Molecular Photoswitches to Light-up Materials, Devices, and 3D-Printing

The ability to use light to control and power advanced materials and devices in a dynamic

fashion with high spatial and temporal resolution offers tremendous opportunities. For this

purpose, molecular photoswitches that undergo reversible changes upon illumination have

taken center stage and become key ingredients. 1 To develop them into high-performing

materials and practical applications, the switching processes must be highly efficient and

reliable and therefore necessitate continuing optimization of key parameters. These

involve spectral separation and selective addressability in attractive wavelength regions

that enable sufficient light penetration, high quantum yields for switching in both directions,

enhanced (photo)chemical resistance enabling highly repetitive switching without fatigue,

among others. Most importantly, the photoswitchable system has to undergo significant

changes of a desired physicochemical property to maximize its overall achievable

modulation.

This presentation will introduce the design principles of molecular photoswitches and

highlight various examples from our laboratory that illustrate their use to control material

properties and device function. Particular emphasis will be on xolography as a new

volumetric 3D printing method based on photoswitchable photoinitiators recently

developed 2 and commercialized by the start-up company xolo. 3

1. Goulet-Hanssens, A.; Eisenreich, F.; Hecht, S. Adv. Mater. 2020, 32, 1905966.

2. Regehly, M.; Garmshausen, Y.; Reuter, M.; König, N. F.; Israel, E.; Kelly, D. P.; Chou,

C.-Y.; Koch, K.; Asfari, B.; Hecht, S. Nature 2020, 588, 620-624.

3. www.xolo3d.com