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dz2 Orbitals Mediated Bound Magnetic Polarons in Ferromagnetic Ce Doped BaTiO3 Nanoparticles and its Enriched Two Photon Absorption Cross Section
摘要： Enriched ferromagnetism and two photon absorption (TPA) cross section of perovskite BaTiO3 nanoparticles are indispensible for magnetic and optical data storage applications. In this work, the hydrothermally synthesized Ce doped BaTiO3 nanoparticles exhibit the maximum room temperature ferromagnetism (4.26×10-3 emu/g) at 4 mol% due to the increase of oxygen vacancies as evidenced by X-ray photoelectron, electron spin resonance spectroscopies and density functional theory (DFT) calculations. Hence, the oxygen vacancy constituted bound magnetic polaron (BMP) model has been invoked to explain the enhancement of ferromagnetism. BMP theoretical model indicates the increase of BMP magnetization (M0, 3.0 to 4.8×10-3 emu/g) and true spontaneous moment per BMP (meff, 4 to 9.88×10-4 emu) on Ce doping. DFT calculations show that BMPs mediate via Ti d orbitals leading to the ferromagnetism. Besides, it is understood that the magnetic moment induced by Ce at Ba site is higher than Ce at Ti site in the presence of oxygen vacancies. Open aperture Z-scan technique displays the highest TPA coefficient β (7.08×10-10 m/W) and TPA cross section σTPA (455×104 GM) at 4 mol% of Ce as a result of robust TPA induced excited state absorption. A large σTPA is attributed to the longer excited state lifetime τ (7.63 ns) of charge carriers created by oxygen vacancies and Ce ions which encounter several electronic transitions in the excited sub-states.
关键词： Ce doping,oxygen vacancies,bound magnetic polarons,two photon absorption,DFT calculations,Z-scan technique,BaTiO3 nanoparticles,ferromagnetism
更新于2025-11-19 16:56:35
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A Spectroscopic Study of Tautomeric Equilibrium of Salicylideneaniline in ZSM-5 Zeolites
摘要： Salicylideneaniline (SA) sorbed in cation-exchanged M-ZSM-5 (M = H+, Li+, Na+, K+, Rb+, Cs+ and Zn2+) zeolites was studied by spectroscopic techniques assisted by quantum-chemical calculations. The nature of extra-framework cations present in the zeolite void was found to affect the spectral signature of the sorbed SA molecule that points to the shift of tautomeric equilibrium between the enol and keto forms. Small size cations, such as H+ and Li+, stabilize a cis-keto SA tautomer along with a enol one in the zeolite structure. The calculations indicate that the sorbed cis-keto tautomer may have the dipole large enough to be considered as a zwitterion. New features appearing in the spectra with the increase of the cation size were attributed to the presence of trans-keto SA tautomer, which up to now has been observed only in time-resolved spectroscopic experiments. A strong interaction of the molecule with cations in Zn-ZSM-5 zeolite results in the chelation of enol SA with the divalent Zn2+ ions. The results of the study suggest that the tautomeric equilibrium of molecules belonging to the Schiff base family can be tuned by the con?nement in the nanoporous materials via a choice of topology of zeolite framework and the nature of extra-framework cations.
关键词： spectroscopy,tautomer,DFT calculations,ZSM-5,equilibrium,salicylideneaniline,zeolite
更新于2025-11-19 16:56:35
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Excited state intramolecular single proton transfer mechanism of pigment yellow 101 in solid state: Experiment and DFT calculation
摘要： To investigate fluorescence mechanism of Pigment Yellow 101 (P. Y. 101) in solid state, three aromatic aldehyde azines (1-3) including P. Y. 101 have been synthesized and compared with each other. Results indicated that P. Y. 101 prepared by solvothermal method is actually the mixture of two polymorphs, whose molecular packing mode can be transformed into each other by recrystallizing or external stimuli such as pressure and grinding. The ESIPT properties of 1-3 were investigated by DFT/TD-DFT calculations and time-correlated single photon counting (TCSPC) technique. Both experimental and theoretical results revealed that the dual fluorescence properties of P. Y. 101 in solid state are ascribed to the excited-state intramolecular single proton transfer fluorescence emissions of two structurally different polymorphs rather than the results of the sequential or concerted excited-state intramolecular double proton transfers, which provide a potential valuable tool for developing multistimuli-responsive luminescent materials.
