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Understanding the effect of the carbon on the photovoltaic properties of the Cu2ZnSnS4
摘要： In this work, crystalline structure, formation energy, electronic, optical and current-voltage properties of Cu2ZnSnS4 (CZTS) with the presence of carbon (C) impurity at various sites is studied using the first-principles density functional theory (DFT) based on the generalized gradient approximation (GGA). Here, we considered possible four substitutional configurations of carbon doped CZTS supercells: Cu by C (Ccu), Cu by Zn (Czn), Sn by C (Csn) and S by C (CS). It was found that the presence of C leads to the formation of localized polarons which have dual functionality; (i) cause an increase in the scattering-limited mobility which reduces the transport efficiency, (ii) create deep acceptor level which acts as a recombination center allowing the scattering of the generated charges carriers. An enhancement in the photo-absorption is observed due to an increase in the density of states at the valence bands after the incorporation of C. This results in the efficiency enhancement by 8%. In addition, the presence of C reduces the transport efficiency and improves the photogeneration efficiency of CZTS in solar cell applications.
关键词： Carbon doped CZTS,Localized polaron,DFT,Optical properties,Solar cell,Electronic structure
更新于2025-09-23 15:19:57
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Effect of Electron Withdrawing/Donating Groups on the Sensitizing Action of the Novel Organic Dye a??3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acida?? for N-type Dye Sensitized Solar Cells: A Theoretical Study
摘要： Computational studies using DFT and TDDFT approaches have been performed to study a series of metal free donor-π-acceptor (D-π-A) dyes. Taking the novel organic D5 dye (3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid) as the primary structure, with triphenylamine as the donor, cyanoacrylic acid as the acceptor and a thiophene group as the π-linker, we have studied the effect of the substitution of different electron withdrawing and electron donating groups at different positions on the dye efficiency, by analyzing the geometry, charge distribution, electron injection and absorbance spectra. Electron injection has also been addressed for the substituted dyes immobilized on TiO2. Our calculations show that adding electron withdrawing groups at specific positions will lead to a higher efficiency of the dye.
关键词： TDDFT,electron withdrawing groups,DFT,electron donating groups,dye sensitized solar cells,D5 dye
更新于2025-09-23 15:19:57
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TD-DFT+TB: An Efficient and Fast Approach for Quantum Plasmonic Excitations
摘要： We study the quantum plasmonic features of gold and silver nanoparticles using TD-DFT+TB, a new density functional theory approach to the calculation of excited states, which combines a full DFT ground state with tight-binding approximations in the linear response calculation. In this framework, the optical properties of closed-shell Ag, Au and bimetallic Ag-Au nanoparticles with tetrahedral symmetry (with 20, 56, 120 and 165 atoms) and icosahedral structure (with 13, 55 and 147 atoms) were obtained and compared to full linear response time-dependent density functional theory (TD-DFT) as a reference and also time-dependent density functional based tight binding (TD-DFTB) as a low-cost alternative approach. We find an excellent agreement of TD-DFT+TB calculated absorption spectra with the TD-DFT reference with errors less than 0.15 eV in peak positions, while TD-DFTB shows larger errors of about 1 eV. The computational cost for the ground state calculation is identical for TD-DFT and TD-DFT+TB, but the excited state calculation becomes about a hundred times faster when applying the TB approximation and is then almost negligible for the overall timing of the calculation. In contrast to TD-DFTB, which can only be applied to element combinations for which a suitable DFTB parametrization is available, TD-DFT+TB can be applied to any combination of elements. To assess the accuracy of TD-DFT+TB for different combinations of atoms, the plasmonic properties of bimetallic clusters with different ratios of Ag and Au atoms were obtained and the trend of energy and intensity reproduced in good agreement with TD-DFT, which is not possible using TD-DFTB with standard parameter sets.
关键词： quantum plasmonic,bimetallic Ag-Au nanoparticles,gold and silver nanoparticles,optical properties,TD-DFT+TB
更新于2025-09-23 15:19:57
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Comparative Study of Decomposition adsorption of Sarin on ZnnOnand CdnOn(n=1,4), by Theoretical Method
摘要： The calculations of the electronic and structural properties for interactions of Sarin with ZnnOnand CdnOn(n=1,4) have been conducted by B3LYP/6-31++G(d,p) level of DFT method. The ZnOaffects on disconnection of propyl bond of Sarin and Cd4O4 interacts with Fluorine atom of Sarin. The results of Radial Distribution Function (RDF) show that the interaction of Sarin is probable at 380 K with ZnO as covalent bond and at 308 K with Cd4O4 by Van der waals forces.
关键词： DFT,Sarin,Decomposition,ZnnOn,RDF,CdnOn
更新于2025-09-23 15:19:57
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Anion intercalated layered-double-hydroxide structure for efficient photocatalytic NO remove
摘要： Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides (LDHs) have great promising potential for photocatalytic applications. In this study, we have successfully synthesized the ZnAl–LDH intercalated the single anion between ZnAl cationic interlayer without anionic impurities by using a facile calcining and reconstructing routes. The electron structure and surface chemical state of the prepared products have been investigated by combining the DFT calculation and experimental characterization methods. UV–vis DRS was used to certify the light absorption of the prepared products, and we performed the DFT calculation to demonstrate the density of state and activation of reactant. These results suggested that the ZnAl–LDH–CO3 possessed the more proper band structure and superior ability to activate NO and O2 for accelerating the photocatalytic NO oxidation activity. Moreover, the In situ DRIFTS with dynamically monitoring intermediates and products over the ZnAl–LDH–CO3 was adopted to declare the photocatalytic NO oxidized process during the photocatalytic reaction process. This work illustrated the influence of different interlayer anions to the electron structure and surface chemical state of ZnAl–LDH structure through the experimental verification combined DFT calculation and the photocatalytic NO oxidized process via In situ DRIFTS analyzing, which would provide a novel way to design and fabricate the efficient photocatalysis, and understand the reaction process.
关键词： In situ DRIFTS,ZnAl–LDH,DFT calculation,Reaction process and mechanism,Photocatalytic NO oxidation
更新于2025-09-23 15:19:57
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UV irradiation induce NLO modulation in photochromic Styrylquinoline-Based Polymers: Computational and Experimental Studies
摘要： Functionalized photochromic materials have attracted a growing interest during the last few decades since they are promising materials to be used in optoelectronics and photonics. In this paper, the results of the nonlinear optical (NLO) investigation (second and third harmonic generation) of spin deposited high-quality thin films of styrylquinoline containing methacrylic polymers studied by using Maker fringes technique employing 30 ps laser pulses at fundamental wavelength of 1064 nm are presented. Photochromic styrylquinoline units were oriented in the thin films by corona poling technique promoting second order NLO activity. Strong dependence of the NLO response upon the structure of the polymers has been found, which is related to the different charge transfer within the styrylquinoline fragments. These investigations were completed by theoretical studies using HOMO-LUMO energy levels theory and the first and second order hyperpolarizability values. Good compatibility has been achieved between the theoretical and experimental results. Studied styrylquinoline-based polymers showed the contrast in NLO response after their trans-cis photoisomerization making them interesting for using in photonic devices.
关键词： NLO properties,second and first order hyperpolarizability,harmonic generation,functionalized polymers,DFT and TDHF calculations,styrylquinoline
更新于2025-09-23 15:19:57
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Experimental and theoretical investigations of 4-hydroxy L-proline cadmium chloride nonlinear optical crystal
摘要： The solution grown structure 4-hydroxy L-proline cadmium chloride (4HLPCC) single crystal has been done by means of X-ray diffraction method. The computational quantum mechanical modelling method was performed with B3LYP level and LanL2DZ basis set to determine optimized geometry, dipolar moment, linear polarizability, first order hyperpolarizability, atomic charges of various atoms, thermodynamic parameters, HOMO-LUMO energy gap and vibrational frequencies of 4HLPCC. The vibrational frequencies of 4HLPCC were observed experimentally through FTIR and FT-RAMAN analyses and compared with theoretical frequencies. The electric properties were detected by dielectric studies. The frequency doubling of the grown crystal was made with Kurtz-Perry powder technique.
