Effect Of External Electric Field Research Articles

Molecular modeling of the structural, electronic, excited state dynamic, and the photovoltaic properties of the oligomers of n-corannulene (n = 1–4)

Despite the fact that n-corannulene oligomers (n = 1–4) have a variety of electronic and optical properties, including the ability to be tuned and the potential to be used as light-harvesting materials, there has not been a computational assessment of their structural, electronic, and optical properties. Herein, a computational evaluation of the concerned materials regarding their potent use in solar cell technology has been conducted via DFT/CAM-B3LYP and M062X/6-311+G level of theory. It was observed that the calculated 1st frequency of the n-Corannulene (n = 1–4) were 144.15, 106.36, 48.96 and 42.21 respectively. Notably, the computed cohesive energy value increased as the number of Corannulene units increases while the electronic characteristics revealed that the chemical activity of the structures increased as the number of oligomers rose. Both calculation techniques demonstrate that the number of n-Corannulene oligomers increases the HOMO energy while decreasing the LUMO energy based on the external electric field (EF) effect. The findings demonstrated that as EF intensity increases, the energy gap (Eg/eV = |EHOMO-ELUMO|) of these molecular systems decreases which can be attributed to a decrease in the electron transfer potential barrier. The 4-Corannulene systems showed the highest wave length of adsorption for the investigated compound at 546.18 nm, with the highest oscillator strength of 0.2708 and the lowest transition energy of 2.2700 eV, arising from S0–S1 (H-L) and the highest major percentage contribution of 93.34 % in comparison to the investigated compounds. We are hopeful that this research will help experimental researchers understand the potential of n-Corannulene, specifically 4-corannulene, as powerful material for a variety of applications ranging from solar cell, photovoltaic properties and many others.

Toward metal- and catalyst-free Reactions: Deciphering the substituent and external electric field effects on the Diels-Alder reaction between ethylene and nitrosoethylene

The substituents on the diene and/or dienophile can contribute to the decrease or increase of this energy. However, there are other approaches to catalyze chemical reactions, particularly Diels-Alder reactions, for example, the application of an electric field along the reaction axis. The existence of an external electric field (EEF), properly oriented, has the potential to further stabilize or destabilize these electron density contributors and thus influence the energy. The goal of this study was to compare the activation energies of the Diels-Alder reaction between ethylene and nitrosoethylene, using an electric field, Lewis acid (BH3) as catalysts, and the influence of substituents. All calculations were performed with Gaussian09 software. The compounds were fully optimized using the restricted Hartree-Fock method with the basis set 6-31G, and single-point energies were determined with the MP3 method and basis set 6-31G. The effects of EEFs were studied using the “Field = M ± N” keyword with F values (F=±0.125 au and ± 0.080 au) along the preferred axis. The lowest activation barrier is encountered when the electric field is applied, followed by the use of borane as the Lewis acid.

Electronic and optical characteristics of Silicane/GeAs van der Waals heterostructures: Effects of external electric field and biaxial strain: A first-principles study

The van der Waals heterostructure offers unusual physical properties to design novel structures for efficient optoelectronic applications. To enhance the low mobility of monolayer SiH and broaden the light absorption coefficient and range of monolayer SiH, a lattice-matched SiH/GeAs vdWh has been constructed. At the same time, the basic electronic and optical properties were investigated by first-principles calculations. The SiH/GeAs vdWh with six different structural configurations were compared, and the most stable configuration model H2 has a type-II band alignment with an indirect bandgap semiconductor value of 1.54 eV. It is associated with a strong charge transfer. Moreover, SiH/GeAs vdWh possesses anisotropic transport properties with high electron mobility along the y-direction. Interestingly, both external electric field and biaxial strain can adjust band offsets and bandgaps values. After applying vertical electric fields, The SiH/GeAs vdWh has a mutual transformation from type-I (symmetric) to type-II(staggered) to type-III(broken) band alignment, and metal-semiconductor phase transitions occurred at −0.35 and 0.15 V/Å. Besides, it's found that band alignment transition from type-II to type-I emerged under the in-plane biaxial strain of 2% and transformed indirect into direct bandgap. More importantly, tensile biaxial strain can enhance the visible-light absorption while sustaining type-II band alignment, which is favorable for photocatalysis of visible light. Our results indicate that the SiH/GeAs vdWh's moderate bandgap, excellent transport properties and optical performance may have potential applications in the field of nanoelectronic and optoelectronic devices.

