Hole Energy Research Articles

Энергетический спектр и волновые функции дырок в 2D-сверхрешетках из квантовых проволок (GaAs/AlAs)

A numerical analysis of the hole energy spectrum and wave functions in a 2D (GaAs/AlAs) quantum wire (QWr) superlattice (SL) with arbitrary cross-section is presented. The intricate fourfold degenerate nature of valence band Г8 of the given materials is taken into account. The presented approach is based on a modified effective mass method, wherein the microscopic structure of the heterostructure and hole kp-interaction in the valence band are considered. It is shown that the solution of this problem in a k-representation is reduced to an eigenvalue problem for a matrix Hamiltonian. Superlattices of quantum wires with different cross-sections (square, circle, ellipse, and ring) are considered as an example. The influence of superlattice parameters on the hole energy spectrum is studied. Anti-crossing effects in the hole dispersion law are observed. For the hole ground and excited states, the wave function spatial distribution in the plane perpendicular to the QWr axis is also studied.

On the Necessity to Replace the Spherical Shape of Black Holes with a Disc Shape and Doubling their Energy

At the present time, black holes are reduced to the parameters of the Schwarzschild sphere. It is shown that Schwarzschild determined only half of the mass and energy of a black hole, and its spherical shape makes it difficult to interact with the external environment. The elimination of this drawback is the main goal of this work, and the substantiation of the shape, structure and parameters of black holes on the basis of the strict laws of the material world is its scientific novelty. The Methods of Research: Used in the work are based on deduction and induction, as well as on the application of reliable laws of physics and the general principles of the theory of knowledge. Work Results: It is proposed to replace the Schwarzschild sphere at the quantum level of the material world with a hole-die, which consists of 2 layers of hexagonal prisms of circular space quanta, formed from 6 regular trihedral prisms of elementary space quanta. The length of all their faces is λG =4.05126∙10-35m and is equal to the wavelength of the gravitational field forming this hole. Its energy and mass are doubled to the energy E = mc2 due to the rotation of the gravitational field in it. The radical change of the disk hole-die by concentric columns per λG quantum is justified. A possible connection between black and white holes is shown. Conclusion: Strict calculated dependences are found and numerical values are obtained on their basis, confirming the new parameters of disk-shaped black holes.

4D Einstein–Gauss–Bonnet Gravity Coupled to Modified Logarithmic Nonlinear Electrodynamics

Spherically symmetric solution in 4D Einstein–Gauss–Bonnet gravity coupled to modified logarithmic nonlinear electrodynamics (ModLogNED) is found. This solution at infinity possesses the charged black hole Reissner–Nordström behavior. We study the black hole thermodynamics, entropy, shadow, energy emission rate and quasinormal modes. It was shown that black holes can possess the phase transitions and at some range of event horizon radii black holes are stable. The entropy has the logarithmic correction to the area law. The shadow radii were calculated for variety of parameters. We found that there is a peak of the black hole energy emission rate. The real and imaginary parts of the quasinormal modes frequencies were calculated. The energy conditions of ModLogNED are investigated.

Particles Dynamics in Schwarzschild like Black Hole with Time Contracting Horizon

The black holes radiate their mass and energy in the form of gravitational waves and Hawking-radiation, which lead to a decrease in the mass and energy of the black holes. During the formation of gravitational waves and Hawking radiation, the mass and energy of black holes reduce continuously with the passage of time t. For this reason the metric tensor of the black hole should depends on time t. In this work, a time-dependent term is introduced in the horizon of black hole without losing its symmetry structure by using the approximate Noether symmetry equation. The time-dependent term affects the effective potential, effective force, and all the dynamic features of the black hole. They are discussed for neutral and charged particles. Profiles of the escape velocity of colliding particles are also taken into consideration. Lyapunov exponent is used to check the stability of the orbits of the black hole. Hawking temperature, Bekenstein entropy, Komar energy, and specific energy at horizon of the black hole are discussed in this scenario.

