cfaed Seminar Series

cfaed Seminar Series

Koen Vandewal , Institut für Angewandte Photophysik (IAPP), TU Dresden

Charge-transfer states for organic solar cells and NIR photo-detectors

04.02.2016 (Thursday) , 13:00 - 14:00
TU Dresden, Hallwachsstraße 3, Seminar Room 115 , Hallwachsstraße 3 , 01069 Dresden

Organic solar cells based on interfaces between electron donor and electron acceptor molecules have incident-photon-to-extracted-charge conversion yields of over 85%, and absorbed photon-to-extracted-charge conversion yields of 90-100%. Their power conversion efficiency is currently limited by their low operating voltage, as compared to the optical gap of the main absorber material, indicating large energy losses per absorbed photon.

Within the talk, possibilities for increasing the operating voltage are going to be explored and the influence of the donor-acceptor interfacial area, electronic coupling and molecular reorganization will be discussed. Charge transfer (CT) states at the donor-acceptor interface play hereby an important role. These states have interesting fundamental properties which will be exploited to enable narrow band, near-IR photo-detection. This new type of photodetector competes in the nearinfrared (NIR) wavelength range with standard organic photodetectors but extends their detection range to longer wavelengths.

Koen Vandewal received his MSc in photonics engineering from Ghent University (Belgium) in 2004 and his PhD in Physics from Hasselt University (Belgium) in 2009. Subsequently, he spent 2 years as a postdoctoral researcher in the Biomolecular and Organic Electronics group at Linkoping University (Sweden), followed by a 2 year postdoc at Stanford University (USA), investigating charge carrier generation and recombination processes in organic optoelectronic devices. Since 2014 he holds the endowed chair for Organic Photovoltaics at the Institut für Angewandte Photophysik (IAPP) of the Technische Universität Dresden (Germany).

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