A new copolymer PBDTP‐DTBT based on benzothiadiazole and alkylphenyl substituted benzodithiophene is synthesized and characterized. The correlation of the evolution of the morphology and photovoltaic ...performance is investigated. The power conversion efficiency of the polymer solar cells based on PBDTP‐DTBT/PC71BM (1:1.5, w/w) reaches up to 8.07%, under the irradiation of AM 1.5G, 100 mW/cm2.
The interfacial assembly of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer and carboxylated carbon quantum dots (c-CQDs) at the water/oil interface and the morphology of the ...resultant assemblies, transferred to a solid substrate, were investigated as a function of pH and the molecular weight of PS-b-P2VP. As expected, the interfacial assembly of PS-b-P2VP and c-CQDs decreased the interfacial tension between the water and toluene. The assembly of the PS-b-P2VP is strongly dependent on pH, that is, the extent of protonation of the P2VP block and, in the presence of the c-CQDs, the extent of interactions between the P2VP block and the c-CQDs. The behavior of the P2VP block also influences the state of the PS block, with the entanglement of the PS block increasing with decreasing pH, since the extension of the PVP block into the aqueous phase increases the packing density of the PS block at the interface. This is reflected in the modulus of the assemblies at the interface where marked changes are observed. The interactions between the CQDs and PS-b-P2VP are found to be sufficiently strong to show the potential of manipulating the structure of the interface with the BCP micelles.
Solid ferromagnetic materials are rigid in shape and cannot be reconfigured. Ferrofluids, although reconfigurable, are paramagnetic at room temperature and lose their magnetization when the applied ...magnetic field is removed. Here, we show a reversible paramagnetic-to-ferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water-oil interface. These ferromagnetic liquid droplets exhibit a finite coercivity and remanent magnetization. They can be easily reconfigured into different shapes while preserving the magnetic properties of solid ferromagnets with classic north-south dipole interactions. Their translational and rotational motions can be actuated remotely and precisely by an external magnetic field, inspiring studies on active matter, energy-dissipative assemblies, and programmable liquid constructs.
The interfacial broadening between two different epoxy networks having different moduli was nanomechanically mapped. The interfacial broadening of the two networks produced an interfacial zone having ...a gradient in the concentration and, hence, properties of the original two networks. This interfacial broadening of the networks leads to the generation of a new network with a segmental composition corresponding to a mixture of the original two network segments. The intermixing of the two, by nature of the exchange reactions, was on the segmental level. By mapping the time dependence of the variation in the modulus at different temperatures, the kinetics of the exchange reaction was measured and, by varying the temperature, the activation energy of the exchange reaction was determined.
Nanoparticle surfactants (NPSs) assembled at the oil–water interface can significantly lower the interfacial tension and be used to structure liquids. However, to realize the three-dimensional ...printing of one liquid in another, high-viscosity liquids, for example, silicone oil, have been generally used. Here, we present a simple, low-cost approach to print water in low-viscosity toluene by using a new type of polyelectrolyte surfactant, sodium carboxymethyl cellulose surfactant (CMCS), that forms and assembles at the oil–water interface. The interfacial activity of CMCSs can be enhanced by tuning parameters, such as pH and concentration, and the incorporation of a rigid ligand affords excellent mechanical strength to the resultant assemblies. With CMCS jammed at the interface, liquids can be easily printed or molded to the desired shapes, with biocompatible walls that can be used to encapsulate and adsorb active materials. This study opens a new pathway to generate complex, all-liquid devices with a myriad of potential applications in biology, catalysis, and chemical separation.