High dimensional AdS-like black hole and phase transition in Einstein-bumblebee gravity* *Supported by the Scientific Research Fund of the Hunan Provincial Education Department (19A257 and 19A260), the National Natural Science Foundation (NNSFC) of China (11247013), Hunan Provincial Natural Science Foundation of China (2015JJ2085)

In this study, we obtained an exact high dimensional anti-de Sitter (AdS) black hole solution in Einstein-bumblebee gravity theory. This AdS-like black hole can only exist with a linear functional potential of the bumblebee field. We found that the Smarr formula and the first law of black hole thermodynamics can still be constructed in this Lorentz symmetry breaking black hole spacetime, but the conceptions of the black hole horizon area/entropy and the volume inside the horizon should be renewed due to its anisotropy. We also found that two types of phase transition exist: small-large black hole phase transition and Hawking-Page phase transition, like those of the Schwarzschild AdS black hole. After Lorentz symmetry breaking, the black hole mass at the divergent point of heat capacity becomes small, and the Gibbs free energy of the meta-stable large black hole is also smaller, showing that the large stable black hole can be more easily formed.

Quantum mechanical modeling of fused rings-based small-donor molecules with enhanced optoelectronic attributes for high performance organic photovoltaic cells

Seven small molecule donors (S1–S7) have been theoretically formulated by the end-capped modeling of acceptors of reference SR. Through density functional and its time-dependent theory, different photo-physical, morphological, and opto-electronic aspects of the newly reported molecules were analyzed with reference to the SR molecule. Amongst the different studied features were the absorption maxima (λmax), transition density matrix, frontier molecular orbitals, reorganization energies of hole and electron, excitation energies, bandgaps, fill factor, and open circuit voltage (VOC), etc. Individually, the S4 molecule had the smallest bandgap and electron reorganization energy, the highest ionization potential and λmax, as well as the smallest excitation energy in the analyzed gas and chloroform phases. While the smallest interaction coefficient was seen to be of S1. The VOC of all the donor molecules computed with respect to PC61BM acceptor revealed the greatest VOC and fill factor of S1 and S4 molecules. So, it could be understood that these molecules, with special reference to S1 and S4, might outperform SR in a variety of ways, and hence are suggested to experimentalists for future innovations of organic photovoltaic cells.

Horizon Thermodynamics in f(R,G)$f(R,\mathcal {G})$ Gravity

AbstractIn this manuscript, we evaluate the validity of the horizon first law in the framework of gravity. We propose that the energy and entropy of a black hole must be consistent with their relating integration values. The feasibility of the newly proposed horizon 1st law as a result of equations of motion in gravity, will have significant importance in our illustration. The derivation of black hole energies and entropies in the framework of specific models will be helpful in future research. We study that how the positivity of energy and entropy can impose additional restrictions on the domain of gravity. Moreover, we shall consider a flat FLRW model corresponding to theory and will derive the related Friedman equations. The Cai‐Kim technique will then be used to evaluate the expression for energy flux passing through the horizon in insignificantly small time. In addition, we use the Clausius relation related to the evident boundary as well as the Cai‐Kim technique and the relating Friedmann equations, to find the expression for horizon entropy.

Excellent surface plasmon and hot carrier properties of transition metal nitride at different temperatures

Plasmonic materials that exhibit excellent plasmonic behavior at high temperatures would greatly expand existing applications, but the search for such materials is ongoing. Transition metal nitrides with good conductivity and high-temperature stability are promising candidates for temperature-dependent plasmonic applications. Here, we systematically investigate the temperature-dependent surface plasmon and hot carrier properties of TiN and VN. Significantly, high temperatures significantly affect the phonon-assisted intraband transition processes. Meanwhile, TiN and VN exhibit efficient optical absorption and low surface plasmon loss at different temperatures, which are comparable to or even higher than Ag. In particular, the surface plasmon response of TiN extends to visible light, making it an excellent candidate for low-loss and broadband plasmonic applications at high temperatures. In contrast, VN exhibits a much narrower plasmonic window, which is mainly suitable for infrared low-loss plasmonic devices. For hot carriers, the energy and probability distributions of hot holes in TiN and hot electrons in VN exhibit robustness to temperature. Meanwhile, transport properties indicate that the temperature effect on hot holes is significantly higher than that on hot electrons in TiN and VN. Therefore, we expect that the reported results will provide theoretical guidance for the design of next-generation high-temperature plasmonic devices.

