Energy Level Shifts Research Articles

The impact of molecular orientations on the energy levels of A-D-A acceptors: implications for the charge separation driving force of organic solar cells.

The energetic landscape of charge carriers, namely the ionization potential (IP) and electron affinity (EA), can play a crucial role in the charge separation and migration processes for organic solar cells (OSCs). However, the impact of molecular orientations on the energy levels remains elusive, especially in acceptor-donor-acceptor (A-D-A) type nonfullerene acceptors (NFAs) with intrinsic anisotropy. Using the self-consistent quantum mechanics/embedded charge (sc-QM/EC) approach, we have investigated the energy level shifts from the edge-on or face-on surfaces to the bulk phase for three typical NFA crystals, IDIC-4F, INIC-4F, and Y6. The results point out that the surface-to-bulk changes in IP are limited within 0.2 eV for both the orientations due to the mutual counteraction between the electrostatic and induction effects. In sharp contrast, the EA values are substantially decreased from the bulk to the surfaces; especially, for the face-on orientation, the reduction reaches 0.5-0.8 eV. This indicates that the face-on orientation can provide a significant driving force for electrons moving from the surface or the interface to the bulk phase and thus improve the charge separation efficiency. Our work indicates that enhancing the face-on orientation is an effective method to increase the charge separation driving force for the OSCs based on A-D-A NFAs.

Resonance ionization spectroscopy of high-lying 4sns and 4snd Rydberg levels of odd calcium isotopes

Calcium Rydberg levels are of significant interest for efficient and isotope-selective resonance ionization of trace radionuclides such as calcium-41 (41Ca). In this study, we report novel, to our knowledge, measurement data on the energy level shifts of 43Ca for 4sns 1S0 and 4s(n−1)d1D2 (n=40, 45, 50, 55, 60) Rydberg levels due to hyperfine-induced singlet–triplet mixing specific to isotopes with an odd mass number. Both 3S1 and 3D J triplet signals corresponding to forbidden transitions were enhanced for 43Ca at the high principal quantum numbers n=55 and 60, indicating a mixing of singlet components to some extent.

A Josephson junction-coupled neuron with double capacitive membranes

The channel currents have distinct magnetic field effect and any changes of the electromagnetic field or electirc stimulus will change the membrane potential effectively. A feasible neuron model considers the distinct physical characteristic is more suitable to mimic the neural activities accompanying with shift in energy level. A Josephson junction (JJ) is connected to a neural circuit for estimating the effect of external magnetic field and two capacitors are connected via a linear resistor for mimicing the capacitive field beside two sides of the cell membrane. Its equivalent Hamilton energy is calculated to show the relation between firing mode and energy level. Noisy disturbance is imposed to predict the occurrence of coherence resonance, and the biophysical neuron is excited to present higher energy level. This new neuron model can address the field effect and the biophysical property of cell membrane considered as combination of capacitive fields in double capacitors. It can mimic the physical property of outer and inner membranes, and energy exchange across the double membranes explains the energy mechanism in neural activities. Time-varying energy diveristy between capacitive field is crucial for supporting continuous firing activities. The JJ channel discerns slight changes in external magnetic field and regularity is stabilized under coherence resonance in presence of noisy excitation on the membrane or ion channels.

The correlation between bipolar disorder not otherwise specified progression with patients’ clinical and demographic characteristics

Introduction: Bipolar disorder not otherwise specified is a complex condition characterized by unusual shifts in mood, energy levels, and behavior. Objectives: This study aimed to investigate the relationship between bipolar disorder not otherwise specified progression and patients’ clinical and demographic characteristics. Patients and Methods: Data for this study was obtained from a cross-sectional study conducted between the years 2008-2021. The study investigated 171 patients with bipolar disorder not otherwise specified. The data collection tool was the content of the file registered in the psychiatry department of the hospital, which was based on the physician’s interview with the patient. Data analysis was conducted using statistical tests in SPSS version 26 software. Results: Out of 171 patients, 80 (46.8%) were men with a mean age of 39.5 ± 12.2 years. The results found that the duration of symptoms onset to hospitalization in patients with mania symptoms was related to gender, family history of mental illness, and history of opium abuse. On the other hand, the duration of symptoms onset to hospitalization in patients with major depressive episodes (MDEs) was related to education level, marital status, and family history of mental illness (P<0.05). In the patients with both Mania and MDEs’ symptoms, no statistically significant correlation was found between patients’ characteristics with the duration of symptoms onset to their hospitalization (P>0.05). Conclusion: Identification of related risk factors and early treatment of bipolar disorder not otherwise specified, along with addressing potential comorbidities such as family heredity and opium abuse, can help improve patients’ outcomes and quality of life. Clinicians should consider these factors when assessing these patients to provide appropriate treatment and support.

