This Materials World Network project is a joint research and education activity between scientists and students at University of Illinois at Urbana-Champaign and Hahn-Meitner Institute in Germany to study fundamental issue-how the boundaries between crystals in a class of materials known as polar-covalent semiconductors affect their optical and electronic properties. Polar covalent semiconductors such as copper indium diselenide [CuInSe2] and related materials have the greatest potential for ultimate energy conversion efficiency in a large-area device. This research program addresses the primary fundamental science issue currently facing these materials-how do the boundaries between crystals affect the performance of the device. The primary objective of this award is to grow large, thin single crystals of CuInSe2 joined in well-defined grain boundaries that can be studied and modeled in detail. Advanced optical probe methods with nanoscale resolution will be employed to examine the way in which light interacts with the material and how the grain boundary affects the behaviors. The result will be a comprehensive understanding of grain boundaries in polar covalent semiconductors from AlN to ZnSe in general. The crystal growth techniques applied and the general scientific issues studied would have strong implications for a class of materials used in solar cells, and they have been identified as the most promising renewable energy technology for large-scale power generation. The program brings together the leading fundamental science research groups in Germany and at the University of Illinois, and will expand ongoing research activities and greatly increase graduate and undergraduate student exchange. %%% The project could enhance the understanding one of the core unique features of polar covalent semiconductors, namely their ability to function in the presence of structural defects. The results would have potential implications for grain boundary passivation in other semiconductors, and for improvement in optical devices such as photovoltaics, light emitters, and photosensors. International exchange will provide enhanced training and exchange of ideas between researchers including students in the US and Germany. The value added by the international collaboration is in exchange of research techniques to be applied and training of US graduate and undergraduate students in techniques in which the German group specializes. The proposed undergraduate and graduate students interactions with students in K-12 including classroom visits, distance research experiences where students will perform experiments using the UIUC facilities via the internet and open house exhibits would increase the understanding and appreciation of sciences among the students.
