Environmentally Compatible Organic Solar Cells

KIT Coordinates “MatHero” Project

Environmentally compatible production methods for organic solar cells from novel materials are in the focus of “MatHero”. The new project coordinated by Karlsruhe Institute of Technology (KIT) aims at making organic photovoltaics competitive to their inorganic counterparts by enhancing the efficiency of organic solar cells, reducing their production costs and increasing their life-time. “Green” processes for materials synthesis and coating play a key role. “MatHero” is funded by the European Commission with an amount of EUR 3.5 million.

Organic solar cells will open up entirely new markets for photovoltaics. These “plastic solar cells” have several advantages: They are light-weight, mechanically flexible, can be produced in arbitrary colors, and hence allow a customized design for a variety of applications. Moreover, organic solar cells can be produced by printing processes with a low consumption of materials and energy, enabling the inexpensive production of high numbers of solar cells. In order to become competitive in established markets, various challenges still have to be mastered. The energy conversion efficiency has to be improved to more than ten percent. Costs of materials synthesis have to be reduced. The life-time of the materials and modules has to be enhanced to more than ten years.

Self-healing Plastics Developed

Novel Polymer Network that Selfheals Rapidly and Repeatedly at Relatively Low Temperatures

Scratches in the car finish or cracks in polymer material: Self-healing materials can repair themselves by restoring their initial molecular structure after the damage. Scientists of the Karlsruhe Institute of Technology and Evonik Industries have developed a chemical crosslinking reaction that ensures good short-term healing properties of the material under mild heating. The KIT group headed by Christopher Barner-Kowollik uses the possibility of crosslinking functionalized fibers or small molecules by a reversible chemical reaction for the production of self-healing materials. These so-called switchable networks can be decomposed into their initial constituents and reassembled again after the damage. The advantage is that the self-healing mechanism can be initiated any time by heat, light or by the addition of a chemical substance. “Our method does not need any catalyst, no additive is required,” Professor Barner-Kowollik says. The holder of the Chair for Preparative Macromolecular Chemistry at KIT studies syntheses of macromolecular chemical compounds.

It took about four years of research for the working group of Barner-Kowollik, together with the Project House Composites of Creavis, the strategic innovation unit of Evonik, to develop a novel polymer network. At comparably low temperatures from 50°C to 120°C, the network exhibits excellent healing properties within a few minutes. Reducing the time needed for healing and optimizing the external conditions, under which the healing process takes place, are the major challenges of research relating to self-healing materials. Using the healing cycle developed by them, the KIT researchers have found a large number of intermolecular compounds that close again within a very short term during cooling. Mechanical tests, such as tensile and viscosity tests, confirmed that the original properties of the material can be restored completely. “We succeeded in demonstrating that test specimens after first healing were bound even more strongly than before,” Barner-Kowollik says.

The self-healing properties can be transferred to a large range of plastics known. Apart from self-healing, the material is given another advantageous property: As flowability is enhanced at higher temperatures, the material can be molded well. A potential field of application lies in the production of fiber-reinforced plastics components for automotive and aircraft industries.

Infos: www.kit.edu

In Karlsruhe entdeckt!

Elektromagnetische Wellen

Vor 125 Jahren veröffentlichte Heinrich Hertz „Über Strahlen elektrischer Kraft“. In Karlsruhe sprang der Funke über – heute nutzt die ganze Welt elektromagnetische Wellen, um von unterwegs, zu jeder Zeit und an jedem Ort zu kommunizieren. Ob W-LAN, Mobilfunk, Radio oder Fernsehen: Den grundlegenden physikalischen Effekt, der die drahtlose Datenübertragung ermöglicht, entdeckte ein Erfinder in Karlsruhe. 1886 war es dem Physiker Heinrich Hertz an der damaligen Technischen Hochschule Karlsruhe – heute Karlsruher Institut für Technologie (KIT) – erstmals gelungen, elektromagnetische Wellen vom Sender zu einem Empfänger zu übertragen.

Centre for Creative Founders

"Perfect Futur": Opening in the Old Slaughterhouse

More than 40 building enterprises at the expense of 2.6 million took part in the restoration and conversion of the landmarked building, in which "Perfekt Futur" has been formed. It is a city of disused sea freight containers, which offers space for creative working. "There is a grand idea behind this project and many will think further", mayor Dr. Frank Mentrup recalls the intention of building a creative centre in 2004.

In the Course of the "Masterplan"

During Karlsruhe's application as cultural capital of Europe 2010, the idea assumed shape and had been complemented and concretised in the course of the Masterplan 2015, with the idea of sponsoring young founders of businesses and establishments for cultural or creative economy. "The structural concept is everything but ordinary. It certainly posed some special challenges," mayor Dr. Mentrup remarked and thanked everyone involved in the project, the Fächer GmbH, the Kulturamt, and the Wirtschaftsförderung for "showing the courage to break new ground in order to help founders in creative branches with creating a nucleus for the creative enterprises of tomorrow."