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In this study, the surface properties of iron microparticles were modified for the manipulation of liquid droplets using atmospheric pressure plasma jets. These modified hydrophobic iron microparticles were prepared by synthesizing fluorinated silica nanocomposites on the surfaces of iron microparticles under atmospheric pressure plasma. The compositions of the silica nanocomposites were controlled by the deposition of hexamethyldisiloxane and fluoroalkylsilane precursors. The fluorinated silica nanocomposites were then used with iron microparticles to prepare magnetic liquid marbles. The contact angles of the iron microparticles and the fluorinated silica nanoparticle coating on the glass surface were both 154°, which indicated that the surfaces of these particles were superhydrophobic. Higher hexamethyldisiloxane precursor flow rates produced more silica nanocomposites and resulted in greater roughness and larger contact angles. Changes in surface roughness were characterized by atomic force microscopy. X-ray photoelectron spectroscopy showed that C–F bonds were present on the modified glass surface. The presented approach allows rapid and highly efficient modification of uneven surfaces and can therefore be employed to render hydrophilic, superhydrophobic, and oleophilic surfaces. Moreover, the described hydrophobic iron microparticles can be used for the controlled magnetic manipulation of water droplets and oil–water separation.

Metal nanoparticle-decorated graphene oxides are promising materials for use in various optoelectronic applications because of their unique plasmonic properties. In this paper, a simple, environmentally friendly method for the synthesis of gold nanoparticle-decorated graphene oxide that can be used to improve the efficiency of organic photovoltaic devices (OPVs) is reported. Here, the amino acid glycine is employed as an environmentally friendly reducing reagent for the reduction of gold ions in the graphene oxide solutions. Transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and Raman spectroscopy are used to characterize the material properties of the resulting nanomaterials. Furthermore, these nanocomposites are employed as the anode buffer layer in OPVs to trigger surface plasmonic resonance, which improved the efficiency of the OPVs. The results indicate that such nanomaterials appear to have great potential for application in OPVs.

Wide-band gap absorber materials are prerequisites for well-performing tandem photovoltaic devices. Especially, perovskites received huge attention due to their tunable band gap and outstanding optoelectronic properties. Although perovskite solar cells are known to be highly efficient, high-open-circuit voltage losses remain a prevalent issue for wide-band gap perovskites. Within this work, we have investigated the application of the cross-linkable fullerene derivative [6,6]-phenyl-C61-butyric styryl dendron ester (c-PCBSD) as a cathodic interlayer in wide-band gap perovskite solar cells. We could obtain increased open-circuit voltage compared to pristine devices, attributed to fast electron transfer between the perovskite and the interlayer. The changed charge carrier dynamics result in a reduction of non-radiative losses, which consequently decreases the open-circuit voltage loss. Graphical abstract

We successfully address the challenge of aligning single-walled carbon nanotubes （SWNTs） and conjugated polymer chains in composite nanofibers for enhancing their opto-electrical properties. A pore-filling template strategy has been developed to prepare such nanocomposites from SWNTs and poly（para-phenylene vinylene） （PPV） chains, with both species well-oriented aligned along the pore axis. Addition of the SWNTs leads to a remarkable increase in photocurrent of four orders of magnitude as compared to equivalent pristine PPV nanofibers. Further analysis indicates that the strong photocurrent enhancement is not simply an effect of alignment, but additionally benefits from alignment-enhanced interaction of polymer chains with SWNTs, as supported by density functional theory （DFT） calculations.

Three polyfluorene derivatives (P1-P3) emitting blue, green and red light were prepared via a Suzuki coupling method. Polyhedral oligomeric silsesquioxanes (POSS) were integrated into the center core of the derivatives to create stellar light-emitting polymers (POSS-P1-POSS-P3). The glass-transition and decomposition temperatures were raised after introducing POSS moieties. The starlike polymers showed a reduced emissive band at 540 nm when annealing at 200 deg C. The result implies that integrated POSS at the center core suppresses the keto effect generally occurring for polyfluorenes. Double-layer light-emitting devices of indium tin oxide/poly(ethylenedioxythiophene)/polymer/Ca/Al were fabricated to evaluate polymer potential. Compared with pristine polymers, the maximum brightness and the current efficiency of devices using POSS-containing polymers as active layers were enhanced. A blending method using P1 or POSS-P1 as the host matrix further improved device performance.

