13 research outputs found
Synthesis and performance of new polymers bearing thermally cleavable solubilizing groups for use in printable organic electronics
Microscopic Theory of Light-Induced Deformation in Amorphous Side-Chain Azobenzene Polymers
Investigation of Solution-Processed Ultrathin Electron Injection Layers for Organic Light-Emitting Diodes
We study two types of water/alcohol-soluble aliphatic amines, polyethylenimine (PEI) and polyethyleni-mine-ethoxylated (PEIE), for their suitability as electron injection layers in solution-processed blue fluorescent organic light-emitting diodes (OLEDs). X-ray photoelectron spectroscopy is used to determine the nominal thickness of the polymer layers while ultraviolet photoelectron spectroscopy is carried out to determine the induced work-function change of the
silver cathode. The determined work-function shifts are as high
as 1.5 eV for PEI and 1.3 eV for PEIE. Furthermore, atomic force microscopy images reveal that homogeneous PEI and PEIE layers are present at nominal thicknesses of about 11 nm. Finally, we solution prepare blue emitting polymer-based OLEDs using PEI/PEIE in combination with Ag as cathode layers. Luminous efficiency reaches 3 and 2.2 cd A−1, whereas maximum luminance values are as high as 8000 and 3000 cd m−2for PEI and PEIE injection layers, respectively. The prepared devices show a comparable performance to Ca/Ag OLEDs and an
improved shelf lifetime
Inkjet Printed, High Mobility Inorganic-Oxide Field Effect Transistors Processed at Room Temperature
Processing Follows Function: Pushing the Formation of Self-Assembled Monolayers to High-Throughput Compatible Time Scales
Self-assembled monolayers (SAMs) of organic molecules can be used to tune interface energetics and thereby improve charge carrier injection at metal–semiconductor contacts. We investigate the compatibility of SAM formation with high-throughput processing techniques. Therefore, we examine the quality of SAMs, in terms of work function shift and chemical composition as measured with photoelectron and infrared spectroscopy and in dependency on molecular exposure during SAM formation. The functionality of the SAMs is determined by the performance increase of organic field-effect transistors upon SAM treatment of the source/drain contacts. This combined analytical and device-based approach enables us to minimize the necessary formation times via an optimization of the deposition conditions. Our findings demonstrate that SAMs composed of partially fluorinated alkanethiols can be prepared in ambient atmosphere from ethanol solution using immersion times as short as 5 s and still exhibit almost full charge injection functionality if process parameters are chosen carefully. This renders solution-processed SAMs compatible with high-throughput solution-based deposition techniques