Search

The structure of the energy levels of excited symmetric donor–acceptor octupolar molecules suggests a completely symmetric state and a degenerate doublet. For most molecules, the doublet is the first excited state, which is called the normal level order, but there are molecules with the reverse level order. Symmetry breaking charge transfer (SBCT) and its effect on the transient dipole moment in these structures are studied. It has been established that for reverse level order, SBCT is possible only if the reorganization energy exceeds a certain threshold, whereas for the normal level order, there is no such threshold. The lowest completely symmetric excited state is shown to become bright after SBCT. The dependence of the fluorescence transition dipole moment on the SBCT extent is calculated. It was established that the direction and magnitude of the transition dipole moment change similarly to the change in the dipole moment for the reverse level order, whereas for the normal level order, the changes are opposite. The effect of solvent thermal fluctuations on the transition dipole moment is simulated and discussed. A way for controlling the direction of the transition dipole moment by an external electric field is suggested. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of photoinduced processes in complex systems is crucial for the development of advanced energy-conversion materials. In this study, we investigate the nonadiabatic dynamics using time-convolution (TC) and time-convolutionless (TCL) quantum master equations (QMEs) based on treating electronic couplings as perturbation within the framework of multistate harmonic (MSH) models. The MSH model Hamiltonians are mapped from all-atom simulations such that all pairwise reorganization energies are consistently incorporated, leading to a heterogeneous environment that couples to the multiple electronic states differently. Our exploration encompasses the photoinduced charge transfer dynamics in organic photovoltaic carotenoid–porphyrin–C60 triad dissolved in liquid solution and the excitation energy transfer (EET) dynamics in photosynthetic Fenna–Matthews–Olson complexes. By systematically comparing the perturbative TC and TCL QME approaches with exact quantum-mechanical and various semiclassical approximate kernels, we demonstrate their efficacy and accuracy in capturing the essential features of photoinduced dynamics. Our calculations show that TC QMEs generally yield more accurate results than TCL QMEs, especially in EET, although both methods offer versatile approaches adaptable across different systems. In addition, we investigate various semiclassical approximations featuring the Wigner-transformed and classical nuclear densities as well as the governing dynamics during the quantum coherence period, highlighting the trade-off between accuracy and computational cost. This work provides valuable insights into the applicability and performance of TC and TCL QME approaches via the MSH model, offering guidance for realistic applications to condensed-phase systems on the atomistic level. [ABSTRACT FROM AUTHOR]

In photodynamic therapy (PDT) treatment, heavy-atom-free photosensitizers (PSs) are a great source of singlet oxygen photosensitizer. Reactive oxygen species (ROS) are produced by an energy transfer from the lowest energy triplet excited state to the molecular oxygen of cancer cells. To clarify the photophysical characteristics in the excited states of a few experimentally identified thionated (>C=S) molecules and their oxygenated congeners (>C=O), a quantum chemical study is conducted. This study illustrates the properties of the excited states in oxygen congeners that render them unsuitable for PDT treatment. Concurrently, a hierarchy is presented based on the utility of the lowest-energy triplet excitons of thionated compounds. Their non-radiative decay rates are calculated for reverse-ISC and inter-system crossover (ISC) processes. In addition, the vibronic importance of C=O and C=S bonds is clarified by the computation of the Huang–Rhys factor, effective vibrational mode, and reorganization energy inside the Marcus–Levich–Jörtner system. ROS generation in thionated PSs exceeds their oxygen congeners as kf ≪ kISC, where radiative decay rate is designated as kf. As a result, the current work offers a calculated strategy for analyzing the effectiveness of thionated photosensitizers in PDT. [ABSTRACT FROM AUTHOR]

We systematically applied excited-state normal mode analysis to investigate and compare the relaxation and internal conversion dynamics of a free-base porphyrin (BP) with those of a novel functional porphyrin (FP) derivative. We discuss the strengths and limitations of this method and employ it to predict very different dynamical behaviors of the two compounds and to clarify the role of high reorganization energy modes in driving the system toward critical regions of the potential energy landscape. We identify the modes of vibrations along which the energy gap between two excited-state potential energy surfaces within the Q band manifold may vanish and find that the excess energy to reach this "touching" region is significantly reduced in the case of FP (0.16 eV) as compared to the one calculated for BP (0.92 eV). Our findings establish a link between the chemical functionalization and the electronic and vibrational structure that can be exploited to control the internal conversion pathways in a systematic way. [ABSTRACT FROM AUTHOR]

Absorption spectra of the solvatochromic dye 2,6-diphenyl-4-2,4,6-triphenyl-1-pyridinophenolate (B30) were measured in seven solvents of varying polarity over temperature ranging from each solvent's freezing point to 300 K. The excitation energies and their variances allowed calculations of the solvent reorganization energies, reorganization free energies and reorganization entropies as functions of temperature. The entropies of solvent packing around the chromophore are found to make major contributions to the reorganization free energies. The variances of the excitation energies depend only weakly on temperature, in disagreement with an expression that is often used for solvent reorganization free energies. Polar solvents reduce the transition dipole strength of B30's long-wavelength absorption band, probably because interactions with the solvent enhance the charge-transfer character of the transition. The dipole strength drops further at low temperatures. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) is an extremely powerful, highly effective, and widely used approach to understanding the nature of chemical processes in atomic details for proteins. The accuracy of results from MD simulations is highly dependent on force fields. Currently, molecular mechanical (MM) force fields are mainly utilized in MD simulations because of their low computational cost. Quantum mechanical (QM) calculation has high accuracy, but it is exceedingly time consuming for protein simulations. Machine learning (ML) provides the capability for generating accurate potential at the QM level without increasing much computational effort for specific systems that can be studied at the QM level. However, the construction of general machine learned force fields, needed for broad applications and large and complex systems, is still challenging. Here, general and transferable neural network (NN) force fields based on CHARMM force fields, named CHARMM-NN, are constructed for proteins by training NN models on 27 fragments partitioned from the residue-based systematic molecular fragmentation (rSMF) method. The NN for each fragment is based on atom types and uses new input features that are similar to MM inputs, including bonds, angles, dihedrals, and non-bonded terms, which enhance the compatibility of CHARMM-NN to MM MD and enable the implementation of CHARMM-NN force fields in different MD programs. While the main part of the energy of the protein is based on rSMF and NN, the nonbonded interactions between the fragments and with water are taken from the CHARMM force field through mechanical embedding. The validations of the method for dipeptides on geometric data, relative potential energies, and structural reorganization energies demonstrate that the CHARMM-NN local minima on the potential energy surface are very accurate approximations to QM, showing the success of CHARMM-NN for bonded interactions. However, the MD simulations on peptides and proteins indicate that more accurate methods to represent protein–water interactions in fragments and non-bonded interactions between fragments should be considered in the future improvement of CHARMM-NN, which can increase the accuracy of approximation beyond the current mechanical embedding QM/MM level. [ABSTRACT FROM AUTHOR]

