Highly Transparent Conducting Nanopaper for Solid State Foldable Electrochromic Devices

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 12; no. 46; pp. 6370 - 6377
• Main Authors: Kang, Wenbin, Lin, Meng-Fang, Chen, Jingwei, Lee, Pooi See
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 01-12-2016; Wiley Subscription Services, Inc
• Subjects: Deformation; Devices; electrochromics; Electrochromism; Electrodes; Electronics; foldable electronic devices; Folding; nanopaper; Nanostructure; Nanotechnology; Solid state; transparent conductive electrodes; nanopaper; transparent conductive electrodes; foldable electronic devices; electrochromics
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201600979

It is of great challenge to develop a transparent solid state electrochromic device which is foldable at the device level. Such devices require delicate designs of every component to meet the stringent requirements for transparency, foldability, and deformation stability. Meanwhile, nanocellulose, a ubiquitous natural resource, is attracting escalating attention recently for foldable electronics due to its extreme flexibility, excellent mechanical strength, and outstanding transparency. In this article, transparent conductive nanopaper delivering the state‐of‐the‐art electro‐optical performance is achieved with a versatile nanopaper transfer method that facilitates junction fusing for high‐quality electrodes. The highly compliant nanopaper electrode with excellent electrode quality, foldability, and mechanical robustness suits well for the solid state electrochromic device that maintains good performance through repeated folding, which is impossible for conventional flexible electrodes. A concept of camouflage wearables is demonstrated using gloves with embedded electrochromics. The discussed strategies here for foldable electrochromics serve as a platform technology for futuristic deformable electronics.
By leveraging the unique surface properties of nanocellulose, foldable nanopaper electrode with outstanding electro‐optical performance is achieved. A fully foldable transparent solid state electrochromic device based on this mechanically compliant transparent conductor with excellent stability against folding is realized. The foldable transparent electrode as well as the foldable device may find broad applications for futuristic wearable and portable electronics.