- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Photostable coumarin containing azo dyes with multifunctional property
摘要： A series five coumarin azo disperse dyes with thiophene bridge are synthesized using diazotized aniline derivatives which are confirmed by FT-IR, 1H NMR, 13C NMR, and CHN analysis. The dyes are applied on polyester and nylon material. The multifunctional properties (lightfastness, washing fastness, sublimation fastness, K/S, UPF, and antimicrobial activity) of the dyed fabric are determined. The dye 3a (-NO2) show red shifted absorption (649 nm) and blocking 95.5-97.4% of UV radiations with 96% antimicrobial property. The geometries of all the azo dyes are optimized using Density Functional Theory (DFT). The Global Reactivity Descriptors (GRD) are evaluated at the same method of theory. The GRD obtained shows a linear relation with lightfastness and UPF ratings. The antimicrobial activity of all synthesized dyes are determined by AATCC 100 test method and it is correlated with the HOMO-LUMO energy band gap.
关键词： UPF,fastness property,Coumarin-azo dyes,global reactivity descriptors,HOMO-LUMO gap,antimicrobial activity
更新于2025-09-23 15:23:52
-
Long-Range Activationless Photostimulated Charge Transport in Symmetric Molecular Junctions
摘要： Molecular electronic junctions consisting of nitroazobenzene oligomers covalently bonded to a conducting carbon surface using an established 'all-carbon' device design were illuminated with UV?vis light through a partially transparent top electrode. Monitoring junction conductance with a DC bias imposed permitted observation of photocurrents while varying the incident wavelength, intensity, molecular layer thickness, and temperature. The photocurrent spectrum tracked the in situ absorption spectrum of nitroazobenzene, increased linearly with light intensity, and depended exponentially on applied bias. The electronic characteristics of the photocurrent differed dramatically from those of the same device in the dark, with orders of magnitude higher conductance and very weak attenuation with molecular layer thickness (β = 0.14 nm?1 for thickness above 5 nm). The temperature dependence of the photocurrent was opposite that of the dark current, with a 35% decrease in conductance between 80 and 450 K, while the dark current increased by a factor of 4.5 over the same range. The photocurrent was similar to the dark current for thin molecular layers but greatly exceeded the dark current for low bias and thick molecular layers. We conclude that the light and dark mechanisms are additive, with photoexcited carriers transported without thermal activation for a thickness range of 5?10 nm. The inverse temperature dependence is likely due to scattering or recombination events, both of which increase with temperature and in turn decrease the photocurrent. Photostimulated resonant transport potentially widens the breadth of conceivable molecular electronic devices and may have immediate value for wavelength-specific photodetection.
关键词： charge transport,optoelectronics,photocurrent,molecular electronics,molecular orbital energy,tunneling barrier,HOMO?LUMO gap,photoinduced transport
更新于2025-09-23 15:22:29
-
Hetero-Orientation Epitaxial Growth of TiO2 Splats on Polycrystalline TiO2 Substrate
摘要： In the present study, the effect of titania (TiO2) substrate grain size and orientation on the epitaxial growth of TiO2 splat was investigated. Interestingly, the splat presented comparable grain size with that of substrate, indicating the hereditary feature of grain size. In addition, hetero- and homo-orientation epitaxial growth was observed at deposition temperatures below 400 °C and above 500 °C, respectively. The preferential growth of high-energy (001) face was also observed at low deposition temperatures (≤ 400 °C), which was found to result from dynamic nonequilibrium effect during the thermal spray deposition. Moreover, thermal spray deposition paves the way for a new approach to prepare high-energy (001) facets of TiO2 crystals.
关键词： hetero-orientation epitaxial growth,preferential growth,crystal morphology,homo-orientation epitaxial growth,deposition temperature,hereditary feature
更新于2025-09-23 15:22:29
-
Monodisperse Six-Armed Starbursts based on Truxene-Cored Multibranched Oligofluorenes: Design, Synthesis, and Stabilized Lasing Characteristics
摘要： A series of monodisperse six-armed conjugated starbursts (Tr1F, Tr2F and Tr3F) containing a truxene core and multibranched oligofluorene bridges capped with diphenylamine (DPA) units has been designed, synthesized, and investigated as robust gain media for organic semiconductor lasers (OSLs). The influence of electron-rich DPA end-groups on their optoelectronic characteristics has been discussed at length. DPA cappers effectively raise HOMO levels of the starbursts, thus enhancing the hole injection and transport ability. Solution-processed electroluminescence devices based on the resulting six-armed starbursts exhibited efficient deep-blue electroluminescence with clear reduced turn-on voltages (3.2~3.5 V). Moreover, the resulting six-armed molecules showed stabilized electroluminescence and amplified spontaneous emission with low thresholds (27.4~63.9 nJ pulse-1), high net gain coefficients (80.1~101.3 cm-1), and small optical loss (2.6~4.4 cm-1). Distributed feedback OSLs made from Tr3F exhibited low lasing threshold of 0.31 kW/cm2 (at 465 nm). The results suggest that the construction of truxene-centered six-armed conjugated starbursts with the incorporation of DPA units can effectively enhance EL properties by precisely regulating the HOMO energy levels, and further optimizing their optical gain properties.