Insight of charge injection barrier at the copper/epoxy resin interface with cross-linking molecules: First-principles calculation and experimental verification

Understanding charge injection at a metal/cross-linking epoxy resin (EP) interface facilitates the design and application of high-power electric and electronic devices. This paper focuses on the charge injection barrier at the metal/EP interfaces using first-principles calculation. Two fragmentary structures, obtained from cross-linking EP with amine and anhydride curing agent, were selected to construct interface models on a Cu(111) slab. The injection barrier, dipole moment, charge transfer, and vacuum energy level shift (Δ) at the interfaces were examined. The model with the anhydride groups produced higher electron and hole injection barriers than the interface model with the amine groups. The model with the amine groups had a higher Δ, which was derived from molecule dipole and charge transfer. An increase in the work function and Δ caused by an electric field caused an increase in the electron injection barrier and a decrease in the hole injection barrier. Experimental results of the methyl tetrahydrophthalic anhydride cross-linking EP showed a higher charge injection than that of m-phenylenediamine cross-linking EP, providing experimental verification of the theoretical calculation.

Precision Spectroscopy of Radiation Transitions between Singlet Rydberg States of the Group IIb and Yb Atoms

The measurements of microwave (μw) and radio-frequency (RF) radiation quantitative parameters may be based on the quantum–optical approach to determine the spectral characteristics of radiation transitions between the Rydberg states of atoms. Frequencies and matrix elements are calculated for dipole transitions between opposite-parity Rydberg states nL 1L and n′L±1 1L±1 (where n′= n,n±1,n±2) of the singlet series in the alkaline–earth–metal-like atoms of group IIb (Zn, Cd, Hg) and Yb. The matrix elements determine the shifts of Rydberg-state energy levels in the field of resonance μw or RF radiation, splitting the resonance of electromagnetically induced transparency (EIT) for intensely absorbed probe radiation. Numerical computations based on the single-electron quantum defect method (QDM) and the Fues’ model potential (FMP) approach with the use of the most reliable data from the current literature on quantum defect values are performed for frequencies and matrix elements of transitions between singlet Rydberg states of 1S0-, 1P1-, 1D2-, and 1F3-series in Zn, Cd, Hg, and Yb atoms. The calculated data are approximated by polynomials in the powers of the principal quantum numbers. The polynomial coefficients are determined with the use of a standard curve-fitting interpolation polynomial procedure for numerically calculated functions. These approximation expressions provide new possibilities for accurately evaluating the frequencies and matrix elements of dipole transitions between Rydberg states over a wide range of quantum numbers n >> 1, accompanied by the emission and absorption of μw and RF photons.

Investigation of carrier density modulation in water motion-induced ionovoltaic electricity generation

The solid-liquid interfacial effect plays a pivotal role in electricity generation from the interaction between a solid surface and dynamic water motion, but demonstration of the exact source in energy conversion is deficient and understandings of fluidic processes with water and corresponding charge carrier movement have been non-straightforward to date. Herein, the mechanism of water motion-induced energy generation at 2D nanomaterials is demonstrated by water contact-driven carrier density modulation and regarding fermi energy level shift. When water infiltrates into a nanoporous graphitic channel, a non-linear current density (J)-voltage (V) characteristic is found between wet-dry regions which provides a clue that water interaction repels its major carriers (p-type, holes), thereby motivating electron-rich state on the wet region. This unique characteristic yields the potential asymmetry and hence, drives respective majority charge carriers from wet and dry regions simultaneously to the external circuit. Such dynamic carrier motions are also supported by metal electrode configuration, which relies on the energy state of each region. By observing that the desired configuration brings about a synergic impact on output performance, the source of electricity generation is identified by proving modulated electronic energy levels between wet and dry regions.

Intrinsic Photoconductivity Spectral Dependence as a Tool for Prediction of Open-Circuit Voltage in Organic Solar Cells

Organic materials are known for their variety of molecules. Methods to predict the parameters of organic photovoltaic (OPV) cells are required to avoid the time- and resource-consuming processes of manufacturing and testing OPVs. Usually, the open-circuit voltage (Uoc) is estimated as the difference between the ionization energy level of the electron donor molecule (Id) and the electron affinity level of the electron acceptor molecule (EAa). Various measurement methods are used to determine the energy level values of pure materials, which, when combined with energy level shifts due to the donor:acceptor interactions, make these estimations less precise. In this work, photoconductivity measurements were applied to the donor:acceptor films. Near threshold energy, the electron can be directly transferred from the donor to the acceptor molecule. The obtained charge transfer energy (ECT) shows the difference between Id and EAa in the film. This difference was compared to the Uoc value of an OPV made of the same donor:acceptor combination. We show that this approach provides less scattered results and a higher correlation coefficient compared to the Uoc estimation using energy level values.

