Variations in the open‐circuit voltage (V oc) of ternary organic solar cells are systematically investigated. The initial study of these devices consists of two electron‐donating oligomers, S2 (two units) and S7 (seven units), and the electron‐accepting [6,6]‐phenyl C71 butyric acid methyl ester (PC71BM) and reveals that the V oc is continuously tunable due to the changing energy of the charge transfer state (E ct) of the active layers. Further investigation suggests that V oc is also continuously tunable upon change in E ct in a ternary blend system that consists of S2 and its corresponding polymer (P11):PC71BM. It is interesting to note that higher power conversion efficiencies can be obtained for both S2:S7:PC71BM and S2:P11:PC71BM ternary systems compared with their binary systems, which can be ascribed to an improved V oc due to the higher E ct and an improved fill factor due to the improved film morphology upon the incorporation of S2. These findings provide a new guideline for the future design of conjugated polymers for achieving higher performance of ternary organic solar cells.
Optically active ethynylhelicene pentamers and hexamers linked by disulfide bonds were synthesized. They formed self-assembled monolayers (SAMs) with double helix structure on gold surfaces, which were analyzed by infrared reflection-absorption spectroscopy (IR-RAS), quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and circular dichroism (CD). Double helix SAMs could be formed on gold surfaces either from double helices or random coils in solution. The double helices on the surface were more stable than in solution. This result suggested the presence of strong intercomplex interactions between double helix complexes on the surface. 相似文献
The reactive end groups of nonvolatile oligomers obtained by controlled thermal degradation of poly(propylene-ran-ethylene) and poly(propylene-ran-1-butene) were determined by 1H and 13C NMR spectroscopy. The molar ratio of unsaturated to saturated end groups was found to be about 9:1. The average number of unsaturated end groups per molecule was between 1.6 and 1.8, indicating that 60–80 mol% of the oligomer molecules were telechelic, having two terminal unsaturated end groups. These oligomers had a lower polydispersity than the raw material, despite their lower molecular weight and melting temperature. Although the end groups resulting from each monomer unit could be detected by 13C NMR, the end group composition differed from that of the main chains of the raw materials. The end group composition was satisfactorily explained by the differences in bond dissociation energy and activation energy of elementary reactions that occurred during thermal degradation, based on the monomer composition of the raw materials. 相似文献
The mechanical properties of unidirectional GFRPs based on an ED-22 epoxy resin were investigated. The resin was modified
with a PSK-1 polysulphone or a PEF-3a epoxyurethane oligomer. Triethanolaminotitanate or diaminodiphenilsulphone was used
as a hardener. The modification did not improve the mechanical properties of GFRPs in quasi-static loading; but in a low-speed
impact loading, the shear strength of epoxypolysulphone GFRPs with 20 wt.% PSK-1 increased by 20–25%. For all the GFRPs investigated,
the shear strength grew linearly with the logarithm of loading rate. The introduction of the modifiers increased the fracture
toughness considerably: by 100 and 70% for GFRPs modified with 20 wt.% PSK-1 and 50 wt.% PEF-3a, respectively.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp.739–758, November–December, 2006. 相似文献
Fluoroalkyl end-capped acrylic acid oligomer-encapsulated magnetic nanoparticles were prepared by the coprecipitation of aqueous ferric and ferrous ions in the presence of the corresponding oligomers under alkaline conditions. The dynamic light scattering measurements showed that these fluorinated oligomer magnetic nanoparticles were encapsulated in the self-assemblies of fluoroalkyl end-capped oligomers. Fluoroalkyl end-capped oligomer-encapsulated magnetic nanoparticles thus obtained were applied to the dispersion of magnetic particles on the poly(methyl methacrylate) film surface to exhibit not only the surface active property imparted by fluorine but also magnetic behavior toward a permanent magnet. 相似文献