共查询到20条相似文献,搜索用时 15 毫秒
1.
Cai-Rong Zhang Li Liu Jian-Wu Zhe Neng-Zhi Jin Li-Hua Yuan Yu-Hong Chen Zhi-Qiang Wei You-Zhi Wu Zi-Jiang Liu Hong-Shan Chen 《Journal of molecular modeling》2013,19(4):1553-1563
The computations of the geometries, electronic structures, dipole moments and polarizabilities for indoline and triphenylamine (TPA) based dye sensitizers, including D102, D131, D149, D205, TPAR1, TPAR2, TPAR4, and TPAR5, were performed using density functional theory, and the electronic absorption properties were investigated via time-dependent density functional theory with polarizable continuum model for solvent effects. The population analysis indicates that the donating electron capability of TPA is better than that of indoline group. The reduction driving forces for the oxidized D131 and TPAR1 are slightly larger than that of other dyes because of their lower highest occupied molecular orbital level. The absorption properties and molecular orbital analysis suggest that the TPA and 4-(2,2diphenylethenyl)phenyl substituent indoline groups are effective chromophores in intramolecular charge transfer (IMCT), and they play an important role in sensitization of dye-sensitized solar cells (DSCs). The better performance of D205 in DSCs results from more IMCT excited states with larger oscillator strength and higher light harvesting efficiency. While for TPA dyes, the longer conjugate bridges generate the larger oscillator strength and light harvesting efficiency, and the TPAR1 and TPAR4 have larger free energy change for electron injection and dye regeneration. 相似文献
2.
Ji Zhang Yu-He Kan Hai-Bin Li Yun Geng Yong Wu Yu-Ai Duan Zhong-Min Su 《Journal of molecular modeling》2013,19(4):1597-1604
We report a DFT, TDDFT and DFTB investigation of the performance of two donor-π-acceptor (D-π-A)-type organic dyes bearing different electron-withdrawing groups (EWG) for dye-sensitized solar cells (DSSCs) to evaluate which EWG is better for an acrylic acid acceptor, i.e., Cyano (–CN) or o-nitrophenyl (o-NO2–Ph). A series of theoretical criteria applied successfully in our previous work to explain the different performance of organic dyes related to open-circuit photovoltage (V oc) and short-circuit current density (J sc) were used to evaluate the performance of the dyes with just different EWG. Our calculated results reveal that dye 2 with o-NO2–Ph has a larger vertical dipole moment, more electrons transferred from the dye to the semiconductor and a lower degree of charge recombination, which could lead to larger V oc; while the larger driving force and comparable light harvesting efficiency could lead to higher J sc , highlighting the potential of o-NO2–Ph as an EWG in an acrylic acid acceptor. Figure
CN or o-NO2-Ph? Which is better for acrylic acid acceptor of donor-π-acceptor (D-π-A) dyes used in dye-sensitized solar cells (DSSCs) has been evaluated by DFT/TDDFT calculations. 相似文献
3.
Density functional theory (DFT) calculations and molecular dynamics (MD) simulations on the atomic level were performed on
three different substituted banana-shaped compounds derived from 1,3-phenylene bis[4-(4-n-hexyloxyphenyliminomethyl)benzoate]
(P-6-O-PIMB). The DFT studies were carried out on the isolated molecules, and in the MD simulations clusters were treated
with up to 64 monomers. The effect of polar substituents, such as chlorine and the nitro group, on the central 1,3-phenylene
unit of banana-shaped compounds was investigated. In particular, flexibility, polarity, electrostatic potential (ESP) group
charge distributions, B-factors, bending angles and molecular lengths were considered. The MD results were analysed by trajectories
of significant torsion angles as well as order parameters such as radial atom pair distribution functions g(r), orientational
correlation functions g(o), diffusion coefficients (D) and root mean square deviations (RMSD) values. The g(r) and g(o) values
show that a certain long range order is generated by the introduction of a NO2 group in the 2-position of the central 1,3-phenylene ring. In contrast, the chlorination at the 4 and 6 positions of the
central 1,3-phenylene unit decreases the long range order tendency by its perturbation effect on the conformations in such
molecules. Moreover, g(r) and g(o) values, as well as diffusion coefficients, show that in the NO2 substituted compound the formation of microphase areas is preferred. Finally, the aggregation effect in such compounds was
studied in a systematic way by a comparison of the conformational properties of the isolated molecules and the monomers in
the clusters.