Organic semiconductors (OSCs) are widely used in flexible display, renewable energy, and biosensors, owing to their unique solid-state physical and optoelectronic properties. Among the abundant crystal library of OSCs, asymmetric aryl anthracene derivatives have irreplaceable advantages due to the interplay between their distinct π-conjugated geometry and molecular stacking as well as efficient light emission and charge transport properties that can be simultaneously utilized. However, the poor crystal stacking patterns of most asymmetric molecules limit their utility as excellent OSCs. Thus, it is crucial to clarify the structural features that enable the extremely ordered stacking and favorable electronic structure of asymmetric anthracene derivatives to become high-performance OSCs. This contribution investigates the charge transport properties of a series of asymmetric aryl anthracene derivatives to reveal the modulation factors of the molecular stacking modes and to explore the structural factors, which are beneficial to charge transport. The analysis demonstrated that the vinyl-linker facilitated the injection of hole carriers, and the alkynyl-linker effectively reduces the reorganization energy. Importantly, the linear polarizability and permanent dipole moment of a single molecule play a vital regulation to molecular stacking modes and the transfer integral of the dimer. The "head-to-head stacking" motif shows a compact stacking pattern and the maximum 2D anisotropic mobility more than 10 cm2 V−1 s−1. These findings sharpen our understanding of the charge transport properties in asymmetric organic semiconductors and are essential for developing a diverse range of high-performance OSC materials. [ABSTRACT FROM AUTHOR]

In this study, we have designed five new conjugated acceptors of donor–π–acceptor–π–donor (D–π–A–π–D) type, utilizing quinacridone as the donor and thiophene as the π-bridging component and incorporating five distinct central acceptor units. Our aim is to explore how different central acceptor units impact the geometric, electrical, optical, charge transport, and photovoltaic characteristics of these acceptor molecules. To achieve this, we have employed the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The results, including frontier molecular orbital analysis and several crucial parameters such as bond length alteration, the charge transfer rate, and power conversion efficiency, indicate that enhancing the electron-withdrawing characteristics of the central acceptor units boosts the performance of the designed acceptor molecules. The observed reorganization energy values confirm the electron-accepting nature of the compounds under study. Moreover, the absorption properties demonstrate that compounds C2 and C4 exhibit the highest maximum absorption values. Analysis of the D/A blend properties suggests that complexes A1/C2 and A1/C4 could facilitate efficient charge carrier separation within the D/A active layer. Furthermore, the photovoltaic performance of the D/A complexes indicates that complex A1/C2, with a predicted power conversion efficiency of 30.33%, stands out as the most promising candidate for use in organic solar cells. [ABSTRACT FROM AUTHOR]

This article discusses the challenges and importance of selectively functionalizing C-H bonds in organic molecules, particularly C(sp3)-H bonds. The authors focus on the azolation of benzylic C-H bonds using photoredox catalysis, which allows for the streamlined synthesis of high-value motifs. They conducted a computational study using density functional theory to understand the reaction mechanism and regioselectivity of this transformation. The study provides insights into the steps involved in the reaction and suggests potential directions for further exploration in C-H azolation within photoredox systems. [Extracted from the article]

Dye-sensitized solar cells (DSSCs) are an excellent alternative solar cell technology that is cost-effective and environmentally friendly. The geometry, reactivity descriptors, light-harvesting efficiency, molecular radii, diffusion coefficient, and excited oxidation state potential of the proposed complex were investigated. The calculations in this study were performed using DFT/TDDFT method with B3LYP functional employed on the Gaussian 09 software package. The calculations were used the 6–311 + + G(d, p) basis set for the C, H, N, O, Cl atoms and the LANL2DZ basis set for the Re atom, with the B3LYP functional.. The balance of hole and electron in this complex has increased the efficiency and lifetime of DSSCs for photovoltaic cell applications. The investigated compound shows that the addition of the TPA substituent marginally changes the geometric structures of the 2, 2′-bipyridine ligand in the T1 state. As EDsubstituents were added to the compound, the energy gap widened and moved from ELUMO (− 2.904 eV) (substituted TPA) to ELUMO (− 3.122 eV) (unsubstituted). In the studying of solvent affects; when the polarity of the solvent decreases, red shifts appears in the lowest energy an absorption and emission band. Good light-harvesting efficiency, molecular radii, diffusion coefficient, excited state oxidation potential, emission quantum yield, and DSSC reorganization energy, the complex is well suited for use as an emitter in dye-sensitized solar cells. Among the investigated complexes mentioned in literature, the proposed complex was a suitable candidate for phosphorescent DSSC. [ABSTRACT FROM AUTHOR]

Context: In the present work, the influence of aromatic ring substitution on a series of small-donor organic molecules (A, B, C, D, and E) with isoxazole cores was investigated for photovoltaic applications in organic solar cells. Frontier molecular orbital analysis, chemical reactivity descriptors, dipole moment, and population analysis showed that all the organic materials have intramolecular charge transfer abilities capable of donating electrons to the acceptor material (PCBM). The required photovoltaic parameters such as Voc, FF, Jsc, LHE, and other associated optoelectronic parameters are reported. The results demonstrate that aromatic ring substitution influences charge transfer and power conversion efficiencies of solar cells. That is, an increase in the aromatic character of a material increases its charge transfer, and as a result, its photovoltaic properties are increased. Additionally, all the investigated derivatives are good charge transporters with suitable electron reorganization energies, which are beneficial for minimizing energy loss. Hence, these organic derivatives with isoxazole backbones are promising materials and may provide fresh insights into the design of new materials for organic solar cell applications. Method: All calculations were performed using DFT and the ORCA 4.1.0 program package as the main tool for geometry optimization and frequency calculations. The Avogadro 1.2.1 visualization tool was used to prepare all input files executed by ORCA 4.1.0. The BP86, B3LYP, and wB97M series of functionals coupled with the def2/TZVP basis set were employed for geometry optimization. All energy-related calculations were carried out using the M06-2x functional. Multiwfn version 3.7 was used for aromaticity and population analysis. Excited state and UV-visible spectra were simulated using the TD-DFT method at the CAM-B3LYP-D3, wB97X-D3, and PBE0-D3 coupled with the ma-def2-TZVP basis set. Moreover, solvent effects were incorporated using the SMD scheme as incorporated in the ORCA software. Lastly, the RIJCOSX approximations were used to speed up calculations while maintaining accuracy. [ABSTRACT FROM AUTHOR]

Context: For the advancement in fields of organic and perovskite solar cells, various techniques of structural alterations are being employed on previously reported chromophores. In this study, the end-capped engineering is carried out on DBT-4F (R) by modifying terminal acceptors to improve optoelectronic and photovoltaic attributes. Seven molecules (AD1-AD7) are modeled using different push–pull acceptors. DFT/B3LYP/6-31G along with its time-dependent approach (TD-DFT) are on a payroll to investigate ground state geometries, absorption maxima (λmax), energy gap (Eg), excitation energy (Ex), internal reorganization energy, light harvesting efficiency (LHE), dielectric constant, open circuit voltage (VOC), fill factor (FF), etc. of OSCs. AD1 displayed the lowest band gap (1.76 eV), highest λmax (876 nm), lowest Ex (1.41 eV), and lowest binding energy (0.21 eV). Among various calculated parameters, all of the sketched molecules demonstrated greater dielectric constant when compared to R. The highest dielectric constant was exhibited by AD3 (56.26). AD5 exhibited maximum LHE (0.9980). Lower reorganization energies demonstrated improved charge mobility. AD5 and AD7 (1.63 and 1.68 eV) have higher values of VOC than R (1.51 eV). All novel molecules having outperforming attributes will be better candidates to enhance the efficacy of OSCs for future use. Methods: Precisely, a DFT and TD-DFT analysis on all of the proposed organic molecules were conducted, using the functional MPW1PW91 at 6-31G (d,p) basis set to examine their optoelectronic aspects, additionally the solvent-state computations were studied with a TD-SCF simulation. For all these simulations, Guassian 09 and GuassView 5.0 were employed. Moreover, the Origin 6.0, Multiwfn 3.8, and PyMOlyze 1.1 software were utilized for the visual depiction of the graphs of absorption, TDM, and DOS, respectively of the studied molecules. A number of crucial aspects such as FMOs, bandgaps, light-harvesting efficiency, electrostatic potential, dipole moment, ionization potential, open-circuit voltage, fill factor, binding energy, interaction coefficient, chemical hardness–softness, and electrophilicity index were also investigated for the studied molecules. [ABSTRACT FROM AUTHOR]

