The most stable supramolecular structural configuration of DES3 with extensive hydrogen bonding network was simulated by B3LYP/6-31G/d,p.
The DES3 was most stable structure due to lowest heat of ...formation as compared to their individual compounds.
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•Investigate the properties of hydrogen-bonded supramolecular structures by DFT method.•Calculation of physico-chemical of the eutectic mixture using quantum simulation.•Thermodynamic stabilities of eutectic mixture and individual molecules were simulated.•Deep eutectic solvents showed an enhanced hydrogen-bonded supramolecular structure.
The structural properties of choline chloride-based deep eutectic solvents (DESs) are investigated using the molecular dynamics simulations approach. The effect of different donor groups i.e. ethylene glycol, malic acid, tartaric acid, glycerol and oxalic acid with choline chloride acceptor in the formation of supramolecular structures are studied by employing different functionals. Different thermodynamic properties such as heat of formation, charge mobility, interaction energies, electronic energy, zero-point energy, dipole moment, heat capacity, entropy, bond angles and dihedral angles of the eutectic mixture are anticipated. Among all the deep eutectic solvents, DES3 is found to be more stable in terms of an extensive hydrogen-bonded network with maximum heat of formation (−5.94 × 104 eV). The extensive hydrogen bond network in DES3 also leads to substantially higher polarizability (222.124 au), thermal stability (345.14 kcal mol−1), heat capacity (121.43 Calmol−1K) and entropy (222.04 Calmol−1K−1). However, the viscosity of DES1 is found lowest (37 cP) with the highest conductivity (6.34 mS cm−1), dipole moment (16.14 Debye) and electron mobility (0.0919644 eV) and hole mobility (0.0477745 eV). This work will provide a new visualization of the supramolecular structure of choline chloride-based DESs with physical and electronic properties.
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Three regioregular benzodithiophene‐based donor–donor (D–D)‐type polymers (PBDTT, PBDTT1Cl, and PBDTT2Cl) are designed, synthesized, and used as donor materials in organic solar cells (OSCs). Because ...of the weak intramolecular charge‐transfer effect, these polymers exhibit large optical bandgaps (>2.0 eV). Among these three polymers, PBDTT1Cl exhibits more ordered and closer molecular stacking, and its devices demonstrate higher and more balanced charge mobilities and a longer charge‐separated state lifetime. As a result of these comprehensive benefits, PBDTT1Cl‐based OSCs give a very impressive power conversion efficiency (PCE) of 17.10% with a low nonradiative energy loss (0.19 eV). Moreover, PBDTT1Cl also possesses a low figure‐of‐merit value and good universality to match with different acceptors. This work provides a simply and efficient strategy to design low‐cost high‐performance polymer donor materials.
Three D–D type wide‐bandgap donor polymers (PBDTT, PBDTT1Cl, and PBDTT2Cl) are designed and facilely synthesized. Organic solar cells (OSCs) based on PBDTT1Cl exhibit a high power conversion efficiency of 17% and a low nonradiative energy loss of 0.19 eV. In addition, PBDTT1Cl has a very low figure‐of‐merit and good universality, indicating its potential as a low‐cost polymer donor for high‐performance OSCs.
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•The FCN hybrids exhibited excellent photo-Fenton oxidation performance.•The Fe2O3 QDs loading improved the charge mobility and catalytic sites.•Enhanced activity mechanism and roles ...of active species were elucidated.
Currently, the photo-Fenton oxidation has been increasingly studied in the domain of contaminant elimination. However, the lack of active sites and the slow charge migration in the catalytic process, still limit its practical application. 3D/0D hybrids offer a better opportunity for improving photo-Fenton activity due to their high charge mobility and increased number of catalytic sites, which is highly desirable but remains a large challenge. Herein, 3D interconnected porous g-C3N4 hybridized with Fe2O3 QDs (FCN) was developed and exhibited a porous structure and large specific areas. A large number of active sites and rapid charge separation/migration were achieved by the loading of ultrasmall Fe2O3 QDs on the surface of g-C3N4. Moreover, the high charge mobility of this material promoted the fast conversion of Fe3+ to Fe2+, resulting in the optimum synergistic effect between the photocatalytic and Fenton oxidation processes. Thus, the FCN catalysts exhibited excellent photo-Fenton oxidation activity towards the decomposition of organic contaminants (such as phenol, 2,4-dibromophenol, 2,4,6-trichlorophenol, rhodamine B and methyl orange). In addition, the roles of active species in the photo-Fenton oxidation reaction were also studied, and the results imply that the hydroxyl radicals played the most important role in the degradation of organic contaminants.
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Trapping negative charges in polymer electrolytes using a frog‐shaped, ether‐functionalized anion (EFA) is presented by H. Zhang, J. Carrasco, M. Armand, and co‐workers in their Communication on page ...12070 ff. The bis(trifluoromethanesulfonyl)imide anion (TFSI), shown as a slippery tadpole, is highly mobile in poly(ethylene oxide) (PEO) matrix. In contrast, the ethylene oxide legs in EFA endow trapping interactions between the anion and PEO, which suppresses mobility (Artwork: Scixel, J. Carrasco, H. Zhang, M. Armand).