Interface Energy Alignment between Lead Halide Perovskite Single Crystals and TIPS-Pentacene.

At present, there is a huge development in optoelectronic applications using lead halide perovskites. Considering that device performance is largely governed by the transport of charges across interfaces and, therefore, the interfacial electronic structure, fundamental investigations of perovskite interfaces are highly necessary. In this study, we use high-resolution soft X-ray photoelectron spectroscopy based on synchrotron radiation to explore the interfacial energetics for the molecular layer of TIPS-pentacene and lead halide perovskite single crystals. We perform ultrahigh vacuum studies on multiple thicknesses of an in situ formed interface of TIPS-pentacene with four different in situ cleaved perovskite single crystals (MAPbI3, MAPbBr3, FAPbBr3, and CsxFA1-xPbBryI3-y). Our findings reveal a substantial shift of the TIPS-pentacene energy levels toward higher binding energies with increasing thickness, while the perovskite energy levels remain largely unaffected regardless of their composition. These shifts can be interpreted as band bending in the TIPS-pentacene, and such effects should be considered when assessing the energy alignment at perovskite/organic transport material interfaces. Furthermore, we were able to follow a reorganization on the MAPbI3 surface with the transformation of the surface C 1s into bulk C 1s.

Fitting for the energy levels of hydrogen

Atomic hydrogen energy levels calculated to high precision are required to assist experimental researchers working on spectroscopy in the pursuit of testing quantum electrodynamics (QEDs) and probing for physics beyond the Standard Model. There are two important parts to the problem of computing these levels: an accurate evaluation of contributions from QED and using an accurate value for the proton charge radius as an input. Recent progress on QED corrections to the fine structure, as well as increasing evidence that a proton charge radius in the range of 0.84 fm is favored over the previously adopted larger value in the 0.88 fm range, has advanced the field, yet several state-of-the-art measurements remain in contradiction with this smaller value. Motivated by on-going and future work in this area, we present here a simple parameterization for the energy levels of hydrogen at the level of hyperfine structure using the so-called relativistic Ritz approach. The fitting of a finite sample of QED-generated levels at low to intermediate principal quantum number, n, gives a generally applicable formula for all values of n for each distinct angular momentum channel, given in this work up to orbital angular momentum number . We also provide a simple linear parameterization for the shift in hydrogen energy levels as a function of the proton radius, providing a useful cross check for extant and future measured energy intervals.

Multifunctional Thiophene Cascading SnO2/Perovskite Interfaces for Efficient and Stable MAPbI3 Photovoltaics.

The power conversion efficiency (PCE) and stability of n-i-p perovskite solar cells (PSCs) are significantly affected by inherent defects of SnO2 and perovskite layers. In this work, we incorporate 2-bromo-3-thiophenic acid (BrThCOOH) as a multifunctional passivant to simultaneously passivate the defects of SnO2 surface and perovskite layer. BrThCOOH permeates evenly into the MAPbI3 and coordinates with Pb2+ and iodine vacancies (VI+) to reduce surface defect density and inhibit the decomposition of MAPbI3. Carboxylic acid effectively passives the oxygen vacancy on the surface of SnO2 through coordination bonds, reducing the probability of electron capture by SnO2 surface defects, thus contributing to electron transport in device. The interaction of BrThCOOH with MAPbI3 and SnO2 surfaces leads to an upward shift in energy levels, reducing energy loss during charge migration. The optimal MAPbI3 device with BrThCOOH-modified SnO2 (T-SnO2) reveals an improved PCE of 21.12%, much higher than that of the control one (19.12%). The hydrophobicity of BrThCOOH-modified MAPbI3 is also improved, which is beneficial to the durability of the device. After 100 h of storage in the environment, the generated PSCs maintain their initial PCE of 75%, demonstrating excellent long-term stability without any encapsulation.

