28 Nov 3D-printed optoelectronics
Researchers at the Universities of Heidelberg and Stuttgart report that they have succeeded in printing conductive polymers in three dimensions. The complex two- and three-dimensional structures created using digital light processing (DLP) can be manipulated electrochemically to change their color, according to the researchers. This opens up new perspectives for the manufacture of 3D-printed optoelectronic devices, for example.
Complex structures straight out of the printer
Digital Light Processing (DLP) is a light-based 3D printing process that can form a light-sensitive polymer into a three-dimensional object layer by layer through selective irradiation with UV light. “While the technology is already being used successfully in dentistry, for example, it has been difficult to use it for conductive polymers with applications in optoelectronics and thus to print directly,” explains Professor Eva Blasco. The scientist and her team at the Institute for Molecular Systems Engineering and Advanced Materials at Heidelberg University are conducting research into novel functional materials for 3D printing. The project was carried out in close cooperation with Professor Sabine Ludwigs and her group at the Institute of Polymer Chemistry at the University of Stuttgart, who are experts in conductive polymers and electrochemical switching.
3D structures that change color
The two research teams developed a type of methacrylate-based ink that contains redox-active carbazole groups. These redox units enable such materials to absorb or release electrons in their polymer chain. This makes them electrically conductive and capable of changing color depending on their oxidation or reduction state. The scientists have succeeded in using this photoconductive ink formulation to produce structures that remain electrochemically manipulable even after printing and whose properties can therefore be altered. “This was made possible by close, interdisciplinary collaboration in our laboratories in Heidelberg and Stuttgart,” emphasize the participating doctoral students Christian Delavier and Svenja Bechtold.
Concept for the production of electrochromic structures using digital light processing (left); right: potential application in a spectroelectrochemical experiment. Image: University of Stuttgart / GRK 2948 / F. Sterl
Door opener for display innovations or soft robotics
According to the researchers, this carbazole-containing ink formulation already enabled the direct additive manufacturing of two-dimensional pixel arrays and checkerboard patterns, as well as a three-dimensional pyramid consisting of several layers. Originally almost transparent, these complex structures first took on a light green, then a dark green, and finally an almost black color through electrochemical stimulation. “This process is completely reversible and can be controlled with pixel precision depending on the structure. What is particularly exciting is the control in the third dimension, i.e., in terms of the height of the architectures,” emphasizes Ludwigs. According to Blasco and Ludwigs, the combination of high-resolution, light-based 3D printing with redox polymers opens up new possibilities for the additive manufacturing of pixel displays or actuators for soft robotics applications in which the volume can be switched electrochemically.
Funding
The research was conducted as part of the graduate college “Mixed Ion-Electron Transport: From Fundamentals to Applications” (GRK 2948), which is supported by both universities. The graduate college is funded by the German Research Foundation.
Original publication:
[C. Delavier, S. Bechtold, M. H. Dodds, E. Blasco and S. Ludwigs: 3D Digital Light Processing of Redox-Active Polymers for Electrochemical Applications; Advanced Functional Materials (13. November 2025), DOI: 10.1002/adfm.202518546