Professor Christoph T. Koch, PhD was elected new director of the Department of Physics of the Humboldt-Universität zu Berlin. Prof. Koch has been at HU since 2015 and focuses on the development of new methods in quantitative transmission electron microscopy and their application to materials science problems. He has been a member of IRIS Adlershof since 2016 and is a member of the research building commission. Prof. Dr. Heiko Lasker was elected as his deputy. IRIS Adlershof congratulates them both and wishes them every success in their new role.
Everything revolves around IRIS Adlershof in the current issue of the WISTA-magazine "Potenzial". In the following three articles different areas of IRIS Adlershof are introduced:
Turning science fiction into science fact
Professor Jürgen P. Rabe, director of the Integrative Research Institute for the Sciences IRIS Adlershof, about building bridges, joint labs, and a new research building
A hub for basic research, teaching, and industrial application
How the Integrative Research Institute for the Sciences IRIS Adlershof supports many different technology start-ups
Focusing on advanced materials
A graduate school in Adlershof offers top qualification and turns teams into families
A team of researchers from the Helmholtz-Zentrum Berlin (HZB) and Humboldt-Universität zu Berlin has succeeded for the first time in producing light-emitting diodes (LEDs) from a hybrid perovskite semiconductor material using inkjet printing.This opens the door to broad application of these materials in manufacturing many different kinds of electronic components.The scientists achieved the breakthrough with the help of a trick: "inoculating" (or seeding) the surface with specific crystals.
Microelectronics utilise various functional materials whose properties make them suitable for specific applications. For example, transistors and data storage devices are made of silicon, and most photovoltaic cells used for generating electricity from sunlight are also currently made of this semiconductor material. In contrast, compound semiconductors such as gallium nitride are used to generate light in optoelectronic elements such as light-emitting diodes (LEDs). The manufacturing processes also different for the various classes of materials.
Transcending the materials and methods maze
Hybrid perovskite materials promise simplification – by arranging the organic and inorganic components of semiconducting crystal in a specific structure. “They can be used to manufacture all kinds of microelectronic components by modifying their composition“, says Prof. Emil List-Kratochvil, head of a Joint Research Group at HZB and Humboldt-Universität. What's more, processing perovskite crystals is comparatively simple. “They can be produced from a liquid solution, so you can build the desired component one layer at a time directly on the substrate“, the physicist explains.
First solar cells from an inkjet printer, now light-emitting diodes too
Scientists at HZB have already shown in recent years that solar cells can be printed from a solution of semiconductor compounds – and are worldwide leaders in this technology today. Now for the first time, the joint team of HZB and HU Berlin has succeeded in producing functional light-emitting diodes in this manner. The research group used a metal halide perovskite for this purpose. This is a material that promises particularly high efficiency in generating light – but on the other hand is difficult to process. “Until now, it has not been possible to produce these kinds of semiconductor layers with sufficient quality from a liquid solution“, says List-Kratochvil. For example, LEDs could be printed just from organic semiconductors, but these provide only modest luminosity. “The challenge was how to cause the salt-like precursor that we printed onto the substrate to crystallise quickly and evenly by using some sort of an attractant or catalyst“, explains the scientist. The team chose a seed crystal for this purpose: a salt crystal that attaches itself to the substrate and triggers formation of a gridwork for the subsequent perovskite layers.
Significantly better optical and electronic characteristics
In this way, the researchers created printed LEDs that possess far higher luminosity and considerably better electrical properties than could be previously achieved using additive manufacturing processes. But for List-Kratochvil, this success is only an intermediate step on the road to future micro- and optoelectronics that he believes will be based exclusively on hybrid perovskite semiconductors. “The advantages offered by a single universally applicable class of materials and a single cost-effective and simple process for manufacturing any kind of component are striking“, says the scientist. He is therefore planning to eventually manufacture all important electronic components this way in the laboratories of HZB and HU Berlin. List-Kratochvil is Professor of Hybrid Devices at the Humboldt-Universität zu Berlin and head of a Joint Lab founded in 2018 that is operated by HU together with HZB. In addition, a team jointly headed by List-Kratochvil and HZB scientist Dr. Eva Unger is working in the Helmholtz Innovation Lab HySPRINT on the development of coating and printing processes – also known in technical jargon as "additive manufacturing" – for hybrid perovskites. These are crystals possessing a perovskite structure that contain both inorganic and organic components.
The work was published in Materials Horizons, the journal of the Royal Society of Chemistry, in an article entitled: „Finally, inkjet-printed metal halide perovskite LEDs – utilizing seed crystal templating of salty PEDOT:PSS“
Felix Hermerschmidt, Florian Mathies, Vincent R. F. Schröder, Carolin Rehermann, Nicolas Zorn Morales, Eva L. Unger, Emil. J. W. List-Kratochvil. DOI: 10.1039/d0mh00512f
The European project HI-ACCURACY with the involvement of the Hybrid Devices group at Humboldt-Universität zu Berlin, and coordinated by Joanneum Research, started on April 1st, 2020. HI-ACCURACY is funded by HORIZON 2020 research framework programme with a total volume of around 5 million euros and a project term of 36 months.
According to current estimates, the global market for printed, flexible and organic electronics amounts to 28.3 billion euros with an annual growth rate of >8%. This market is mainly dominated by the display industry, which is looking for new and innovative ways to increase screen resolution and incorporate new user interfaces throughout the display range. High-resolution printing technology is an important factor in achieving these goals.
HI-ACCURACY aims to produce structures with very high resolution up to the μm range and thus the next generation of large area production of flexible organic electronics. This goal is to be achieved through a unique range of advanced materials and printing inks combined with scalable, cost-effective printing and coating processes that require no or minimal vacuum. HI-ACCURACY will thus demonstrate the production of front and backplane structures with structure sizes approaching 1 μm that can operate at frequencies of >1MHz.
Further information on the project can be found here.
Further information on the work of the Hybrid Devices group can be found here.
This year's Fischer-Nernst Study Award of the Department of Chemistry of Humboldt-Universität zu Berlin has been awarded to Max Heyl for his Master's thesis work on the exfoliation and polymer-free transfer of TMDC monolayers using template-stripped gold substrates. Max Heyl has conducted this work as part of the Collaborative Research Center CRC 951 - "Hybrid Inorganic/Organic Systems for Opto-Electronics (HIOS)", where he now also continues to working as a doctoral student in the Hybrid Device group of the Prof. Emil List-Kratochvil, who is a Deputy Director of IRIS Adlershof.
The German Research Foundation (DFG) has approved a new Collaborative Research Centre (CRC) at Humboldt-Universität zu Berlin. The CRC 1404 entiteld „FONDA – Foundations of workflows for large- scale scientific data analysis“ will initially be funded for four years from July 1, 2020. Spokesperson of the CRC is Prof. Ulf Leser from the Department of Computer Science of Humboldt-Universität zu Berlin. The new research network focuses on the research of techniques, processes and tools that enable scientists to be more productive when creating and using data analysis workflows. Special emphasis is laid on portability, adaptability and reliability that are important for this goal. On the part of IRIS Adlershof, the professors Claudia Draxl, Christoph T. Koch and Alexander Reinefeld are involved in the new CRC.
We congratulate the successful applicants and wish the new project a good start.