The effects of external electric field and additional strain on electronic and magnetic properties of CrI3/SnC heterostructure

The electronic properties of CrI3/SnC heterostructure are investigated by the first-principles method. The Curie temperature (Tc) of CrI3/SnC heterostructure (57.1 K) is higher than that of monolayer CrI3 (∼45 K) significantly, and the nonmagnetic SnC monolayer is also magnetized. CrI3/SnC heterostructure shows an intrinsic type-II band alignment with the band gap (Eg) of 0.34 eV, which facilitates the separation of photogenerated electrons and holes in photoelectric devices. Applying strain and electric field (Eext) can effectively tune the electronic properties of the heterostructure. The transition from semiconductor to metal can be observed when applying greater horizontal strain or stronger Eext. The highest Tc can reach 89.4 K and 207.2 K by applying vertical compressive strain and horizontal uniaxial compressive strain, respectively. The half-metal feature can be realized when Eext = −0.8 V/nm. These findings suggest a new possibility for developing magnetic heterostructure devices.

Effect of external electric field on the electronic structure of MoSe2/Arsenene heterojunction

In this paper, the effects of the thermostability, band structure, and the external electric field on the electronic structure of MoSe2/Arsenene heterojunction are calculated based on the density functional theory. The calculation results show that the MoSe2/Arsenene heterojunction is a type-II heterojunction with a bandgap of 0.89[Formula: see text]eV. When MoSe2 and arsenene combine by van der Waals force, the electrons are transferred from MoSe2 to arsenene, the holes are transferred from arsenene to MoSe2, with the direction of the internal electric field from MoSe2 to arsenene. The MoSe2/Arsenene heterojunction with valence band top and conduction band bottom contributed by arsenene and MoSe2, respectively, shows excellent thermostability at room temperature. The external electric field can effectively modulate the electronic structure of heterojunction. When the electric field is negative, electrons are transferred from MoSe2 to arsenene and holes from arsenene to MoSe2. The Fermi level of arsenene moves down while that of MoSe2 moves up. When the electric field is positive, the direction of electron and hole transfer are opposite to that when the electric field is negative. The Fermi energy level of arsenene and MoSe2 also move in the opposite direction.

Effects of vacancy and external electric field on the electronic properties of the MoSi2N4/graphene heterostructure

Recently, the newly synthesized septuple-atomic layer two-dimensional (2D) material MoSi2N4 (MSN) has attracted attention worldwide. Our work delves into the effect of vacancies and external electric fields on the electronic properties of the MSN/graphene (Gr) heterostructure using first-principles calculation. We find that four types of defective structures, N-in, N-out, Si and Mo vacancy defects of monolayer MSN and MSN/Gr heterostructure are stable in air. Moreover, vacancy defects can effectively modulate the charge transfer at the interface of the MSN/Gr heterostructure as well as the work function of the pristine monolayer MSN and MSN/Gr heterostructure. Finally, the application of an external electric field enables the dynamic switching between n-type and p-type Schottky contacts. Our work may offer the possibility of exceeding the capabilities of conventional Schottky diodes based on MSN/Gr heterostructures.

Electric field as a crystallization switch of heterogeneous ice formation

Using molecular dynamics simulations, we investigated the effect of external electric field on ice formation with the present of a substrate surface. It turns out that the electric field can affect the ice formation on substrate surface by altering the dipole orientation of interfacial water molecules (IWs): a crossover from inhibiting to promoting ice formation with the increase of electric field strength. According to the influence of the electric field on ice formation, the electric field strength range of 0.0 V nm−1–7.0 V nm−1 can be divided into three regions. In the region I and region III, there are both ice formation on the substrate surface. While, the behavior of IWs in the region I and region III are distinguished, including the arrangements of oxygen atoms and the dipole orientation distribution. In region II, ice formation does not occur in the system within 5 × 200 ns simulations. The IWs show a disorder structure, preventing the ice formation process on substrate. The interfacial water molecular orientation distribution and two-dimensional free energy landscape reveals that the electric field can alter the dipole orientation of the interfacial water and lead a free energy barrier, making the ice formation process harder. Our result demonstrates the external electric field can regulate the behavior of IWs, and further affect the ice formation process. The external electric field act as a crystallization switch of ice formation on substrate, shedding light into the studies on the control of ice crystallization.