In this work, sidechain engineering on conjugated fused‐ring acceptors for conformation locking is demonstrated as an effective molecular design strategy for high‐performance nonfullerene organic ...solar cells (OSCs). A novel nonfullerene acceptor (ITC6‐IC) is designed and developed by introducing long alkyl chains into the terminal electron‐donating building blocks. ITC6‐IC has achieved definite conformation with a planar structure and better solubility in common organic solvents. The weak electron‐donating hexyl upshifts the lowest unoccupied molecular orbital level of ITC6‐IC, resulting in a higher VOC in comparison to the widely used ITIC. The OSCs based on PBDB‐T:ITC6‐IC reveal a promising power conversion efficiency of 11.61% and an expected high VOC of 0.97 V. The weaker π–π stacking induced by steric hindrance affords ITC6‐IC with enhanced compatibility with polymer donors. The blend film treated with suitable thermal annealing exhibits a fibril crystallization feature with a good bicontinuous network morphology. The results indicate that the molecular design approach of ITC6‐IC can be inspirational for future development of nonfullerene acceptors for high efficiency OSCs.
Conformation locking by introducing alkyl chains onto central electron‐donating building blocks has been explored on fused‐ring electron acceptor for high‐performance nonfullerene organic solar cells. PBDB‐T:ITC6‐IC based devices treated with suitable thermal annealing reveal a promising power conversion efficiency of 11.61% and an expected high VOC of 0.97 V with a small energy loss.
Highly efficient electron extraction is achieved by using a photoconductive cathode interlayer in inverted ternary organic solar cells (OSCs) where a near‐IR absorbing porphyrin molecule is used as ...the sensitizer. The OSCs show improved device performance when the ratio of the two donors varies in a large region and a maximum power conversion efficiency up to 11.03% is demonstrated.
Liquids lack the spatial order required for advanced functionality. Interfacial assemblies of colloids, however, can be used to shape liquids into complex, 3D objects, simultaneously forming 2D ...layers with novel magnetic, plasmonic, or structural properties. Fully exploiting all‐liquid systems that are structured by their interfaces would create a new class of biomimetic, reconfigurable, and responsive materials. Here, printed constructs of water in oil are presented. Both form and function are given to the system by the assembly and jamming of nanoparticle surfactants, formed from the interfacial interaction of nanoparticles and amphiphilic polymers that bear complementary functional groups. These yield dissipative constructs that exhibit a compartmentalized response to chemical cues. Potential applications include biphasic reaction vessels, liquid electronics, novel media for the encapsulation of cells and active matter, and dynamic constructs that both alter, and are altered by, their external environment.
The assembly of gold, silica, and cellulose nanoparticles at the oil–water interface is used to 3D print water in oil. The diameter of the channels is between 10 and 1000 µm. Liquids can be readily flowed through the channels. The shapes are highly deformable and their lifetime can be tuned from hours to months.
Two donor–acceptor (D–A) polymers are obtained by coupling difluoro‐ and dichloro‐substituted forms of the electron‐deficient unit BDOPV and the relatively weak donor moiety dichlorodithienylethene ...(ClTVT). The conductivity and power factors of doped devices are different for the chlorinated and fluorinated BDOPV polymers. A high electron conductivity of 38.3 and 16.1 S cm−1 are obtained from the chlorinated and fluorinated polymers with N‐DMBI, respectively, and 12.4 and 2.4 S cm−1 are obtained from the chlorinated and fluorinated polymers with CoCp2, respectively, from drop‐cast devices. The corresponding power factors are 22.7, 7.6, 39.5, and 8.0 µW m−1 K−2, respectively. Doping of PClClTVT with N‐DMBI results in excellent air stability; the electron conductivity of devices with 50 mol% N‐DMBI as dopant remained up to 4.9 S m−1 after 222 days in the air, the longest for an n‐doped polymer stored in air, with a thermoelectric power factor of 9.3 µW m−1 K−2. However, the conductivity of PFClTVT‐based devices can hardly be measured after 103 days. These observations are consistent with morphologies determined by grazing incidence wide angle X‐ray scattering and atomic force microscopy.
Two n‐type polymers based on dichlorodithienylethene (ClTVT) are synthesized. Using the two polymers doped with CoCp2 and N‐DMBI, respectively, organic thermoelectric devices are prepared and compared. Doping of PClClTVT with N‐DMBI results in excellent air stability; the electrical conductivity and power factor are still maintained at 4.9 S m−1 and 9.3 µW m−1 K−2 after 222 days.
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