关键词： Polarizability,4-hydroxy L-proline cadmium chloride,DFT,Nonlinear optical properties,Hyperpolarizability
更新于2025-09-23 15:19:57
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Atomic Layer Deposition of Al <sub/>2</sub> O <sub/>3</sub> Using Aluminum Tri-Isopropoxide (ATIP): A Combined Experimental and Theoretical Study
摘要： The aluminum precursor plays a crucial role in the Al2O3 ALD process. Up to date, trimethyl aluminum (TMA) is one of the most widely used precursors in experimental and theoretical studies. However, its application at industrial scale can pose safety risks since it is pyrophoric and extremely reactive with water. Aluminum alkoxides offer a promising alternative, but have received far less attention. A combined theoretical and experimental investigation is carried out on the Al2O3 ALD process using aluminum triisopropoxide (ATIP) as a prototypical example of Al-alkoxide precursors. The experimental results pointed out that the thermal ALD process using ATIP and water has a maximal growth per cycle (GPC) of 1.8 ?/cycle at temperatures of 150°C to 175°C. Based on the in-situ mass spectrometry analysis and DFT calculations, the formation of the alumina film mainly occurs during the water pulse by ligand exchange reactions between water and adsorbed precursors, while during the ATIP pulse only adsorption of ATIP and/or its dissociation occur. Design of heteroleptic precursors containing alkoxide group as basic ligand is challenging, but greatly promising for future industrial scale Al2O3 ALD.
关键词： Al2O3,DFT calculations,Atomic Layer Deposition,Aluminum Triisopropoxide,Ligand Exchange Reactions
更新于2025-09-23 15:19:57
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Novel electronic structures and enhanced optical properties of boron phosphide/blue phosphorene and F4TCNQ/blue phosphorene heterostructures: a DFT + NEGF study
摘要： Blue phosphorene (Blue-p), an allotrope of black phosphorene, has attracted extensive interest due to its hexagonal crystal with a flat arranged layer of phosphorus atoms. However, the indirect band gap of Blue-p greatly hinders its applications in optoelectronics. By stacking both boron phosphide (BP) and the organic molecule 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) with Blue-p, we construct BP/Blue-p and F4TCNQ/Blue-p heterostructures. We reveal that the BP/Blue-p heterostructure possesses a direct band gap of 0.605 eV and is tunable via in-plane strain and an external electric field. Moreover, it also has remarkable optical absorption in the UV region and enhanced transport properties. Furthermore, by doping with F4TCNQ, the F4TCNQ/Blue-p heterojunction displays type-II semiconducting properties with a flat valence band and Van Hove singularities at the Fermi level, which can be used to achieve extremely low in-band tunneling, yielding low static power dissipation and large drive currents in the ON regime of transistors. Due to the superior electronic, optical and transport properties, Blue-p-based heterostructures are promising candidates for electronic and optical device applications.
关键词： DFT,optical properties,electronic properties,transport properties,Blue phosphorene,heterostructures,boron phosphide,F4TCNQ,NEGF
更新于2025-09-23 15:19:57
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Investigation on the photophysical properties of a series of promising phosphorescent iridium (III) complexes with modified cyclometalating ligands
摘要： Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were applied to investigate the electronic structures and photophysical properties of a series of phosphorescent iridium (III) complexes, [(C^N)2Ir(N^N)]+(PF6)(cid:2), in which C^N = 4-aryl-1-benzyl-1H-1, 2, 3-triazoles. Herein, aryl = phenyl, biphenyl, three-phenyl aromatic for complexes 1a, 2a, 3a (N^N = 2, 20-bipyridine) and aryl = 40, 60-di?uorophenyl, 60-?uoro-biphenyl, 60-?uoro-three-phenyl aromatic for complexes 1b, 2b, 3b (N^N = 4, 40-di-tert-butyl-2, 20-bipyridine), respectively. The geometric/electronic con?gurations, absorption/emission properties and phosphorescent performances have been outlined for each of the complexes. Based on the two simpli?cations presented in this paper and the available experimental data, the phosphorescent radiative rates for complexes 1a-3b were approximately obtained to be: 1.20 (cid:3) 106 s(cid:2)1, 1.68 (cid:3) 105 s(cid:2)1, 2.19 (cid:3) 107 s(cid:2)1, 3.85 (cid:3) 106 s(cid:2)1, 1.85 (cid:3) 107 s(cid:2)1 and 1.50 (cid:3) 107 s(cid:2)1, respectively. In view of the electroluminescent applications in OLED, our present research work is of great importance for the design and synthesis of organo-transition metal complexes with improved phosphorescent performances.
关键词： Phosphorescence,Photophysical properties,Time-dependent DFT,Iridium (III) complexes,Density functional theory (DFT)
更新于2025-09-19 17:15:36