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Ab initio Calculations of Optoelectronic Properties of Antimony Sulfide nano-thin film for Solar Cell Applications
摘要： Antimony sulfide (Sb2S3) micro thin-film have been received great interest as an absorbing layer for solar cell technology. In this study, to explore its further potential, electronic and optical properties of Sb2S3 simulated nano-thin film are investigated by the first-principles approach. To do so, the highly accurate full-potential linearized augmented plane wave (FP-LAPW) method framed within density functional theory (DFT) as implemented in the WIEN2k package is employed. The films are simulated in the [001] direction using the supercell method with a vacuum along z-direction so that slab and periodic images can be treated independently. From our calculations, indirect band gap energy values of Sb2S3 for various slabs are found to be 0.568, 0.596 and 0.609 eV for 1, 2 and 4 slabs respectively. Moreover, optical properties comprising of real and imaginary parts of the complex dielectric function, absorption coefficient, refractive index are also investigated to understand the optical behavior of the obtained simulated Sb2S3 thin films. From the analysis of their optical properties, it is clearly seen that Sb2S3 thin films have good values for optical absorption parameters in the visible and ultraviolet wavelength range, showing the aptness of antimony sulphide thins films for versatile optoelectronic applications as a base material.
关键词： DFT,Solar cell,optical properties,Sb2S3,thin-film,LAPW
更新于2025-09-11 14:15:04
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Combined statistical physics models and DFT theory to study the adsorption process of paprika dye On TiO2 for dye sensitized solar cells
摘要： This study reported the combination of advanced statistical physics modeling and density functional theory (DFT) investigation for the interpretation of the adsorption of Paprika dye on TiO2 surface for dye sensitized solar cells. By using a statistical physics modeling method, an adequate monolayer model with four energies was successfully used to interpret the adsorption process at a macroscopic level. The DFT simulation has been used to study the interaction of the Paprika dye on TiO2 surface to understand some of the atomistic details that are crucial to the dye/semiconductor interaction. We pay particular attention to the adsorption modes, geometries and energies between the paprika dye and TiO2. The DFT simulation determined different binding modes which participated in the adsorption of Paprika dye on TiO2 surface: monodentate coordination via hydrogen atom bond, monodentate coordination via oxygen atom bond and bidentate coordination via two oxygen atoms bond. In particular, calculations showed that the interaction between the paprika dye and TiO2 is strengthened with the bidentate coordination mode via the two hydroxyl and ether functionalities groups involved in the adsorption process.
关键词： Statistical physics modeling,Dye sensitized solar cells,Paprika oleoresin dye,Adsorption isotherms,DFT simulation
更新于2025-09-11 14:15:04
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Electronic Structures and Catalytic Activities of Niobium Oxides as Electrocatalysts in Liquid Junction Photovoltaic Devices
摘要： Two types of nanosized niobium oxides and their composite: pseudo-hexagonal Nb2O5 (TT-Nb2O5), monoclinic NbO2 (M-NbO2) and the coexistence of TT-Nb2O5 and M-NbO2 (TT-Nb2O5/M-NbO2) are successfully synthesized through the urea-metal chloride route, and they exhibit excellent catalytic activity and photovoltaic performance in dye-sensitized solar cells (DSSCs). First-principles density function theory (DFT) calculations show that their catalytic activity is significantly influenced by their intrinsic electronic structures and properties. The lone-pair 4d1 electrons of Nb4+ in M-NbO2 enhance the Nb-I interaction and promote the electron transfer from the M-NbO2 counter electrode (CE) to I, and thus resulting in superior catalytic properties in M-NbO2 based DSSCs. In addition, the adsorption energy of I on the M-NbO2 surface is in the optimal energy range of 0.3?1.2 eV, and the Fermi level of M-NbO2 is 0.6 eV, which is higher than the I3? reduction reaction (IRR) potential and I3? can be spontaneously reduced to 3I?. This work provides a general strategy for understanding the electronic structures and catalytic activities of transition metal compounds as CE catalysts for DSSCs.
关键词： electrocatalytic activity,counter electrodes,first-principles DFT calculations,dye-sensitized solar cells,niobium oxides
更新于2025-09-11 14:15:04
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Discussion of Photovoltaic Mechanisms of Organic Semiconductor Solar Cells; 有機半導体太陽電池の発電機構に関する一考察;
摘要： We have studied photovoltaic mechanisms of an organic solar cell using phthalocyanine for a p-type semiconductor and fullerene C60 for an n-type semiconductor in quantum chemistry simulation. This study examines computation of the electronic state of the phthalocyanine–fullerene C60 bimolecular system in the ground state by the DFT method using long-range corrected hybrid functional CAM-B3LYP. Some double bonds in unimolecular phthalocyanine become semi-double bonds in the bimolecular system. Furthermore, some carbon atoms in a fullerene molecule are negatively charged in the bimolecular system. These results suggest the generation of positive holes and conduction electrons in the bimolecular system. Investigation of reports about simulation in an excited state and the actual measurement of electric conductivity has revealed that these positive holes and conduction electrons in the ground state facilitate the migration of positive holes and conduction electrons generated in a photoactive layer by light irradiation.
