The single-port concept: combining optical glucose measurement with insulin infusion.

The aim of this study was to develop a single-port system that combines glucose monitoring and insulin infusion. In a preclinical proof-of-concept trial, the performance of the glucose measurement at the site of insulin infusion was assessed. Glucose levels were clamped from 40 to 250 mg/dL by intravenous glucose infusion and subcutaneous insulin infusion via the glucose sensor.

Variable tunneling barriers in FEBID based PtC metal-matrix nanocomposites as a transducing element for humidity sensing.

The development of simple gas sensing concepts is still of great interest for science and technology. The demands on an ideal device would be a single-step fabrication method providing a device which is sensitive, analyte-selective, quantitative, and reversible without special operating/reformation conditions such as high temperatures or special environments. In this study we demonstrate a new gas sensing concept based on a nanosized PtC metal-matrix system fabricated in a single step via focused electron beam induced deposition (FEBID).

Highly efficient color-stable deep-blue multilayer PLEDs: preventing PEDOT:PSS-induced interface degradation.

Highly efficient and stable blue light emission is observed in novel copolymers that are produced from specially designed building blocks. A PEDOT:PSS-induced chemical degradation of the polymer light-emitting diodes (PLEDs) is identified at the interface, and it is found to be accompanied by a shift in the emission color. A method to prevent this highly undesirable interaction is presented.

Deep blue polymer light emitting diodes based on easy to synthesize, non-aggregating polypyrene.

Thorough analyses of the photo- and devicephysics of poly-7-tert-butyl-1,3-pyrenylene (PPyr) by the means of absorption and photoluminescence emission, time resolved photoluminescence and photoinduced absorption spectroscopy as well as organic light emitting devices (OLEDs) are presented in this contribution. Thereby we find that this novel class of polymers shows deep blue light emission as required for OLEDs and does not exhibit excimer or aggregate emission when processed from solvents with low polarity. Moreover the decay dynamics of the compound is found to be comparable to that of well blue emitting conjugated polymers such as polyfluorene.

Focus Issue: Organic light-emitting diodes-status quo and current developments.

The guest editors introduce the Optics Express Energy Express supplement Focus Issue, "Organic Light-Emitting Diodes," which includes six invited articles addressing the challenges of light outcoupling and light management in OLEDs.

An investigation on focused electron/ion beam induced degradation mechanisms of conjugated polymers.

Irradiation damage, caused by the use of beams in the electron microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures that are being processed. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on irradiation by electron and ion beams. The effect is even higher when materials are subjected to energetic species such as ions that possess high momentum and relatively low mean path due to their mass.

Molecular triangles: synthesis, self-assembly, and blue emission of cyclo-7,10-tris-triphenylenyl macrocycles.

A set of cyclo-7,10-tris-triphenylenyl macrocycles have been prepared by a Yamamoto cyclotrimerization protocol. In these novel macrocycles, three triphenylene units are covalently linked to each other, resulting in the formation of triangular-shaped molecules. The fully planar derivative revealed pronounced self-assembly behavior.

Core, shell, and surface-optimized dendrimers for blue light-emitting diodes.

We present a novel core-shell-surface multifunctional structure for dendrimers using a blue fluorescent pyrene core with triphenylene dendrons and triphenylamine surface groups. We find efficient excitation energy transfer from the triphenylene shell to the pyrene core, substantially enhancing the quantum yield in solution and the solid state (4-fold) compared to dendrimers without a core emitter, while TPA groups facilitate the hole capturing and injection ability in the device applications. With a luminance of up to 1400 cd/m(2), a saturated blue emission CIE(xy) = (0.

A planar waveguide optical sensor employing simple light coupling.

An optical sensor concept utilizing the sensing layer as the light propagating layer and a new method to couple light into a planar waveguide is presented. The concept enables simple manufacturing by coating or printing techniques and the integration of organic (plastic) opto-electronic components.

Ion beam degradation analysis of poly(3-hexylthiophene) (P3HT): can cryo-FIB minimize irradiation damage?

In this study, to assess the influence of the temperature on the ion beam degradation, irradiation experiments on organic semiconductor materials were performed for both cryogenic and room temperature conditions. Thin P3HT films on silicon substrates were exposed to increasing ion doses in dual beam FIB. The degradation behaviour by means of a decrease in the C[double bond, length as m-dash]C band which corresponds to a loss of conjugation was investigated by means of Raman spectroscopy.

Phosphorescent organic light-emitting devices: working principle and iridium based emitter materials.

Even though organic light-emitting device (OLED) technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs), further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this technology. Along these lines, the present work reviews the essentials of OLED technology putting special focus on the general working principle of single and multilayer OLEDs, fluorescent and phosphorescent emitter materials as well as transfer processes in host materials doped with phosphorescent dyes. Moreover, as a prototypical example of phosphorescent emitter materials, a brief discussion of homo- and heteroleptic iridium(III) complexes is enclosed concentrating on their synthesis, photophysical properties and approaches for realizing iridium based phosphorescent polymers.

Defect chemistry of polyfluorenes: identification of the origin of "interface defects" in polyfluorene based light-emitting devices.

Deprotonation of hydroxy terminated polyfluorenes results in a greenish emission also providing a rational explanation for so called "interface defects" in polymeric light-emitting devices (PLEDs).

The influence of the metal grain size on polymer/metal bilayer wrinkling.

We report on the observation of wrinkling processes in very thin polymer/metal bilayer structures prepared spin casting and sputter preparation, respectively. The study utilizes a viscoelastic conjugated polymer typically used in optoelectronic devices with a film thickness of 100 nm. After careful thermal annealing of the polymer films thin gold layers were deposited ranging from 20 nm to 45 nm which induces a slow wrinkling process without the influence of an external stimulus.

Breakdown of the mirror image symmetry in the optical absorption/emission spectra of oligo(para-phenylene)s.

The absorption and emission spectra of most luminescent, pi-conjugated, organic molecules are the mirror image of each other. In some cases, however, this symmetry is severely broken. In the present work, the asymmetry between the absorption and fluorescence spectra in molecular systems consisting of para-linked phenyl rings is studied.

Ladder-type pentaphenylenes and their polymers: efficient blue-light emitters and electron-accepting materials via a common intermediate.

A new route to ladder-type pentaphenylenes has been developed in which both good hole-accepting p-type and electron-accepting n-type materials can be prepared from a common intermediate. This key intermediate is a pentaphenylene diester 5 obtained in high yield by Suzuki coupling of 2 equiv of fluorene boronates with 2,5-dibromoterephthalate. Addition of aryllithium followed by ring closure with boron trifluoride produced a blue-emitting ladder-type pentaphenylene.