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Pyrene Based NLOphoric D‐π‐A‐π‐D Coumarin‐Chalcone and Their Red Emitting OBO Difluoride Complex: Synthesis, Solvatochromism, Z‐scan, and Detailed TD‐DFT Studies
摘要： NLOphoric D-π-A-π-D coumarin chalcone 5 and their BF2 complex 6 were designed, synthesized and characterized through Mass,13C-NMR, and 1H-NMR analysis. Their Photophysical properties are extensively studied in solvents of different polarity. On BF2 complexation of coumarin chalcone shows highly red shift in absorption and emission spectra compared to uncomplexed coumarin chalcone. Positive solvatochromism observed which is well supported by linear and multilinear regression analysis. For BF2 complexed coumarin-chalcone 6 the solvent dipolarity (CSdP) is the main factor responsible for slightly red shift in absorption spectra, and also for the highly red-shift in emission spectra. Frontier molecular orbital, molecular electrostatic potential and Generalized Mulliken-Hush analysis revealed intramolecular charge transfer in these compounds. Nonlinear optical (NLO) properties for compounds 5 and 6 were studied by solvatochromic and computational method. The linear polarizability (α), first-order hyperpolarizability (β) and second-order hyperpolarizability (γ) of compounds were studied by the time dependent density functional theory using three different functionals namely B3LYP, BHHLYP and CAM(cid:0) B3LYP with the 6–31 G (d) basis set. BF2 complexed compound 6, show higher values for αe + αv as well as βe+βv compared to compound 5. Third order nonlinear optical susceptibility (χ(3)) of these compounds obtained by Z-scan analysis. Third-order (χ(3)) non-linear optical properties of BF2 complexed coumarin-chalcone 6 were observed to be several times higher than those of the uncomplexed coumarin-chalcone 5 these justify the design approach.
关键词： NLOphoric,Z-Scan,positive solvatochromism,pyrene-chalcones,TD-DFT,solvatochromic NLO
更新于2025-09-11 14:15:04
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New small organic molecules based on thieno[2,3-b]indole for efficient bulk heterojunction organic solar cells: a computational study
摘要： This study aims to evaluate the characteristics of novel organic D-π-A-π-D class small-molecules by using carefully the density functional theory, and time-dependent density functional theory calculations. Thedesigned sequence of (D-A) BHJ-1a to BHJ-4a in organic Bulk Heterojunction (BHJ) solar cells has been comprehensively analysed. Thiéno[2,3-b]indole (TI) has been used as donor, and Diketopyrrolopyrrole (DPP) as acceptor for all compounds. In order to improve the electronic, photovoltaic, and opticalproperties, we have substituted thiophene unit with furan, thieno[2,3-b]thiophene, thiazole and thiazolothiazole as π-bridge moieties. Thus, the result shows that the wise choice of the π-bridge units plays a significant role in improving Egap, producing a high bathochromic shift, and increasing VOC as well as a theoretical power conversion efficiency (PCE) over 7%. Interestingly, BHJ-4a with suitable π-bridge presents the optimal electronic properties with low band gap (1.870 eV) and high VOC (1.534 eV). Furthermore, we have modelled a Bulk heterojunction organic photovoltaic cells based on donor-PCBM complex in order to achieve the optimum Egap and VOC. Consequently, the obtained results provide a new way to design BHJ small molecule donors with higher power conversion efficiency.
关键词： BHJ organic solar cells,DFT,PCBM,UV–Vis,thiéno[2,3-b]indole
更新于2025-09-11 14:15:04
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The photophysical properties and electronic structures of bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT) derivatives as hole-transporting for organic light-emitting diodes (OLEDs)
摘要： By using the quantum methods DFT and TD-DFT in this paper, the optoelectronic properties and electronic structures of eight compounds Ci (i=1-8) based on bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT) with D-π-D structure for Ci (i=1-5); and D-π-A for Ci (i=6-8) have been calculated and discussed theoretically in the aim to consider them as hole-transporting materials (HTM) in OLEDs. The calculated electronic levels by B3LYP of studied compounds show that the proper energy of Ci (i=6-8) is so matching for efficiency injecting into hole-injection layer (HIL). The compounds having D-π-A structure seem more efficient than those having D-π-D structure. The optoelectronic properties for studied compounds obtained by TD-CAM-B3LYP elucidate that C6, C7 and C8 compounds behave as electron donating molecules and induce charge transfer character in the UV-visible absorptions and emission electronic spectra. Furthermore, the calculated reorganization energies, ionization potential (IP) and electron affinity (EA) also provide that the extended C6, C7 and C8 compounds have the highest charge-transporting ability among all compounds. It is found that the D-π-A more influence on the electronic and optoelectronic properties than the D-π-D structure. The assumed compound C7 is found to be a good candidate for blue-emitting material. Understanding these properties is important to design HTMs with exceptional properties, such as stability and high efficiency.
