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SFB 595:  Electric Fatigue in Functional Materials

Subject Area Materials Science and Engineering
Chemistry
Geosciences
Computer Science, Systems and Electrical Engineering
Term from 2003 to 2014
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 5485550
 
Final Report Year 2015

Final Report Abstract

Electrical fatigue is the degradation of functional materials properties due to cyclic electric load. Fatigue phenomena reduce the lifetime of device components used for example in sensors, actuators, for energy storage and in microelectronics. The collaborative research center SFB 595 has investigated fatigue phenomena in ferroelectrics, organic semiconductors, battery materials and transparent electrodes under in operando conditions and designed new materials with improved cycle stability for reliable components in functional devices. For all material classes under investigation we could show how ionic and electronic charge carriers interact with each other and with microstructural elements in the bulk as well as at interfaces (grain boundaries and domain walls) and interphases (electrode / electrolyte). These processes cause reversible and irreversible variations of local structures and fields, but also local electric currents and polarizations. The characteristic cycle numbers depend on the phase and defect properties of the respective material, but also on microstructural features, composite and domain structures. The detailed understanding of fatigue and aging phenomena has eventually guided the search for new materials with improved cycle stability. In the area of ferroelectrics, lead-free ceramics based on Na0.5Bi0.5TiO3 were transferred into device applications by materials design combining synthesis, characterization and modelling. The understanding of fatigue phenomena in organic semiconductors has guided the development of new materials based on poly-3-Hexylthiophens and stimulated the re-evaluation of compounds based on polyphenylenvinyle, while “all-solidstate” batteries where realized in the research dealing with ionic conductors.

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