Unraveling the complexation effect of electron transporting materials with Liq on the charge transport properties: A theoretical perspective

The effect of coordinated structures of electron transporting materials (ETMs) withlithium quinolate (Liq)on charge transport characteristics was theoretically investigated.Thereorganization energies of holes(λh)and electrons (λe)ofETM-Liqsimultaneously increased compared with those of ETMs, indicating that the charge transporting is retarded. Interestingly,λeofETM-(Liq)n increased, whileλh decreased. Regarding transfer integrals forholes (th) and electrons (te),th‘s ofT2T-LiqandBPyTP2-Liqwere significantly reduced withteofT2T-Liqdecreasing tremendously.Consequently, the hopping rates of holes of Liq-complexes were reduced, while that of electrons ofBPyTP2-Liqincreased and that ofT2T-Liq/TSPO1-Liqwas reduced.

Shadows and gravitational weak lensing by the Schwarzschild black hole in the string cloud background with quintessential field* *G. Mustafa acknowledges the Grant No. ZC304022919 to support his Postdoctoral Fellowship at Zhejiang Normal University. F.A. acknowledges the support of Inha University in Tashkent and research work has been supported by the Visitor Research Fellowship at Zhejiang Normal University. This research

In this study, we observe that, in the presence of the string cloud parameter a and the quintessence parameter γ, with the equation of state parameter , the radius of the shadow of the Schwarzschild black hole increases as compared with that in the pure Schwarzschild black hole case. The existence of both quintessential dark energy and the cloud of strings increases the shadow size; hence, the strength of the gravitational field around the Schwarzschild black hole increases. Using the data collected by the Event Horizon Telescope (EHT) collaboration for M87* and Sgr A*, we obtain upper bounds on the values of a and γ. Further, we see the effects of a and γ on the rate of emission energy for the Schwarzschild black hole. We notice that the rate of emission energy is higher in the presence of clouds of strings and quintessence. Moreover, we study the weak deflection angle using the Gauss-Bonnet theorem. We show the influence of a and γ on the weak deflection angle. We notice that both a and γ increase the deflection angle α.

Tailoring Interfacial Charge Transfer for Optimizing Thermoelectric Performances of MnTe‐Sb2Te3 Superlattice‐Like Films

AbstractInterfacial charge transfer has a vital role in tailoring the thermoelectric performance of superlattices (SLs), which, however, is rarely clarified by experiments. Herein, based on epitaxially grown p‐type (MnTe)x(Sb2Te3)y superlattice‐like films, synergistically optimized thermoelectric parameters of carrier density, carrier mobility, and Seebeck coefficient are achieved by introducing interfacial charge transfer, in which effects of hole injection, modulation doping, and energy filtering are involved. Carrier transport measurements and angle‐resolved photoemission spectroscopy (ARPES) characterizations reveal a strong hole injection from the MnTe layer to the Sb2Te3 layer in the SLs, originating from the work function difference between MnTe and Sb2Te3. By reducing the thickness of MnTe less than one monolayer, all electronic transport parameters are synergistically optimized in the quantum‐dots (MnTe)x(Sb2Te3)12 superlattice‐like films, leading to much improved thermoelectric power factors (PFs). The (MnTe)0.1(Sb2Te3)12 obtains the highest room‐temperature PF of 2.50 mWm−1K−2, while the (MnTe)0.25(Sb2Te3)12 possesses the highest PF of 2.79 mWm−1K−2 at 381 K, remarkably superior to the values acquired in binary MnTe and Sb2Te3 films. This research provides valuable guidance on understanding and rationally tailoring the interfacial charge transfer of thermoelectric SLs to further enhance thermoelectric performances.

Exponential corrected thermodynamics of Born–Infeld BTZ black holes in massive gravity

It is known that entropy of black hole gets correction at quantum level. Universally, these corrections are logarithmic and exponential in nature. We analyze the impacts of these quantum corrections on thermodynamics of Born–Infeld BTZ black hole in massive gravity by considering both such kinds of correction. We do comparative analysis of corrected thermodynamics with their equilibrium values. Here, we find that the exponential correction yields to the second point of the first-order phase transition. Also, quantum correction affects significantly the Helmholtz free energy of larger black holes. We study the equation of state for the exponential corrected black hole to obtain a leading order virial expansion.

