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Uppsala Universitet

Uppsala University (www.uu.se) is a general university (35,000 students) covering a broad range of teaching and research. The University is rated 70th-100th worldwide and counts approximately 5000 researchers. UU researchers have obtained 7 Nobel prices, of which 2 Nobel prizes in material analysis techniques. The Ångström Laboratory hosts 1100 employees of UU making it one of the biggest materials research centres in Scandinavia. The Laboratory has a focus in energy and health materials.

The Division of Applied Materials Science has activities in synthesis and analysis of novel materials and counts about 60 researchers. The solar activity of analysis of CIGS and kesterite based solar cells in this division has started in 2005 in the Leifer. The activities on these materials groups include analysis of structure, chemical composition and electronic structure with down to atomic scale resolution. In these polycrystalline samples, grain boundaries play a key role in obtaining high efficiency. We have contributed to the understanding of the electronic property of grain boundaries by analysing segregations, diffusion and structure in the boundaries and their environment by transmission electron microscopy techniques. In particular, we have developed EELS and EDS techniques to understand more details about the composition and valence state of the elements in the grain boundaries. The group has worked in the EU SNAPSUN project, where third generation SiNP based absorber layers were developed. 3D electron tomography has been developed to analyse the distribution of the grain boundaries and 3D spectroscopic electron tomography allowed for the discovery of hitherto unknown interfacial layers between the NPs and the matrix material. In kesterite materials TEM analysis has contributed to the understanding of highest efficiencies of the related solar cells.