Figure Molecular dynamics (MD) simulations on the aggregation behaviour of substituted banana-shaped compounds
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Yongzhen Wu Xi Zhang Wenqin Li Zhong‐Sheng Wang He Tian Weihong Zhu 《Liver Transplantation》2012,2(1):149-156
For a sensitizer with a strong π‐conjugation system, a coadsorbent is needed to hinder dye aggregation. However, coadsorption always brings a decrease in dye coverage on the TiO2 surface. Organic ‘‘D–A–π–A’’ dyes, WS‐6 and WS‐11, are designed and synthesized based on the known WS‐2 material for coadsorbent‐free, dye‐sensitized solar cells (DSSCs). Compared with the traditional D–π–A structure, these D–A–π–A indoline dyes, with the additional incorporated acceptor unit of benzothiadiazole in the π‐conjugation, exhibit a broad photoresponse, high redox stability, and convenient energy‐level tuning. The attached n‐hexyl chains in both dyes are effective to suppress charge recombination, resulting in a decreased dark current and enhanced open‐circuit voltage. Electrochemical impedance spectroscopy studies indicate that both the resistance for charge recombination and the electron lifetime are increased after the introduction of alkyl chains to the dye molecules. Without deoxycholic acid coadsorption, the power‐conversion efficiency of WS‐6 (7.76%) on a 16 μm‐thick TiO2 film device is 45% higher than that of WS‐2 (5.31%) under the same conditions. The additional n‐hexylthiophene in WS‐11 extends the photoresponse to a panchromatic spectrum but causes a low incident photon‐to‐current conversion efficiency. 相似文献
5.
Palanivel Senthilkumar Chandrasekaran Nithya Ponnusamy Munusamy Anbarasan 《Journal of molecular modeling》2013,19(10):4561-4573
The metal-free organic dye sensitizer 2,3′-diamino-4,4′-stilbenedicarboxylic acid has been investigated for the first time for dye-sensitized solar cell applications. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations (performed using the hybrid functional B3LYP) were carried out to analyze the geometry, electronic structure, polarizability, and hyperpolarizability of 2,3′-diamino-4,4′-stilbenedicarboxylic acid used as a dye sensitizer. A TiO2 cluster was used as a model semiconductor when attempting to determine the conversion efficiency of the selected dye sensitizer. Our TD-DFT calculations demonstrated that the twenty lowest-energy excited states of 2,3′-diamino-4,4′-stilbenedicarboxylic acid are due to photoinduced electron-transfer processes. Moreover, interfacial electron transfer between a TiO2 semiconductor electrode and the dye sensitizer occurs through electron injection from the excited dye to the semiconductor’s conduction band. Results reveal that metal-free 2,3′-diamino-4,4′-stilbenedicarboxylic acid is a simple and efficient sensitizer for dye-sensitized solar cell applications. 相似文献
6.
