MATERIALS | PHOTOVOLTAICS
to be an advantage in solar cells as well as in other uses such as light sensors. This material’s ability to sense circularly polaris- ing light is due to its chirality, or 3D molecular shape. (For instance, two molecules may have the same structure but be mirror images of one another.) Because of this property, various mol- ecules can ‘sense’ the underlying nature of the electromagnetic radiation. The next step, say the researchers, is to expand the trials to include several different materials and examine how molecules and light interact in them. The research was published in Nature Photonics.
Above: German researchers will spend four years improving the performance of printed organic solar cells
The team found that using atomic layer deposi- tion allowed layers of high quality to be grown – in a method that is scalable to industrial processes such as roll-to-roll processing. “Our aim was to make organic solar cells more
efficient and to use methods that are scalable,” he said. The efficiency is close to the current record for
organic solar cells (around 19%) – but he points out that the team has not yet optimised the other layers.
“It may be a bit early for industrial partners to
take this on, as we need to do some more research first,” said Garcia Romero. “We hope that our use of atomic layer deposition will inspire others in the field.”
Light sensor Researchers in Sweden has adapted material used in organic solar cells as a special light sensor in electronics. The sensor can be used to detect circularly polarised red light, which may be useful in applica- tions such as self-driving vehicles – where night vision is important. “Constructing high-quality sensors that can detect circularly polarising light in the near-infrared spectrum has long been a challenge,” said Feng Gao, professor in the department of physics, chemistry and biology at Linköping University. “Thanks to further development of a material normally used in solar cells, we can now detect circularly polarised light across the entire visible light spectrum.” The polymeric material may have a spherical molecular structure known as fullerene – or a different structure, in which case the material is called non-fullerene. The material used in the current study is non-fullerene, which has turned out
36 FILM & SHEET EXTRUSION | April 2024
Four-year project The German Research Foundation (DFG) is to fund a research group on printed organic solar cells over the next four years. Scientists from seven universities will participate
in the project, led by TU Chemnitz. The inter-univer- sity research group intends to identify and control the factors that are important for the efficiency and stability of printed organic solar cells. The project goal is to print high-performance, durable organic solar cells at low cost on an industrial scale. One group led by Eva Herzig – junior professor for dynamics and structure formation at the University of Bayreuth – will investigate the active layers of organic solar cells. Their focus is on how the conversion of sunlight into free charge carriers is influenced by the arrangement of the molecules. Herzig’s team specialises in researching the active layer of organic solar cells, where sunlight is converted into free charge carriers – electrons and holes. “We want to investigate how the arrangement of the molecules in the active layer can be influenced when organic solar cells are printed,” she said. “Another central question is how stable this targeted nanostructure will be in the final printed solar cell.” The group will use X-ray analysis to observe and influence the drying of very thin organic layers. In addition, experiments are planned at major research facilities such as the German Electron Synchrotron (DESY) in Hamburg.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.tugraz.at �
www.opvstability.eu �
www.kaist.ac.kr �
www.rug.nl �
www.liu.se �
www.dfg.de �
www.uni-bayreuth.de
www.filmandsheet.com
IMAGE: IMAGE: EVA HERZIG, UNIVERSITY OF BAYREUTH
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