Angela Poschlad

Selective Dispersion of Large‐Diameter Semiconducting Single‐Walled Carbon Nanotubes with Pyridine‐Containing Copolymers

The purity of single-walled carbon nanotubes (SWNTs) is a key parameter for their integration in electronic, optoelectronic and photonic devices. Samples of pristine SWNTs are inhomogeneous in terms of electric behavior and diameter and contain a variety of amorphous carbon and catalyst residues. To obtain high performance devices, purification of SWNTs is required. Conjugated polymers have emerged as efficient solubilizing and sorting agents for small diameter SWNTs (HiPco tubes, 0.7 nm1.1 nm are lacking. Several pyridine-containing copolymers were synthesized for this purpose and showed efficient and selective extraction of semiconducting large diameter SWNTs (PLV tubes, Ø>1.1 nm). High concentration and high purity suspensions are obtained without the use of ultracentrifugation, which gives an up-scaling potential of the method. The emission wavelength is in near infrared region around 1550 nm and fits with broadly used telecommunication wavelength window. The processes taking place at the interface were simulated by a newly designed hybrid coarse-grain model combining density functional theory and geometrical calculation to yield insights into the wrapping processes with an unprecedented level of details for such large diameter SWNTs.

Different interface orientations of pentacene and PTCDA induce different degrees of disorder.

AbstractOrganic polymers or crystals are commonly used in manufacturing of today‘s electronically functional devices (OLEDs, organic solar cells, etc). Understanding their morphology in general and at the interface in particular is of paramount importance. Proper knowledge of molecular orientation at interfaces is essential for predicting optoelectronic properties such as exciton diffusion length, charge carrier mobility, and molecular quadrupole moments. Two promising candidates are pentacene and 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA). Different orientations of pentacene on PTCDA have been investigated using an atomistic molecular dynamics approach. Here, we show that the degree of disorder at the interface depends largely on the crystal orientation and that more ordered interfaces generally suffer from large vacancy formation.

A service-oriented framework for integration of domain-specific data models in scientific workflows

Abstract Managing data exchange in scientific workflow simulations is a challenge for which existing solutions have only limited success. Basing on a data-model approach we developed a service-oriented, platform- and language-independent framework which provides seamless access for heterogeneous applications to data storage resources distributed over grids and clouds. After implementing a working prototype of the framework we demonstrated its benefits for a complex workflow application from the domain of multiscale materials modeling. Because of its generic architecture and wide standards conformity the framework can be deployed as grid or cloud middleware for various other domains of computational science to enable rapid development of complex workflow applications.