Context: Three donor (D)–acceptor (A)-type temperature-activated delayed fluorescent (TADF) molecules of 9-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-3,9′-bicarbazole (o-TrzDCz), 9-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-3,9′-bicarbazole (m-TrzDCz), and 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-3,9′-bicarbazole (p-TrzDCz) were designed in this paper, and the photophysical properties, including the intersystem crossing rate, the reorganization energies (λ), and the intersystem crossing/reverse intersystem crossing (ISC/RISC) rate, were simulated to explore the effect of substitution sites on their TADF character. The values of the twist angle between the D and A moieties in ground state and the molecular root-mean-square deviation (RMSD) of the S1 and T1 states referenced to the S0 state indicate that o-TrzDCz possess bigger steric hindrance and stabler molecular configuration. The λ values of the ISC/RISC process should be 0.06/0.04 eV for o-TrzDCz, which are much smaller than those of m-TrzDCz (0.51/0.41 eV) and p-TrzDCz (1.93/1.06 eV). At the same time, o-TrzDCz possess the biggest kRISC (7.28 × 106 s−1) and kr (3.12 × 106 s−1) values and the smallest kp (0.10 s−1) value among the three titled molecules. These data indicate that o-TrzDCz should have more excellent TADF character than m-TrzDCz and p-TrzDCz. In a word, this research presents that adjusting the molecular linking manner should be a charming way to explore novel high-efficient TADF molecules. Methods: Quantum chemical calculations were performed at PBE0/6-31G* level by Gaussian 09 and ORCA 4.1.0 software packages, and reorganization energies and Huang-Rhys were performed by the DUSHIN program and MOMAP 2019B software package based on the Gaussian 09 output files, while the phosphorescence rates were performed at B3LYP/6-31G* level by Dalton 2021. [ABSTRACT FROM AUTHOR]

Context: This study delves into hole-electron transport and distribution properties inherent in mono-brominated dibenzofuran (DBF) and dibenzothiophene (DBT) isomers. As determined by frontier molecular orbitals, all brominated structures have narrower bandgaps than their primary structures. The TD-DFT calculation showed that 2BDBT had the highest absorption wavelength of all molecules at 315.35 nm. Notably, the study unveils remarkably low electron and hole reorganization energies due to bromine substitution in DBF and DBT molecules. Specifically, the 4BDBF has the lowest hole reorganization energy of all DBF configurations, 0.229 eV. In addition, 3BDBF has 0.226 eV less electron reorganization energy than all other molecules. Compared to DBT, 3BDBT has the lowest electron reorganization energy of 0.254 eV. Overall, this research sheds significant light on the fundamental electronic and hole transport characteristics of bromine-substituted DBF and DBT isomers, highlighting their promising role in polymer design as donors/acceptors for advanced organic electronic applications. Methods: Molecular structures were optimized using Density Functional Theory (DFT) B3LYP/6-311 + + G (d, p) level of theory, and the study further elucidates these molecules' energy levels and absorption spectra through Time-Dependent Density Functional Theory TD-DFT; these calculations were performed using Gaussian 09W software package. The key parameters such as reorganization energies, Electron Localization Function map, Laplacian Bond Order, and NCI-RDG were meticulously examined for the molecules with the results of DFT calculations were analyzed and displayed by utilizing the software packages VMD 1.9.4 and Multiwfn 3.8, aiming to comprehend their charge transport and distribution properties. [ABSTRACT FROM AUTHOR]

The efficiency of photovoltaic solar cells (PSCs) heavily relies on hole-transport materials (HTMs). Understanding the intricate relationship between structure and properties is pivotal in crafting effective HTMs. In this study a set of 4 new organic molecules were strategically crafted using different core and π-linkers to analyze their role as potential novel HTMs. We delve into understanding and investigate how their structures influence the electronic, optical, and hole-transport properties of designed HTMs using DFT and TDDFT methodology. The efficacy of the newly designed molecules is assessed across multiple dimensions, encompassing frontier molecular orbitals, absorption spectra, hole mobility, electrostatic potential (ESP), transition density matrix, density of states, reorganization energy (RE), binding energy (BE), dipole moment stability etc., providing a comprehensive evaluation of their performance. The calculated properties are further compared with well known HTM spiro-OMeTAD. Results indicate that three out of the four analyzed compounds can serve as preferential HTM candidate for PSC device as a consequence of narrow band gap, small excitation energy, low RE of hole, good stability and low binding energy. Our ESP results suggest that achieving planarity between the core and the linking phenyl group within the triphenylamine moiety is crucial for enhancing charge transport efficiency and elevating the optical and electronic characteristics of the investigated HTMs. This study provides crucial insights for the deliberate and effective design of high-performance HTMs. [ABSTRACT FROM AUTHOR]

Researchers have closely inspected the progress in solar cell technology over the past few decades, driven by the increasing demand for renewable energy sources like solar power. In this study, the experimentally synthesized dye was employed as a reference molecule, with an acceptor–donor–acceptor (A–D–A) framework. Within this molecule, the cyanoacrylic acid group served as the anchoring acceptor moiety, while the electron donor moiety was oligothiophene. To enhance the optoelectronic and photovoltaic properties, we envisioned the development of five novel dyes to be used in the dye-sensitized solar cells, designated as UM1–UM5. These molecules were distinguished from the reference (R) by modifying the acceptor moiety. Various quantum analyses were investigated, including reorganization energies, absorption maxima, binding and excitation energies, transition density matrices (TDM), fill factor, LHE, Voc, dipole moments, and density of states (DOS). Our approach involved utilizing the DFT method along with the functional and basis set i.e., B3LYP and 6-311G (d,p) respectively, for comprehensive evaluation. The results unveiled that UM2, featuring the thioxothiazolidine group in its acceptor moiety, exhibited the most significant redshift in absorption (624 nm) compared to the other fabricated dyes. UM2 resulted in the lowest energy bandgap (2.30 eV), smallest excitation energy (1.98 eV), highest oscillator strength (2.16), improved electron and hole mobilities, and highest light harvesting efficiency (0.993), establishing it as the most suitable choice among the designed dyes. Additionally, adsorption of the R and UM1–UM5 on (TiO2)9 anatase surface and FMO analysis of these complexes confirmed effective electron injection from anchoring dyes to the semiconductor layer. These enhancements ultimately promise higher conversion efficiency in dye-sensitized SCs. [ABSTRACT FROM AUTHOR]

