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3D structured laser engraves decorated with gold nanoparticle SERS chips for Paraquat herbicide detection in environments
摘要： Fabrication of SERS-active substrates is a thrust area of research in the field of SERS. Here, we report the fabrication of a new SERS-active substrate composed of Au nanostructures grown on aluminum sheets marked with laser lines (L-Mark SERS chips). The SERS activity of these SERS chips exploited with environmentally important herbicide, paraquat, and dye molecule of methylene blue. Density functional theory (DFT) calculation was performed to theoretically study the molecular structure and Raman vibrational modes of the paraquat. A detailed discussion has been devoted to uniformity, reproducibility, and practical utility of the fabricated substrates. Especially, great amount of discussion has been given to paraquat detection in soil extracts. The results emanate the ultra-sensitive detection of paraquat, uniform enhanced signals over the substrates, and high reproducibility. The report successfully demonstrated the detection of paraquat in drinking water, tap water, agri-water, environmental water, and soil extracts. Liquid chromatography-mass spectrometry (LC-MS) measurements were also performed to demonstrate the realiability of the SERS method. The L-Mark SERS chips based paraquat detection is simple, rapid, and sensitive. We propose that the present sensors hold the potential to be used in herbicide detection and monitoring in-the-field experiments.
关键词： Au nanostructures,SERS,DFT,L-Mark SERS chips,Paraquat,LC-MS
更新于2025-09-12 10:27:22
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New organic molecular based on Bis-Dipolar Diphenylamino-EndcappedOligo Aryl Fluorene Application for organic solar cells
摘要： In this work, we report on the structural, optical and electronic properties of a series of D-π-A-π-D type bis-dipolar Diphenylamino-Endcappedoligoarylfluorenes, (OF(2)Ar-NPh(2)). These molecules are studied by means of quantum chemical calculations based on density functional theory (DFT) using B3LYP functional with 6-31G(d,p) for all atoms and all states (ground and excited ). The study of the geometrical parameters, ground state (p, n) showed that the structures of these molecules are planar. As a result, the electronic properties HOMOs, LUMOs, energy gaps, were determined from the fully optimized structures. The absorption of these molecules were calculated using (TD-DFT)-B3LYP/631G (d,p) method. This fundamental information is a valuable data in designing and making promising materials for optoelectronic applications.
关键词： Optoelectronic applications,DFT,Organic,Photovoltaic cells
更新于2025-09-12 10:27:22
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Synthesis, characterization, optical properties, computational characterizations, QTAIM analysis and cyclic voltammetry of new organic dyes for dye-sensitized solar cells
摘要： In recent years, dye-sensitized solar cells (DSSCs) have regarded as potential solar cells for the next generation of photovoltaic technologies. Many organic compounds are explored and used in DSSCs to produce low-cost devices and improve the cell efficiency. In this work, three new heterocyclic purple dyes are synthesized from the reaction of 3-nitropyrazolo[1,5-a]pyridine with various arylacetonitriles for dye-sensitized solar cells (DSSCs), exhibiting high molar extinction coefficients and a broad absorption range led to the good photovoltaic performance of 6.95e7.18%. Physical spectral, analytical data and optical properties are established the structures of the new dyes. The optimized geometries and relevant frontier orbitals of the dyes are obtained by density functional theory (DFT) at the level of B3LYP/6-311 + G(d,p). Electrostatic potential maps and electron density maps of the dyes were also obtained by atoms in molecules (AIM) analysis. Cyclic voltammetry measurement was performed to evaluate the electrochemical properties of the dyes and reversible oxidation waves were observed for them.
