From April to June 2017 I had the chance to work for 3 months with the Salleo Research Group at Stanford University. The research visit was financed in part by the cfaed INSPIRE grant and in part by the Graduate Academy through a travel grant for short-term research stays abroad. During my time in the group I was trying to shed light on the charge carrier transport in thin films of semiconducting polymers synthesized as part of the Organic/Polymer Path in collaboration with the Leibniz Institute for Polymer Research.
The main reason for my visit of the group was the application of charge-modulation spectroscopy to our polymers. This technique has only been established in a few research groups around the world and gives information about the degree of freedom charge carriers have close to the semiconductor/dielectric interface based on the optical absorption of the carriers. The results will help us optimizing the device performance of field-effect transistors.
Furthermore, right next to Stanford University is the Stanford Synchrotron Radiation Lightsource, a Department of Energy user facility for very bright electromagnetic radiation. During my 3 months I was lucky enough to get multiple days and nights at the facility to investigate the film structure of our materials by x-ray scattering techniques. This allows us to correlate the structural and electronic properties of our semiconducting polymers.
Das cfaed ist über viele Gebäude verteilt - mindestens eins davon ist eine ganz besondere Perle mit einem großen Nachhall an bewegter und spannender Geschichte, deren Spuren heute u.a. bis ins MoMA New York führen. Die Rede ist von der Villa Ida Bienert, dem cfaed-Verwaltungssitz und gleichzeitig auch Forschungsort mit den Laboren unseres Lehrstuhls für Organische Bauelemente. Die Fotografin Uta Caroline Thom hat sich über einen Zeitraum von rund anderthalb Jahren dem Haus, seiner Vergangenheit und Gegenwart genähert, immer wieder neue Motive eingefangen, verfremdet, überlagert, und daraus ihre ganz eigene Sicht auf die Villa Bienert entwickelt. Seit 10.4. ist die daraus entstandene Ausstellung zu sehen.
One of our recent scientific pursuits included a visit of Prof. Stefan Mannsfeld, Postdoc Mike Hambsch and PhD student Rishi Shivare to the Synchrotron Light Source (ELETTRA) based in Trieste, Italy. The main motivation to visit such a research facility is the opportunity to work with intensely bright x-ray radiation.
In our case, we examined a wide range of organic semiconductors, using wide and small angle x-ray scattering. It lets us probe molecular and mesoscale structure of molecules and better understand how structural modifications affect device performance (for example in organic field effect transistors and solar cells). Doing experiments at a synchrotron is truly a unique experience, it is fascinating to see hundreds of scientists working round the clock.
In fall 2016, cfaed carried out its first Cluster-wide Scientific Image Contest. 22 different researchers or teams participated and sent in around 60 images. At the General Assembly in December Prof. Fettweis revealed the winners and handed over the awards. Now we are happy to present the winning pictures on our website and in the social channels!
Congratulations to the winners of the cfaed Scientific Image Competition!
Organized by the network “Absol(E)vent’ the cfaed - Chair for Organic Devices hosted an event to present “Printable solar cells, OLEDs and transistors” to a group of 20 former members of TU Dresden. After a little introduction of Prof. Stefan Mannsfeld and Prof. Sebastian Reineke on the topic there was a tour through the laboratories at the historic “Bienert-Villa” to show printable electronic on flexible materials. It was a successful event with a lot of interesting questions and discussions and a good opportunity to show our scientific work.
Welcome to Yichu Zheng, our new PhD student. Yichu received her Masters degree from East China University of Science and Technology in January 2016. We are happy to have her at the Chair for Organic Devices.
After we previously demonstrated, that controlling the ink-flow with our FLUENCE technique leads to massive improvements in the film structure and performance for small organic semiconductor inks, a new paper, published in Nature Communications, describes our modification of the FLUENCE approach to work with conjugated semiconducting polymers. The question here was: can we achieve similar control over the morphology of polymer films as we achieved for the small molecules. The answer is yes, but in order to work for polymers, the structures controlling the ink flow needed to be shrunk from tens of micrometers down to as small as possible. New shearing blades with photo-lithographic structured pillars of 1-2 micrometer diameter and pitch were produced. These specially structured blades improved the morphology of printed polymer films for organic solar cells and enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation.