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 Karl Franzens University Graz

Graz University of Technology 

Air-stable Hydrogen-bonded Semiconductors: A Paradigm Change
Dr. Mihai Irimia-Vladu
Joanneum Research Weiz
17:00 - 18:00 Tuesday 23 October 2012 KFU HS 05.01

Organic electronics has a tremendous potential for the development of electronic products that are air-stable, non-toxic, and environmentally friendly. In their quest to identify novel materials featuring all the above characteristics, scientists are often inspired both by the apparent simplicity and by the true complexity of nature. We took up the inspiration by natural chromophores and investigated the yet unexplored and uncharted class of H-bonded natural and nature-inspired semiconductors. In nature, many pigments are hydrogen-bonded small molecules as opposed to larger, van der Waals bonded synthetic molecules like pentacene, phthalocyanines or oligothiophenes. Such natural pigments demonstrate H-bonding as well as -stacking. When processed in thin films, they generate extensive long-range ordered structures with crystalline textures showing a single preferential orientation, unlike the typical herringbone pattern found in many van der Waals bonded semiconductors. We implemented air-stable unipolar and ambipolar H-bonded, natural or natureinspired semiconductor materials in organic field effect transistors and various types o f integrated circuits. We recorded field-effect mobilities in excess of 1 cm2/Vs for many investigated molecules (e.g. indigoids, anthraquinones, acridones, etc.) in OFET device configuration. We found excellent stability to degradation of those devices and excellent charge transport in air during testing periods of several months. Nature inspires us to choose among a wide range of cheap and extensively available materials for creating new electronic functionalities, coming closer to a vision of a sustainable electronics world.