Polypyridyl transition metal complexes for application in optoelectronic devices: characterization and film preparation studies

This doctoral thesis deals with the electrochemical and optical characterization of electro-optically active materials, in particular 2,2′,6′,2″-terpyridine-based metallopolymers and ruthenium(II) polypyridyl-type complexes, as well as thin-film processability studies thereof. The optical investigations on metallopolymers that are composed of π-conjugated chromophores, 2,2′,6′,2″-terpyridine linker units, and zinc(II) metal ions reveal a broad range of UV-vis absorption and emission wavelengths as well as high photoluminescence quantum yields proving the suitability for luminescent devices (e. g. OLEDs, PLEDs). In contrast, the explored ruthenium(II) complexes, which are based on a new type of tridentate, 1,2,3-triazole-containing ligands, show electrochemical and optical properties making them capable candidates as photosensitizers, e. g. for usage in dye-sensitized solar cells (DSSCs). Furthermore, for both zinc(II)-2,2′,6′,2″-terpyridine-based metallopolymers and ruthenium(II) complexes, the preparation of thin films is studied. On the one hand, the metallopolymers are successfully processed via inkjet-printing technique to gain thin, luminescent deposits. On the other hand, ruthenium(II) complexes of different tridentate polypyridyl-type ligands, namely of 2,6-di(quinoline-8-yl)pyridines and of cyclometalated 1,2,3-triazole-containing ligands, are processed through anodic electrochemical polymerization yielding thin polymeric electrode coatings

Polymeric blatter's radical via CuAAC and ROMP

A Blatter radical‐containing polymer backbone is synthesized via copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) and consecutive ring‐opening metathesis polymerization. For this, an alkyne‐functionalized Blatter radical is synthesized and used for the described CuAAC, yielding a polymerizable derivative of the radical. The resulting polymer is electrochemically investigated in cyclic voltammetry experiments, paving the way for the possible utilization of triazinyl radicals in all‐organic polymer batteries. Furthermore, the simple modification of the alkyne bond makes further derivatization easily accessible

Tailored Charge Transfer Kinetics in Precursors for Organic Radical Batteries: A Joint Synthetic‐Theoretical Approach **

Abstract The development of sustainable energy storage devices is crucial for the transformation of our energy management. In this scope, organic batteries attracted considerable attention. To overcome the shortcomings of typically applied materials from the classes of redox‐active conjugated polymers (i. e., unstable cell voltages) and soft matter‐embedded stable organic radicals (i. e., low conductivity), a novel design concept was introduced, integrating such stable radicals within a conductive polymer backbone. In the present theory‐driven design approach, redox‐active (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyls (TEMPOs) were incorporated in thiophene‐based polymer model systems, while structure‐property relationships governing the thermodynamic properties as well as the charge transfer kinetics underlying the charging and discharging processes were investigated in a systematical approach. Thereby, the impact of the substitution pattern, the length as well as the nature of the chemical linker, and the ratio of TEMPO and thiophene units was studied using state‐of‐the‐art quantum chemical and quantum dynamical simulations for a set of six molecular model systems. Finally, two promising candidates were synthesized and electrochemically characterized, paving the way to applications in the frame of novel organic radical batteries.Radical approach : Molecular models of stable organic radicals incorporated in a conjugated backbone, with application in the field of organic radical batteries, are investigated by means of multiconfigurational methods. The theory‐guided design allows to tune the charge transfer kinetics as well as the underlying thermodynamics. Auspicious systems are synthesized and characterized electrochemically. imag

Livland nach der Eintheilung Heinrich des Letten und zu den Zeiten der Bischöffe u Ordenmeister bis 1562

Ilmunud lisakaardina L.A. Mellini atlases: Atlas von Liefland : oder von den beyden Gouvernementen u. Herzogthümern Lief- und Ehstland und der Provinz Oeselhttp://tartu.ester.ee/record=b1712790~S1*es

Hydrophilic Crosslinked TEMPO‐Methacrylate Copolymers – a Straight Forward Approach towards Aqueous Semi‐Organic Batteries

