4 results
Search Results
Now showing 1 - 4 of 4
- ItemSintering of ultrathin gold nanowires for transparent electronics(Washington D.C. : American Chemical Society, 2015) Maurer, Johannes H.M.; González-García, Lola; Reiser, Beate; Kanelidis, Ioannis; Kraus, TobiasUltrathin gold nanowires (AuNWs) with diameters below 2 nm and high aspect ratios are considered to be a promising base material for transparent electrodes. To achieve the conductivity expected for this system, oleylamine must be removed. Herein we present the first study on the conductivity, optical transmission, stability, and structure of AuNW networks before and after sintering with different techniques. Freshly prepared layers consisting of densely packed AuNW bundles were insulating and unstable, decomposing into gold spheres after a few days. Plasma treatments increased the conductivity and stability, coarsened the structure, and left the optical transmission virtually unchanged. Optimal conditions reduced sheet resistances to 50 Ω/sq.
- ItemTemplated Self-Assembly of Ultrathin Gold Nanowires by Nanoimprinting for Transparent Flexible Electronics(Washington, DC : ACS Publications, 2016) Maurer, Johannes H. M.; González-García, Lola; Reiser, Beate; Kanelidis, Ioannis; Kraus, TobiasWe fabricated flexible, transparent, and conductive metal grids as transparent conductive materials (TCM) with adjustable properties by direct nanoimprinting of self-assembling colloidal metal nanowires. Ultrathin gold nanowires (diameter below 2 nm) with high mechanical flexibility were confined in a stamp and readily adapted to its features. During drying, the wires self-assembled into dense bundles that percolated throughout the stamp. The high aspect ratio and the bundling yielded continuous, hierarchical superstructures that connected the entire mesh even at low gold contents. A soft sintering step removed the ligand barriers but retained the imprinted structure. The material exhibited high conductivities (sheet resistances down to 29 Ω/sq) and transparencies that could be tuned by changing wire concentration and stamp geometry. We obtained TCMs that are suitable for applications such as touch screens. Mechanical bending tests showed a much higher bending resistance than commercial ITO: conductivity dropped by only 5.6% after 450 bending cycles at a bending radius of 5 mm.
- ItemThe role of ligands in coinage-metal nanoparticles for electronics(Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2017) Kanelidis, Ioannis; Kraus, TobiasCoinage-metal nanoparticles are key components of many printable electronic inks. They can be combined with polymers to form conductive composites and have been used as the basis of molecular electronic devices. This review summarizes the multidimensional role of surface ligands that cover their metal cores. Ligands not only passivate crystal facets and determine growth rates and shapes; they also affect size and colloidal stability. Particle shapes can be tuned via the ligand choice while ligand length, size, ω-functionalities, and chemical nature influence shelf-life and stability of nanoparticles in dispersions. When particles are deposited, ligands affect the electrical properties of the resulting film, the morphology of particle films, and the nature of the interfaces. The effects of the ligands on sintering, cross-linking, and self-assembly of particles in electronic materials are discussed.
- ItemMultivalent bonds in self-assembled bundles of ultrathin gold nanowires(Cambridge : Royal Society of Chemistry, 2016) Reiser, Beate; Gerstner, Dominik; González-García, Lola; Maurer, Johannes H.M.; Kanelidis, Ioannis; Kraus, TobiasUltrathin gold nanowires are unusual colloidal objects that assemble into bundles with line contacts between parallel wires. Each molecule in the contact line interacts with many ligand and solvent molecules. We used X-ray scattering and electron microscopy to study how these interactions control assembly.