Enhancing the device performance of a blue light‐emitting copolymer using CdSe/ZnS quantum dots

An alternating triarylamine‐functionalized fluorene‐based copolymer synthesized using a Suzuki–Miyaura cross‐coupling procedure is used as blue emitting layer in polymer light‐emitting diodes (PLEDs). Subsequently, the effects of CdSe/ZnS quantum dots (QDs) on the optoelectronic properties of the copolymer are investigated. Therefore, CdSe/ZnS QDs are embedded into the copolymer matrix and hybrid PLEDs are fabricated. The devices comprised of CdSe/ZnS QDs reveal enhanced performances, yielding about 3.4 times more luminous efficiency than that of the device without QDs. Further enhancement is achieved by using electron transport layer; the luminous efficiency rose from 0.065 to 1.740 cd A^?1 for the hybrid PLEDs, corresponding to a superb 27‐fold intensification of the efficiency. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 147–156     

Polymeric ruthenium bipyridine complexes: New potential materials for polymer solar cells

Methyl methacrylate‐containing bipyridine monomers were synthesized with a hydoxy‐functionalized bipyridine. The 4′‐methyl group of the 2,2′‐bipyridine was used to introduce hydoxy‐functionalized alkyl spacers of two different lengths. Two, different synthetic routes were applied for the preparation of the hydoxy‐functionalized bipyridine via a bromo‐(C₇ spacer) or a silylated‐(C₃ spacer) intermediate. A copolymer of poly(methyl methacrylate) with bipyridine units in the side chains was prepared by free‐radical copolymerization and characterized with ¹H NMR, ultraviolet–visible, and IR spectroscopy as well as gel permeation chromatography. The bipyridine units of the copolymer were reacted with ruthenium bipyridine precursors. The resulting graft copolymers displayed promising photophysical and electrochemical properties, opening interesting perspectives for applications in the field of solar‐cell devices. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 374–385, 2004     

Unveiling Photodeactivation Pathways for a New Iridium(III) Cyclometalated Complex

We report the synthesis and characterization of a neutral heteroleptic Ir^III complex bearing 6‐fluoro‐2‐phenylbenzo[d]thiazole as cyclometalating ligand and (Z)‐6‐(9H‐carbazol‐9‐yl)‐5‐hydroxy‐2,2‐dimethylhex‐4‐en‐3‐one as ancillary ligand. The photodeactivation mechanisms have been elucidated through extensive density functional theory (DFT) calculations. The active role of metal‐centered (³MC) triplet excited states in the nonradiative deactivation pathways is, for first time, confirmed in such complexes.     

Growth of n-Paraffin Crystals from Solution and the Effect of Polymers on Themy

The crystallization of n-paraffins has been investigated. The crystallizations were carried out in dilute solution under carefully defined cooling conditions. In some of the runs small quantities of synthetic polymers which were similar in structure to the n-paraffins were added to the solutions. The studies have shown that the habits of the crystals are very sensitive to the growth conditions, that n-paraffins are potent mutual crystal modifers, and that the addition of small amounts of polymers can affect the crystal growth considerably.     

A Novel Light‐Emitting Mixed‐Ligand Iridium(III) Complex with a Terpyridine‐Poly(ethylene glycol) Macroligand

Summary : A monoterpyridine‐poly(ethylene glycol) (mono‐tpy‐PEG) and a novel monoterpyridine‐PEG‐functionalized iridium(III ) complex were successfully synthesized and fully characterized by means of NMR, IR, and UV‐vis spectroscopy, as well as gel permeation chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The functionalized monoterpyridine iridium(III ) complex was synthesized by a bridge‐splitting reaction of a dimeric iridium(III ) precursor complex using a chelating terpyridine ligand with a poly(ethylene glycol) tail. With this approach, a new class of light‐emitting polymeric materials revealing interesting optical properties was made avaialable.

Upon excitation of a spin‐coated film of the iridium(III ) complex prepared here, a yellow emission color (two bands in figure) was observed.     

A Mixed Ruthenium Polypyridyl Complex Containing a PEG‐Bipyridine Macroligand

Summary: An amino‐functionalized bipyridine ligand was prepared in order to serve as a bridging unit to an activated low‐molecular‐weight monomethyl ether of poly(ethylene glycol) (PEG). Coordination of a ruthenium(II ) phenantroline precursor onto the formed PEG‐containing bipyridine ligand yielded a metal‐containing polymer which shows interesting properties for solar cell applications.

A schematic of the described polymeric ruthenium(II ) complex and its absorption and emission properties.     

Highly charged ion Coulomb crystallization in mixed strongly coupled plasmas

The investigation of highly charged ion Coulomb crystallization in mixed strongly coupled plasmas is of interest in many areas: white dwarf astrophysical plasmas are believed to have very similar thermodynamic properties, cold highly charged ions can be used as an object for high precision laser spectroscopy of fine and hyperfine transitions in the visible due to the absence of Doppler broadening and, an entirely new area of research is the potential application to highly charged ion based quantum computing schemes. We report the formation of such plasmas in a cryogenic Penning trap. These plasmas consisting of many species including Be⁺ and Xe⁴⁴⁺ or Be⁺ and Xe¹⁵⁺ ions, are formed at a temperature of less than 4 K. The temperatures were obtained by applying a laser based sympathetic cooling scheme. The determination of the temperature and density from the laser resonance width and the fluorescence imaging of the Be⁺ clouds, respectively, yields a Coulomb coupling constant for the centrifugally separated Xe plasma high enough for crystallization. A molecular dynamics code, developed just for this purpose, was run to clarify the understanding of these plasmas and it was possible to show consistency between experiment and simulation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Origin of trimuon events in high-energy neutrino interactions

The properties of 76 neutrino-initiated μ^?μ^?μ⁺ events observed in the CDHS detector in the 350 GeV and 400 GeV wide-band beams at the CERN SPS are discussed. For neutrino energies > 30 GeV and muon momenta ? 4.5 GeV, the average trimuon rate is (3.0±0.4)×10^?5 of the single-muon event rate. The data are in agreement with normal charged-current interactions with the additional production of a muon pair by both hadronic and radiative processes. No evidence is found for either heavy-lepton or heavy-quark cascades. Upper limits for these two possibilities are established.     

Inclusive interactions of high-energy neutrinos and antineutrinos in iron

We present results on charged current inclusive neutrino and antineutrino scattering in the neutrino energy range 30–200 GeV. The results include a) total cross-sections; b)y distributions; c) structure functions; and d) scaling violations observed in the structure functions. The results, as well as their comparison with the results of electron and muon inclusive scattering, are in agreement with the expectations of the quark parton model and QCD.