Water-Writing Pattern on PEDOT:PSS Inverse Opal Films through the Synergistic Effect of Morphology/Conformation Transition

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has received tremendous attention in the energy field owing to its high conductivity, ease of processing, biocompatibility, and low cost-effectiveness. Combining PEDOT:PSS and photonic crystals (PCs) is expected to promote the development of high-performance optoelectronic devices. The conductivity of PEDOT:PSS at present can only be measured through specific equipment, and the visualization of optoelectronic integration still remains a challenge. In this study, various patterned PEDOT:PSS inverse opal (PEDOT:PSS-IO) films are constructed by associating the conductivity of PEDOT:PSS with the structural color of PCs based on the synergistic effect of morphology/conformation transition, which achieves the visualization of optoelectronic integration. Morphology transition of the PEDOT:PSS-IO film alters from the interconnected to gradual closure pore structure, accompanied by an unusual blueshift of the stopband, which can be attributed to the collapse/reconstruction of the frame of the PEDOT:PSS-IO film. Conformation transition of PEDOT chains converts from the benzene to quinone structure, accompanying an enhancement of conductivity, which resulted from PSS removal and secondary doping. Under the induction of a polar solvent, the PEDOT:PSS-IO film brings the changes in optical/electrical dual-signals based on the synergistic effect of morphology/conformation transition. This phenomenon can be developed for the creation of a conductive PC pattern by using a polar solvent (water) as an ink, which is beneficial for the visualization of optoelectronic integration. This work provides essential significance for the fabrication of functional optoelectronic devices.