Highly transparent to red/green/blue photo-crosslinkable polymer for patterned electrochromic device

Abstract

Polymer-based electrochromic materials have potential application prospects in the field of displays, but the lack of a highly transparent state to red/green/blue color state limits their development and commercial applications. Herein, it is proposed to design and synthesize photo-crosslinkable polymers based on different donor or acceptor groups modified phenothiazine or triphenylamine as electrochromic units and cinnamate as photo-crosslinking units. The influences of different donor or acceptor groups, such as phenyl and methoxy, on the electrochemical and spectroelectrochemical behavior of the polymers are clarified in order to achieve neutral, highly transparent states and red/green/blue colors in the oxidation states without the intermediate color state. The crosslinkable system inside the polymer changes its intrinsic soluble characteristic into a solvent-resistant property, thus resulting in a stable polymer film via the UV irradiation method. Hence, an all-solid-state electrochromic device was fabricated by separately utilizing three photo-crosslinkable polymer films as an electrochromic layer, which shows obvious reversible electrochromism with the “RGB” patterns, demonstrating it as a candidate for electronic paper and electronic tags.