Direct Water‐Writing/Electroerasing Pattern on PEDOT Inverse Opals

Abstract This work presents a reversible direct water‐writing/electroerasing pattern on poly(3,4‐ethylene dioxythiophene) inverse opals (PEDOT‐IOs). The PEDOT‐IO‐0 is fabricated by potentiostatic polymerization of EDOT such that PEDOT infiltrates the interstices of a photonic crystal (PC) template, and the template is subsequently removed. The PEDOT‐IO‐I is obtained by reducing PEDOT‐IO‐0. There are four states and three different switches of PEDOT‐IOs: the first switch is the irreversible reduction of PEDOT‐IO‐0 to PEDOT‐IO‐I (neutral state). The second switch is the reversible electrochemical process between neutral and oxidized PEDOT‐IO‐I accompanied by a reversible stopband shift owing to ionic doping/dedoping. The third switch is the water treatment process of PEDOT‐IO‐I (oxidation state) to form PEDOT‐IO‐II, which induces a blueshift in the stopband owing to water‐induced removal of ions and shrinkage of the periodic structure. Combining the switches of PEDOT‐IO‐I and PEDOT‐IO‐II, a reversible water‐writing/electroerasing procedure is realized in the full‐solid state, producing multicolor patterns by water (a friendly ink) writing at different times. The as‐prepared PC pattern could be erased electrochemically. Reversible e‐paper can be successfully achieved based on the switches of PEDOT‐IOs, providing a novel method for the fabrication of functional optic materials.