关键词： Dye-sensitized solar cells,DFT,3-Nitropyrazolo[1,5-a]pyridine,AIM,Cyclic voltammetry,Purple dyes
更新于2025-09-12 10:27:22
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New organic materiel based on benzothiadiazole for Photovoltaic application Solar Cells
摘要： In this work, we have studied conjugated polymers based on benzothiadiazole. the quantum chemical calculations on the structure and electronic and optics properties using the density functional theory (DFT), for the ground- and excited-state properties, respectively, using CAM-B3LYP and the 6-31G(d, p) basis set. These results will be devoted to the influence of the substitution benzothiadiazole on the electronic and optoelectronic properties of the polymer. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of these compounds were calculated and compared to LUMO of fullerenes,C60 [6,6]-phenyl- C61-butyric-acid methyl ester to estimate the effectiveness of these molecules as electron donors in bulk heterojunction (BHJ) small molecules-fullerene solar cells. The absorption energies have been obtained from TD-DFT calculations performed on the excited-state optimized S geometries. Finally, the theoretical results suggest that both the introduction of benzothiadiazole groups contribute significantly to the electronic and optoelectronic properties of the alternating donor–acceptor–donor conjugated systems studied.
关键词： Benzothiadiazole,BHJ,DFT,Optoelectronic properties,Photovoltaic cells
更新于2025-09-12 10:27:22
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Theoretical Study on Factors Influencing the Efficiency of D–π′–A′–π–A Isoindigo-Based Sensitizer for Dye-Sensitized Solar Cells
摘要： We investigated metal-free dyes based on isoindigo by performing density functional theory and Time-dependent density functional theory calculations to improve the efficiency of dye-sensitized solar cells. The D–π′–A′–π–A organic dyes (TIDP and TIDT) used triphenylamine as donor, thiophene as the π′-linker between the donor and auxiliary acceptor, and a phenyl or thiophene ring as the π-linker between the auxiliary acceptor and acceptor. TIDP and TIDT exhibit good charge-transfer properties. The TIDP-based device provides better device performance with a PCE of 4.11%. Calculated results reveal that the phenyl ring directly linking the auxiliary acceptor and acceptor causes a small tilt angle in the TiO2–adsorped dye, resulting in enhanced electron-injection rates, more efficient packing of adsorbed dye molecules, and slow charge recombination at the TiO2 surface. The performance of the TIDT-based device (η = 2.46%), arises from decreased electron-injection rates and fast charge recombination caused by the large dihedral angle of the adsorbed dye. This research identifies a potential π′-linker group and reveals the influence of the π-linker on photovoltaic performance in organic dyes.
关键词： auxiliary acceptor,Isoindigo dye,DFT,DSSC
更新于2025-09-12 10:27:22
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Molecular design of novel indacenodithiophene‐based organic dyes for efficient dye‐sensitized solar cells applications
摘要： Indacenodithiophene (IDT)-based high-efficiency photovoltaics have received increasing attention recently. This paper reports a density functional theory investigation of the electronic and optical properties of three IDT-based organic dyes together with the dye/(TiO2)46 interface. In order to enhance the photoelectric properties of IDT dyes, this paper considers two methods for the structure modification of the experimentally reported dye DPInDT (J. Org. Chem. 2011, 76, 8977): the extension of the conjugation length by dithienothiophene as well as the heteroatom substitution of the bridging atoms by electron-rich nitrogen atoms. Our calculations show that both methods obviously affect the distributions of the molecular orbitals and notably red shift the absorption peaks of around 20 nm, with the former method demonstrating enhanced light harvesting efficiency. The structure modifications proposed also enhance the emission spectrum properties for IDT-based organic dyes. The calculated ultrafast injection time of electrons from the excited state of IDT dyes to the (TiO2)46 belongs to the femtosecond order of magnitude, and is ideal for efficient photoelectric conversion process in dye-sensitized solar cells (DSSCs) applications. The IDT dyes designed in this paper have good electronic and spectroscopic properties. This study is expected to provide useful guidance for the development of novel IDT dyes for applications in DSSCs.