Abstract Crosslinked hydrophilic poly(2,2,6,6‐tetramethylpiperidinyl‐ N ‐oxyl‐co‐[2‐(methacryloyloxy)‐ethyl]trimethyl ammonium chloride) [poly(TEMPO‐ co ‐METAC)] polymers with different monomer ratios are synthesized and characterized regarding a utilization as electrode material in organic batteries. These polymers can be synthesized rapidly utilizing commercial starting materials and reveal an increased hydrophilicity compared to the state‐of‐the‐art poly(2,2,6,6‐tetramethylpiperidinyl‐ N ‐oxyl‐4‐methacrylate) (PTMA). By increasing the hydrophilicity of the polymer, a preparation of cathode composites is enabled, which can be used for aqueous semi‐organic batteries. Detailed battery testing confirms that the additional METAC groups do not impair the battery behavior while enabling straight‐forward zinc‐TEMPO batteries.Organic cathode in aqueous electrolyte : A crosslinked hydrophilic 2,2,6,6‐tetramethylpiperidine‐ N ‐oxyl radical (TEMPO) bearing polymer was synthesized, which enables aqueous battery chemistries that have not been compatible with poly(TEMPO‐methacrylate) derived structures before. Extensive battery testing was performed, to reveal the battery chemistry of the polymer containing composite electrodes in an aqueous semi‐organic zinc coin‐cell setup. imag

Aqueous Redox Flow Battery Suitable for High Temperature Applications Based on a Tailor‐Made Ferrocene Copolymer

Abstract Water‐soluble, and ferrocene‐containing methacrylamide copolymers with different comonomer ratios of the solubility‐promoting comonomer [2‐(methacryloyloxy)‐ethyl]‐trimethylammonium chloride (METAC) are synthesized in order to obtain a novel, temperature‐stable electrolyte for aqueous redox flow batteries. The electrochemical properties of one chosen polymer are studied in detail by cyclic voltammetry and rotating disc electrode (RDE) investigations. Additionally, the diffusion coefficient and the charge transfer rate are obtained from these measurements. The diffusion coefficient from RDE is compared to the value from synthetic boundary experiments at battery concentrations, using an analytical ultracentrifuge, yielding diffusion coefficients of a similar order of magnitude. The polymer is further tested in a redox flow battery setup. While performing charge and discharge experiments against the well‐established bis ‐(trimethylammoniumpropyl)‐viologen, the polymer reveals high columbic efficiencies of >99.8% and desirable apparent capacity retention, both at room temperature as well as at 60 °C. Further experiments are conducted to verify the stability of the active compounds under these conditions in both charge states. Lastly, the electrochemical behavior is linked to the characteristics of the polymers concerning absolute values of the molar mass and diffusion coefficients.A new ferrocene containing monomer is synthesized and its copolymerization with a water‐solubility promoting comonomer is investigated. The electrochemical and solution characteristics of a corresponding polymer are studied in detail. With a coulombic efficiency of >99.8% in an aqueous redox flow battery setup at 60 °C, a cheap, robust system for use at elevated temperatures is presented. imag

Cardiac magnetic resonance imaging using an open 1.0T MR platform : a comparative study with a 1.5T tunnel system

Background: Cardiac magnetic resonance imaging (cMRI) has become the non-invasive reference standard for the evaluation of cardiac function and viability. The introduction of open, high-field, 1.0T (HFO) MR scanners offers advantages for examinations of obese, claustrophobic and paediatric patients. The aim of our study was to compare standard cMRI sequences from an HFO scanner and those from a cylindrical, 1.5T MR system. Material/Method: Fifteen volunteers underwent cMRI both in an open HFO and in a cylindrical MR system. The protocol consisted of cine and unenhanced tissue sequences. The signal-to-noise ratio (SNR) for each sequence and blood-myocardium contrast for the cine sequences were assessed. Image quality and artefacts were rated. The location and number of non-diagnostic segments was determined. Volunteers' tolerance to examinations in both scanners was investigated. Results: SNR was significantly lower in the HFO scanner (all p0.05). Overall, only few non-diagnostic myocardial segments were recorded: 6/960 (0.6%) by the HFO and 17/960 (1.8%) segments by the cylindrical system. The volunteers expressed a preference for the open MR system (p<0.01). Conclusions: Standard cardiac MRI sequences in an HFO platform offer a high image quality that is comparable to the quality of images acquired in a cylindrical 1.5T MR scanner. An open scanner design may potentially improve tolerance of cardiac MRI and therefore allow to examine an even broader patient spectrum

Ultra-stable long distance optical frequency distribution using the Internet fiber network

We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The stable frequency optical signal is processed enabling uninterrupted propagation on both directions. The robustness and the performance of the link are enhanced by a cost effective fully automated optoelectronic station. This device is able to coherently regenerate the return optical signal with a heterodyne optical phase locking of a low noise laser diode. Moreover the incoming signal polarization variation are tracked and processed in order to maintain beat note amplitudes within the operation range. Stable fibered optical interferometer enables optical detection of the link round trip phase signal. The phase-noise compensated link shows a fractional frequency instability in 10 Hz bandwidth of 5x10-15 at one second measurement time and 2x10-19 at 30 000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network