关键词： B3LYP,DFT,bis[1]benzothieno[6,7-d:6',7'-d']benzo[1,2-b:4,5-b']dithiophene (BBTBDT),OLEDs
更新于2025-09-11 14:15:04
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Synthesis, characterization and modeling of self-assembled porphyrin nanorods
摘要： Porphyrin nanorods were prepared by ion-association between free-base meso 5,10,15,20-tetrakis-(4-N-methylpyridinium)porphyrin cations and tetraphenylborate anions. The nanorods have variable lengths (up to a few micrometers long) and diameters (~50–500 nm). Their structure at the molecular level was elucidated by combining multinuclear solid state NMR spectroscopy, synchrotron X-ray powder diffraction and DFT calculations.
关键词： DFT modeling,solid state NMR,NMR crystallography,nanorods,porphyrin,self-assembly
更新于2025-09-11 14:15:04
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Benzothiazole pyrazole containing emissive azo dyes decorated with ESIPT core: Linear and non linear optical properties, Z scan, optical limiting, laser damage threshold with comparative DFT studies
摘要： Positional isomers of "benzothiazoles-pyrazole based azo dyes containing separate with ESIPT core" are analyzed for their "linear and non-linear optical (NLO)" properties. Dyes are emissive in ACN having Stokes shift in the range of 75 nm. Spectroscopic properties are further utilized to calculate band gap by CV. Band gap obtained by DFT and cyclic voltammetry (CV) are in good agreement with each other. Vertical excitation in six different functionals is compared with experimental absorption maxima. Non-linear absorptive coef?cient (b), nonlinear refractive index (?2), third-order non-linear optical suscep- tibility (c3) and optical limiting (OL) in acetone, ethanol and DMSO are obtained using Z-scan technique and results are appreciable than previously reported dyes. Satisfactory laser damage threshold (LDT) values are in the range of 7.9e9.7 (cid:1) 1013 W/m2. TGA study indicates that these compounds are useful in several high-temperature processes in the construction of electronic and optical devices. The geometry of the dyes are optimized at "B3LYP/6-311 t G (d,p) level". "Molecular Electrostatic Potential" (MEP), "Frontier Molecular Orbitals" (FMO) are presented using "Density Functional Theory (DFT)" to gain structural insights. Relatively new electrophilicity descriptor- "Hyperhardness" for both the molecules are calculated which suggests the stability of molecules. Global hybrid (GH) functional (B3LYP, BHandHLYP) and range separated hybrid (RSH) (CAM-B3LYP, uB97, uB97X, and uB97XD) functional are used to calculate linear and NLO properties. uB97 is a more suitable functional observed for determining bo and g. Direct relation in-between "dipole moment" (m) and "linear polarizability" (a) is also presented. These dyes can emerge as attractive NLOphores in optoelectronic applications.
关键词： ESIPT,NLO,Z-scan,LDT,DFT,Emissive azo dyes,Benzothiazole-pyrazole
更新于2025-09-11 14:15:04
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Cost benefit modeling of AB <sub/>2</sub> X <sub/>4</sub> (A=Cd; B=Ga; X=S, Se) solar photovoltaic (PV) materials
摘要： Present paper focus towards implementation and commercialization of emerging solar PV technology with cost effective manner. Energy band gap, absorption coefficients and module implementation cost for 1KW solar power plant for ternary AB2X4 (A= Cd; B= Ga; X= S, Se) solar photovoltaic (PV) system is investigated here. All the material related calculations are carried out using density functional theory [1] and cost related calculations by using mathematical expressions. By performing a comparative cost study between proposed materials based solar photovoltaic module and crystalline based solar photovoltaic module we concluded that present material will be cost effectively commercialized as compare to Crystalline Si.
关键词： Solar PV,Cost,DFT
更新于2025-09-11 14:15:04
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Similarity and Specificity of Chlorophyll <i>b</i> Triplet State in Comparison to Chlorophyll <i>a</i> , as Revealed by EPR/ENDOR and DFT Calculations.
