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Fall Retreat 2019

In September, the members of HyPerCells met with their colleagues from the department "Organic and Hybrid Solar C ells" from FZ Jülich for a joint retreat.

The retreat offers the possibility for members of the graduate school as well as guests to present their recent research results. This not only exchanges know-how and experiences but also promotes synergies between researchers from different fields of perovskite research.

Best Presentation Award of the Young Crystallographers

Frederike Lehmann received a prize for her presentation at the annual conference of the German Society of Crystallography in Leipzig on 28 March 2019. She is doing her doctorate in the Department of Structure and Dynamics of Energy Materials at the HZB under Prof. Dr. Susan Schorr at the Graduate School HyPerCell.

In her lecture she presented her work on hybrid perovskite materials, which are being investigated as an exciting new class of materials for highly efficient solar cells. Hybrid perovskites are semiconductors and have a so-called bandgap in the appropriate energy range, so that the energy-rich blue and green parts of the solar spectrum in particular can be efficiently converted into electricity.

Frederike Lehmann's work deals with the chemical synthesis of hybrid perovskites and the analysis of their properties. She investigates both inorganic (CsPbI3) and organic perovskites in which organic molecules such as formamidinium or methylammonium are incorporated into the structure instead of cesium. By targeted substitution, she succeeded in producing a high-temperature modification at room temperature whose band gap is particularly suitable for solar cells. This is particularly important because perovskites are used in thin-film solar cells whose quality suffers in high-temperature processes.  The "Best Presentation Award of the Young Crystallographers" is associated with a book voucher.


Poster award for Johannes Sutter

Johannes Sutter, PhD student at HZB, was awarded a poster prize at the "International Conference on Perovskite Solar Cells, Photonics and Optoelectronics (NIPHO19)". The conference took place from 25-27 February 2019 in Jerusalem.

Johannes Sutter is working on his PhD in the Nano-SIPPE group of Prof. Dr. Christiane Becker, his experimental work is done in the Helmholtz Innovation Lab HySPRINT at HZB. He won a poster prize at the first international conference at which he was able to present his work. The prize from the scientific publisher Wiley was associated with a book voucher worth 300 euros.

Sutter develops nanostructures at interfaces in perovskite-silicon tandem solar cells in order to facilitate spin coating of perovskite. These nanostructures should have low reflection values and good electronic properties.

By combining the processes of nanoimprint lithography and reactive ion etching, it is possible to transfer the nanostructures into crystalline silicon. Both optical and electronic investigations show that such interface structures can improve the properties of perovskite silicon tandem cells. 


PSCO poster award for Eike Köhnen

Eike Köhnen received an award for his poster on perovskite silicon tandem cells at the 4th International Conference on Perovskite Solar Cells and Optoelectronics (PSCO 2018) in Lausanne, Switzerland. He is a PhD student in the Junior Research Group on Perovskite Tandem Cells led by Dr. Steve Albrecht.

Tandem cells made of organometallic perovskite layers and silicon have the potential for very high efficiencies. While perovskites in particular convert blue parts of the light spectrum into electrical energy, silicon uses the red parts of the light. Eike Köhnen is working on the design of a so-called monolithic tandem cell.

For his poster, which he presented at the 4th International Conference on Perovskite Solar Cells and Optoelectronics (PSCO) in Lausanne, Switzerland, he received an award sponsored by Wiley Science Publishers.

Köhnen has realized a highly efficient monolithic tandem solar cell with an efficiency of 25 percent, which has also been certified by independent bodies. The tandem cell was manufactured at HZB, the silicon cell being produced at HZB-Institute PVcomB and the perovskite cell at HySPRINT. By optimizing the optical and electrical properties of the tandem-top contact, it was even possible to achieve an efficiency of 26 percent, which is the highest efficiency currently published in the literature for this tandem architecture. Since the spectrum arriving on Earth changes over the course of the day, Köhnen also investigated the influence of the spectrum on the behavior of the tandem solar cell.



Poster award for Frederike Lehmann

Frederike Lehmann from the HZB Department Structure and Dynamics of Energy Materials received a poster award at an international conference, the ICTMC-21 in Boulder, Colorado, USA. She presented her results on the synthesis and characterization of hybrid perovskite materials, which are considered interesting candidates for novel solar cells.

Frederike Lehmann is doing her doctorate at the HyPerCell graduate school in the department of Prof. Dr. Susan Schorr on different hybrid perovskite materials. This class of materials is extremely interesting for novel and inexpensive solar cells.

Frederike Lehmann does not only produce these materials using various synthesis methods, but also characterizes their structure and analyzes their optical and electronic properties. "I am also trying to modify these properties through targeted doping or substitution of certain elements in hybrid perovskites by other elements or chemical building blocks," explains Lehmann. For example, with the goal to vary the band gap and simultaneously increase the material stability in order to optimise those materials for solar cells.

At the 21st International Conference on Ternary and Multinary Compounds (ICTMC-21), which took place in Boulder, Colorado, USA, in September, Frederike Lehmann presented her work with a poster and received an award for her contribution.

Title of the poster: „Stabilizing the cubic phase of the triple cation hybrid perovskite (FA1-xMAx)1-yCsyPbI3 solid solution”



How to Make over 20% Efficient Perovskite Solar Cells

In a recent method paper published in Chemistry of Materials, HyPerCells members Christian M. Wolff, Martin Stolterfoht, Nga Phung and workgroup leaders Steve Albrecht, Dieter Neher and Antonio Abate
together with the renowned scientists Michael Saliba (Adolphe Merkle Institute) and Juan Pablo Correa-Baena (Massachusetts Institute of Technology) provide detailed descriptions and explanations on how to achieve highly efficient perovskite tandem solar cells on varios device architectures. The joint publication also underlines the excellent connection between the HyPerCells graduate school and other leading scientists and research institutes worldwide.

HyPerCells Lecture Series

As part of a lecture series within the HyPerCells graduate school, it was an honour and pleasure to welcome Prof. Dr. Filippo de Angelis from the University of Perugia at the Helmholtz-Zentrum in Berlin Adlershof.

Other prestigious speakers in the series so far were amongst others Dr. Giulia Grancini, EPFL, Dr. Selina Olthof, University of Cologne, Dr. David Egger, University of Regensburg, Dr. Felix Deschler, University of Cambridge, Dr. Jarvist Frost, Imperial College London and Prof. Dr. Henk J. Bolink, University of Valancia.

HyPerCells Fall Retreat 2017

The HyPerCells graduate school meets for the fall retreat 2017 in Akademie Schmöckwitz on 11 to 12 October 2017. The retreat offers the possibility for members of the graduate school as well as guests to present their recent research results. This not only exchanges know-how and experiences but also promotes synergies between researchers from different fields of perovskite research.

21.4 % Record Efficiency Realised

Perovskite solar cells with record efficiencies of over 20 per cent have been realised by Christian Wolff and Martin Stolterfoht. Following their publication in the journal Energy & Environmental Science they were able to push the solar cell performance up to 21.4 % power conversion efficiency which is the highest value reported so far for "inverted" perovskite solar cells with undoped contact layers.

Christian Wolff wins poster prize at PSCO conference in Genova

Christian Wolff is awarded with the Nature poster prize for best multidisciplinary presentation on the 2nd international conference "Perovkite Solar Cells and Optoelectronics" (PSCO) in Genova, September 2016. The results presented in his poster have recently been published in the journal Advanced Materials.