I am very grateful with MAPEX for the economical and logistic support to visit the University of Bremen in September 2019, and for being hosted by Prof. Dr. Jürgen Gutowski and his Semiconductor Optics group, Institute of Solid State Physics. The aim of my visit was to study the mechanisms of photogenerated charge recombination in hybrid heterojunctions for solar cell applications using impedance spectroscopy and photoluminescence. The understanding of such mechanisms is fundamental to implement proper strategies to increase the efficiency of solar cells.

During my stay in the group, I gained an insight about optical characterization techniques, i.e., time resolved photoluminescence, which allows to understand fundamental recombination processes occurring in semiconductors. I also had the opportunity to share some knowledge about impedance spectroscopy to some colleges of the group. Impedance spectroscopy technique can be used to determine charge-carrier trap states that promote recombination at interfaces and at the bulk of the materials forming heterojunctions. The fruitful results of this stay are being prepared for publication.

I would like to highlight that this time in Bremen contributed significantly to consolidate my collaboration with the group of Prof. Dr. Jürgen Gutowski and with other members of the Faculty of Physics and Electrical Engineering. It is particularly important for my new position as Junior Professor of Veracruz University, Mexico, since we have defined guidelines for future joint research projects which also involve mobility of students and researchers to and from Mexico. All together, this is part of an initiative of Dr. Alejandra Castro-Carranza, Research Ambassador of the University of Bremen for Mexico, to form a scientific network conformed by members of the University of Bremen and of potential Mexican universities to develop jointly low-cost technology for sustainable applications, e.g., clean energy and detection of pollutants in the environment. See www.bremex-steaps.net/. 

Last but not least, I am also very grateful to my host, Prof. Dr. Jürgen Gutowski, for his feedback and the fruitful discussions, and for letting me know more about German culture and hospitality.