A new series of 4‐hexyl‐4H‐thieno[3,2‐b]indole (HxTI) based organic chromophores is developed by structural engineering of the electron donor (D) group in the D–HxTI–benzothiadiazole‐phenyl‐acceptor platform with different fluorenyl moieties, such as unsubstituted fluorenyl (SGT‐146) and hexyloxy (SGT‐147), decyloxy (SGT‐148) and hexyloxy‐phenyl substituted (SGT‐149) fluorenyl moieties. In comparison to a reference dye SGT‐137 with a biphenyl‐based donor, the effects of the donating ability and bulkiness of the fluorenyl based donor in this D–π–A‐structured platform on molecular properties and photovoltaic performance are investigated to establish the structure–property relationship. The photovoltaic performance of dye‐sensitized solar cells (DSSCs) is improved according to the bulkiness of the donor groups. As a result, the DSSCs based on SGT‐149 show high power conversion efficiencies (PCEs) of 11.7% and 10.0% with a [Co(bpy)3]2+/3+ (bpy = 2,2′‐bipyridine) and an I?/I3? redox electrolyte, respectively. Notably, the co‐sensitization of SGT‐149 with a SGT‐021 porphyrin dye by utilizing a simple “cocktail” method, exhibit state‐of‐the‐art PCEs of 14.2% and 11.6% with a [Co(bpy)3]2+/3+ and an I?/I3? redox electrolyte, respectively. 相似文献
7.
Wichien Sang-aroon Seksan Laopha Phrompak Chaiamornnugool Sarawut Tontapha Samarn Saekow Vittaya Amornkitbamrung 《Journal of molecular modeling》2013,19(3):1407-1415
Essential parameters related to the photoelectrochemical properties, such as ground state geometries, electronic structures, oxidation potential and electron driving force, of cochineal insect dyes were investigated by DFT and TDDFT at the B3LYP/6-31+G(d,p) level of the theory. The results show that the major charge flow dynamic for all dyes is the HOMO→LUMO transition. The bi-coordinated binding mode, in which the dye uses one carboxyl- and hydroxyl oxygen bound to Ti(IV), is found for all dye-TiO2 systems. Additionally, the doubly bi-coordinated binding mode in which the dye used both carboxyl groups bound to two Ti(IV) is also possible due to high energy distribution occupied at anchoring groups. This study highlights that most of these insect dyes can be good photosensitizers in dye-sensitized solar cells based on their strong binding to the TiO2 surface, good computed excited state oxidation potential and thermodynamically favored electron driving force. 相似文献
8.
Next‐generation organic solar cells such as dye‐sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) are studied at the National Institute of Advanced Industrial Science and Technology (AIST), and their materials, electronic properties, and fabrication processes are investigated. To enhance the performance of DSSCs, the basic structure of an electron donor, π‐electron linker, and electron acceptor, i.e., D–π–A, is suggested. In addition, special organic dyes containing coumarin, carbazole, and triphenylamine electron donor groups are synthesized to find an effective dye structure that avoids charge recombination at electrode surfaces. Meanwhile, PSCs are manufactured using both a coating method and a laser deposition technique. The results of interfacial studies demonstrate that the level of the conduction band edge (CBE) of a compact TiO2 layer is shifted after TiCl4 treatment, which strongly affects the solar cell performance. Furthermore, a special laser deposition system is developed for the fabrication of the perovskite layers of PSCs, which facilitates the control over the deposition rate of methyl ammonium iodide used as their precursor. 相似文献
9.
Photoinduced absorption (PIA) spectroscopy, where the excitation is provided by a square-wave modulated (on/off) monochromatic light source, is a versatile tool in the study of dye-sensitized solar cells. Spectra of transient species, such as the oxidized dye, can easily be obtained and their kinetics can be explored using frequency or time-resolved techniques. Experimental PIA conditions can be kept close to typical solar cell operating conditions, allowing extraction of relevant time constants. PIA is also a suitable method to study the quality of pore filling in case of solid hole conductors. Dye molecules that are not in direct contact with the hole conductor will have long lifetimes in their oxidized state and appear clearly in the PIA spectrum. The basic principles of PIA are explained using the example of electron injection and recombination in dye-sensitized TiO2 in the absence of redox electrolyte. 相似文献
10.