Recent advances in synthetic methods, combined with tip‐induced on‐surface chemistry, have enabled the formation of numerous cyclocarbon molecules. Here, we investigate computationally the experimentally studied C16 and C18 molecules as well as their van der Waals (vdW) complexes with several typical donor and acceptor molecules. Our results demonstrate a remarkable electron‐withdrawing ability of cyclocarbon molecules. The vdW complexes of C16 and C18 exhibit a thermodynamically favorable photoinduced electron transfer (ET) from the donor partner to the cyclocarbons that occurs on a picosecond time scale. The lower reorganization energy of C16 compared to C18 leads to a significant acceleration of the ET reactions. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties has attracted considerable interest, showcasing their potential for 100 % exciton harvesting, which marks a significant advancement in the realm of organic ECL. However, the challenge of elucidating the precise contribution of TADF to the enhanced ECL efficiency arises due to the lack of comparative studies of organic compounds with or without efficient TADF properties. In this study, we present four carbazole‐benzonitrile molecules possessing similar chemical structures and comparable exchange energy (ΔEST). Despite their comparable properties, these compounds exhibited varying TADF efficiencies, warranting a closer examination of their underlying structural and electronic characteristics governing the optical properties. Consequently, intense ECL emission was only observed from 4CzBN with a remarkable TADF efficiency, underscoring the substantial difference in the ECL signal among molecules with comparable ΔEST and similar spectral properties but varying TADF activity. [ABSTRACT FROM AUTHOR]

Organic photothermal materials have attracted increasing attention because of their structural diversity, flexibility, and compatibility. However, their energy conversion efficiency is limited owing to the narrow absorption spectrum, strong reflection/transmittance, and insufficient nonradiative decay. In this study, two quinoxaline‐based D–A‐D–A‐D‐type molecules with ethyl (BQE) or carboxylate (BQC) substituents were synthesized. Strong intramolecular charge transfer provided both molecules with a broad absorption range of 350–1000 nm. In addition, the high reorganization energy and weak molecular packing of BQE resulted in efficient nonradiative decay. More importantly, the self‐assembly of BQE leads to a textured surface and enhances the light‐trapping efficiency with significantly reduced light reflection/transmittance. Consequently, BQE achieved an impressive solar‐thermal conversion efficiency of 18.16 % under 1.0 kW m−2 irradiation with good photobleaching resistance. Based on this knowledge, the water evaporation rate of 1.2 kg m−2 h−1 was attained for the BQE‐based interfacial evaporation device with an efficiency of 83 % under 1.0 kW m−2 simulated sunlight. Finally, the synergetic integration of solar‐steam and thermoelectric co‐generation devices based on BQE was realized without significantly sacrificing solar‐steam efficiency. This underscores the practical applications of BQE‐based technology in effectively harnessing photothermal energy. This study provides new insights into the molecular design for enhancing light‐trapping management by molecular self‐assembly, paving the way for photothermal‐driven applications of organic photothermal materials. [ABSTRACT FROM AUTHOR]

Organic photothermal materials have attracted increasing attention because of their structural diversity, flexibility, and compatibility. However, their energy conversion efficiency is limited owing to the narrow absorption spectrum, strong reflection/transmittance, and insufficient nonradiative decay. In this study, two quinoxaline‐based D–A‐D–A‐D‐type molecules with ethyl (BQE) or carboxylate (BQC) substituents were synthesized. Strong intramolecular charge transfer provided both molecules with a broad absorption range of 350–1000 nm. In addition, the high reorganization energy and weak molecular packing of BQE resulted in efficient nonradiative decay. More importantly, the self‐assembly of BQE leads to a textured surface and enhances the light‐trapping efficiency with significantly reduced light reflection/transmittance. Consequently, BQE achieved an impressive solar‐thermal conversion efficiency of 18.16 % under 1.0 kW m−2 irradiation with good photobleaching resistance. Based on this knowledge, the water evaporation rate of 1.2 kg m−2 h−1 was attained for the BQE‐based interfacial evaporation device with an efficiency of 83 % under 1.0 kW m−2 simulated sunlight. Finally, the synergetic integration of solar‐steam and thermoelectric co‐generation devices based on BQE was realized without significantly sacrificing solar‐steam efficiency. This underscores the practical applications of BQE‐based technology in effectively harnessing photothermal energy. This study provides new insights into the molecular design for enhancing light‐trapping management by molecular self‐assembly, paving the way for photothermal‐driven applications of organic photothermal materials. [ABSTRACT FROM AUTHOR]

Some topological features of multisite Hamiltonians consisting of harmonic potential surfaces with constant site-to-site couplings are discussed. Even in the absence of Duschinsky rotation, such a Hamiltonian assumes the system-bath form only if severe constraints exist. The simplest case of a common bath that couples to all sites is realized when the potential minima are collinear. The bath reorganization energy increases quadratically with site distance in this case. Another frequently encountered situation involves exciton-vibration coupling in molecular aggregates, where the intramolecular normal modes of the monomers give rise to local harmonic potentials. In this case, the reorganization energy accompanying excitation transfer is independent of site-to-site separation, thus this situation cannot be described by the usual system-bath Hamiltonian. A vector system-bath representation is introduced, which brings the exciton-vibration Hamiltonian in system-bath form. In this, the system vectors specify the locations of the potential minima, which in the case of identical monomers lie on the vertices of a regular polyhedron. By properly choosing the system vectors, it is possible to couple each bath to one or more sites and to specify the desired initial density. With a collinear choice of system vectors, the coupling reverts to the simple form of a common bath. The compact form of the vector system-bath coupling generalizes the dissipative tight-binding model to account for local, correlated, and common baths. The influence functional for the vector system-bath Hamiltonian is obtained in a compact and simple form. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (RT-ILs) are promising electrolytes for electrocatalysis. Understanding the effects of the electrode–electrolyte interface structure on electrocatalysis in RT-ILs is important. Ultrafast mass transport of redox species in N-methyl-N-ethyl-pyrrolidinium polybromide (MEPBr2n+1) enabled evaluation of the reorganization energy (λ), which reflects the solvation structure in the inner Helmholtz plane (IHP). λ was achieved by fitting the electron transfer rate-limited voltammogram at a Pt ultramicroelectrode (UME) to the Marcus–Hush–Chidsey model for heterogeneous electron transfer kinetics. However, it is time-consuming or even impossible to prepare electrode materials, including alloys of numerous compositions in the form of UME, for each experiment. Herein, we report a method to evaluate the λ of MEPBr2n+1 by scanning electrochemical cell microscopy (SECCM), which allows high throughput electrochemical measurements using a single electrode with high spatial resolution. Fast mass transport in the nanosized SECCM tip is critical for achieving heterogeneous electron transfer-limited voltammograms. Furthermore, investigating λ on a high-entropy alloy materials library composed of Pt, Pd, Ru, Ir, and Ag suggests a negative correlation between λ and the work function. Given that the potential of zero charge correlates with the work function of electrodes, this can be attributed to the surface-charge sensitive ionic structure in the IHP of MEPBr2n+1, modulating the solvation energy of the redox-active species in the IHP. [ABSTRACT FROM AUTHOR]

We determine the zero-frequency charge current noise in a metal–molecule–metal junction embedded in a thermal environment, e.g., a solvent, dominated by sequential charge transmission described by a classical master equation, and we study the dependence of specific model parameters, i.e., the environmental reorganization energy and relaxation behavior. Interestingly, the classical current noise term has the same structure as its quantum analog, which reflects a charge correlation due to the bridging molecule. We further determine the thermodynamic uncertainty relation (TUR) defininig a bound on the relationship between the average charge current, its fluctuation, and the entropy production in an electrochemical junction in the Marcus regime. In the second part, we use the same methodology to calculate the current noise and the TUR for a protoype photovoltaic cell in order to predict its upper bound for the efficiency of energy conversion into useful work. [ABSTRACT FROM AUTHOR]