Quantum information diode based on a magnonic crystal

Exploiting the effect of nonreciprocal magnons in a system with no inversion symmetry, we propose a concept of a quantum information diode (QID), i.e. a device rectifying the amount of quantum information transmitted in the opposite directions. We control the asymmetric left and right quantum information currents through an applied external electric field and quantify it through the left and right out-of-time-ordered correlation. To enhance the efficiency of the QID, we utilize a magnonic crystal. We excite magnons of different frequencies and let them propagate in opposite directions. Nonreciprocal magnons propagating in opposite directions have different dispersion relations. Magnons propagating in one direction match resonant conditions and scatter on gate magnons. Therefore, magnon flux in one direction is damped in the magnonic crystal leading to an asymmetric transport of quantum information in the QID. A QID can be fabricated from an yttrium iron garnet film. This is an experimentally feasible concept and implies certain conditions: low temperature and small deviation from the equilibrium to exclude effects of phonons and magnon interactions. We show that rectification of the flaw of quantum information can be controlled efficiently by an external electric field and magnetoelectric effects.

Effects of external electric and magnetic field on the nonlinear optical rectification, second, and third-harmonic generations in GaAs/AlGaAs asymmetric triple quantum well

Effects of external electric and magnetic field on the nonlinear optical rectification, second, and third-harmonic generations in GaAs/AlGaAs asymmetric triple quantum well

Ab initio study of electric field effects on phonon vibrations in tetragonal ZrO2

The effects of external electric fields on phonon-associated phenomena, such as phase transformation and diffusion in ZrO2 ceramics, have been reported from recent experiments. This study examined the effects of external direct current (DC) electric fields on the phonon vibration properties in a tetragonal ZrO2 unit cell based on the density-functional perturbation theory. Phonon dispersions and densities of states were analyzed with optimized structures under varying external DC electric fields up to 45 mV/Å. The field sensitivities of phonon characteristics exhibited significant orientation dependence and were attributed to ionic polarization associated with symmetry breaking in dielectric properties. Optical phonons showed considerable field sensitivities particularly near the Brillouin zone boundaries, such as in the M (π/a, π/a, 0) to X (0, π/a, 0) and A (π/a, π/a, π/c) to R (0, π/a, π/c) directions, where doubly degenerate phonon frequencies exhibited splitting behaviors associated with the symmetry breaking between two unique oxygen atoms in the original unit cell. In contrast, transversal acoustic phonons demonstrated a softening trend with increasing field strengths around the Z (0, 0, π/c) point, where imaginary and splitting frequencies were obtained under electric fields of >40 mV/Å, indicating the potential phase transformation from the tetragonal to orthorhombic symmetries under strong external electric fields.

Effect of external electric fields in the charge transfer rates of donor-acceptor dyads: A straightforward computational evaluation.

We present a straightforward and low-cost computational protocol to estimate the variation of the charge transfer rate constant, kCT, in a molecular donor-acceptor caused by an external electric field. The proposed protocol also allows for determining the strength and direction of the field that maximize the kCT. The application of this external electric field results in up to a >4000-fold increase in the kCT for one of the systems studied. Our method allows the identification of field-induced charge-transfer processes that would not occur without the perturbation caused by an external electric field. In addition, the proposed protocol can be used to predict the effect on the kCT due to the presence of charged functional groups, which may allow for the rational design of more efficient donor-acceptor dyads.

Modulation of contact types and Schottky barrier in Ti3C2T2/TiSi2N4 (T = O or OH) van der Waals heterostructures by biaxial strain and external electric field

A new kind of two-dimensional semiconductor, MA2Z4, has shown exceptional electrical and mechanical properties, that make it suitable for use as a semiconductor device. In this paper, metallic Ti3C2T2 (T = O or OH) and semiconductor TiSi2N4 van der Waals heterostructures are constructed, and their interfacial characteristics are investigated under the effect of biaxial strain and external electric field. Due to the different terminations on Ti3C2 surfaces, Ti3C2O2/TiSi2N4 exhibits an n-type Schottky contact whose Schottky barrier is 0.718 eV, and Ti3C2(OH)2/TiSi2N4 exhibits an Ohmic contact. Furthermore, the Ti3C2O2/TiSi2N4 heterojunction can be changed from n-type Schottky contact to p-type Schottky contact by applying biaxial strain or external electric field, while the Ti3C2(OH)2/TiSi2N4 heterojunction keeps an Ohmic contact unchanged during the process. Our results demonstrate their potential as candidates for tunable nanoelectronic devices and field-effect transistors.

