with the same pulsed laser beam in the presence of a uniform electric field, resulting in the formation of Ag–Au alloy NPs. The synthesized colloidal alloy NPs were characterized using scanning electron microscopy and UV–vis absorption spectroscopy. The results indicate that the EEF can reduce significantly the Ag–Au alloy formation time. The results also show that the wavelength of the localized surface plasmon resonance of alloy NPs decreased by the applied electric field.

Effect of external electric field on the tautomeric equilibrium and structure of 2‐carbamido‐1,3‐indandione

Abstract2‐Carbamido‐1,3‐indandione (CAID) is a new reliable fluorescent biomarker and it exists in two tautomeric forms: 2‐(hydroxyl‐aminomethylidene)‐indan‐1,3‐dione (A) and 2‐carboamide‐1‐hydroxy‐3‐oxo‐indan (B). The structures of the tautomers and the transition state for intramolecular proton transfer are located at MP2/6‐31+G(d) level for each magnitude and for opposite directions of the applied electric field. According to our SCS‐MP2/6‐31+G(d) field‐free calculations tautomer A prevails (59.3%) while variation of the electric field strength along the direction from the indandione moiety to the carbamido fragment (+x‐direction) leads to stabilization of tautomer B. The two tautomeric forms become isoenergetic at 2.571 V/Å when the applied electric field is parallel to the direction from amino to the hydroxyl group (−y‐direction) in CAID, and at 3.085 V/Å tautomer B (51.9%) is slightly favored. Apparently, an external electric field has a strong influence on the tautomeric equilibrium in the CAID molecule.