The project set out to create an electrochromic casting resin that could be used to produce actively switching, highly stable glass composites without the need for energy‑intensive vapor deposition or sputtering steps. By modifying commercially available transparent, highly adhesive casting resins, the team was able to introduce sufficient electrical conductivity while preserving the original optical clarity and bonding strength. The modified resin already contains the precursor monomer of the electrochromic dye. After the resin is UV‑cured into a glass composite, the monomers are electrochemically polymerised on a fluorine‑doped tin oxide (FTO) coated glass surface. The resulting conjugated polymer films switch reversibly between a colourless and a coloured state when a small polymer‑specific voltage of less than 2.0 V is applied. This low‑voltage operation is a key advantage for practical applications in shipbuilding and architecture, where power consumption and safety are critical.

The mechanical performance of the electrochromic composites matches that of conventional, non‑electrochromic casting‑glass composites. The resin’s adhesive properties remain unchanged, ensuring that the glass panels can withstand the loads required in marine and building environments. Importantly, the process can be integrated into existing industrial workflows: the resin is applied by standard dip‑coating or other scalable coating techniques, cured by UV light, and then the electrochromic layer is formed in situ. This eliminates the need for separate deposition steps such as spin‑coating, Langmuir‑Blodgett, or sputtering, which are difficult to scale to large areas.

Scalability was demonstrated by producing large‑area glass panels of up to 1.2 m². The dip‑coating approach allows uniform film deposition over such dimensions without the thickness variations that typically plague spin‑coating. The electrochemical polymerisation step is performed on the finished composite, so the polymer layer is deposited directly onto the glass substrate, avoiding the formation of insoluble precipitates that would otherwise require additional processing. The resulting panels exhibit stable, reversible colour change, high optical transparency in the off state, and robust adhesion, making them suitable for use as smart windows or protective coatings.

The collaboration that enabled these advances involved Fraunhofer Institute for Applied Polymer Research (IAP), SolEchrom GmbH, and TILSE GmbH. Fraunhofer IAP provided expertise in polymer chemistry and casting‑glass technology, SolEchrom contributed knowledge of electrochromic materials and device integration, and TILSE GmbH supplied industrial scale‑up capabilities and process engineering. The project ran over a period of three years, during which the partners iterated resin formulations, conducted electrochemical characterisation, and performed mechanical testing. Funding was secured through a German research programme that supports the development of advanced materials for the maritime and architectural sectors, ensuring that the technology could be transferred to industry partners for commercial deployment.