This study aims to identify a 5‐bromosalicylaldehyde (5BSA) and assess its performance for application in organic solar cells. In the current work, the 5BSA was investigated using various techniques such as FT‐IR, Raman, NMR, and UV‐Vis spectroscopy to characterize the title molecule. The possible conformers of the 5BSA were studied using the MMFF methodology in Spartan software. The geometry optimization of modifications for each conformation was computed using the DFT approach for the B3LYP/6‐311++G(d,p) functional. The energy and dipole moment of most stable form were determined −1879057.42 kcal/mol and 1.455 Debye, respectively. The FT‐IR and Raman vibrational frequencies, the H1 and C13 NMR chemical shift values (in vacuum and in DMSO‐d6), the UV spectrum calculations (both in vacuum and in the solvent ethanol), the HOMO‐LUMO energy, and the map of MEP. Meanwhile, by considering the properties of organic photovoltaic cells, the open‐circuit voltage (VOC), hole reorganization energy (λh) and electron reorganization energy (λe), light‐harvesting efficiency (LHE), total reorganization energy (λtotal), the short‐circuit current density (Jsc), the driving force (ΔGinject), binding energy (Eb) were also computed for the title compound. In addition, transition density matrix (TDM) and density of states (DOS) analyses were conducted for the 5BSA molecule. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbon (PAH) compounds are prospective materials for highly efficient narrowband organic light‐emitting diodes. Specifically, boron‐nitrogen doped PAHs exhibit multiple resonance (MR) effect toward thermally activated delayed fluorescence (TADF) and narrow full width at half‐maximum (FWHM). Currently, the molecular design strategy for bathochromic‐shifted narrowband MR‐TADF emitters is a hotspot and challenging puzzle. Herein, a carbonyl is fused in the boron‐nitrogen doped PAH for constructing a boron/nitrogen/carbonyl MR‐TADF emitter. Benefiting from the carbonyl, the developed emitter exhibits enhanced intramolecular charge transfer and decreased reorganization energy, which displays bathochromic‐shifted narrowband emission pertinently. As a consequence, the proof‐of‐concept compound TCZBAO achieves an emission peak at 522 nm and narrow FWHM of 39 nm, while the carbonyl‐free TCZBAC exhibits an emission peak at 502 nm and FWHM of 46 nm. Maximum external quantum efficiencies of 36.1 % and 32.4 % are realized for the devices based on TCZBAO and TCZBAC, respectively, indicating the guiding significance of the proposed design strategy for developing bathochromic‐shifted narrowband MR‐TADF emitters. [ABSTRACT FROM AUTHOR]

Polarons are prevalent in condensed matter systems with strong electron-phonon coupling. The adiabaticity of the polaron relates to its transport properties and spatial extent. To date, only adiabatic small polaron formation has been measured following photoexcitation. The lattice reorganization energy is large enough that the first electron-optical phonon scattering event creates a small polaron without requiring substantial carrier thermalization. We measure that frustrating the iron-centered octahedra in the rare-earth orthoferrite ErFeO3 leads to antiadiabatic polaron formation. Coherent charge hopping between neighboring Fe3+-Fe2+ sites is measured with transient extreme ultraviolet spectroscopy and lasts several picoseconds before the polaron forms. The resulting small polaron formation time is an order of magnitude longer than previous measurements and indicates a shallow potential well, even in the excited state. The results emphasize the importance of considering dynamic electron-electron correlations, not just electron-phonon-induced lattice changes, for small polarons for transport, catalysis, and photoexcited applications. [ABSTRACT FROM AUTHOR]

In a previous study, we proposed an open quantum network model of a quantum battery (QB) that possesses dark states owing to its structural exchange symmetries. While in a dark state, the QB is capable of storing an exciton without any environment-induced population losses. However, when the structural exchange symmetry is broken, the QB begins to discharge the exciton towards its exit site. In this article, we start by demonstrating that this QB is not only loss-free with respect to exciton population during the storage phase, but also with respect to the QB energy. We then explore the exciton population and energy transfer dynamics of the QB during the discharge phase over a wide range of site energies, bath temperatures, and bath reorganization energies. Our results shed light on how to optimize the QB's population and energy transfer dynamics for different purposes. [ABSTRACT FROM AUTHOR]

Context: Organic semiconductors (OSCs) have attracted a great deal of interest in recent days. There are various types of OSCs, among which small molecules have various inherent benefits. Further research is needed to advance this new kind of material because the field is still developing, and the current focus is on creating small molecules that exist naturally for OSCs. OSCs with nonlinear optical (NLO) characteristics offer a significant advantage over others. Thus, this study theoretically investigates naturally occurring anthraquinones such as chrysophanol and rhein as potential OSCs, as well as their NLO properties. The calculated properties include the ionization potential (IP), electron affinity (EA), and bandgap (Eg). The FMO energy levels together with the Eg, IP (8.17–8.53 eV), and EA (1.87–2.44 eV) suggest the semiconductor nature of the studied compounds. The calculated values of reorganization energy (λ) and transfer integrals (V) suggest the p-type character of both molecules. Rhein has the lowest λh (0.19 eV) and Eg (3.28 eV) and the highest Vh, predominantly because of its better p-type character. The polarizability increases due to the presence of an electron-withdrawing substituent, leading to better NLO performance for Rhein, which is supported by its lower LUMO and Eg values. Methods: The studied molecules were optimized with the DFT/B3LYP-GD3/6-31+G(d,p) method using Gaussian 16 software. The crystal structure was simulated with Materials Studio 7.0, and the V values were calculated with the ADF package. The CDD and DOS plots were obtained with the Multiwfn 3.8 program. [ABSTRACT FROM AUTHOR]

Purely organic sulfone‐embedded materials play a significant role in thermally activated delayed fluorescence (TADF) emitters with theoretical 100 % exciton utilization for highly efficient organic light‐emitting diodes. However, intrinsic emission mechanism featuring twisted intramolecular charge transfer design strategy leads to severe structural distortion between ground state and excited state, disabling traditional sulfone‐based TADF emitters to achieve narrowband emission and high colour purity for wide colour gamut display. Recently, sulfone‐embedded narrowband TADF emitters have gradually emerged. Herein, we summarize the currently reported sulfone‐based narrowband emitters, with emphasis on the perspectives of molecular design, role of sulfone group in fused skeleton, photophysical property as well as future application prospect of this sort of materials. [ABSTRACT FROM AUTHOR]

In the present work, a well organised pathway for the eco‐friendly synthesis of a series of 4,5‐diarylpyrazole‐1‐carboxylates has been reported. The resulted compounds were characterized by different spectroscopic techniques (IR, 1H‐NMR & 13C‐NMR and HRMS). To shed light on various properties of interests, density functional theory (DFT) was utilized to optimize the ground state geometry of synthesized pyrazoles. Time dependent density functional theory (TDDFT) was used to investigate the impact of various functionals on the absorption wavelength i.e., B3LYP, M062X, BHandHLYP, B3P86, CAM‐B3LYP, and PBE0. Among all these functional, CAM‐B3LYP and BHandHLYP were in good consent with the experimental results. With an aim to enhance the optoelectronic properties, 10 new derivatives were designed by varying the various substituents on the aryl ring. Among all these synthesized pyrazole molecule, Methyl 4‐(4‐Methoxyphenyl)‐5‐(3‐nitrophenyl)‐1H‐pyrazole‐1‐carboxylate 3a and Methyl 4‐(4‐Methoxyphenyl)‐5‐(4‐nitrophenyl)‐1H‐pyrazole‐1‐carboxylate 3b exhibited better optoelectronic properties with HOMO‐LUMO gap of 3.38 eV. To the best of our knowledge, the studies of photophysical properties of these 1,4,5‐trisubstituted pyrazoles for optoelectronic uses has been reported first time by our research group. [ABSTRACT FROM AUTHOR]