关键词： organic dyes,DFT simulations,indacenodithiophene,molecular design
更新于2025-09-12 10:27:22
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A computational study of the electronic structure and optical properties of the complex TeO<sub>2</sub>/TeO<sub>3</sub> oxides as advanced materials for nonlinear optics
摘要： Electronic structure of series of tellurium oxide crystals within the TeO2—TeO3 binary system is studied with generalized gradient approximation to DFT, hybrid DFT-HF method with the PBE0 and B3LYP exchange-correlation functionals and with quasiparticle G0W0 approach. Comparison with available experimental data revealed significant underestimation of the band gap values within DFT. The hybrid DFT-HF method leads to slightly overestimated values of the bandgap, and the best agreement with experimental data provides the “one-shot” G0W0 calculations starting from Kohn-Sham solutions. The electronic structure of tellurium oxides is discussed in details. It is found that the bandgap value decreases proportionally to fraction of tellurium atoms in octahedral coordination. This change is due to formation of gap states by 5s(Te) electrons which do not participate in Te(VI)–O bonding. Dielectric susceptibilities are calculated within Random Phase approximation for the series of tellurium oxides and high nonlinear properties of the compounds are predicted by empirical Miller’s rule.
关键词： Ab initio,DFT,tellurium oxides,GW,nonlinear optics,electronic structure
更新于2025-09-12 10:27:22
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Photophysical, electrochemical, and DFT studies of the novel azacrown-bridged dinuclear ruthenium dye sensitizers for solar cells
摘要： A dinuclear ruthenium bipyridyl complex with 1,10-diaza-18-crown-6 bridging ligand was synthesized and characterized. Its photophysical and electrochemical properties were also studied. DFT computations were performed to complement the experimental investigations. Analysis of the results indicates that the path in which charges move from one metal center to the other is significant for effective electronic coupling. However, electron transfer between the two ruthenium centers is hindered by the azacrown bridging ligand, compared to the smooth electronic transfer reported for a related dye involving an azo bridging ligand.
关键词： Bridging ligands,Dinuclear ruthenium complex,DFT,Charge transfer,Electronic coupling
更新于2025-09-12 10:27:22
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Combined SERS/DFT studies of push–pull chromophore self-assembled monolayers: insights into their surface orientation
摘要： Having clear and deep information on the surface/interface of deposited molecules is of crucial importance for the development of efficient optoelectronic devices. This paper reports on a joint experimental/theoretical hybrid approach based on Raman spectroscopy in order to provide information on the orientation of push–pull chromophores deposited onto a gold surface. In addition, several parameters can strongly control or impede the orientation of such molecules on the surface such as: the molecular structure, the surface itself, the method of deposition and the solvents used. From this approach, additional information has been highlighted such as perpendicularly depositing the molecule on the surface, the bithiophene compounds displaying more solvent effects compared to terthiophene molecules and so on. According to the results, the joint SERS/DFT study proves to be an effective tool for probing the arrangement of push–pull chromophores and selecting the right experimental conditions to tune the surface properties.
关键词： SERS,DFT,push–pull chromophores,surface orientation,self-assembled monolayers
更新于2025-09-12 10:27:22
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Dimethylaniline functionalised pyrene fluorophores; dual colour pH switching in solution and self-assembled monolayers
摘要： A pyrene charge transfer fluorophore with three ionizable N,N-dimethylaniline moieties was explored as an interfacial pH switch. The parent carboxylate compound and the thiolated derivative were shown by spectroscopy combined with DFT calculation to be successively and reversibly protonated. Protonation leads to progressive decrease of intensity of the 550 nm centered N,N-dimethylaniline to pyrene charge transfer emission which on protonation of the third site, leads to extinction of this transition and evolution of an intense blue (450 nm) pyrene-centered emission. Concomitant loss of the charge transfer absorbance was observed and the changes are reversed on neutralization of pH. A self-assembled monolayer of the thiolated derivative was prepared on gold and found from voltammetry of ferricyanide/ferrocyanide probe to form close packed monolayers. The probe voltammetry, label-free electrochemical impedance spectroscopy of the film was monitored as a function of pH and progressive, but reversible protonation steps were reflected in decreasing film resistance. The Stokes shift of the probe prevents self-quenching so a broad, charge transfer fluorescence centered around 540 nm was recorded for the self-assembled monolayer where as per solution, progressive and reversible reduction in intensity was observed. The facile assembly, impedance and optical switching make these materials potentially interesting as on–off or two colour on–off–on fluorescence switches with potential applications in logic gates or in responsive surface applications.
关键词： DFT calculation,self-assembled monolayer,fluorescence,charge transfer,pH switch,pyrene
更新于2025-09-12 10:27:22