Theoretical study of the electric and the magnetic dipole in UV-Vis and ECD of fluralaner: the folded conformation and the extended conformation

In our contribution, we have carried out a theoretical study of the transition characteristics of one-photon absorption (OPA) spectra of the folded conformation and the extended conformation of fluralaner. The electronic transitions in OPA are visualized with charge difference density (CDD) and transition density matrix (TDM) to explain the charge transfer via hole-electron distribution. We also analyze the transition dipole electric/ magnetic moment by using the isosurface (real space) and TDM diagram in order to determine the portions of molecules which have the most contribution in ECD spectra.

Density functional study on electric structure and optical properties in Na-doped 3C-SiC

Structural stability along with the electronic and the optical properties of intrinsic 3C-SiC, [Formula: see text] and [Formula: see text] are studied by the first-principles calculations. [Formula: see text] system possesses the most considerate stability with lowest binding energy [Formula: see text] and formation energy [Formula: see text] compared to [Formula: see text]. It is observed that the non-filled impurity energy levels in the vicinity of the Fermi level can subsequently give rise to an enhancement of electrical conductivity of 3C-SiC. Through the analysis of charge difference density maps, it is found that covalence of bonds between the Na atom and nearby C atom reduces in varying degrees. In different concentrations of Na doping systems, especially for the supercell of [Formula: see text], the real and imaginary parts of the dielectric constant are visibly added in the energy range of 0–0.5 eV, demonstrating that the dielectric loss property of the 3C-SiC is improved evidently. These features confirm that the Na-doped 3C-SiC semiconductor is propitious to the wide application of 3C-SiC in the field of absorbing materials.

Electronic structures and optical properties of IV A elements-doped 3C-SiC from density functional calculations

Electronic structures and optical properties of IV A elements (Ge, Sn and Pb)-doped 3C-SiC are investigated by means of the first-principles calculation. The results reveal that the structure of Ge-doped system is more stable with a lower formation energy of 1.249 eV compared with those of Sn- and Pb-doped 3C-SiC systems of 3.360 eV and 5.476 eV, respectively. Doping of the IV A elements can increase the band gap, and there is an obvious transition from an indirect band gap to a direct band gap. Furthermore, charge difference density analysis proves that the covalent order of bonding between the doping atoms and the C atoms is Ge–C [Formula: see text] Sn–C [Formula: see text] Pb–C, which is fully verified by population values. Due to the lower static dielectric constant, the service life of 3C-SiC dramatically improved in production practice. Moreover, the lower reflectivity and absorption peak in the visible region, implying its wide application foreground in photoelectric devices.

Photoactuated Properties of Acetylene-Congeners Non-Metallic Dyes and Molecular Design for Solar Cells

This paper theoretically simulated (using DFT and TD-DFT in N,N-dimethylformamide (DMF) solvent) the photodynamic properties of three non-metallic dye molecules with D-π-A1-π-A2 structure. The total photoelectric conversion efficiency (PCE) could be evaluated by the following parameters: the geometric structures, the electronic structures, and the absorption spectra, the analyses of charge difference density (CDD) and natural bond orbitals (NBO), the analyses of ionization potential (IP) and electron affinity (EA) from electronic contribution capacity, the reorganization energies (λh, λe, and λtotal), and the chemical reaction parameter (h, ω, ω-, and ω+) for intramolecular charge transfer (ICT) processing, the excited lifetime (τ) and the vertical dipole moment (μnormol). The ∆Ginject, the ∆Gdyeregen, the light harvesting efficiencies (LHE) and the excited lifetime (τ) were used to explain experimental JSC. The experimental trend of VOC was explained by the calculation of ∆ECB and μnormol. Moreover, the 15 dyes were designed by adding the electron-donor groups (–OH, –NH2, and –OCH3) and the electron-acceptor groups (–CF3, –F, and −CN) to the LS-387 molecular skeleton, which improved electronic contribution, intramolecular charge transfer (ICT), and optoelectronic performance.

Photoinduced charge transfer by one and two-photon absorptions: physical mechanisms and applications

We review photoinduced charge transfer in organic solar cells without and with an external electric field and then we introduce the visualization methods of the transition density, charge difference density and transition density matrix for the analysis of the photoinduced charge transfer in a neutral system and a charged system excited by one-photon and two-photon absorption.