关键词： The ground state,Semi-double bond,Negative charge,DFT method,Organic solar cell,Photovoltaic mechanisms
更新于2025-09-11 14:15:04
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Distortion‐Controlled Red‐Shift of Organic Dye Molecules
摘要： We show quantum chemically how structural distortion of an aromatic dye molecule can be leveraged to rationally tune its optoelectronic properties. Using a quantitative Kohn-Sham MO approach in combination with Time-Dependent DFT (TD-DFT), we have investigated the influence of various structural and electronic tuning parameters on the HOMO–LUMO gap of a benzenoid model dye, amongst others: (i) out-of-plane bending of the aromatic core; (ii) bending of the bridge with respect to the core; (iii) the nature of the bridge itself; and (iv) π-π stacking. Our study reveals the coupling of multiple structural distortions as a function of bridge length and number of bridges in benzene to be chiefly responsible for a decreased HOMO–LUMO gap and consequently the red-shifting of the absorption wavelength associated with the lowest singlet excitation (ca. 560 nm) in our model cyclophane systems. These physical insights together with a rational approach for tuning the oscillator strength were leveraged for the proof-of-concept design of the intense near-infrared (NIR) absorbing cyclophane dye 18 at 785 nm. Our design may contribute to a new class of distortion-controlled NIR absorbing organic dye molecules.
关键词： Cyclophane,NIR Absorption,Structural Distortion,HOMO–LUMO gap,Time-Dependent DFT
更新于2025-09-11 14:15:04
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Density functional theory evaluation of cation-doped bismuth molybdenum oxide photocatalysts for nitrogen fixation
摘要： This study investigates the photocatalytic nitrogen fixation on a cation-doped surface (BixMy)2MoO6 where (M = Fe, La, Yb) in both the orthorhombic and monoclinic configurations using a density functional theory (DFT) approach with experimentally validated model inputs. The proceeding discussion focuses on the Heyrovsky-type reactions for both the associative and dissociative reaction pathway related to nitrogen reduction. Key fundamental insight in the reduction mechanism is discussed that relates the material properties of the substitutional ions to the nitrogen and hydrogen affinities. Physical insight is gathered through interpretation of bound electronic states at the surface. Compositional phases of higher Fe and Yb concentrations resulted in decreased MoeO binding and increased affinity between Mo and the N and H species on the surface. The modulation of the MoeO binding is induced by strain as Yb and Fe are implemented, this, in turn, shifts energy levels and modulates the band gap energy by approximately 0.2 eV. This modification of MoeO bond as substitution occurs is a result of the orbital hybridization of MeO (M = Fe, Yb) that causes a strong orbital interaction that shifts states up toward the Fermi. The optimal composition was predicted to be an orthorhombic configuration of (Bi0.75Fe0.25)2MoO6 with a predicted maximum thermodynamic energy barrier of 1.4 eV. This composition demonstrates effective nitrogen and hydrogen affinity that follows the associative or biological nitrogen fixation pathway.
关键词： Gibbs energy,Thermodynamics,Inorganic,DFT,Nitrogen fixation
更新于2025-09-11 14:15:04
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First-principle study of the polarization, atomic displacements and electronic structure of angular-deformed barium titanate
摘要： The in?uence of β and γ angular deformation on polarization, TieO(3) bond distances, atomic displacements, number of states, valence charge distributions and valance charge asymmetry of barium titanate (BaTiO3) has been investigated using local density approximation. The results show that for all angles of 89.5°≤ β&γ ≤ 90.5°, there is a clear correlation between polarization, TieO(3) bond distances, atomic displacements and number of 2 orbital. For the case of γ-deformation the values of polarization and the other parameters are approximately constant in the range of 89.8°≤γ ≤ 90.2° and an abnormal behavior is observed at γ = 89.6°. In this case valence charge asymmetry of Ti 3d orbital has a direct relation with the polarization and atomic displacements of Ti atoms for the whole region of γ, especially at γ = 89.6°. In the case of β-deformation, an approximately symmetrical behavior versus β variations is observed for all above-mentioned parameters. In this case, a direct relation between valence charge asymmetry of Ti 3d orbital, polarization and atomic displacements is remarkable only for β > 89.8° and the region of β < 89.8° does not reveal such a direct relation.