关键词： Organic gain media,Organic light-emitting diodes (OLEDs),Conjugated starburst molecules,Organic semiconductor lasers (OSLs),HOMO levels
更新于2025-09-23 15:22:29
-
Enhanced NLO activity of organic 2-methyl-5-nitroaniline crystal: Experimental and computational investigation with and without silver addition
摘要： The nonlinear optical (NLO) material, 2-methyl-5-nitroaniline (M5NA), is synthesized and the crystals are grown by slow evaporation technique. The theoretical vibrational spectral analyses are done for the first time for M5NA using B3LYP computational method with the basis set cc-pVTZ. Natural Bond Orbital (NBO) and Atoms In Molecules (AIM) analyses are carried out for obtaining the charge transfer interactions and the Hirshfeld surface analysis with the fingerprint plot is performed for finding out the intermolecular interaction sites of the molecule. Using the theoretical and experimental IR and Raman spectra, the vibrations of M5NA are estimated. Changes in the linear and nonlinear optical properties with the addition of silver nanoparticles are studied from the UV–vis absorption spectra and the Z-Scan curves. A comparison of the hyperpolarizability values is done with pure and silver-added M5NA.
关键词： NLO,HOMO-LUMO,DFT,Vibrational spectroscopy,Silver nanoparticles
更新于2025-09-23 15:22:29
-
Structural, vibrational, spectroscopic, NMR and quantum chemical studies on fullerene and bromofullerenes
摘要： The most stable, optimized structures of fullerene (C60) and bromofullerenes (C60Br6) molecules were predicted by the density functional theory calculations using B3LYP method with 6311G(d,p) basis set. The obtained parameters were estimated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Bromofullerene (C60Br6) was architectured by directly bonding with bromine atom at C60 reactive sites. Theoretically calculated vibrational wavenumbers were assigned and compared. Ultraviolet-visible spectrum was mimicked by Polarizable Continuum model. The 13C NMR spectra were simulated by nuclear magnetic tensor GIAO for C60 and C60Br6 relative to tetramethyl silane. The molecular electrostatic potential surface was simulated. The transition between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) revealed different charge transfer possibilities which occur for the molecule and other related molecular properties were computed and tabulated. Natural bond orbital (NBO) analysis was carried out to image the charge transfer between the localized bonds and lone pairs of the electrons. The enhanced reactivity and peculiar energy gap by the substitution of bromine in fullerene pave way for designing the optoelectronic devices and bioactive molecules which will be useful in the field of sensors and carbon nano medicine.
关键词： HOMO,Fullerene,LUMO,NMR,Bromofullerene
更新于2025-09-23 15:21:21
-
Small bandgap non-fullerene acceptor enables efficient PTB7-Th solar cell with near 0 eV HOMO offset
摘要： Three small bandgap non-fullerene (SBG NFAs) acceptors, BDTI, BDTI-2F and BDTI-4F, based on a carbon-oxygen bridged central core and thieno[3,4-b]thiophene linker, end-capped with varied electron-withdrawing terminal groups, were designed and synthesized. The acceptors exhibit strong absorption from 600 nm to 1000 nm. The optimal device incorporating designed NFA and PTB7-Th polymer donor achieves a power conversion efficiency of 9.11% with near 0 eV HOMO offset. The work presents a case study of efficient non-fullerene solar cells with small HOMO offsets, which is achieved by blending PTB7-Th with fine-tuned SBG acceptor.