We have simulated the effect of changing the end groups in BTP core with five organic units of 1,3-Indandione (IN), 2-thioxothiazolidin-4-one (Rhodanine), propanedinitrile (Malononitrile), (2-(6-oxo-5,6-dihydro-4H-cyclopenta[c]thiophen-4-ylidene)malononitrile) (CPTCN) and 2-(3-oxo-2,3-dihydroinden-1-ylidene (IC), and two halogenated units of (4F) IC and (4Cl) IC on the optical and photovoltaic properties of the BTP DA'D core molecular unit. Thus modified, seven molecular structures are considered and their optical properties, including HOMO and LUMO energies and absorption spectra are simulated in this paper. On the basis of HOMO and LUMO energies, it is found that two of the seven molecules, BTP-IN and BTP-Rhodanine, can act as donors and the other four, BTP-(4F) IC, BTP-(4Cl) IC, BTP-CPTCN and BTP-IC, as acceptors in designing bulk heterojunction (BHJ) organic solar cells (OSCs). Using these combinations of donors and acceptors in the active layer, eight BHJ OSCs, such as BTP-IN: BTP-(4F) IC, BTP-IN: BTP-(4Cl) IC, BTP-IN: BTP-CPTCN, BTP-IN: BTP-IC, BTP-Rhodanine: BTP-(4F) IC, BTP-Rhodanine: BTP-(4Cl) IC, BTP-Rhodanine: BTP-CPTCN and BTP-Rhodanine: BTP-IC, are designed, and their photovoltaic performance is simulated. The photovoltaic parameters J s c , V o c and FF for all eight BHJ OSCs and their power conversion efficiency (PCE) are simulated. It is found that the BHJ OSC of the BTP-IN: BTP-CPTCN donor–acceptor blend gives the highest PCE (14.73%) and that of BTP-Rhodanine: BTP-(4F) IC gives the lowest PCE (12.07%). These results offer promising prospects for the fabrication of high-efficiency BHJ OSCs with the blend of both donor and acceptor based on the same core structure. [ABSTRACT FROM AUTHOR]

An effective way to enhance the photovoltaic properties of a small molecule is to modify the side groups into donor units. Herein three news small molecules A‐π‐D‐π‐A, denoted Dye1‐3, have been designed, from experimentally reported one noted (R), by insertion of various heteroatoms (S, O, Se) on the electron‐donating benzodithiophene (Donor (D = BDT)) part. From the calculated results, the dihedral angle between BDT and side‐chain affects the distribution of density on the ground state, gap energy, and intramolecular charge transfer of Dyes. In particular, the Dye3 compound, with the smaller dihedral angle, shows that the furan groups in the side chain of D, participates in the distribution of density on the ground state and consequently the charge transfer is improved. Additionally, Dye3 has the lower reorganization energy revealing that this material exhibits better charge mobility. Using the Scharber diagram, Dye3‐PCBM heterojunction shows a power conversion efficiency of around 7%. Overall, this work suggests that the photovoltaic properties can be affected by the modification of heteroatoms on side groups of donor parts in small molecules. [ABSTRACT FROM AUTHOR]

The total reorganization energy of the system and its components, the solvent reorganization energy and the transformation energy of reactants (water clusters [(H2O)nOH]-), during electrocatalytic hydrogen evolution on binary alloys of molybdenum with iron subgroup metals (Fe, Co, Ni) in an alkaline medium (30 wt.% NaOH solution) have been calculated. The calculated values of the solvent reorganization energy and the reorganization energy of water clusters are in agreement with the Marcus - Dogonadze - Kuznetsov theory. The dependence of the total reorganization energy of the system, the solvent reorganization energy, and the reorganization energy of discharging species (water clusters) on the electrolyte temperature has been calculated. It was shown that the total reorganization energy of the system and the activation energy of the electron-transfer reaction of electrocatalytic hydrogen evolution (HER) on binary alloys of molybdenum with iron subgroup metals in an alcaline vedium (30 wt.% NaOH solution) decrease linearly with increasing electrolyte temperature in the following order: Fe-54 at. % Mo > Ni-54 at. % Mo > Co-52 at. % Mo. The temperature dependences of the water cluster discharge reorganization energy and the activation energy on binary molybdenum alloys are linear and intersect in the boiling point region of 30 wt.% NaOH solution 384.7 K. At this temperature, the electrode process is limited by the diffusion of regenerating water clusters to the electrode surface. The calculated diffusion activation energy Ad is 9.9 kJ·mol-1. The value of the system reorganization energy Aris 39.8 kJ·mol-1, which is consistent with the theory of Markus - Dogonadze - Kuznetsov. Electrocatalytic activity of binary alloys of molybdenum with iron subgroup metals at 30 wt.% NaOH solution at this temperature is maximum and does not depend on the nature of the alloy. [ABSTRACT FROM AUTHOR]

Context: Various innovative molecules have been designed and explored for use in organic photovoltaics. In this study, we devised novel molecules (KZ1–KZ7) specifically for organic solar cells (OSCs). The newly formulated acceptor compounds possess a lower bandgap (Eg = 1.85–2.02), along with bathochromic shift (λmax = 713–788 nm) compared to the reference (Eg = 2.04 eV and λmax = 774 nm). Moreover, the FMO results identified the distinct charge transfer from HOMO to LUMO, which was strongly corroborated by the TDM maps. Similarly, the new designed molecules show less excitation energy (Ex = 1.31–1.54(gas)) than reference (Ex = 1.72). Likewise, all designed molecules (KZ1–KZ7) have demonstrated an analogous open circuit voltage (Voc) with the donor polymer PTB7-Th. All seven designed molecules (KZ1–KZ7) exhibited more fill factor ranging from 97.08 to 97.29 than reference 95.25 and PCE of between 8 and 20% at short circuit current densities of 9, 12, and 15 mA cm−2. Overall, the findings support that designed molecules can be potential molecules for future practical applications. Methods: Geometric calculations were conducted with Gaussian 09W software, and the findings were visualized using Gauss View software. DFT and TD-DFT were employed to evaluate various parameters for R and designed molecules (KZ1–KZ7). Firstly, four functionals including B3LYP, CAM-B3LYP, MPW1PW91, and ωB97XD with 6-31G(d,p) DFT level were applied to R to decide the best level for results. After appropriate analysis, the MPW1PW91/6-31G(d,p) was selected for further examination by comparing the experimental and DFT-based absorption graphs of R. External and internal reorganization energy are the two main factors contributing to reorganization energy. External energy refers to changes in external environment, while internal energy deals with information related to internal geometrical symmetry or the internal environment. The effect of outside factors or external reorganizational energy is omitted because it creates too little change. [ABSTRACT FROM AUTHOR]