关键词： Aromatic aldehyde azines,DFT calculation,P. Y. 101,Excited-state intramolecular proton transfer,Polymorphs
更新于2025-11-19 16:56:35
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Indoline and benzothiazole-based squaraine dye-sensitized solar cells containing bis-pendent sulfonate groups: Synthesis, characterization and solar cell performance
摘要： Two new symmetric squaraine sensitizers (SQTHZ and SQIND) carrying benzothiazole and indoline moieties as strong electron donating groups to inject the electron into the TiO2 nanoparticles were tested as DSSC. The theoretical calculations and absorption results show that the electron density of LUMO of SQTHZ is delocalized in the whole chromophore, leading to strong electronic coupling between SQTHZ sensitizer and the conduction band of TiO2. Furthermore, the presence of long alkyl chain with pendent bis-SO3- groups would inhibit recombination and decrease the dye aggregation. Interestingly, SQTHZ displayed UV-Vis and NIR absorption at a longer wavelength compared to SQIND. This structure feature, as well as optical properties, would lead to improved efficiency of dye-sensitized solar cell with overall better photovoltaic performance (η of 3.31 %, Jsc of 7.65 mA/ cm2, Voc of 0.59, ff of 0.71 and IPCE of 47 % at 674 nm) compared to SQIND.
关键词： Photoelectrochemical properties,DFT,Dye-sensitized solar cell,Symmetric squaraine dyes
更新于2025-11-19 16:46:39
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Tunable Photophysical Properties of Thiophene Based Chromophores: Conjoined Experimental and Theoretical Investigation
摘要： In this paper we report synthesis and photophysical properties of six novel thiophene derivatives (ThD) with D-π-A structure. The subject of this work are three nitrophenyls (1) BT-Th-NO2 and three benzonitriles (2) BT-Th-CN, substituted at different positions of aromatic ring ((a) ortho-, (b) meta- or (c) para-). Dyes were obtained using simple three-step synthesis and their chemical structures were confirmed by 1H and 13C NMR, IR as well as high resolution mass spectrometry. The influence of positional isomerism on optical properties has been explored experimentally and theoretically. The photophysical properties were investigated using steady-state as well as time-resolved spectroscopy and the obtained results were supported by quantum-chemical calculations. TD-DFT calculations indicated that charge-transfer strength can be correlated with the observed optical properties. In addition, the influence of the acceptor position on photoluminescence spectra, fluorescence quantum yields and emission lifetimes was specified. We show that ThD optical properties can be tuned in wide spectral range by the change made in only single step of synthesis reaction.
关键词： push-pull chromophores,Thiophene derivatives,TD-DFT,quantum yield,charge transfer
更新于2025-11-19 16:46:39
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Time-dependent DFT and experimental study on visible light photocatalysis by metal oxides of Ti, V and Zn after complexing with a conjugated polymer
摘要： Density Functional Theory (DFT) and Time Dependent (TD)-DFT studies predict substantial modifications in optical properties of Transition Metal Oxides (TMOs) of Ti, V and Zn by complexing them with conjugated polymer polythiophene (PTh). The TMO nanostructures were synthesized and their complexes with polymers were fabricated using a chemical oxidative polymerization method. Coating of the TMOs with PTh and the nano-dimensional nature of the samples was confirmed by various morphological investigations such as infrared (IR), X-ray di?ractographs (XRD), High Resolution Transmission Electron Microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM) techniques. The prepared samples were found to be a visible light driven photocatalyst. The sensitization of the complexes has been explained in terms of relative ordering of frontier orbitals of PTh and the TMO, and PTh qualified as an e?cient photosensitizer for all three metal oxides on the basis of its electronic characteristics. Since the Highest Occupied Molecular Orbital (HOMO) of PTh lies well between the band gap of all three TMOs, the electron transfer from donor (PTh) to acceptor (TMO) is facilitated. The appreciable red shift in the absorption spectrum and decrease in the optical band gap calculated by Tauc’s plot confirmed substantial reduction in the band gap of the formed complex in comparison to their bare counterparts. The isodensity plots established the PTh–TMO complexes as donor acceptor complexes and intermolecular charge transfer quantified the electron transfer from PTh (donor) to the TMOs (acceptor).
关键词： conjugated polymer,TD-DFT,visible light,metal oxides,DFT,photocatalysis,polythiophene,band gap tuning
更新于2025-11-14 17:04:02
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0D/2D AgInS2/MXene Z-scheme heterojunction nanosheets for improved ammonia photosynthesis of N2
摘要： In order to explore efficient photocatalysts for N2 reduction reaction (NRR), 0D AgInS2 nanoparticles and 2D MXene (Ti3C2) nanosheets with different mass ratios are employed for building Z-scheme heterostructures. The resultant hybrids exhibit excellent interfacial charge transfer ability according to their optical and photo-electro properties. As a result, the obtained composite (30 wt% AgInS2) shows significant improvement on the photocatalytic performance for N2 fixation with a high ammonia yield rate of 38.8 μmol/(g·h) under visible-light illumination (> 400 nm). Meanwhile, the DFT calculations show that the activation of N2 in a dinuclear end-on bound structure could lead to high adsorption energy (Ead = -5.20 eV). Moreover, the mechanism of enhanced photocatalytic activity was proposed in terms of the quantum calculation between Ti3C2 and N2. This work provides new systems for enhanced NRR performance.
