Organic semiconductor materials are promising key technologies for the development of state-of-the-art optoelectronic components and are used in photovoltaics as well as in sensor technology and microelectronics. In order to produce thin organic semiconductor films automatically and with well-defined properties, researchers led by Leibniz IPHT in Jena have developed a new technological approach for the deposition of thin films with high molecular precision. The method they have described, which can be used to produce thin films with customized electronic properties, is presented in the journal Advanced Materials.
Manufacturing process enables customized production of thin semiconductor films
Organic semiconductors, which generally consist of carbon-based molecular materials or polymers, are used in a wide range of modern applications: For example, the ultra-thin, mechanically flexible and lightweight semiconductor thin films are used in modern transistors, sensitive sensors or organic solar cells. Their energy conversion potential and thus their functionality is determined by the electronic energy levels of the organic thin films, which depend on the molecules as well as their arrangement and the interactions between neighboring molecules within the thin films.
A German-American team of scientists - led by the Leibniz Institute of Photonic Technology (Leibniz IPHT) - has succeeded in developing a novel manufacturing process that can be used to automatically and precisely fabricate thin semiconductor films with customized structural and electronic properties. The method presented in the journal Advanced Materials is intended to enable the targeted production of thin films with controllable interactions between molecular neighbors and specific energy levels.
Rolling deposition of semiconductor thin films
The presented "Rolling Transfered Langmuir Layer" technique, a further development of the established Langmuir-Blodgett technique for the deposition of thin films, is suitable for the production of monolayers of organic semiconductor molecules at air-water interfaces. For this purpose, a molecular layer that forms on a water surface is transferred to a solid carrier material. The molecular monolayer is deposited onto the substrate using a specific rolling transfer system developed by the researchers, which contains the substrate to be coated and which is moved over the molecular film on the water surface. The molecular layer formed at the air-water interface ultimately adheres to the substrate due to the rolling motion.
"The process we have developed also makes it possible to deposit crystalline films, the production of which was previously associated with considerable effort using established methods and often led to surface defects such as fractures in the organic thin films. With the presented process, we can reduce these surface defects to a minimum and produce both monolayers and several thin films with individual properties directly, uniformly and with high quality in a scalable manner," explains PD Dr. habil. Martin Presselt, head of the Organic Thin Films and Interfaces working group at Leibniz IPHT, who developed the new method together with his team.
Precisely fitting thin films
Two parameters play a decisive role in the production of semiconducting thin films with tailored structural and energetic properties: "Firstly, the rolling transferred Langmuir layer technique can be used to systematically vary the packing density of the molecules within a layer, which can range from very densely packed to less densely packed, via the surface pressure during deposition. On the other hand, the number of superimposed molecule layers and thus the thickness of the thin films can be precisely adjusted. In this way, semiconductor thin films with targeted interactions between neighboring molecules and specific energy levels can be reproducibly produced," says Dr. Sarah Jasmin Finkelmeyer, a scientist in the Organic Thin Films and Interfaces working group, who played a key role in developing the new method.
The technological approach developed by the researchers lays the foundation for the fabrication of novel (opto)electronic components with optimized properties based on thin films. For example, organic photovoltaic modules that efficiently generate electrical energy from sunlight can be further developed, as can thin films that convert sunlight into chemical energy. (OM-12/23)
Scientific publications
The scientists published their findings in the journal Advanced Materials:
S. J. Finkelmeyer, E. J. Askins, J. Eichhorn, S. Ghosh, C. Siegmund, E. Täuscher, A. Dellith, M. L. Hupfer, J. Dellith, U. Ritter, J. Strzalka, K. Glusac, F. H. Schacher, M. Presselt, Tailoring the weight of surface and intralayer edge states to control LUMO energies, Advanced Materials (2023)
Contact us
Leibniz Institute of Photonic Technology e.V.
Albert-Einstein-Str. 9
07745 Jena (Germany)
Phone: 03641-206-00
E-mail: institut@leibniz-ipht.de
www.leibniz-ipht.de
Scientific contact:
PD Dr. habil. Martin Presselt
Head of the Organic Thin Films and Interfaces group at Leibniz IPHT
Phone: +49 (0) 3641 - 206-418
E-mail: martin.presselt@leibniz-ipht.de
About the Leibniz Institute of Photonic Technology (IPHT)
Light is at the center of research at Leibniz IPHT. Scientists are researching innovative photonic processes and tools for use in clinical diagnostics, such as infection and cancer diagnostics, pharmaceuticals and process control, as well as in food and environmental safety. A key objective is to accelerate translation: the implementation of research results in practice - from ideas to instruments