New developments in the field of Lewis acidity are highlighted, with the focus of novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements. Several important basics, illustrated by modern examples (classification of Donor‐Acceptor (DA) complexes, amphoteric nature of any compound in terms of DA interactions, reorganization energies of main group Lewis acids and the role of the energies of frontier orbitals) are presented and discussed. It is emphasized that the Lewis acidity phenomena are general and play vital role in different areas of chemistry: from weak "atomophilic" interactions to the complexes of Lewis superacids. [ABSTRACT FROM AUTHOR]

This study's primary objective is to give a thorough examination of the comparative charge transport and optoelectronic characteristics of all conceivable isomers of benzodithiophene (BDT) and benzodiselenophene (BDSe). Density Functional Theory (DFT) simulations have been performed on all the possible isomers of benzodithiophene (BDT) and benzodiselenophene (BDSe) and results are compared with corresponding experimental known isomers. The absorption energies and HOMO–LUMO energy levels were predicted by Time-Dependent Density Functional Theory (TD–DFT). Electron and hole Reorganization Energies (RE), Hole Extraction Potential (HEP) and Electron Extraction Potential (EEP), Ionization Potentials (IP) and Electron Affinities (EA) of all the isomers are reported. The UV–visible absorption of BDT and BDSe isomers are between 250–417 nm and 290–445 nm respectively. Comparatively, the simulated hole and electron reorganization energy of all the BDT and BDSe isomers have low values and hence expected applications in the field of Organic Optoelectronic Devices. [ABSTRACT FROM AUTHOR]

A simple strategy to simultaneously achieve fast reverse intersystem crossing (RISC) and low non‐radiative decay rates in thermally activated delayed fluorescence (TADF) emitters is still lacking. Here, the green TADF emitters containing aromatic ketones and prepared D‐Ph and D‐PhCz containing different amounts of deuterium are deuterated to study the mechanism of deuterium on the performance improvement of TADF devices. Due to the heavy atom effect of deuterium, the non‐radiative transition rate constant (knr) of D‐Ph and D‐PhCz decreases. Most importantly, deuterium reduces the reorganization energy (λ) of (T1‐S1), which greatly improves the reverse intersystem crossing rate constant (kRISC) and the exciton utilization efficiency. The results show that the external quantum efficiency of D‐Ph and D‐PhCz increases to 25.69% and 24.92%, respectively. This study provides a simple and efficient strategy for reducing non‐radiative energy loss and increasing kRISC to achieve high‐performance TADF emitters. [ABSTRACT FROM AUTHOR]

Metalloproteins, known to efficiently transfer electronic charge in biological systems, recently found their utilization in nanobiotechnological devices where the protein is placed into direct contact with metal surfaces. The feasibility of oxidation/reduction of the protein redox sites is affected by the reorganization free energies, one of the key parameters determining the transfer rates. While their values have been measured and computed for proteins in their native environments, i.e., in aqueous solution, the reorganization free energies of dry proteins or proteins adsorbed to metal surfaces remain unknown. Here, we investigate the redox properties of blue copper protein azurin, a prototypical redox-active metalloprotein previously probed by various experimental techniques both in solution and on metal/vacuum interfaces. We used a hybrid quantum mechanical/molecular mechanical computational technique based on density functional theory to explore protein dynamics, flexibility, and corresponding reorganization free energies in aqueous solution, vacuum, and on vacuum gold interfaces. Surprisingly, the reorganization free energy only slightly decreases when azurin is dried because the loss of the hydration shell leads to larger flexibility of the protein near its redox site. At the vacuum gold surfaces, the energetics of the structure relaxation depends on the adsorption geometry; however, significant reduction of the reorganization free energy was not observed. These findings have important consequences for the charge transport mechanism in vacuum devices, showing that the free energy barriers for protein oxidation remain significant even under ultra-high vacuum conditions. [ABSTRACT FROM AUTHOR]

The availability of large, high-quality datasets is crucial for artificial intelligence design and discovery in chemistry. Despite the essential roles of solvents in chemistry, the rapid computational dataset generation of solution-phase molecular properties at the quantum mechanical level of theory was previously hampered by the complicated simulation procedure. Software toolkits that can automate the procedure to set up high-throughput explicit-solvent quantum chemistry (QC) calculations for arbitrary solutes and solvents in an open-source framework are still lacking. We developed AutoSolvate, an open-source toolkit, to streamline the workflow for QC calculation of explicitly solvated molecules. It automates the solvated-structure generation, force field fitting, configuration sampling, and the final extraction of microsolvated cluster structures that QC packages can readily use to predict molecular properties of interest. AutoSolvate is available through both a command line interface and a graphical user interface, making it accessible to the broader scientific community. To improve the quality of the initial structures generated by AutoSolvate, we investigated the dependence of solute–solvent closeness on solute/solvent identities and trained a machine learning model to predict the closeness and guide initial structure generation. Finally, we tested the capability of AutoSolvate for rapid dataset curation by calculating the outer-sphere reorganization energy of a large dataset of 166 redox couples, which demonstrated the promise of the AutoSolvate package for chemical discovery efforts. [ABSTRACT FROM AUTHOR]

Optimizing energy and charge transfer is key in design and implementation of efficient layered conductive metal–organic frameworks (MOFs) for practical applications. In this work, for the first time, we investigate the role of both long-range excitonic and short-range charge transfer coupling as well as their dependency on reorganization energy on through-space charge transfer in layered MOFs. A π-stacked model system is built based on the archetypal Ni3(HITP)2, HITP = 2,3,6,7,10,11-hexaiminotriphenylene, layered MOF, and a Frenkel/charge transfer Holstein Hamiltonian is developed that takes into account both electronic coupling and intramolecular vibrations. The dependency of the long- and short-range couplings of secondary building units (SBUs) on the stacking geometry is evaluated, which predicts that photophysical properties of layered MOFs critically depend on the degree of ordering between layers. We show that the impact of the two coupling sources in these materials can be discerned or enhanced by the displacement of the SBUs along the long or short molecular axes. The effects of vibronic spectral signatures are examined in both perturbative and resonance regimes. Although, to the best of our knowledge, displacement engineering in layered MOFs currently remains beyond reach, the findings reported here offer new details on the photophysical structure–property relationships in layered MOFs and provide suggestions on how to combine elements of molecular design and engineering to achieve desirable properties and functions for nano- and mesoscale optoelectronic applications. [ABSTRACT FROM AUTHOR]

We examine the impact of the intrinsic molecular reorganization energy on switching in two-state quantum-dot cellular automata cells. Switching a bit involves an electron transferring between charge centers within the molecule. This, in turn, causes the other atoms in the molecule to rearrange their positions in response. We capture this in a model that treats the electron motion quantum-mechanically but the motion of nuclei semiclassically. This results in a non-linear Hamiltonian for the electron system. Interaction with a thermal environment is included by solving the Lindblad equation for the time-dependent density matrix. The calculated response of a molecule to the local electric field shows hysteresis during switching when the sweep direction is reversed. The relaxation of neighboring nuclei increases the localization of the electron, which provides an intrinsic source of enhanced bistability and single-molecule memory. This comes at the cost of increased power dissipation. [ABSTRACT FROM AUTHOR]

