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On Tuesday, 6 December 2022, Dr. Eike Köhnen received the Tiburtius Prize (First Place) for outstanding dissertations. Eike Köhnen has contributed to significantly increasing the efficiency of tandem solar cells made of perovskite and silicon, to the point of setting world records.

Eike Köhnen worked on so-called tandem solar cells, a new type of photovoltaic technology that promises significantly higher efficiencies. In Prof. Steve Albrecht's team (TU Berlin and HZB), he combined conventional silicon solar cells with a perovskite cell and analysed with state-of-the-art methods how losses can occur. These insights helped to increase the efficiency of such tandem solar cells to over 29 %. This value was an absolute world record for more than eight months.

Köhnen also obtained two patents as a PhD student. His thesis was assessed with the top mark summa cum laude. In Albrecht's team, Eike Köhnen was also active in science communication and maintained a lively Twitter account.

"The Tiburtius Prize is an outstanding recognition of this excellent dissertation and Eike's pioneering work in the development of solar cells," says Prof. Steve Albrecht, who supervised the PhD-thesis. Co-supervisor Prof. Bernd Rech, who heads the Helmholtz-Zentrum Berlin as scientific director, adds: "Eike Köhnen has played a major role in our internationally visible successes with tandem solar cells made of perovskite and silicon. I congratulate him on this fine award."

The award is named after Professor Joachim Tiburtius, who was Senator for National Education in Berlin from 1951 to 1963. The State Conference of Rectors and Presidents of Berlin Universities (LKRP) awards three prizes annually, as well as an additional three recognition prizes, to doctoral students at Berlin universities for outstanding dissertations

Title of the dissertation by Eike Köhnen: Optical and Electrical Optimization by Advanced Characterization of Monolithic Perovskite/Silicon Tandem Solar Cells.