关键词： Organic solar cells,Driving force,HOMO offset,Non-fullerene acceptors,Small bandgap
更新于2025-09-23 15:21:01
-
Impact of t-butyl group on the singlet-triplet energy gap via weak orbital overlap of [1,2,5]-thiadiazolo[3,4-C]pyridine based TADF emitters: Structural modification
摘要： We theoretically investigated the combination of D-A and D-spacer (phenyl ring) -A with an electron donating alkyl (t-butyl) group. The strategy of twisting the geometry of the molecule with the alkyl substituents exclusion of strong electron withdrawing or donating groups leads to gain efficient deep blue-blue TADF emitter through maintaining the band gap while the reduction of singlet-triplet energy gap (EST). The t-butyl group strongly twisted the conformation of molecules by the steric hindrance resulted in weak HOMO and LUMO overlap (IH/L) and efficient spatial separation of HOMO and LUMO (rH/L) in the S0 state. In contrast, designed molecules S1 state own large HOMO and LUMO overlap of excited singlet state (IS) and inefficient spatial separation of HOMO and LUMO. The computed results indicated that introducing alkyl group into the phenyl ring of the acceptor of the designed molecules cannot affect the ΔEST. The ΔEST is mainly related to the IH/L, which can be adjusted by tuning the orbital IH/L. The large modular orbital overlap at S1 and T1 excited states resulted large ΔEST occurs in the range of 0.38 to 0.59eV whose dominant contribution switches from charge transfer (CT) to local excitation (LE). Our studied results reiterate (10.1038/srep10923) that modular orbital overlap of IS, HOMO and LUMO overlap of excited triplet state IT, spatial separation of HOMO and LUMO in the excited singlet state (rS) and spatial separation of HOMO and LUMO in the excited triplet state (rT) are the essential factors to determine ΔEST when inconsistencies between ΔEST and IH/L. Increasing the dihedral angle between D and A from molecule 1-4 (9-12), decrease the transition dipole moment which lowering the oscillator strength. When changing the connection position between D and A, molecules 5-8, the oscillator strength reduced to half with respect to molecules 1-4 and 9-12. The present work provides a theoretical understanding of the impact of alkyl substituents on the overlap of HOMO-LUMO resulting to tuning the ΔEST, as well as its influence on the oscillator strength may be a reliable idea to design efficient TADF emitters.
关键词： [1,2,5]-thiadiazolo[3,4-C]pyridine,HOMO-LUMO orbital overlap,fluorescence radiative decay rate,TADF,singlet-triplet energy gap
更新于2025-09-23 15:21:01
-
Tuning HOMO and LUMO of three region (UV, Vis and IR) photoluminescent nitrogen doped graphene quantum dots for photodegradation of methylene blue
摘要： Low cost, gram scale and highly N doped graphene quantum dots (NGQDs) with a broad absorption spectrum was synthesized using hydrothermal method by citric acid and urea. The obtained NGQDs possess wide absorption spectrum from ultraviolet to visible and IR range of wavelength. Optical characterization revealed that NGQDs are highly photoluminescent in three region of light (i.e. UV, Vis and IR). The average thickness is lower than 1 nm, meaning that the NGQDs are single, two or three layers of graphene. Lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the NGQDs determined using a cyclic voltammetry (CV) method, and energy band gap was obtained ～ 1.91 eV. A mechanism of charge carrier generation, separation, transport and photodegradation of methylene blue under illumination was proposed using the energy states. Finally the effect of N concentration on the band gap of NGQDs was simulated and discussed.
关键词： HOMO,NGQD,photodegradation,Quantum ESPRESSO,LUMO,cyclic voltammetry
更新于2025-09-23 15:19:57
-
A DFT study to probe homo-conjugated norbornylogous bridged spacers in dye-sensitized solar cells: an approach to suppressing agglomeration of dye molecules
摘要： This work reports a sigma-bridged framework as spacers to design new dye-sensitized solar cells. The norbornylogous bridged spacer can avoid p–p aggregation of dye molecules on the semiconductor surface in DSSCs. These sesquinorbornatrienes are known to exhibit electron propagation through the interaction of sigma and p orbitals via through bond (OITB) and through space (OITS) mechanisms. Density functional theory (DFT) calculations performed with these spacers and a modelled simple donor unit like N,N-dimethylamine and cyanoacrylic acid as the anchoring group showed significant results with the requisite optical parameters for DSSCs. The newly designed dyes have shown comparable or better optical properties compared to the reference dye molecule with p-conjugated thiophene spacer units. The DGinjection, VOC and mnormal values calculated for the designed dyes were found to be higher than those of the reference system. The trans-sesquinorbornatriene system spacer (6-D) showed a VOC of 3.3 eV, DGinjection of 2.4 eV and oscillatory strength (f) of 0.96. The total and partial density of states indicates a good communication between the valence and conduction band for the designed dyes. Transition density matrix results suggest that the exciton dissociation in the excited state is sufficiently high to overcome the coulombic attraction of the hole. These results are promising for the design of dye molecules with such scaffolds, to achieve better efficiency and to eliminate one of the major issues with p-spacer units in DSSCs.
关键词： homo-conjugated norbornylogous bridged spacers,dye molecules,DFT study,dye-sensitized solar cells,suppressing agglomeration
更新于2025-09-23 15:19:57