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Recent decades have witnessed the rapid development of semiconducting polymers in terms of high charge mobilities and applications in transistors. Significant efforts have been made to develop ...various conjugated frameworks and linkers. However, studies are increasingly demonstrating that the side chains of semiconducting polymers can significantly affect interchain packing, thin film crystallinity, and thus semiconducting performance. Ways to modify the side alkyl chains to improve the interchain packing order and charge mobilities for conjugated polymers are first discussed. It is shown that modifying the branching chains by moving the branching points away from the backbones can boost the charge mobilities, which can also be improved through partially replacing branching chains with linear ones. Second, the effects of side chains with heteroatoms and functional groups are discussed. The siloxane‐terminated side chains are utilized to enhance the semiconducting properties. The fluorinated alkyl chains are beneficial for improving both charge mobility and air stability. Incorporating H bonding group side chains can improve thin film crystallinities and boost charge mobilities. Notably, incorporating functional groups (e.g., glycol, tetrathiafulvalene, and thymine) into side chains can improve the selectivity of field‐effect transistor (FET)‐based sensors, while photochromic group containing side chains in conjugated polymers result in photoresponsive semiconductors and optically tunable FETs.
Recent developments in side chain modifications of conjugated polymers, including alkyl side chains, heteroatom, and functional group containing side chains, are reviewed for field‐effect transistor studies. The review shows that side chain modification can not only improve the charge transport properties, but also endow the conjugated polymers with new functions (malleability, sensing, stimuli‐responsiveness, etc.).
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Exciton interactions in molecular aggregates play a crucial role in tailoring the optical behaviour of π‐conjugated materials. Though vital for optoelectronic applications, ideal Greek cross‐dipole ...(α=90°) stacking of chromophores remains elusive. We report a novel Greek cross (+) assembly of 1,7‐dibromoperylene‐3,4,9,10‐tetracarboxylic tetrabutylester (PTE‐Br2) which exhibits null exciton coupling mediated monomer‐like optical characteristics in the crystalline state. In contrast, nonzero exciton coupling in X‐type (α=70.2°, PTE‐Br0) and J‐type (α=0°, θ=48.4°, PTE‐Br4) assemblies have perturbed optical properties. Additionally, the semi‐classical Marcus theory of charge‐transfer rates predicts a selective hole transport phenomenon in the orthogonally stacked PTE‐Br2. Precise rotation angle dependent optoelectronic properties in crystalline PTE‐Br2 can have consequences in the rational design of novel π‐conjugated materials for photonic and molecular electronic applications.
Monomer‐like aggregates: Null exciton coupling in an ideal Greek cross‐dipole (+) assembly affords monomer‐like optical properties and an exceptional charge‐filtering (selective hole transport) effect in orthogonal chromophore stacks.
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Covalent triazine frameworks (CTFs) represent promising polymeric photocatalysts for photocatalytic hydrogen production with visible light. However, the separation and transfer of charges in CTFs are ...isotropic because of the uniform distribution of donor–acceptor motifs in the skeleton. Herein, to achieve the anisotropic charge carrier separation and migration, thiophene (Th) or benzothiadiazole (BT) unit is selected as the dopant to modify the molecular structure of CTF‐based photocatalysts. Both theoretical and experimental studies reveal that the incorporation of Th or BT units induces the anisotropic charge carrier separation and migration at the interface of CTFs. The optimized polymer manifests a much enhanced photocatalytic activity for photocatalytic hydrogen production with visible light, and thus this study provides a useful tool to design conjugated polymer photocatalysts at the molecular level for solar energy conversion.
Anisotropic charge carrier separation and migration are obtained by the rational design of the molecular structure of covalent triazine frameworks (CTFs). Both theoretical and experimental results prove the enhanced optical absorption, fast charge carrier transfer, and promoted photocatalytic hydrogen production performance of the modified CTFs in comparison with the pristine sample.
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Greek cross stacking (α=90°) mediated negligible exciton coupling has been theoretically known since 1965 (Kasha et al.). In their Communication on page 15696 M. Hariharan and co‐workers report the ...first experimental evidence of null exciton coupling mediated unperturbed photoexcited state properties and selective hole transport in a crystalline Greek cross (+) assembly, thereby highlighting the importance of precise cross stacking in modulating the optoelectronic character of crystalline arenes.
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High electrical conductivity and high Seebeck coefficient are the two important prerequisites for achieving high power factor in organic thermoelectric (TE) materials. However, these two properties ...are quite often in conflict. In this work, we demonstrate that incorporating CNT in a conducting polymer PEDOT:PSS could facilitate the formation of stable and effective conductive channels, which provides an effective approach to optimize the TE parameters with simultaneously enhanced electrical conductivity and Seebeck coefficient against the initial organic TE materials. With further tailoring charge concentration of the SWNT/PEDOT:PSS composite by base treatment, the TE performance could be improved. Nanocomposite of 60 wt% SWNT and PEDOT:PSS exhibits high TE power factor of ∼526 μW m−1 K−2 with Seebeck coefficient of 55.6 μV K−1 and electrical conductivity of 1701 S cm−1, which is by far one of the highest power factors among the reported organic TE nanocomposites. Considering thermal conductivity around 0.4–0.6 W/m K, the highest estimated ZT value of our TE nanocomposite can approach 0.39, demonstrating the feasibility of this strategy to enhance TE performance of organic composite materials.
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