# Stefan Hecht
**Stefan Hecht** (born 1974) is a chemist who works on photoswitchable molecules, using light to remote-control the properties of materials, devices, and their manufacturing.[1](https://orcid.org/0000-0002-6124-0222) He is Einstein Professor of Organic Chemistry and Functional Materials at Humboldt-Universität zu Berlin and became founding director of the Center for the Science of Materials Berlin, and he cofounded the start-up xolo GmbH to commercialize xolography, a volumetric 3D printing method his group invented.[1](https://orcid.org/0000-0002-6124-0222) The Alexander von Humboldt Foundation lists his research fields as organic molecular chemistry and the preparative and physical chemistry of polymers.[2](https://www.humboldt-foundation.de/en/connect/explore-the-humboldt-network/singleview/1073941/prof-dr-stefan-hecht)
| Fact | Detail |
|---|---|
| Field | Organic, polymer, and supramolecular materials chemistry; photoswitchable molecules[1](https://orcid.org/0000-0002-6124-0222) |
| Current position | Einstein Professor of Organic Chemistry and Functional Materials, Humboldt-Universität zu Berlin, since 1 October 2022[1](https://orcid.org/0000-0002-6124-0222) |
| Training | Chemistry at Humboldt-Universität (1992–1997); PhD, UC Berkeley, 2001, advisor Jean M. J. Fréchet[3](https://www.hechtlab.de/en/abouthecht.html) |
| Signature work | "Xolography for linear volumetric 3D printing", *Nature* 2020[4](https://www.nature.com/articles/s41586-020-3029-7) |
| Company | Cofounder of xolo GmbH (2019), commercializing xolography[3](https://www.hechtlab.de/en/abouthecht.html) |
| Honor | Elected ordinary member, Academia Europaea (Chemical Sciences), 2020[5](https://www.ae-info.org/ae/Member/Hecht_Stefan) |
## Career and training
Hecht grew up in Berlin and studied chemistry at Humboldt-Universität zu Berlin from 1992 to 1997, investigating chemiluminescence and photocatalysis; his Diplom thesis research on photochemical rearrangements was carried out at the [University of California](https://www.edgepedia.org/university-of-california), Berkeley, from September 1995 to September 1996.[3](https://www.hechtlab.de/en/abouthecht.html) His doctoral research from 1997 to 2001, also at UC Berkeley, was in organic polymer chemistry under thesis advisor [Jean M. J. Fréchet](https://www.edgepedia.org/jean-m-j-frechet), in the area of dendritic macromolecules.[3](https://www.hechtlab.de/en/abouthecht.html)
Returning to Germany, he was an assistant professor (young investigator) in organic polymer and materials chemistry at Freie Universität Berlin from 2001 to 2004, completing his [Habilitation](https://www.edgepedia.org/habilitation) in June 2006, and he led a group at the Max-Planck-Institut für Kohlenforschung from 2005 to 2006.[3](https://www.hechtlab.de/en/abouthecht.html) In 2006 he became full professor at Humboldt-Universität, holding the Chair of Organic Chemistry and Functional Materials until 2019.[1](https://orcid.org/0000-0002-6124-0222) From August 2019 to December 2022 he was Scientific Director of DWI, the Leibniz Institute for Interactive Materials in Aachen, and held the Chair of Macromolecular Chemistry at [RWTH Aachen University](https://www.edgepedia.org/rwth-aachen-university).[6](https://www.dwi.rwth-aachen.de/en/person/prof-stefan-hecht-phd) Since 1 October 2022 he has been Einstein Professor at Humboldt-Universität and became founding director of the Center for the Science of Materials Berlin.[1](https://orcid.org/0000-0002-6124-0222) He is also involved in the Berlin Cluster of Excellence Unifying Systems in [Catalysis](https://www.edgepedia.org/catalysis) and in Collaborative Research Centers on hybrid inorganic/organic systems for opto-electronics.[7](https://www.einsteinfoundation.de/en/fellows-projects/einstein-fellows-professors/einstein-professors/stefan-hecht)
## Photoswitchable materials
Photoswitches are molecules that reversibly change structure, and with it properties, under light of specific wavelengths. Hecht's group works chiefly with diarylethenes, a switch class valued for materials because it can be made air-stable and solution-processable; his 2020 review in *Advanced Materials* describes diarylethene switches built into small-molecule materials such as 2,7-dialkylbenzothieno(3,2-b)benzothiophenes (BTBTs), and argues that such switches must be tailored not only in their electronic structure but for the material environment they operate in.[8](https://doi.org/10.1002/adma.201905966)
## Remote-controlled catalysis and polymerization
His 2018 *Nature Catalysis* paper reported a single photoswitchable catalyst system that gives in situ remote control over the ring-opening polymerization of l-lactide and regulates the incorporation of trimethylene carbonate and δ-valerolactone monomers in copolymerizations.[9](https://www.nature.com/articles/s41929-018-0091-8) The mechanism places a phenol moiety inside a diarylethene structure: light-induced keto–enol tautomerism switches the hydrogen-bonding-mediated monomer activation reversibly ON and OFF, so the polymerization can be started, stopped, and steered from a distance while it runs.[9](https://www.nature.com/articles/s41929-018-0091-8) His RWTH faculty page describes the broader program: catalyst systems toggled between ON and OFF states let living polymerization and copolymerization be controlled by light.[10](https://www.chemie.rwth-aachen.de/cms/chemie/Die-Fachgruppe/Profil/Professorium-vol2/~lvtwk/Stefan-Hecht/)
