Fully Screen‐Printed Stretchable Organic Electrochemical Transistors

Stretchable organic electrochemical transistors (OECTs) are promising for wearable applications within biosensing, bio‐signal recording, and addressing circuitry. Efficient large‐scale fabrication of OECTs can be performed with printing methods but to date there are no reports on high‐performance fully printed stretchable OECTs. Herein, this challenge is addressed by developing fully screen‐printed stretchable OECTs based on an architecture that minimizes electrochemical side reactions and improves long‐term stability. Fabrication of the OECTs is enabled by in‐house development of three stretchable functional screen‐printing inks and related printing processes. The stretchable OECTs show good characteristics in terms of transfer curves, output characteristics, and transient response up to 100% static strain and 500 strain cycles at 25% and 50% strain. The strain insensitivity of the OECTs can be further improved by strain conditioning, resulting in stable performance up to 50% strain. Finally, an electrochromic smart pixel is demonstrated by connecting a stretchable OECT to a stretchable electrochromic display. It is believed that the development of screen‐printed stretchable electrochemical devices, and OECTs in particular, will pave the way for their use in wearable applications and commercial products.