关键词： Electronic investigation,Angular deformation,DFT,Atomic displacements,Barium titanate
更新于2025-09-11 14:15:04
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First-principle calculation of the electronic structures and optical properties of the metallic and nonmetallic elements-doped ZnO on the basis of photocatalysis
摘要： In the present paper, the electronic structure and the optical properties of metallic and nonmetallic elements-doped ZnO were investigated based on the principle of photocatalysis by first-principle density functional theory. Element doping shortens the band gap of ZnO. Due to the p-type characteristics, Fe, Cu, B and N doping brings impurity states over the Fermi level of ZnO, resulting in the shortening of the band gap, extending the absorption and utilization of solar light and thus enhancing the photocatalytic properties of ZnO. However, no impurity states appear in the band gap of Cd- and S-doped ZnO due to the intrinsic doping of Cd and S. Further investigations indicate that different doping atoms can indeed alter the near-Fermi level density of states (DOS) of ZnO and their electronic structures via substitution of zinc and oxygen atoms. In addition, the optical properties of ZnO are improved after doped with different atoms by comparing with those of pure ZnO. Due to the difference of their outer shell electrons of the doped atoms, the optical absorption properties of the investigated materials are followed as the following order: Fe-/B-doped ZnO>Cu-/N-doped ZnO>Cd-/S-doped ZnO>pure ZnO.
关键词： Doped ZnO,Density functional theory (DFT),Photocatalysis,First principle calculation
更新于2025-09-11 14:15:04
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Molecular Packing and Solid-state Fluorescence of Conjugated Compounds of Carbazole-acrylonitrile Derivatives
摘要： In this review paper, have been investigated three novel crystal structures of three molecules with carbazole substituents as the electron-donor group. These molecules, 2-(phenyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (I), 2-(3''-pyridyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (II), and 2-(4-pyridyl)-3-(N-ethyl-(3′-carbazolyl))acrylonitrile (III) in their structure, possess the electron-donor carbazole moiety, a -CN group attached to the double bond, and a phenyl or a pyridine function at the meta- or para-position. It was revealed with the help of single crystal diffraction X-ray analysis that there exists no difference in the crystal system, because all the compounds were crystallized in monoclinic system with space group P21/c. For determining the effect of the position of the nitrogen atom substitution on the crystal properties, has been analyzed and contrasted the molecular packing in a single crystal with that of other previously reported carbazole derivatives. The double bond bearing N-ethylcarbazole,–CN, phenyl or pyridine groups was observed to impart sufficient polarity in order to show slipped π-stacking aggregation in the solid state, affecting the compounds in the solid state and consequently affecting their fluorescence properties. The substitution at the para position was reported to exhibit more multiple C-H...π interactions as well as an interesting and unexpected short contact distance between adjacent N...N molecules those brought a conformational change resulting in an edge-to-face alignment in the molecules and affecting the best relative photoluminescence efficiency of the sample.
关键词： crystal structures,aggregation,cyano-substituted,Acrylonitrile derivatives,N-carbazole-acrylonitriles photophysical properties,TD-DFT calculations,pyridine derivatives
更新于2025-09-11 14:12:44
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Structure-property relationship of novel monosubstituted Ru (II) complexes for high photocurrent and high efficiency DSSCs: Influence of donor versus acceptor ancillary ligand on DSSCs performance
摘要： Two novel high molar extinction coefficient monosubstituted-bipy Ru (II) complexes, IA-5 and IA-6, based on D-D-π and π-A-π-A ancillary ligands were synthesized with the aid of Knoevenagel reaction, to study the influence of the electron donor and electron acceptor ancillary ligand and number of anchoring group (COOH) on the light harvesting efficiency (LHE), ground and excited state oxidation potentials, incident-photon-to-current conversion efficiency (IPCE), short-circuit photocurrent density (J), and total solar-to-electric conversion efficiency (%η) for DSSCs, and their device performances were studied and showed a maximum of PCE of 7.81% (JSC = 17.61 mA cm?2, VOC = 0.69 V and FF = 64.05%) for dye IA-6 compared to PCE of 7.74% (JSC = 15.83 mA cm?2, VOC = 0.74 V and FF = 65.37%) for N719 dye. The photophysical and photoelectrochemical properties discussed herein addressed the significant impact of the electron donor and electron acceptor ancillary ligand and the number of anchoring groups on JSC and %η in DSSCs. The molecular structures of IA-5 and IA-6 were characterized using UV–Vis, emission spectrophotometry, FT-IR, ESI-MS, and 1H NMR. To probe the interrelationship between the chemical structure, photophysical and photoelectrochemical properties, molecular modeling studies, implemented in Gaussian, were employed. DFT/TD-DFT calculations were used to calculate the thermodynamics and electronic properties of IA-5 and IA-6 including HOMO and LUMO isosurfaces, lowest singlet-singlet electronic transitions (E0-0), ground and excited states oxidation potentials, GSOP and ESOP, which were in excellent agreement with the experimental results. Surprisingly, the insertion of the strong electron acceptor benzodithiazole in the ancillary ligand of IA-5 showed that the frontier LUMO shifted by 100% from 2,2′-bipyridyl-4,4′-dicarboxlic acid to the ancillary ligand containing benzodithiazole with electron injection accomplished from the anchoring group tethered to benzodithiazole. This new finding of relocating the LUMO from bipy-dicarboxylic acid to the other ancillary ligand would open the door for the molecular engineering of better light harvesting and more efficient Ru (II) complexes for DSSCs.
关键词： DFT and TD-DFT,Electron acceptor,Dye solar cells,Molecular modeling,Electron donor,Solar-to-electric conversion
更新于2025-09-10 09:29:36