The synthesis and characterization of side-chain liquid crystalline (LC) polyacrylates and polyoxiranes containing bistolane side-groups are presented. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry and optical polarizing microscopy. All of the obtained monomers and polymers reveal an enantiotropic nematic phase. The birefringences of the LC monomers are in the range from 0.35–0.6 depending on the measuring wavelength. The photoluminescence (PL) and electroluminescence (EL) properties of the obtained monomers and polymers are also reported.

We have investigated the role of the trapping process in degradation mechanisms of poly(9,9-dihexylfluorene-co- N , N -di(9,9-dihexyl-2-fluorenyl)- N -phenylamine) (PF) based diodes, after aging (at half lifetime) by electrical stress. By using the Charge based Deep Level Transient Spectroscopy, we have determined the trap parameters in PF light emitting devices. The mean activation energies of the traps are in the range 0.13–0.60 eV from the band edges with capture cross sections of the order of 10 –18 to 10 –20  cm 2 . The trap densities are in the range of 10 –16 to 10 –17  cm −3 . Upon aging, no new trap levels have been found indicating that the electrical stress did not create additional defect level in the polymer in contrast to previous investigations on other organic materials, which reported that the degradation of devices in humid atmosphere lead to the onset of new traps acting as recombination centers. Furthermore, aging would not affect uniformly the defect levels in the polymer. Shallow trap states (below 0.3 eV) remain stable, whereas the enhancement in trap density of deeper trap levels (above 0.3 eV) have been observed, suggesting that degradation by electrical stress leads to an increase in density of deep levels.

Two benzothiadiazole-based liquid crystalline polyacrylates were synthesized. These polymers revealed a nematic liquid crystal phase and exhibited photoluminescence as well as polarized electroluminescence when incorporated into light-emitting diode applications. The polymers showed dichroic ratios of about 8.3-8.8 in UV-vis absorption and photoluminescence emission. The polymer with vinylene linkages (P2) showed better electroluminescence device performance than that with acetylene linkages (P1). The P2 device emitted red light at 604 nm with a turn-on voltage at 6 V, and a maximum polarized luminance of 235 cd/m^sup 2^ at 12 V, with an efficiency of 0.09 cd/A and a polarization ratio of 6.5.[PUBLICATION ABSTRACT]

The synthesis of segmented copolymers of aromatic polyether sulfone and liquid crystalline polyester containing flexible spacers is presented. The segmented copolymers were prepared by solution condensation of hydroxy-terminated polyether sulfone with diacid compounds 1–5 and 4,4′-dihydroxybiphenyl in a mixture of triphenylphosphine, pyridine and hexachloroethane. The obtained polymers show a glass transition at around 160 °C which belongs to the segmental motion of polyether sulfone blocks, and one or two melting transitions which belong to the thermal transitions of LCP blocks. Optical polarized microscopy verifies that the obtained segmented copolymers present a nematic liquid crystalline phase at a temperature higher than their melting transitions.

A series of new side-chain liquid crystalline (LC) polyacetylenes containing 4-(trans-n-alkylcyclohexanylcarbonyloxy)phenyl 4-alkynyloxybenzoate side groups were synthesized by using [Rh(nbd)Cl]2, WCl6 and MoCl5 as polymerization catalysts. The synthesized polymers were characterized by differential scanning calorimetry, optical microscopy and X-ray diffraction measurements. The monomers showed a nematic phase while all polymers revealed the nematic, smectic A and smectic C phases. X-ray diffraction measurements proved that all the polymers show an interdigitated bilayer structure. The optical properties of the polymers were investigated by UV-vis and photoluminescent spectroscopies. The polymer films emitted green-blue photoluminescence at about 500 nm.