Présenté par Siegfried Bauer, Soft Matter Physics, Johannes Kepler University, Linz, Austria .

In the talk I will give a brief review of our latest work in the diverse areas of macroelectronics, soft machines and energy harvesting, obtained by many co-operations within our university and with many research teams in leading universities.

Macroelectronics is a recent branch of electronics mainly driven by research on large area displays. Based on our initial work on large area position sensitive detection schemes with cellular polymers and organic photodiodes, we developed solutions to make any large area screen interactive, techniques currently commercialized by the spin-off company isiQiri.
Organic semiconductors are still an active area of research, where our contributions are mainly in the identification of highly unusual material systems. H-bonded analogues of tetra- and pentacene, epindolidione and quinacridone show large field effect mobilities and stable hole transport in air, questioning the necessity of strong intramolecular pi-conjugation for efficient charge transport. Epindolidione and quinacridone are better known as yellow and magenta charges in ink-jet printers.

Ultrathin and lightweight organic solar cells with high flexibility are over ten times thinner, lighter and more flexible than any other solar cell of any technology to date. They reversibly withstand extreme mechanical deformation and have unprecedented solar cell-specific weight, with potential applications in stretchable electronics, the latest frontier of research in macroelectronics. While solar cells deliver energy, energy must also be stored for stand alone stretch electronic systems. We have demonstrated two years ago the first ultrastretchable dry gel cell battery, able to withstand mechanical stretching up to 100 %. Ultrathin electronics with a total thickness of around 2 μm allows bending with a radius of 5 μm. Such electronic foils can be even crumpled without failure and may pave a way for imperceptible electronics.
Stretchable electronics relies on elastomers. When an electric field is applied to soft elastomers, the thickness decreases and the area expands. This simple and robust principle is used in soft robotic systems, and most recently also in energy harvesting of mechanical energy from human gait or ocean waves. In the final part of the talk I will highlight our contributions to this field, like voltage triggered area expansions of 1700 % in dielectric elastomer membranes, as well as tools for analyzing the efficiency of dielectric elastomers for the conversion of mechanical into electrical energy.

I hope the talk will show that soft materials developed from scientific curiosity to real world applications.

Work supported by the Austrian Science Funds and by the European Research Council with the Advanced Investigators Grant 'Soft-Map'.