Quantum Otto heat engine with Pöschl–Teller potential in contact with coherent thermal bath

Work and efficiency of quantum Otto heat engines (QOHEs) can increase by using non-thermal baths or by inhomogeneous scaling of energy levels of the working substance. Given these points, at first, we construct the coherent thermal state for a trigonometric Pöschl–Teller (PT) potential. Then using a particle in this potential, which has unequally spaced energy levels, as a working substance, we investigate the work extraction and the efficiency of QOHEs that operates between cold and hot coherent thermal baths. The results show that changing the PT potential parameters in the adiabatic processes of QOHE, which causes an inhomogeneous shift in energy levels or/and make use of the hot coherent thermal bath, improve work extraction and efficiency of QOHE relative to the classical counterpart.

Indotricarbocyanine dyes relevant for photodynamic therapy and their radicals: Substituent effects studied by optical and electrochemical methods

Photodynamic therapy is an effective and minimally invasive treatment method for cancer. A deeper understanding of the photocytotoxicity mechanism of cyanine dyes is necessary for the development of more efficient photosensitizers. We combine electrochemistry, optical and ESR spectroscopy, and quantum chemical calculations to study indotricarbocyanine dyes relevant for photodynamic therapy. The incorporation of 4-meso-chloride and a 3,5-o-phenylene bridge into the polymethine chain results in a hypsochromic shift of the absorption spectrum by ca. 30 nm and in a downward shift of the frontier orbitals energy levels by 0.1–0.3 eV. In addition, such substitution imparts stability to the electrogenerated radical dications of the dyes. The presence of 4-meso-chloride and a 3,5-trimethylene bridge in the polymethine chain causes the absorption spectrum to shift bathochromically by almost 40 nm and the HOMO–LUMO energy gap to decrease by ca. 0.1 eV. The radical dication of the dye with such substitution is particularly stable and exhibits improved electron delocalization. The radical dication of the dye with an unsubstituted polymethine chain is unstable due to its propensity to form dimers. The substituents at the nitrogen atoms are shown to have almost no influence on the optical and electrochemical properties of the indotricarbocyanine dyes. The radical dications of the dyes with an o-phenylene bridge can oxidize bromide ions, unlike the radical dications of the dyes with an unsubstituted polymethine chain or with a trimethylene bridge. The reported data can be used to develop new indotricarbocyanine dyes with desired characteristics.

Engineering isospectrality in multidimensional photonic systems

Abstract Selective manipulation of energy levels plays an essential role in realizing multichannel wave devices. One of the representative examples is to utilize the concept of quasi-isospectrality: a family of wave systems with an almost identical spectrum except for a part of energy levels. Most approaches toward quasi-isospectrality have employed analytical methods based on symmetry or tridiagonalization, such as supersymmetry, Householder, or Lanczos transformations. Although such analytical approaches provide deterministic and stable designs based on operator factorizations, the mathematical strictness in the factorizations, at the same time, hinders isospectral engineering in a given multidimension. Here we develop the semi-analytical method for engineering isospectrality in multidimensional photonic systems. The method provides the systematic perturbation for the target energy level shifts by decomposing the allowed form of system changes into the perturbation basis. We demonstrate the isospectrality of lower-, higher-, and random-order states while imposing the designed shifts on the other states. The stability analysis shows that the accuracy of the method is determined by the ranges of isospectral state numbers and perturbation strength. The systematic, free-form, and multidimensional natures of the proposed method show great potential for the platform-transparent design of multichannel devices.

Non-Hermitian Hamiltonians for linear and nonlinear optical response: A model for plexcitons.

In polaritons, the properties of matter are modified by mixing the molecular transitions with light modes inside a cavity. Resultant hybrid light-matter states exhibit energy level shifts, are delocalized over many molecular units, and have a different excited-state potential energy landscape, which leads to modified exciton dynamics. Previously, non-Hermitian Hamiltonians have been derived to describe the excited states of molecules coupled to surface plasmons (i.e., plexcitons), and these operators have been successfully used in the description of linear and third order optical response. In this article, we rigorously derive non-Hermitian Hamiltonians in the response function formalism of nonlinear spectroscopy by means of Feshbach operators and apply them to explore spectroscopic signatures of plexcitons. In particular, we analyze the optical response below and above the exceptional point that arises for matching transition energies for plasmon and molecular components and study their decomposition using double-sided Feynman diagrams. We find a clear distinction between interference and Rabi splitting in linear spectroscopy and a qualitative change in the symmetry of the line shape of the nonlinear signal when crossing the exceptional point. This change corresponds to one in the symmetry of the eigenvalues of the Hamiltonian. Our work presents an approach for simulating the optical response of sublevels within an electronic system and opens new applications of nonlinear spectroscopy to examine the different regimes of the spectrum of non-Hermitian Hamiltonians.