摘要： An investigation of the photoexcited triplet state of chlorophyll (Chl) b has been carried out by means of Electron Nuclear Double Resonance (ENDOR), both in frozen organic solvent and in protein environment provided by the Water-Soluble Chlorophyll Protein of Lepidium virginicum. Density functional theory (DFT) calculations have allowed the complete assignment of the observed hyperfine couplings corresponding to the methine protons and the methyl groups, leading to a complete picture of the spin density distribution of the triplet state in the tetrapyrrole macrocycle. The triplet state properties of Chl b were found to be similar in many respects to those previously reported for Chl a, although some specificities have been highlighted. Concerning the spin density distribution, the differences are manly localized on the carbon atoms close to the formyl group which, in Chl b, replaces the methyl group of Chl a.
关键词： EPR/ENDOR,triplet state,DFT calculations,Chlorophyll b,spin density distribution
更新于2025-09-11 14:15:04
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[IEEE 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Udine, Italy (2019.9.4-2019.9.6)] 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - ATOMOS: An ATomistic MOdelling Solver for dissipative DFT transport in ultra-scaled HfS <sub/>2</sub> and Black phosphorus MOSFETs
摘要： A state-of-the-art DFT-NEGF based ATOmistic - MOdelling Solver (ATOMOS) was developed and used to assess the physics and fundamental-performance potential of various scaled mono-layer transition-metal-dichalcogenides and black- phosphorus (BP) MOSFETs down to a gate length of 5 nm, including the effect of electron-phonon scattering. Our study highlights the good scalability and drive-current potential of HfS2 and the impact of optical-phonon scattering for BP.
关键词： DFT NEGF,CMOS,2D-material,Semiconductor Physics,Quantum transport
更新于2025-09-11 14:15:04
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Rational design of visible light panchromatic absorption laser dye molecules: The first principle study
摘要： Laser dye molecules play an important role in tunable lasers due to enhancing the laser radiation intensity and increasing the laser adjustable range. The broad spectral bandwidth and visible light absorption allows for the evaluation of multiple fluorescence quenching mechanisms such as excition formation, photoinduced electron transfer, and excited-state proton transfer. A series of organic dye molecules (LD1-4、LA2-5、LU1-5、LV1-4、LI1-4) consisting of simple electron donor (D), conjugated bridge (π) and electron acceptor (A) units were designed using first-principles calculations in order to evaluate their potential for applications in tunable lasers. Furthermore, the optical and electronic properties of the dye molecules are analyzed in detail using density functional theory (DFT) and time-dependent density functional theory (TDDFT), including spectral parameters, energy levels and orbital contributions of organic dye molecules. The results indicate that LI1-3 show high molar extinction coefficient, visible light full color absorption and obvious red-shifted compared to the experimentally synthesized dye LA3. In particular, the newly designed LI3 exhibits not only a 190 nm red-shifted and a higher molar extinction coefficient with an increment of 19%, but also has an extremely broad absorption spectrum covering entire visible absorption spectrum from 380 to 750 nm compared to LD1. We also find that the dyes with dithiophene groups and naphthalene group as the electron donors are better absorption spectrum than dyes with double bond group and benzene group. These calculated results will hopefully contribute to the further development of novel laser dye molecules and further provide scientific support and theoretical guidance for subsequent related research.
关键词： Absorption spectra,Laser dye,DFT/TDDFT,Panchromatic absorption
更新于2025-09-11 14:15:04
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Fullerene-Based Switching Molecular Diodes Controlled by Oriented External Electric Fields
摘要： Employing multi-scale in silico modeling we propose switching molecular diodes on the basis of endohedral fullerenes (fullerene switching diode, FSD), encapsulated with polar molecules of general type MX (M: metal, X: non-metal) to be used for data storage and processing. Here, we demonstrate for MX@C70 systems that the relative orientation of enclosed MX with respect to a set of electrodes connected to the system can be controlled by application of oriented external electric field(s). We suggest systems with two- and four-terminal electrodes, in which the source and drain electrodes help the current to pass through the device and help the switching between the conductive states of FSD via applied voltage. The gate electrodes then assist the switching by effectively lowering the energy barrier between local minima via stabilizing the transition state of switching process if the applied voltage between the source and drain is insufficient to switch the MX inside the fullerene. Using non-equilibrium Green’s function combined with density functional theory (DFT-NEGF) computations, we further show that conductivity of the studied MX@C70 systems depends on the relative orientation of MX inside the cage with respect to the electrodes. Therefore, the orientation of the MX inside C70 can be both enforced (“written”) and retrieved (“read”) by applied voltage. The studied systems thus behave like voltage-sensitive switching molecular diodes, that is a reminiscent of a molecular memristor.
关键词： molecular diodes,DFT-NEGF,data storage,fullerene,electric fields
更新于2025-09-11 14:15:04