## Xolography
Xolography, introduced in *Nature* in 2020, is a dual-color volumetric 3D printing technique that uses photoswitchable photoinitiators to induce local polymerization inside a confined monomer volume where light beams of different wavelengths intersect.[4](https://www.nature.com/articles/s41586-020-3029-7) A UV light sheet at 375 nm activates a dual-color photoinitiator, and a visible-light projection then triggers polymerization only in the intersection region, so the material hardens only where the two beams cross and whole objects form in one step.[11](https://doi.org/10.1002/adma.202410292) Compared with state-of-the-art volumetric methods, the reported resolution is about ten times higher than [computed axial lithography](https://www.edgepedia.org/computed-axial-lithography) without feedback optimization, and the volume generation rate is four to five orders of magnitude higher than two-photon photopolymerization.[4](https://www.nature.com/articles/s41586-020-3029-7) In 2019 Hecht cofounded xolo GmbH to further develop and commercialize the technology.[3](https://www.hechtlab.de/en/abouthecht.html)
## Representative work
The xolography paper, "Xolography for linear volumetric 3D printing", published in *Nature* in 2020 (volume 588, pages 620–624), demonstrated dual-color volumetric printing with the resolution and speed advantages above and established the photoswitchable dual-color photoinitiator on which the method rests.[4](https://www.nature.com/articles/s41586-020-3029-7) His review "Photoswitches: From Molecules to Materials", published in *Advanced Materials* in 2010, is among his most widely cited papers.[12](https://doi.org/10.1002/adma.200904102)
## Recent developments
His group has also reported "Solar Azo-Switches for Effective E→Z Photoisomerization by Sunlight" (*Angewandte Chemie International Edition*, 2024), and "Voltage-Gated Switching of Moiré Patterns in Epitaxial Molecular Crystals" (*ACS Nano*, 2024).[6](https://www.dwi.rwth-aachen.de/en/person/prof-stefan-hecht-phd) At the Center for the Science of Materials Berlin, a team led by Hecht has developed a light-based "molecular clamp" strategy, working with partners in Aachen and at the Max Planck Institute.[13](https://csmb.hu-berlin.de/molecular-clamp/)
## Honors and society memberships
Hecht was elected an ordinary member of the Academy of Europe (Academia Europaea) in 2020, in the Chemical Sciences section.[5](https://www.ae-info.org/ae/Member/Hecht_Stefan) He holds a 2025/2026 lectureship award whose symposium notice highlights xolography and its commercialization by his start-up company.[14](https://tschou.chem.sinica.edu.tw/20260401/)
## References
1. Stefan Hecht (0000-0002-6124-0222), ORCID. https://orcid.org/0000-0002-6124-0222
2. Prof. Dr. Stefan Hecht, Alexander von Humboldt Foundation. https://www.humboldt-foundation.de/en/connect/explore-the-humboldt-network/singleview/1073941/prof-dr-stefan-hecht
3. Prof. Stefan Hecht, Ph.D, HechtLab. https://www.hechtlab.de/en/abouthecht.html
4. "Xolography for linear volumetric 3D printing", *Nature* 588, 620–624 (2020). https://www.nature.com/articles/s41586-020-3029-7
5. Academy of Europe: Hecht Stefan. https://www.ae-info.org/ae/Member/Hecht_Stefan
6. Prof. Stefan Hecht, Ph.D., DWI – Leibniz Institute for Interactive Materials, RWTH Aachen. https://www.dwi.rwth-aachen.de/en/person/prof-stefan-hecht-phd
7. Stefan Hecht, Einstein Foundation Berlin. https://www.einsteinfoundation.de/en/fellows-projects/einstein-fellows-professors/einstein-professors/stefan-hecht
8. "Enlightening Materials with Photoswitches", *Advanced Materials* 32, 1905966 (2020). https://doi.org/10.1002/adma.201905966
9. "A photoswitchable catalyst system for remote-controlled (co)polymerization in situ", *Nature Catalysis* 1, 516–522 (2018). https://www.nature.com/articles/s41929-018-0091-8
10. Stefan Hecht, Fachgruppe Chemie, RWTH Aachen University. https://www.chemie.rwth-aachen.de/cms/chemie/Die-Fachgruppe/Profil/Professorium-vol2/~lvtwk/Stefan-Hecht/
11. "Xolography for Biomedical Applications: Dual-Color Light-Sheet Printing of Hydrogels With Local Control Over Shape and Stiffness", *Advanced Materials* (2024/2025). https://doi.org/10.1002/adma.202410292
12. "Photoswitches: From Molecules to Materials", *Advanced Materials* (2010). https://doi.org/10.1002/adma.200904102
13. "Molecular clamp", Center for the Science of Materials Berlin. https://csmb.hu-berlin.de/molecular-clamp/
14. Lectureship Award Symposium 2025-TCL. https://tschou.chem.sinica.edu.tw/20260401/
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Chemists › Researchers in polymer, supramolecular, and materials chemistry › Supramolecular chemistry and host–guest systems*
*Initially written Sep 20, 2026 · Edited: Oct 15, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license