The Various Methods to Prevent Lithium Toxicity in Treatment for Patients with Bipolar Disorder

Bipolar disorder (BD) is a serious mental illness that leads to considerable shifts in mood, energy, and physical activity levels, impairing a person’s ability to complete day-to-day tasks. About 4.4% of adults in the US report having experienced an episode of BD at least once in their life, and approximately 82.9% of people with BD are left severely impaired. To combat this, doctors prescribe lithium, which is an effective mood stabilizer that can regulate the extreme highs and lows of BD. However, lithium is a toxic substance when it exceeds the therapeutic range, requiring frequent trips to the hospital to evaluate blood lithium levels Such monitoring may not always be effectively feasible, especially for patients experiencing a mental health crisis or patients in rural areas without local medical facilities. 
 Research studies have been conducted to provide patients with alternative methods to avoid lithium toxicity including ways to check the lithium levels on their own Additionally, studies investigate the ideal dosing regimen to prevent toxic side effects, while others aim to prevent toxicity before it happens.

Large-Area Monolayer n-Type Molecular Semiconductors with Improved Thermal Stability and Charge Injection

We fabricated monolayer n-type two-dimensional crystalline semiconducting films with millimeter-sized areas and remarkable morphological uniformity using an antisolvent-confined spin-coating method. The antisolvent can cause a downstream Marangoni flow, which improves the film morphologies. The deposited crystalline monolayer films exhibit excellent thermal stabilities after annealing, which reveals the annealing-induced enhancement of crystallinity. The transistors based on the n-type monolayer crystalline films show linear output characteristics and superior electron mobilities. The improved charge injection between monolayer films and Au electrodes results from the energy level shift as the films decrease to the monolayer, which leads to a lower injection barrier. This work demonstrates a promising method for fabricating air-stable, low-cost, high-performance, and large-area organic electronics.

Ab initio study of the energy level alignment at semiconductor/organic interface: Coadsorption of acceptor and donor ligands with organic dyes

Conditions for ab initio evaluation of the surface band alignment in slab models are critically reviewed. Based on the employed approach, we study the relative energy levels arrangement between aromatic dye and wurtzite semiconductor surface and its dependence on the coadsorption of the representative ligands. The obtained results demonstrate the energy level shifts mediated by surface chemistry at the interface. Predictable control of the electronic properties of organically modified semiconductor surfaces can be used as a versatile adjustable instrument in the performance optimization of optoelectronic devices.

Relativistic light shifts in hydrogenlike ions

We investigate the level structure of heavy hydrogenlike ions in laser beams. In heavy ions, the electrons are tightly bound by the Coulomb potential of the nucleus, which prohibits ionization even by strong lasers. However, interaction with the light field leads to dynamic shifts of the electronic energy levels. We apply a fully relativistic description of the electronic states by means of the Dirac equation. Interaction with the monofrequent laser field is treated by second-order time-dependent perturbation theory. Our formalism goes beyond the Stark long-wavelength dipole approximation and takes into account nondipole effects of retardation and interaction with the magnetic-field components of the laser beam. The resulting level shifts are relevant for experiments at present and near-future laser facilities.

Hydrothermal controlled growth of MoTe2/MoO3−x materials: Synthesis mechanism, light-matter interaction and its photoelectrochemical activity

1 T′ phase molybdenum ditelluride (1 T′-MoTe2) is predicted to be a novel two-dimensional topological insulator that will play a crucial role in future applications ranging from spintronics to quantum electronic devices. Adjusting the introduction to O in MoTe2 is used to tune the charge separation efficiency, which charge to transfer regulation is a challenge. Here, we report the controllable growth of MoTe2/MoO3−x based on the regulation of experimental parameters, and it is necessary to reveal its structure-activity relationship. The characterization result indicated that due to the existence of unsaturated bonds between atoms due to the increase in temperature, the growth direction of nanosheets changes from lateral to agglomeration and stacks into different external morphologies. In addition, the electronic and bonding properties of the MoTe2 surface layer before and after the introduction to O was investigated by photoluminescence spectroscopy and density functional theory calculations. The results suggest that O is absorbed at defect sites and disrupts the Mo-Te covalent bond, resulting in a shift in the characteristic energy level within the optical bandgap. It is demonstrated that the surface of MoTe2 exhibits a higher level of metallic conductivity after O intercalation into tellurium vacancies. The photoelectrochemical experiment results show that MoTe2 after introduction to MoO3−x has optoelectronic properties and are attractive photoelectrochemical materials. Therefore, this work has made significant progress of the study of low-temperature preparation of 1 T′-MoTe2 and the introduction to MoO3−x on its optical properties and electrochemical properties.