The electronic structures of three D-A-π-A indoline dyes (WS-2, WS-6, and WS-11) used in dye-sensitized solar cells (DSSCs) were studied by performing quantum chemistry calculations. The coplanarity of the A-π-A segment and distinct noncoplanarity of the indoline donor part of each dye were confirmed by checking the calculated geometric parameters. The relationships between molecular modifications and the optical properties of the dyes were derived in terms of the partial density of states, absorption spectrum, frontier molecular orbital, and excited-state charge transfer. 3D real-space analysis of the transition density (TD) and charge difference density (CDD) was also performed to further investigate the excited-state features of the molecular systems, as they provide visualized physical pictures of the charge separation and transfer. It was found that modifying the alkyl chain of the bridge unit near the acceptor unit is an efficient way to decrease dye aggregation and improve DSSC efficiency. Inserting a hexylthiophene group next to the donor unit leads to a complicated molecular structure and a decrease in the charge-transfer ability of the system, which has an unfavorable impact on DSSC performance. 相似文献
11.
The affinity and selectivity of protein-protein interactions can be fine-tuned by varying the size, flexibility, and amino acid composition of involved surface loops. As a model for such surface loops, we study the conformational landscape of an octapeptide, whose flexibility is chemically steered by a covalent ring closure integrating an azobenzene dye into and by a disulfide bridge additionally constraining the peptide backbone. Because the covalently integrated azobenzene dyes can be switched by light between a bent cis state and an elongated trans state, six cyclic peptide models of strongly different flexibilities are obtained. The conformational states of these peptide models are sampled by NMR and by unconstrained molecular dynamics (MD) simulations. Prototypical conformations and the free-energy landscapes in the high-dimensional space spanned by the phi/psi angles at the peptide backbone are obtained by clustering techniques from the MD trajectories. Multiple open-loop conformations are shown to be predicted by MD particularly in the very flexible cases and are shown to comply with the NMR data despite the fact that such open-loop conformations are missing in the refined NMR structures. 相似文献
12.
Erik Gabrielsson Hanna Ellis Sandra Feldt Haining Tian Gerrit Boschloo Anders Hagfeldt Licheng Sun 《Liver Transplantation》2013,3(12):1647-1656
A series of four new dyes, based on the D35 type donor moiety with varied linker units, is synthesized using a facile convergent/divergent method, enabled by an improved synthesis of the D35 donor. The dyes are evaluated in dye sensitized solar cells with Co(II/III)(bpy)3‐based electrolytes. By extending the linker fragment, higher photocurrents and solar energy conversion efficiencies are achieved. It is also found that the linker unit plays a crucial role in maintaining a high open‐circuit photovoltage. Based on the photovoltaic performance it is concluded that the hexylthiophene unit is the most suitable for this purpose, as it allows further enhancement of the already high open‐circuit voltage of D35 to 0.92 V. The best dye in this series reaches an efficiency of 6.8%. 相似文献
13.
Peng Gao Hoi Nok Tsao Chenyi Yi Michael Grätzel Mohammad K. Nazeeruddin 《Liver Transplantation》2014,4(7)
The elongation of π‐conjugated bridges between the donor (D) and the acceptor (A) represents a feasible strategy towards enhancement of light‐harvesting in both breadth and depth of organic D‐π‐A dyes suitable for nanocrystalline TiO2‐based dye‐sensitized solar cells (DSSCs). Here, a series of organic dyes with elongating conjugated bridges is synthesized and characterized. DSSC devices employing a cobalt (II/III) redox electrolyte are fabricated using these dyes as light‐harvesting sensitizers. Compared to a dye with the 3,4‐ethylenedioxythiophene (EDOT) linker ( G188 ), the three counterparts with further extended π‐bridges present gradually red‐shifted electronic absorption spectra and a persistent decrease in oxidation potential. The photocurrent action spectra show that the extension of π‐conjugated bridges decreases the open‐circuit photovoltage. The best performance is shown in G268 with a short‐circuit photocurrent density (Jsc) of 16.27 mA cm2, an open‐circuit photovoltage (Voc) of 0.83 V, and a fill factor (FF) of 0.67, corresponding to an overall conversion efficiency of 9.24%. Unexpectedly, G270, which has with the longest π‐bridge , showed the lowest Jsc, Voc, and efficiency. 相似文献
14.
