Gehaltsabhängig: Die Reaktion von Polycyclooctadien (Poly(COD)) und [RhCl(C2H4)2]2 ergab wohldefinierte π‐gebundene Hybridpolymere, deren Größe vom Rhodiumgehalt abhängig war (siehe Bild). Die Reaktion dieser Polymere mit einem Phosphinaldehyd führte zur Regenerierung der ursprünglichen Polymere und beweist damit die Zugänglichkeit des Metalls.

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There is a growing interest in conjugated polymers from both industrial and academic points of views. The reasons are their tunable optoelectronic properties, ease of production, and excellent mechanical properties. However, the ease with which their optoelectronic properties are tunable make devices based on them prone to fast degradation and therefore, short life time. The issue of degradation of organic based optoelectronic devices is the topic of many ongoing researches. However, much less attention is given to degradation processes of the individual components of the devices and their dependence on the environmental conditions. In this work, we report on the degradation of a film of a polyfluorene block copolymer F8BT that is used in a variety of optoelectronic devices under different environments: Sun exposure, heating, and UV exposure in inert and ambient conditions. Degradation was observed in most of the optoelectronic properties of the film. Topographic measurements did not show observable changes of the film morphology following degradation. However, Raman spectroscopy measurements show changes that indicate degradation in one of the building blocks of the copolymer that is associated with electron's conduction. The absolute value of the correlation coefficient between the decrease in the Raman signal and the decrease in the optoelectronic properties is larger than 0.95 under sun exposure it is larger than 0.8 under all other ambient exposures and smaller than 0.65 under inert conditions. These results support the assumption that Oxygen, not necessarily through photo-oxidation, and also water play an important role in the degradation process and indicate the part of the polymer that is most susceptible to degradation.

We report on a new approach for measuring the chemical composition of the 20 nanometers at the top or bottom of a polymer film. This approach is based on a variation of the surface enhanced Raman scattering effect with laser illumination through a thin gold layer (∼4 nm). We show that the introduction of the thin gold layer has little or no effect on the morphology of the film that is spin coated on top of it. We demonstrate that this technique has better than 20 nanometer vertical resolution by studying bilayers of polyfluorines with varying thicknesses and by showing the existence of top and bottom wetting layers in a polymer blend of the same polymers. We also show that the top wetting layer is thinner than the bottom one. The difference in thicknesses explains how a solar cell with an electron blocking layer at the cathode works. ■ INTRODUCTIONIn recent years, organic optoelectronic devices based on polymers and small molecules are becoming more and more popular, ranging from organic light emitting diodes (OLED) 1−7 through organic solar cells, 8−11 organic thin film transistors (OTFT) 12,13 and more. The attractive properties of these devices that make them so popular are large versatility of the optoelectronic properties of the materials, ease of manufacturing, excellent mechanical properties and ultrathin thickness. A commonly used architecture in many devices, such as OLED and organic photovoltaic (OPV), is vertical and hence, their functionality is largely determined by the chemical structure and composition in the vertical direction. For the study of the influence of the chemical structure and composition on the optoelectronic properties, characterization techniques with better than 50 nm vertical resolution need to be developed, because the common thicknesses of these devices is around a hundred nanometer Analysis of the vertical structure is usually performed by using either environmental scanning electron microscopy (ESEM) on a cleaved sample 14 or X-ray photoelectron spectroscopy (XPS). 15 The drawbacks of these two techniques are that they are destructive in nature and therefore, cannot be applied in situ to a working device and they both lack spatial resolution in the horizontal direction. A method that has high spatial resolution in all three directions is nanotomography. 16 This technique gives three-dimensional images with high spatial resolution of the topography of the films. However, this technique cannot give an indication on the chemical composition, unless a specific topography feature can be associated with a specific chemical structure. Moreover, because it is based on transmission electron microscope (TEM) it cannot be applied to working devices. A different approach that is short-range and sensitive to the chemical composition is the surface enhanced Raman scattering technique (SERS). The SERS effect 17−23 is a variant of the Raman effect where the Raman cross-section is considerably enhanced in the presence of plasmons in metals. The SERS effect is used to detect low quantities of ma...

Gehaltsabhängig: Die Reaktion von Polycyclooctadien (Poly(COD)) und [RhCl(C2H4)2]2 ergab wohldefinierte π‐gebundene Hybridpolymere, deren Größe vom Rhodiumgehalt abhängig war (siehe Bild). Die Reaktion dieser Polymere mit einem Phosphinaldehyd führte zur Regenerierung der ursprünglichen Polymere und beweist damit die Zugänglichkeit des Metalls.

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Metallorganische Nanopartikel können durch intramolekulare Vernetzung von Polycyclooctadien mit [RhCl(C2H4)2]2 erzeugt werden. In ihrer Zuschrift auf beschreiben N. G. Lemcoff et al. die gezielte Kontrolle der Nanopartikelgröße über die Menge des zugegebenen Rhodiums. Außerdem kann das ursprüngliche Polymer durch Zugabe eines Phosphinaldehyd‐Derivats regeneriert werden, was die Zugänglichkeit und Reaktivität des eingeschlossenen Metalls beweist.