A computational study of the effect of external heat flux and electric field on the nano-pumping of C20 molecules in carbon nanotubes by molecular dynamics simulation

Nano-pump is a breakthrough that allows a tiny pump to transfer mass inside the atomic channels. These nanostructures can be used in various applications, such as drug delivery systems in clinical cases. Carbon nanotube (CNT) performance as a nano-pump sample was introduced here. For this purpose, Molecular Dynamics (MD) approach, and external heat flux/electric field effect on nano-pump performance were reported. Hence, various physical parameters, such as nano-pumping time, potential/kinetic energy, stress and entropy were reported to describe the nano-pumping performance of CNT samples. Technically, nano-pumping performance was detected by fullerene (C20) molecule displacement inside the NT. The MD outputs indicated by the heat flux implemented inside CNT, nano-pumping process effectively occur. The results show that by increasing the heat flux amplitude ratio from 0.1 to 0.5 W/m2, the displacement time of C20 molecule decreased from 7.49 to 6.96 ps. By amplitude enlarging, the kinetic energy of defined sample converged to 5.70014 eV. This procedure caused more atomic collisions inside the NT, and the nano-pumping process occurred in a smaller time. Furthermore, the electric field caused the nano-pumping process to be delayed in modeled systems. Numerically, by increasing the electric field, the nano-pumping process occurred after 7.85 ps. Increasing the electric field decreased the mechanical wave produced via Cu tip oscillation. This evolution caused the atomic force, and stress on the target particle converged to a lesser value, and the lattice stress value of modeled sample reached 2.12662 × 106 bar.

Влияние электрического поля на рекомбинационную люминесценцию коллоидных квантовых точек сульфида серебра

The paper studies the effect of external electric field on the optical properties of the spherical Ag2S quantum dots. Colloidal Ag2S nanoparticles passivated with 2-mercaptopropionic acid were obtained by photoinduced synthesis in the ethylene glycol. The nanoparticles shape and characteristic size were determined using the transmission electron microscopy. To analyze the external electric field influence, a series of samples was prepared based on the optically passive polymer film, where the nanoparticles were embedded. The films were placed between two glasses coated with the transparent electrodes based on the indium tin oxide (ITO). Intensity value of the external electric field created in such structures reached 500 kV/cm. The photoluminescence signal was registered using the CCD fiber spectrometer with spectral resolution of 1.16 nm. Spectrally resolved nanoparticles photoluminescence kinetics was measured by time-corre-lated counting of the separate photons. It was found that the presence of a field led to an increase in intensity and rate of the photoluminescence relaxation due to the surface states. This fact is related to acceleration of the free holes transportation to the recombination centers in the external electric field. It is shown that under long-term exposure to laser radiation with a wavelength of 405 nm and the average power of 5 mW, the nanocrystal photoluminescent properties could degrade, as it occurs due to formation of new centers of non-radiative recombination and photoionization of the quantum dots

Modulating via External Electric Field an Electronic Band Gaps in 2D 1T-PdS2 monolayer

We have examined structural stability and electronics properties of 2D 1T-PdS2 monolayer within the Density Functional Theory (DFT). 1T-PdS2 monolayer has indirect narrow band gap of 1.16 eV along the wave vector path of Γ-M-K-Γ in first Brillouin zone. The positive phonon dispersion curves at gamma point confirmed the dynamic stability of the 1T-PdS2 monolayer. Under the external electric field effect, the diverting nature has seen in the electronic band gaps within the intensity span of -5.0 V/Å to +5.0 V/Å along ±Z-direction. Hence, we could modulate the band gaps of semiconductor by applying external electric field, which is helpful for band engineering application. In this way, the semiconductor 2D 1T-PdS2 monolayer is capable candidate for nanoelectronics devices.