关键词： N2 reduction,DFT calculations,AgInS2/MXene heterojunction,Photocatalysis
更新于2025-11-14 15:28:36
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Theoretical and experimental study of PTDPV optical and vibrational properties and its application in white electroluminescent blends
摘要： The polymer Poly[tris(2,5-bis(hexyloxy)-1,4-phenylenevinylene)-alt-(1,3-phenylenevinylene)] (PTDPV) has a broad range of visible emission extending from green to red, and thus may be useful for obtaining a white light emitting blend. Nevertheless, the amount of works found in the literature dealing with the optical emission properties of PTDPV is very small. In this work, we performed a study of the optical properties of this material using photoluminescence and of the vibrational properties using Raman and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. At the same time, we use the Density Functional Theory (DFT) method to calculate the optical, vibrational and molecular properties of PTDPV. We have obtained the best DFT results using a hybrid functional and a simple basis set (DFT / B3LYP and 6–31 g *), without addition of correction or polarization factors (+). To reach these conclusions, we compared the HOMO and LUMO values obtained via DFT with those found in the literature. Furthermore, the Raman and IR simulations obtained using this basis set were compared with the experimental results of the PTDPV, showing great agreement. From the vibrational modes obtained, it was possible, using the Lin model [1–3], based on the Franck Condon approximations, to reconstruct the photoluminescence spectrum of the PTDPV. Based on these reconstructed spectra, it was possible to establish the contribution of the different vibrational modes to the vibronic emissions of the photoluminescence spectrum. The quality of the reconstruction obtained with the DFT results and that obtained with the experimental ones are very close, showing the possibility of using in this reconstruction the calculated vibrational modes when the experimental ones are not available. To demonstrate the application of this material, PFO:PTDPV blends were prepared, with which white photoluminescence was obtained. OLEDs prepared with these blends, in suitable proportions, emitted white light using low excitation power, demonstrating the feasibility of using PTDPV in OLEDs for lighting, which could be prepared by solution on large areas.
关键词： Photoluminescence,Raman and FT-IR,DFT method,PTDPV polymer,White electroluminescence
更新于2025-11-14 15:19:41
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Suppression of Iodide Ions Migration via Sb2S3 interfacial Modification for stable Inorganic Perovskite Solar Cells
摘要： In mixed halide perovskite, the halide phase segregation is commonly observed due to halide ions migration, which causes severe stability issues in perovskite devices. Here, we directly revealed the iodide-migration process via potentiostatic treatment in CsPbIBr2 perovskite. The absence of iodide ions was reduced significantly via Sb2S3 interfacial modification. We further employed the DFT calculation to optimize the geometry positions at the perovskite interface and radial distribution functions (RDF) to analyze the atom perturbation. The simulation yielded a slight distortion of perovskite lattice at the interface of Sb2S3-CsPbIBr2 and iodide ions fluctuation was reduced due to the decrease of halide vacancies. In addition, the thermally stimulated current was calculated to evaluate the defects density in the modified perovskite device. Due to the Sb2S3 interaction with perovskite, the device became stable against humidity and maintained photoactive over 400 h. The champion efficiency of 9.31% with 26.31% improvement was obtained in modified CsPbIBr2 perovskite solar cells.
关键词： stability,The mixed halide perovskite,Sb2S3,DFT,iodide ions migration
更新于2025-11-14 15:15:56
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First titanium square fragment {Ti4(μ4-Se)(μ2-Se2)4} in its selenoiodide: Synthesis and structure of Ti4Se9I6
摘要： The first titanium selenoiodide Ti4Se9I6 was synthesized as black crystals by heating of Ti, Se, and I2 at 250 °C in 5:9:5 M ratio. The crystal structure of the compound was solved by X-ray single-crystal diffractometry (sp. gr. P-1, a = 7.9652(10), b = 10.3390(15), c = 15.692(2) ?; α = 79.116(7)°, β = 75.861(7)°, γ = 71.437(7)°; Z = 2) with final R1 = 0.0397. The structure includes square {Ti4(μ4-Se)(μ2-Se2)4} fragment coordinated by four terminal and four bridging μ2-I atoms. Ti4+ has d0 configuration, and stability of the structure fragments is provided by metal to ligand bonding which was confirmed by DFT calculations.
关键词： Metal chalcohalides,Titanium,Square complex,Synthesis,Selenide,X-ray crystal structure,Chain structure,DFT calculations,Iodide
更新于2025-11-14 15:14:40