Transfer-Printed PEDOT:PSS on Stretchability-Enhancing, Biodegradable PVA Substrates towards Stretchable OECTs

Extensive efforts have been invested in advancing flexible devices¹, including biosensors, optoelectronic devices, organic field effect transistors (OFETs), light emitting diodes (LEDs) and organic electrochemical transistors (OECTs)². Building on these achievements, stretchable electronic devices have evolved within the last decade^3,4. To further advance and fully exploit the next generation of stretchable electronics, the innovation of novel device fabrication processes and materials is needed. Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) stands out as a popular material in bioelectronic applications due to its high conductivity, optical transparency, mechanical resilience, commercial availability and biocompatibility. Consequently, significant efforts have been undertaken to transform PEDOT:PSS from a brittle into a flexible and stretchable material. Conventional approaches involve the addition of chemicals such as ionic liquids⁵, surfactants, plasticizers and other organic additives⁶.<br/>Here, we propose an alternative approach towards stretchable electronics: rather than inducing stretchability through such additives, we demonstrate that the mechanical properties of PEDOT:PSS can be adjusted by utilizing diffusion-active substrates. The substrates are infused with a plasticizer that diffuses into the PEDOT:PSS, modifies its glass transition temperature and consequently leads to an enhanced stretchability and an increased conductivity. Chain-alignment and -mobility during elongation are evidenced by a higher crack-on-set-strain (&gt;150%) and an increased conductivity upon strain. A comprehensive (concentration-dependent) analysis, including electrical measurements, atomic force microscopy, and Raman spectroscopy, was undertaken to study the substrate- and PEDOT:PSS-chain alignment upon strain and was correlated with the concentration-dependent diffusion of the plasticizer.<br/>This novel approach towards stretchable electronics is furthermore compatible with our recently developed transfer-printing method for (plasma-patterned) electronic devices and finally led to the successful fabrication of intrinsically stretchable organic electrochemical transistors on biodegradable substrates.<br/><br/>1) Y. Luo, X. Chen et al.: ACS Nano 2023, 10.1021/acsnano.2c12606 2) S. Zhang, F. Cicoira et al.: Chem. Mater. 2017, 10.1021/acs.chemmater.7b00181 3) S. Wang, Z. Bao et al.: Nature 2018, 10.1038/nature25494 4) N. Matsuhisa, T. Someya et al.: Chem. Soc. Rev. 2019, 10.1039/C8CS00814K 5) N. Kim, K. Tybrandt et al.: Nature Commun. 2020, 10.1038/s41467-020-15135-w 6) H. He, J. Ouyang et al.: Marcomolecules 2021, 10.1021/acs.macromol.0c0230