Effects of external magnetic and electric field on multipactor and plasma breakdown of high-power microwave window

In this work, we investigated the effects of an external magnetic field, a DC electrostatic field, and a normal rf electric field on the multipactor and plasma ionization breakdown process near a microwave window by performing kinetic particle-in-cell/Monte Carlo collision simulations, and the underlying mechanism is also given. The magnetic field, parallel to the surface and perpendicular to the tangential rf field, can effectively suppress the electron multipactor process by delaying the electron incidence on the dielectric window and push the plasma breakdown bulk away from the dielectric window. However, when the magnetic field is too strong, the mitigation effect is not significant, and may even enhance the multipactor process at the beginning of the plasma breakdown. The external DC electrostatic field, perpendicular to the surface, can inhibit electron multipactor when it points toward the surface. On the other hand, when the DC electric field direction is reversed, then the electron multipactor process is found to be promoted, and the gas ionization bulk is closer to the dielectric window. The external normal rf electric fields perpendicular to the surface with small amplitudes are found to be capable of promoting the multipactor process. With increasing the amplitude of normal rf electric field, the multipactor process can be suppressed to some degree at the initial stage of the plasma breakdown and the gas ionization bulk region is kept away from the dielectric window surface.

Molecular dynamics simulation of water condensation with nucleus under electromagnetic wave irradiation

The condensation process of water with different nuclei under electromagnetic wave irradiation was studied by molecular dynamics simulation. It was found that there is a different electric-field effect when the condensation nucleus was a small (NH4)2SO4 cluster than a CaCO3 nucleus. Through the analysis of the hydrogen-bond number, energy change, and dynamic behavior, we found that the effect of external electric field on the condensation process mainly comes from the change of potential energy caused by the dielectric response and there is a competition effect between the dielectric response and the dissolution in the system with (NH4)2SO4.

Molecular Dynamics Simulation of the Influence of External Electric Fields on the Glass Transition Temperature of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide

We present the results of molecular dynamics simulations of the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2C1im][NTf2] in the presence of external electric fields (EEFs) of varying strengths to understand the effects of EEFs on the glass transition temperature Tg. We compute Tg with an automated and objective method and observe a depression in Tg when cooling the IL within an EEF above a critical strength. The effect is reversible, and glasses prepared with EEFs recover their original zero-field Tg when heated. By examining the dynamics and structure of the liquid phase, we find that the EEF lowers the activation energy for diffusion, reducing the energetic barrier for movement and consequently Tg. We show that the effect can be leveraged to drive an electrified nonvapor compression refrigeration cycle.

Disclose effect and mechanism of external electric field on RP-1 fuel pyrolysis

To explore the combustion efficiency of aviation fuel in an electric field, a ReaxFF molecular dynamics and density functional theory calculation was performed to study the electric field effect on 3-component RP-1 (methylcyclohexane, n-dodecane, and isododecane) pyrolysis. The electrostatic potential, charge natural population analysis and molecular structure were discussed under electric fields of various directions and strengths. The chemical reaction kinetics and species were analyzed under a wide range of electrostatic fields and temperatures. The key reaction energy of RP-1 components and motion statistics were discussed. The analysis revealed significant changes in molecular charge density and structure, which predicted possible cracking sites. Cyclohexane and chain alkanes exhibited opposite trends of decomposition rates depending on the field strength and temperature. The different trends were detail analyzed by reaction pathways and product distribution. Newly cracking way appeared under electric field. The decomposition reaction barrier was reduced by the electric field overall. While the motion of molecules was inhibited with the field increasing, which decrease the molecular potential energy. This work conducted a comprehensive analysis about effect of external electric field on the RP-1 mixture fuel pyrolysis. offering a potential solution for improving combustion efficiency.

Controllable contact types of Janus MoSH and WSi2N4 van der Waals heterostructures via biaxial strain and external electric field

Using the first-principles calculations, we construct the metallic Janus MoSH and semiconductive WSi2N4 van der Waals heterostructure (VHT) and investigate their interfacial characteristics under the effect of biaxial strain and external electric field. Due to vertical symmetry breaking, there are two kinds of stacking patterns: H or S surfaces in contact with the WSi2N4 monolayers. They are both p-type Schottky contact (ShC) whose p-type Schottky barriers are 0.92 and 0.17 eV, respectively. Under the regulation of the biaxial strain, the MoSH and WSi2N4 VHTs can transform among n-ShC, p-ShC and Ohmic contact (OhC). However, the modulation of the electric field only causes the transition from p-ShC to n-ShC for H surface contact or from p-ShC to OhC for S surface contact. Therefore, the biaxial strain is more effective in adjusting interfacial characteristics than the electric field. Our finding indicates that the Janus MoSH and WSi2N4 VHTs are adjustable for metal/semiconductor contact, which has good potential to apply in Schottky electronic devices.