Olga Malinkiewicz Thais Grancha Agustin Molina‐Ontoria Alejandra Soriano Hicham Brine Henk J. Bolink 《Liver Transplantation》2013,3(4):472-477
Simple bilayer solar cells, using commercially available cationic cyanine dyes as donors and evaporated C60 layer as an acceptor are prepared. Cyanine dyes with absorption maxima of 578, 615 and 697 nm having either perchlorate or hexafluorophosphate counter‐ions are evaluated. The perchlorate dye leads to cells with S‐shape current‐voltage curves; only the dyes with the hexafluorophosphate counter‐ions lead to efficient solar cells. When the wide bandgap dyes are employed, S‐shape current‐voltage curves are obtained when the conductive polymer PEDOT:PSS is used as hole transport layer. Substitution of PEDOT:PSS with MoO3 leads to cells with more rectangular current–voltage curves and high fill factors. Additionally, the cells using the MoO3 layer for hole extraction lead to high open circuit voltages of 0.9 V. In the case that a low bandgap hexafluorophosphate dye is used with the HOMO above that of the PEDOT:PSS the cell performance is independent on the type of hole transport layer employed. Using this approach, bilayer solar cells are obtained with power efficiencies ranging from 1.8 to 2.9% depending on the particular dye employed. These are impressive numbers for bilayer solar cell that are partially solution processed in ambient conditions. 相似文献
15.
Andrew Nattestad Yuen Yap Cheng Rowan W. MacQueen Gordon G. Wallace Timothy W. Schmidt 《Journal of visualized experiments : JoVE》2014,(91)
The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date. 相似文献
16.
Michael Wykes Fabrice Odobel Carlo Adamo Ilaria Ciofini Frédéric Labat 《Journal of molecular modeling》2016,22(12):289
We present hybrid, periodic, spin-polarized density functional theory calculations of antiferromagnetic NiO bulk, of its clean (100) surface and of the binding on this latter of four different organic ligands, relevant for p-type dye-sensitized solar cells (p-DSSC) applications. We find evidence for a strong chemisorption of all ligands to the NiO surface in the form of short interatomic distances between surface Ni atoms and ligand atoms, confirmed by high binding energies. Although the analysis of the impact of the ligand adsorption on the density of states of the NiO substrate reveals significant modifications, the overall picture obtained is in line with the operation principles of p-DSSC in all cases. However, some of the considered ligands significantly shift the density of states to lower energies, which, in p-DSSCs employing these ligands to anchor dyes to NiO, could force the use of dyes with deeper HOMO energies and alternative redox couples capable of accepting electrons from the dye (assuming dye bandgaps in the UV/visible range). 相似文献
17.
Ricchiuto P Rocco AG Gianazza E Corrada D Beringhelli T Eberini I 《Journal of molecular recognition : JMR》2008,21(5):348-354
Chicken liver bile acid binding protein (cL-BABP) crystallizes with water molecules in its binding site. To obtain insights on the role of internal water, we performed two 100 ns molecular dynamics (MD) simulations in explicit solvent for cL-BABP, as apo form and as a complex with two molecules of cholic acid, and analyzed in detail the dynamics properties of all water molecules. The diffusion coefficients of the more persistent internal water molecules are significantly different from the bulk, but similar between the two protein forms. A different number of molecules and a different organization are observed for apo- and holo-cL-BABP. Most water molecules identified in the binding site of the apo-crystal diffuse to the bulk during the simulation. In contrast, almost all the internal waters of the holo-crystal maintain the same interactions with internal sidechains and ligands, which suggests they have a relevant role in protein-ligand molecular recognition. Only in the presence of these water molecules we were able to reproduce, by a classical molecular docking approach, the structure of the complex cL-BABP::cholic acid with a low ligand root mean square deviation (RMSD) with respect to its reference positioning. Literature data reported a conserved pattern of hydrogen bonds between a single water molecule and three amino acid residues of the binding site in a series of crystallized FABP. In cL-BABP, the interactions between this conserved water molecule and the three residues are present in the crystal of both apo- and holo-cL-BABP but are lost immediately after the start of molecular dynamics. Copyright (c) 2008 John Wiley & Sons, Ltd. 相似文献
18.
