Conformationally-restricted bicarbazoles with phenylene bridges displaying deep-blue emission and high triplet energies: systematic structure-property relationships.

The synthesis is reported of twelve new symmetrical carbazole dimers in which the carbazole units are linked via 1,4-phenylene spacers. There are two distinct series of compounds based on the position on the carbazole ring where the phenylene spacer is attached: this is either at carbazole C(3) (series 1a-1f) or at C(2) (series 2a-2f). The central phenylene ring is substituted with either two methyl, two methoxy or two cyano substituents which impart an intramolecular torsional angle between the phenylene and carbazole rings, thereby limiting the extent of π-conjugation between the carbazole units, and raising the triplet energies of the molecules to E 2.

Pyridylpyrazole N^N ligands combined with sulfonyl-functionalised cyclometalating ligands for blue-emitting iridium(iii) complexes and solution-processable PhOLEDs.

A series of blue iridium(iii) complexes (12-15) comprising sulfonyl-functionalised phenylpyridyl cyclometalating ligands and pyridylpyrazole N^N ligands are reported, with an X-ray crystal structure obtained for 12. The complexes are highly emissive with photoluminescence quantum yields of 0.52-0.

Electric Field Induce Blue Shift and Intensity Enhancement in 2D Exciplex Organic Light Emitting Diodes; Controlling Electron-Hole Separation.

A simple but novel method is designed to study the characteristics of the exciplex state pinned at a donor-acceptor abrupt interface and the effect an external electric field has on these excited states. The reverse Onsager process, where the field induces blue-shifted emission and increases the efficiency of the exciplex emission as the e-h separation reduces, is discussed.

Bimetallic cyclometalated iridium(III) diastereomers with non-innocent bridging ligands for high-efficiency phosphorescent OLEDs.

Two phosphorescent dinuclear iridium(III) diastereomers (ΛΔ/ΔΛ) and (ΛΛ/ΔΔ) are readily separated by making use of their different solubilities in hot hexane. The bridging diarylhydrazide ligand plays an important role in the electrochemistry and photophysics of the complexes. Organic light-emitting devices (OLEDs) that use these complexes as the green-emissive dopants in solution-processable single-active-layer architectures feature electroluminescence efficiencies that are remarkably high for dinuclear metal complexes, achieving maximum values of 37 cd A(-1), 14 lm W(-1), and 11% external quantum efficiency.

FRET and competing processes between conjugated polymer and dye substituted DNA strands: a comparative study of probe selection in DNA detection.

Fluorescence resonance energy transfer (FRET) between water-soluble conjugated polymer, poly-(9,9-bis(6'-N,N,N-trimethylammonium)-hexyl-fluorene phenylene) bromide, and ssDNA's labeled with four different types of dyes (Pacific-blue, Alexa-fluor 430, Fluorescein, and ROX) has been investigated. The effect of spectral overlap and Stokes-shift on the efficiency and properties of FRET were studied. In the DNA sequence detection technique that using cationic conductive polymer and the negatively charged DNA the electrostatic interaction leads to strong aggregation.

Improved single nucleotide polymorphisms detection using conjugated polymer/surfactant system and peptide nucleic acid.

An improved assay for the detection of single nucleotide polymorphisms (SNP) of mutant DNA using a combination of peptide nucleic acid (PNA) probes, a cationic conjugated polymer (CCP) and non-ionic surfactant is reported. A comparison between CCP/surfactant and CCP alone shows enhancement in the discrimination between mutant and wild type DNA by a factor of two. A discrimination factor of 70% and 92% was calculated for single and five bases mismatched mutants, respectively when using CCP/surfactant.

Effect of surfactant on water-soluble conjugated polymer used in biosensor.

The effect of nonionic surfactants on the cationic conjugated polymer (CCP), poly{9,9-bis[6-(N,N-trimethylammonium)hexyl]fluorene-co 1,4-phenylene} iodide 1, has been investigated. It is shown that the CCP in various solvents exists in three phases: isolated polymer chains, polymer aggregate, and variable size clusters (partially dissolved polymer). It is shown that nonionic surfactants enhance the photoluminescence (PL) quantum yield of the CCP in water by breakup of polymer aggregates, which eliminates the nonemissive interchain quenching with aggregates and increases surface-to-volume ratio of the CCP.