Effects of external perturbations on light absorption by light/heavy hole excitons in a semi-parabolic quantum well

The effects of electric, magnetic, and intense terahertz laser fields on optoelectronic properties are investigated in a GaAs/AlxGa1-xAs semi-parabolic quantum well. The binding energy, exciton light absorption coefficients, interband transition energies, and dipole elements in the matrix are studied within the structure of the parabolic band and effective-mass approximations. The transition energy difference between the ground-state electron energy level and the ground-state heavy hole (light hole) energy level and matrix elements are carried out as functions of external perturbations with a constant well size. The results exhibit that the exciton binding energies of heavy and light holes reduce as long as the laser dressing parameter is larger. The optical absorption of light hole exciton in the system is stronger than the heavy hole exciton. And the excitonic energies, transition energies, and absorption coefficients are much more sensitive and controlled by changing the external perturbations.

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories.

Non-volatile memories based on the flash architecture with self-assembled III-V quantum dots (SAQDs) used as a floating gate are one of the prospective directions for universal memories. The central goal of this field is the search for a novel SAQD with hole localization energy (Eloc) sufficient for a long charge storage (10 years). In the present work, the hole states' energy spectrum in novel InGaSb/AlP SAQDs was analyzed theoretically with a focus on its possible application in non-volatile memories. Material intermixing and formation of strained SAQDs from a GaxAl1-xSbyP1-y, InxAl1-xSbyP1-y or an InxGa1-xSbyP1-y alloy were taken into account. Critical sizes of SAQDs, with respect to the introduction of misfit dislocation as a function of alloy composition, were estimated using the force-balancing model. A variation in SAQDs' composition together with dot sizes allowed us to find that the optimal configuration for the non-volatile memory application is GaSbP/AlP SAQDs with the 0.55-0.65 Sb fraction and a height of 4-4.5 nm, providing the Eloc value of 1.35-1.50 eV. Additionally, the hole energy spectra in unstrained InSb/AlP and GaSb/AlP SAQDs were calculated. Eloc values up to 1.65-1.70 eV were predicted, and that makes unstrained InGaSb/AlP SAQDs a prospective object for the non-volatile memory application.

(Invited) Extracting Photoelectrochemical Phenomena from Transient X-Ray Experiments

To date, ultrafast X-ray spectroscopy has been used to measure electron and hole energies, mid-gap state recombination, small polaron formation, and transport of carriers in multi-layer junctions – explaining its appeal for studying photocatalysis and photoelectrochemistry. While ultrafast x-ray spectroscopy can measure both structural and electronic dynamics, the resulting transient plots are complex and hard to interpret because of how photoexcitation perturbs the core-level transition. We will discuss progress in theory and experiment that now allows routine interpretation of photoexcited X-ray edges using a customized DFT-GW-Bethe Salpeter Equation approach. In addition to interpreting excited state phenomenon, the code can project the X-ray peak structure and the relevant X-ray Hamiltonian components - such as angular momentum coupling, screening, and state-filling – onto the band structure to help give physical intuition as to why the measured spectra appear the way they do. The talk will cover the general principles of how photoexcitation modifies transient X-ray spectra rather than detailed theory. Example experiments will include photoelectrodes ranging from ZnTe to complex transition metal oxides.

Tuning the visible-NIR absorption of azulenocyanine-based photosensitizers.

A new photosensitizer 1-WS55 (dyad) based on two dyes with excellent properties, azulenocyanine (1) and WS55, is proposed at the density functional theory level (M06/def2-SVP). 1 is a dye having a broad NIR absorption (~ 1000nm), and WS55 is a metal-free organic dye that presents a huge photoelectric conversion efficiency (PCE) of 9.5%. The dyad presents a panchromatic absorption along the UV-Vis-NIR region. It exhibits two intense Q bands (880, 926nm) in the NIR region, one strong band (672nm) in the visible region, and several bands in 300-600nm. Charge transfer bands in the dyad from 1 to WS55 were found in the visible region, which favors the adsorption on an anatase TiO2 surface. The interaction energies dyad (dye)-TiO2 were calculated as a periodic system and corrected by the basis set superposition error. These show better adsorption for the dyad than fragments 1 and WS55. The electron injection calculated from the dye (dyad) to TiO2 suggests an efficient solar energy conversion because of ΔGinj > 0.2eV. Additionally, calculations performed for the reorganization energy of electrons and holes indicate that the dyad presents the highest charge mobility. In summary, the dyad proposed 1-WS55 constitutes an excellent candidate to be used as a potential photosensitizer for the DSSCs.