Aron J. Huckaba Fabrizio Giordano Louis E. McNamara Katelyn M. Dreux Nathan I. Hammer Gregory S. Tschumper Shaik M. Zakeeruddin Michael Grätzel Mohammad K. Nazeeruddin Jared H. Delcamp 《Liver Transplantation》2015,5(7)
Strong electron‐donating functionality is desirable for many organic donor‐π‐bridge‐acceptor (D‐π‐A) dyes. Strategies for increasing the electron‐donating strength of common nitrogen‐based donors include planarization of nitrogen substituents and the use of low resonance‐stabilized energy aromatic ring‐substituted nitrogen atoms. Organic donor motifs based on the planar nitrogen containing heterocycle indolizine are synthesized and incorporated into dye‐sensitized solar cell (DSC) sensitizers. Resonance active substitutions at several positions on indolizine in conjugation with the D‐π‐A π‐system are examined computationally and experimentally. The indolizine‐based donors are observed to contribute electron density with strengths greater than triarylamines and diarylamines, as evidenced by UV/Vis, IR absorptions, and oxidation potential measurements. Fluorescence lifetime studies in solution and on TiO2 yield insights in understanding the performance of indolizine‐based dyes in DSC devices. 相似文献
19.
Titanium dioxide films with organized mesoporous structure were investigated as photoanodes in dye sensitized solar cells. High-quality films were grown on FTO supports by implementing the protocol of supramolecular templating with an amphiphilic triblock copolymer, Pluronic P123. Thicker films were obtained by repeated dip-coating and calcination cycles of up to 10 layers. The TiO2 films were crack-free, optically transparent, and had thicknesses exceeding 2 μm, while still preserving the organized mesoporous morphology. Their roughness factors, determined from Kr-adsorption isotherms, exceeded 500. The sorption of N-3 and N-719 dyes was fitted to a surface coverage of 0.31 molecules/nm2, which is about one third of the ideal dye loading assumed for the (1 0 1) anatase face. The solar performance of multilayer films sensitized with N-945 dye scaled linearly for 1-3 layer films, but approached a plateau for thicker films. 相似文献
20.
Assessing the effect of D59P mutation in the DE loop region in amyloid aggregation propensity of β2‐microglobulin: A molecular dynamics simulation study
下载免费PDF全文
![点击此处可从《Journal of cellular biochemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Simranjeet S. Narang Suniba Shuaib Deepti Goyal Bhupesh Goyal 《Journal of cellular biochemistry》2018,119(1):782-792
Dialysis‐related amyloidosis (DRA) is a severe condition characterized by the accumulation of amyloidogenic β2‐microglobulin (β2m) protein around skeletal joints and bones. The recent studies highlighted a critical role of the DE loop region for β2m stability and amyloid aggregation propensity. Despite significant efforts, the molecular mechanism of enhanced aggregation due to D59P mutation in the DE loop region remain elusive. In the present study, explicit‐solvent molecular dynamics (MD) simulations were performed to examine the key changes in the structural and dynamic properties of wild type (wt) β2m upon D59P mutation. MD simulations reveal a decrease in the average number of hydrogen bonds in the loop regions on D59P mutation that enhances conformational flexibility, which lead to higher aggregation propensity of D59P as compare to wt β2m. The principal component analysis (PCA) highlight that D59P covers a larger region of phase space and display a higher trace value than wt β2m, which suggest an overall enhancement in the conformational flexibility. D59P display two minimum energy basins in the free energy landscape (FEL) that are associated with thermodynamically less stable conformational states as compare to single minimum energy basin in wt β2m. The present study provides theoretical insights into the molecular mechanism behind the higher aggregation propensity of D59P as compare to wt β2m. 相似文献