Photoactive Layer of DSSCS Based on Natural Dyes: A Study of Experiment and Theory

Three natural dyes (Forsythia suspensa, Herba Violae, and Corn leaf) have been investigated as potential sensitizers for dye-sensitized solar cells. UV-vis absorption spectra reveal that three natural dyes mainly contain the compound of pheophytin a. Among three DSSCs, the highest photo electronic conversion efficiencyηis 0.96% with open circuit voltage (VOC) of 0.66 V, short circuit current density (ISC ) of 1.97 mA cm−2, and fill factor (ff) of 0.74. Theoretical time-dependent density functional theory and charge difference density are used to explore the nature of excited states. Results demonstrate that the first state is an intramolecular charge transfer (ICT) state, and electron injection could occur owing to the thermodynamically driving force.

STRUCTURES AND SPECTROSCOPIC PROPERTIES OF THREE AROMATIC HETEROCYCLIC DYE PHOTOSENSITIZERS

The ground-state structures and absorption spectra of three dyes, carbazole, phenothiazine and diphenylamine, were studied by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The strong absorption peak, electron transition as well as the energy levels of molecular orbitals were obtained and compared in the gas and solvent phase. Furthermore, we further calculated the effect of the expanding conjugated bridge on the absorption spectra and the energy levels of molecular orbitals. Visualized method of charge difference density (CDD) was used to show the direction of charge transfer in the molecules of interest during photo-excitation.

Effect of Electronic Acceptor Segments on Photophysical Properties of Low-Band-Gap Ambipolar Polymers

Stimulated by a recent experimental report, charge transfer and photophysical properties of donor-acceptor ambipolar polymer were studied with the quantum chemistry calculation and the developed 3D charge difference density method. The effects of electronic acceptor strength on the structure, energy levels, electron density distribution, ionization potentials, and electron affinities were also obtained to estimate the transporting ability of hole and electron. With the developed 3D charge difference density, one visualizes the charge transfer process, distinguishes the role of molecular units, and finds the relationship between the role of DPP and excitation energy for the three polymers during photo-excitation.

A FIRST PRINCIPLE ANALYSIS ON THE STRUCTURAL AND PHOTO-INDUCED CHARGE TRANSFER IN RUTHENIUM COMPLEXES OF HEXAAZATRIPHENYLENE

Three complexes [ Ru ( CN )4( HAT )]2-( HAT = hexaazatriphenylene ;[ Ru 1]2-), [{ Ru ( CN )4}2 (μ2- HAT )]4-([ Ru 2]4-) and [{ Ru ( CN )4}3(μ3- HAT )]6-([ Ru 3]6-) for supramolecular assemblies are investigated by quantum-chemical calculations. Due to symmetry of complexes, the energy level differences are 2.014 eV and 2.019 eV for [ Ru 2]4- and [ Ru 3]6- complex, which are about 0.4 eV larger than that for [ Ru 1]2- complex. The absorption maximum for [ Ru 1]2- complex in water is at 375.8 nm. Coordination of the second and third Ru(II) center to produce [ Ru 2]4- and [ Ru 3]6- result in a red-shift of this strongest absorption to 453.4 nm and 468.1 nm, respectively. Absorption maximum of three complexes belong to MLCT transitions, which are revealed by frontier molecular orbital theory and charge difference density method.

INTERMOLECULAR CHARGE TRANSFER ENHANCED RESONANCE RAMAN SCATTERING OF CHARGE TRANSFER COMPLEX

Intermolecular charge transfer (ICT) enhanced resonance Raman scattering of charge transfer complex is investigated experimentally and theoretically. The evidence for intermolecular charge transfer on resonance electronic transition is visualized with charge difference density. The resonant Raman spectra reveal that the intensity of Raman peaks are strongly enhanced on the order of 104, by comparing with the normal Raman scattering spectrum. ICT complexes can be used in fluorescence-, photoluminescence-, and electrochemistry-based techniques for sensing target molecules. These strong charge-transfer Raman peaks would enable discrimination of important target molecules from interferants that is normal Raman scattering for the isolated target molecules.