Optical properties of cylindrical quantum dots with diluted magnetic semiconductors structure

The optical properties of diluted magnetic semiconductor cylindrical quantum dot caused by interband transitions are investigated. The behavior of a quantum dot as a function of the energy of an incident photon is studied for various values of temperature, magnetic field, and structural parameters. It is shown that a change in the distance between the energies of electrons and holes in identical quantum states affects the maximum of the absorption coefficient. According to the results obtained, an increase in temperature increases the absorption maximum and shifts it toward lower energy. As the magnetic field increases, the absorption maximum decreases and shifts toward higher energy. In addition, it was found that the absorption threshold frequency varies linearly at high temperatures and nonlinearly at low temperatures depending on the magnetic field.

Photovoltaic properties and enhancement in near-infrared light absorption capabilities of acceptor materials for organic solar cell applications: A quantum chemical perspective via DFT

More than 22% power conversion efficiency (PCE) of organic solar cells (OSCs) has been reported with efficient narrow bandgap acceptor materials as the active layers. And end-capped modifications of such acceptor materials are an efficient approach for designing highly stable and efficient materials for organic solar cell applications. In this study, four new molecules (TOS1 to TOS4) are designed for the active layer of organic solar cells. Density functional theory and time-dependent functional theory have been employed for the computation of various geometric, photovoltaic, optoelectronic properties of newly designed molecules. Different analyses like frontier molecular orbitals, transition density matrix, open-circuit voltage, absorption maxima, excitation and binding energies have been performed and examined with great care. Further, reorganization energy of hole and electron of novel designed molecules has been calculated and results suggested that designed systems are effective contributors for future development of organic solar cells. Overall, the outcomes of this study urge the experimentalists for the future development of highly stable and near-infrared absorbing organic solar cells.

Phosphorus and kalium co-doped g-C3N4 with multiple-locus synergies to degrade atrazine: Insights into the depth analysis of the generation and role of singlet oxygen

In this work, with the help of KH2PO4, a phosphorus and kalium co-doped g-C3N4 with cyano and nitrogen vacancies (PKCN) have been prepared via a simple thermal treatment. The prepared PKCN exhibited excellent singlet oxygen (1O2) generation ability for the highly efficient degradation of atrazine (ATZ), reaching 95% (pH=5) of decomposition efficiency within 60 min under visible light. Density functional theory (DFT) calculation results visualize the role of cyano groups, nitrogen vacancies, K atoms and P atoms, and the synergistic effect of the above four aspects contributed to the three pathways of hole oxidation, energy transfer and dismutation reaction for efficient 1O2 generation. Moreover, the T.E.S.T and soybean culture experiment demonstrated the toxicity of ATZ have been significantly reduced after the photocatalytic process. This work can give deep insights into the roles and synergy of each active unit for designing and synthesizing efficient g-C3N4.

Design of Molecules with Low Hole and Electron Reorganization Energy Using DFT Calculations and Bayesian Optimization.

Materials exhibiting higher mobility than conventional organic semiconducting materials, such as fullerenes and fused thiophenes, are in high demand for applications in printed electronics. To discover new molecules that might show improved charge mobility, the adaptive design of experiments (DoE) to design molecules with low reorganization energy was performed by combining density functional theory (DFT) methods and machine learning techniques. DFT-calculated values of 165 molecules were used as an initial training dataset for a Gaussian process regression (GPR) model, and five rounds of molecular designs applying the GPR model and validation via DFT calculations were executed. As a result, new molecules whose reorganization energy is smaller than the lowest value in the initial training dataset were successfully discovered.