Understanding the formation of the solid–electrolyte interphase (SEI) in lithium-ion batteries is an ongoing area of research due to its high degree of complexity and the difficulties encountered by experimental studies. Herein, we investigate the initial stage of SEI growth, the reduction reaction of ethylene carbonate (EC), from both a thermodynamic and a kinetic approach with theory and molecular simulations. We employed both the potential distribution theorem and the Solvation Method based on Density (SMD) to EC solvation for the estimation of reduction potentials of Li+, EC, and Li+-solvating EC (s-EC) as well as reduction rate constants of EC and s-EC. We find that solvation effects greatly influence these quantities of interest, particularly the Li+/Li reference electrode potential in EC solvent. Furthermore, we also compute the inner- and outer-sphere reorganization energies for both EC and s-EC at the interface of liquid EC and a hydroxyl-terminated graphite surface, where total reorganization energies are predicted to be 76.6 and 88.9 kcal/mol, respectively. With the computed reorganization energies, we estimate reduction rate constants across a range of overpotentials and show that EC has a larger electron transfer rate constant than s-EC at equilibrium, despite s-EC being more thermodynamically favorable. Overall, this manuscript demonstrates how ion solvation effects largely govern the prediction of reduction potentials and electron transfer rate constants at the electrode–electrolyte interface. [ABSTRACT FROM AUTHOR]

Some analytical results for the steady-state properties of the single-molecule tunneling junction are obtained with the use of the broadened classical master equations and classical master equations. The case of the one electronic level of the bridge molecule coupled to a single classical harmonic oscillator is considered within the spin-less model. Based on these equations, we establish some relations between different average values of interest, considering the large bias limit and the limit of the weak electron–oscillator coupling. We derive the analytical expressions for a number of characteristic properties of the tunneling junction in these limiting cases, compare our results with those obtained by the numerically exact calculations, and find that our expressions work very well. In the diabatic regime, the approximate solutions of the classical master equations are suggested, which permit us to introduce the effective temperature Teff and perform rather simple calculations of the average vibrational excitations N and the tunnel current I. It is shown that in the adiabatic regime, the properties of the tunneling junction depend essentially on the effective temperature Teff ad. We obtain the analytical expressions for Teff ad using different approaches for the treatment of the adiabatic regime. For both the diabatic and adiabatic regimes, we calculate Teff, Teff ad, N, and I, compare our results with those available in the literature, and confirm well agreement. The dependence of N and I on the reorganization energy and the position of the electronic level of the bridge molecule is discussed. [ABSTRACT FROM AUTHOR]

Periodic boundary conditions and Ewald sums used in standard simulation protocols require finite-size corrections when the total charge of the simulated system is nonzero. Corrections for ion solvation were introduced by Hummer, Pratt, and García, [J. Chem. Phys. 107, 9275 (1997)]. The latter approach is extended here to derive finite-size correction for the Stokes-shift and reorganization energy applied to electron-transfer reactions. The same correction term, scaling inversely with the box size, adds to the reorganization energy from the energy-gap variance but is subtracted from the reorganization energy calculated from the Stokes shift. Finite-size corrections thus widen the gap between these two quantities, which were recently found to diverge for protein electron transfer. Corrections to the free energy of dipole solvation and the variance of the electric field scale as m2/L3 with the solute dipole m and the box size L. [ABSTRACT FROM AUTHOR]

Understanding and predicting the charge transport properties of π-conjugated materials is an important challenge for designing new organic electronic devices, such as solar cells, plastic transistors, light-emitting devices, and chemical sensors. A key component of the hopping mechanism of charge transfer in these materials is the Marcus reorganization energy which serves as an activation barrier to hole or electron transfer. While modern density functional methods have proven to accurately predict trends in intramolecular reorganization energy, such calculations are computationally expensive. In this work, we outline active machine learning methods to predict computed intramolecular reorganization energies of a wide range of polythiophenes and their use toward screening new compounds with low internal reorganization energies. Our models have an overall root mean square error (RMSE) of ±0.113 eV, but a much smaller RMSE of only ±0.036 eV on the new screening set. Since the larger error derives from high-reorganization energy compounds, the new method is highly effective to screen for compounds with potentially efficient charge transport parameters. [ABSTRACT FROM AUTHOR]

Environmental issues and energy crisis are huge challenges in today's world. As one of green energy sources, thermoelectric (TE) materials have attracted tremendous attraction for they can convert free heat energy to electricity. In our work, through the master equation (ME) method, we studied the characteristics of charge transport in the organic material under nonlinear temperature distributions. Under each temperature distribution, Seebeck coefficient is analyzed with different factors such as the temperature, the reorganization energy and the energetic disorder strength. Especially, Seebeck coefficient of different temperature distributions showed different performances when the reorganization energy changes. Our studies will be helpful to look further into TE properties of organic materials and improve the application of TE devices. [ABSTRACT FROM AUTHOR]

Using the density functional theory (DFT), the influence of substitution of electron-donating (OCH3 and OH) and electron-accepting (F and Cl) groups on the peripheral thiophene units of DRTB-T donor molecule is studied. By optimizing the geometric structure, HOMO and LUMO energies, reorganization energies, optical properties, and photovoltaic properties are simulated. It is found that the ionization potential of the electron-donating derivatives (DRTB-4OCH3 and DRTB-4OH) reduces, but it increases for the electron-accepting derivatives (DRTB-4F and DRTB-4Cl) in comparison with that of DRTB-T. It is also found that the absorption spectra of the electron-donating derivatives (DRTB-4OCH3 and DRTB-4OH) get redshifted, but these get blue shifted for the electron-accepting derivatives (DRTB-4F and DRTB-4Cl) in comparison with those of DRTB-T. These changes in the electronic and optical properties of the modified structures result in higher PCE in BHJ OSCs with the blended active layer of DRTB-4F: NITI, DRTB-4Cl: NITI, in comparison with that of OSC with the active layer of DRTB-T: NITI and the highest being 15.0% in DRTB-4Cl: NITI. Our results may be expected to provide valuable insights into design optimization, leading to the fabrication of more efficient OSCs. [ABSTRACT FROM AUTHOR]

Robust scaffolds were typically applied in thermally activated delayed fluorescence (TADF) molecules to suppress the non‐radiative decay, trigger the fast spin‐flipping, and enhance the light out‐coupling efficiency. Herein, we disclosed for the first time the positive effect of flexible conformation of ancillary groups on the photophysical properties of TADF emitter. The red TADF emitter Ph‐TPA with flexible conformation demonstrated small excited‐state structural distortion and low reorganization energy compared to the counterpart Mc‐TPA with a rigid macrocycle. Consequently, Ph‐TPA showed an excellent photoluminescent quantum yield (PLQY) of 92 % and a state‐of‐the‐art external quantum efficiency (EQE) of 30.6 % at 630 nm. This work could deepen our understanding of structure‐property relationships of organic luminophores and help us to rationalize the design of efficient TADF materials. [ABSTRACT FROM AUTHOR]

Water splitting is a promising method for hydrogen generation, but current catalytic reactions suffer from low efficiency. One possible reason for such inefficiency is a high kinetic barrier for water oxidation, and there is a lack of direct and efficient method to calculate the barrier for each reaction. In this paper, the inner sphere component of the reorganization energy that contributed to the activation energies is calculated. A novel algorithm is used for calculating the reorganization energy based on Marcus theory combined with the climbing image nudged elastic band method used to find transition states and activation energies of the oxygen evolution reaction steps, which allows the calculation of the activation energy at different potentials and without simulating solvation in order to obtain the inner sphere component alone arising from the reorganization of the ionic surface. The new method is tested in both acidic and basic conditions and with explicit water molecules, as well as implicit solvation. It is discovered that the reaction involving the transition of the *O intermediate into *OOH has the highest activation energy of all steps, thus explaining the high coverage of the *O intermediate found by experiments. [ABSTRACT FROM AUTHOR]