Lichtgedanken 05

Rubrik 51 05 | LICHT GEDANKEN The earth should not get more than two degrees warmer compared to pre-in- dustrial times. This target was set by the Paris Agreement in 2015. In order to achieve this goal, global emissions of cli- mate-damaging greenhouse gases must be drastically reduced. This, in turn, requires a global energy revolution: fossil fuels such as oil, gas and coal need to be largely replaced by renewable energy sources. There are, however, problems implementing the climate protection goals, and Dr Micha- el Zürch is convinced that this is not just due to a lack of political will. »The ener- gy revolution would certainly accelerate if we had better solar technology«, says the physicist. He points to the fact that the silicon-based solar modules in use today are only up to around 20 percent efficient. In other words: about three quarters of the solar energy cannot even be used by the modules in use today. »We need alternatives to silicon that will allow for a more efficient conversion of solar energy into electricity.« Zürch will be taking a closer look at these alterna- tives over the next four years: together with his colleagues at the Chair for Quantum Electronics, as well as French and American partners, he has founded the »Quest for Energy« research project. The German Academic Exchange Ser- vice is funding this project with almost one million euros until 2022, within the framework of the German-French re- search initiative »Make our planet great again«. Two-dimensional semiconductor nanomaterials to replace silicon Semiconductor nanomaterials represent a very promising group of materials that could replace silicon in solar modules, as Prof. Dr Christian Spielmann exp- lains. »These thin, two-dimensional ma- terials comprise only a few atomic layers and possess quite extraordinary optical and electronic properties, which make them ideal semiconductors«, explains the physicist, whose team now houses Zürch’s project. The best-known examp- le of such 2D nanomaterials is graphene. The Jena physicists now want to take a closer look at a new class of these mate- rials, into which very little research has been conducted to date: so-called transi- tion metal dichalcogenide. »These are composite materials whose properties vary based on their compo- sition and which can be tailored to suit different applications«, explains Zürch. However, little is currently known about the fundamental processes that take place within these materials when they interact with light. Their special nanoproperties mean that the physical processes occur very quickly in these materials. The physicists now want to examine these in detail, in order to test their suitability as solar material. »We are specifically interested in observing the charge carriers—or the electrons—in the material when they are illuminated with light.« The long-term goal for the researchers is to then use this information to pave the way for the targeted use of composite materials like this in solar technology.  Projects New solar technology for the energy revolution Physicists in Jena are developing and testing new materials for possible use as highly efficient solar cells. Their research project »QUESTforENERGY« is funded by the Federal Ministry of Education and Research under the »Make our Planet Great Again – German Research Initiative« and implemented by the German Academic Exchan- ge Service (DAAD). BY UTE SCHÖNFELDER Dr Michael Zürch investigates semicon- ductor materials that could be used as a substitute for silicon in solar modules.