Charge carrier and exciton dynamics in organic-inorganic perovskite compounds

• Applicant: Dr. Daniel Niesner
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; African, American and Oceania Studies ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2014 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258907979

The fabrication of solar cells made from organic-inorganic perovskite compunds was first reported in 2012. Within one year, the efficiency of those solar cells has been increased from originally 3% to todays more than 15%. The production of the material is simple. Thus it has become one of the most promising candidates for cost-efficient future photovoltaics.From a basic researcher's point of view, the question arises, what the mechanisms of solar-to-electric power conversion are in those solar cells. The materials exhibit a low conductivity in the absence of illumination. So, how are photoexcited carriers transported through the medium? I propose to apply ultrafast spectroscopy to clarify these points. Therefore, perovskites will be illuminated using a laser pulse with a duration of less than a billionth of a second. The reaction of the material will then be followed using a second, similarly short laser pulse.Results of these experiments are not only relevant for application in solar cells. The perovskites under study are part of a much larger group of materials. These systems have in common a layered atomic structure. Their most prominent representative is "graphene", which consists of a single layer of carbon atoms. A. Geim and K. Novoselov were awarded the Nobel prize for transport measurements on graphene in 2010. Columbia University is one of the leading research institues in the world in research on these materials. The intended investigations on both, the current transport within individual perovskite layers as well as the interaction between different layers, may give rise to the discovery of new phenomena in condensed matter physics.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Xiaoyang Zhu