2, InnovationLab, Heidelberg, , Germany
3, POLYMAT, University of the Basque Country UPV/EHU, San Sebastian, , Spain
4, Bioelectronics Laboratory, University of Cambridge, Cambridge, , United Kingdom
Electrofluorochromic devices (EFCD) receive increasing attention in investigation in the past years, because they offer the possibilities for various optical devices. Besides that, the little power consumption, the low voltage requirement and simple device architecture (i.e. electrochemical cell) provide the opportunity for low-cost display devices. To provide a cost-effective method with the freedom of design necessary for smart windows and display applications, inkjet printing can be used as a suitable method with high through-put, low-material waste and up-scaling capabilities to industrial fabrication. These exceptional properties can be extended with the use of biocompatible and biodegradable materials for their use in medical applications or to reduce the waste after usage to a minimum.
Here, we report on inkjet-printed electro(fluoro)chromic devices consisting of biocompatible and biodegradable components on biodegradable deformable gelatin substrates. To simplify the device architecture for the inkjet printing process we chose a parallel electrode configuration with PEDOT:PSS as electrode material. We used two different solid polymer electrolytes, one on the basis of gelatin coated from water and the other on the basis of Poly(D,L-lactide-co-glycolide) (PLGA) from a Dimethyl sulfoxide (DMSO) solution, whereby all of these polymers and solvents are biodegradable and biofriendly. As ionic species we used tetrabutylammonium bis-oxalato borate (TBABOB) which was developed as a non-fluorinated biodegradable salt. The electro(fluoro)chromic layers were made out of two different polymer derivatives consisting triarylamine, namely polyindenofluorene-8-triarylamine (PIF8-TAA) and polytriarylamine (PTAA). The fabricated devices exhibit a sufficient contrast, efficiency and lifetime to be used in deploy-and-forget or short-lifecycle applications with potential use in disposable consumer and health care biofriendly disposable applications.