A5075313239- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Synthesis and characterization of novel inorganic/organometallic compounds
- Metal-Organic Frameworks: Synthesis and Applications
- GaN-based semiconductor devices and materials
- Molecular Junctions and Nanostructures
- Semiconductor Quantum Structures and Devices
- Conducting polymers and applications
- Organophosphorus compounds synthesis
- Radical Photochemical Reactions
- Metalloenzymes and iron-sulfur proteins
- Organometallic Complex Synthesis and Catalysis
- Ga2O3 and related materials
- Synthesis and Properties of Aromatic Compounds
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- Covalent Organic Framework Applications
- Chemical Reaction Mechanisms
- Crystallography and molecular interactions
- Polyoxometalates: Synthesis and Applications
- Chemical Synthesis and Characterization
- Magnetism in coordination complexes
- Molecular spectroscopy and chirality
Advanced Materials and BioEngineering Research
2020-2023
Trinity College Dublin
2018-2023
Greenville College
2019
22q11 Ireland
2019
RWTH Aachen University
2012-2018
University of Stuttgart
1996-2002
Siemens (Germany)
1999-2000
Friedrich-Alexander-Universität Erlangen-Nürnberg
1999
Philipps University of Marburg
1966-1990
By using picosecond time-resolved photoluminescence we have measured the lifetime of excess charge carriers in GaN epitaxial layers grown on sapphire at temperatures up to 300 K. The decay time turns out be dominated by trapping processes low excitation levels. radiative derived from our data is free excitons below 150 K, but also clearly shows gradual thermal dissociation higher temperatures. From data, are able determine exciton binding energy and carrier recombination coefficient....
Bright white light emission in rubrene-doped organic LEDs has been demonstrated using spiro compounds—such as spiro-TAD, shown the Figure—with high glass transition temperatures. These materials show morphological stability for hole transport and of blue light, thus still operate at temperatures well above 100 °C. The devices give a maximum luminance 11800 cd/m2.
A one-dimensional numerical model for the quantitative simulation of multilayer organic light emitting diodes (OLEDs) is presented. It encompasses bipolar charge carrier drift with field-dependent mobilities and space effects, diffusion, trapping, bulk interface recombination, singlet exciton diffusion quenching effects. Using mobility data measured on unipolar single layer devices, reported energetic levels highest occupied lowest unoccupied molecular orbitals, realistic assumptions...
By optical gain spectroscopy we have studied the fundamental laser properties of GaInN/GaN heterostructures grown on sapphire. Utilizing stripe excitation method measured spectra at room temperature. Due to low symmetry wurtzite structure and resulting splitting uppermost valence bands, find only for TE mode. Our analysis shows that is due direct band-to-band transitions in an electron-hole plasma. For amplitudes typically found lasers, carrier densities up 3×1019 cm−3, which are likely lead...
Abstract Die Halbstufenpotentiale zahlreicher arylierter Phenole konnten mit Hilfe einer neu entwickelten rotierenden Graphitelektrode in Acetonitril/Wasser (9:1) alkalischem Puffer für den Einelektronenübergang zu Phenoxylen, sowie Essigsäure/Wasser Zweielektronenübergang Chinolacetaten anodisch gemessen werden. gemessenen Potentiale gehören höchsten durch anodische Polarographie bisher bestimmten.
We investigate electron injection and transport in single-layer devices of 8-hydroxyquinoline aluminum sandwiched between two electrodes. Electrodes comprising a thin lithium fluoride layer are compared with co-evaporated magnesium–silver cathodes pure cathodes. By employing both transient quasistatic current measurements, the impact LiF-layer thickness on is investigated. It demonstrated that contacts 0.1–0.2 nm LiF an capping able to sustain space-charge-limited currents aluminum. Further,...
We investigate the impact of deposition low work function metals such as calcium on thin layers fluorene-type polymers by time-of-flight secondary ion mass spectroscopy. An implantation process rather than a slow metal diffusion is found to be most probable source contamination within polymer layers. This extends range several tens nanometers in organic Photoluminescence and electroluminescence measurements are performed with varying layer thicknesses. The luminescence efficiency exhibits...
We explore fundamental lithium ion (Li+) and triflate counterion (CF3SO3–) transport properties within an electrospun UV-cross-linked poly(ethylene oxide) polymer-gel electrolyte. With modulation of cross-linker (10–30 wt %), the fully swollen fibrous framework swells retains between 1700 1200 % liquid electrolyte exhibits room temperature ionic conductivity up to 6 mS cm–1. 7Li 19F spin–spin relaxation (T2) measurements reveal presence inter- intrafiber ions, where long- short-T2 components...
A novel mixed-metal cobalt–iron polyoxometalate (POM) aids the understanding of role inner, coordinatively saturated metal ions in Weakley archetype POMs on catalytic OER activity.
The impact of oxygen plasma treatment indium tin oxide anodes on performance and durability vapor-deposited organic electroluminescent devices is shown. Investigations focused the long-term stability using driving conditions suitable for passive matrix driven displays. Reliability studies solvent only cleaned samples indicate presence a predominating degradation process at interface between hole injection layer which results in drastic rise operating voltage. This voltage increase could be...
Abstract Aus den Di‐ und Tri‐ tert ‐butylpyrrolen 4–7 wurden mit Tetrafluoroborsäure die ersten nahezu unbegrenzt haltbaren protonierten Alkylpyrrole erhalten.
Abstract Aquatris(3‐cyanopentane‐2, 4‐dionato)scandium(III) undergoes two transformations which can be monitored by X‐ray diffraction as well solid‐state NMR spectroscopy: At 145 K, the mononuclear complex shows a reversible phase transition; in agreement with symmetry principle, this transition of t 2 type proceeds from monoclinic room temperature to triclinic twins at low temperature, twin law corresponding twofold rotation. Under vacuum aqua ligand is irreversibly eliminated and structure...
Using two complementary methods, we have investigated the individual contribution of space charge-limited hole transport in vapor-deposited films 4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (m-MTDATA) to temperature behavior organic light-emitting diodes. In single-layer indium tin oxide/m-MTDATA/Ag structures, measured activation energies current density and mobility as a function applied electric field. Both obtained under steady-state pulsed conditions are comparable,...