Photoelectrochemical and electrochromic properties of polyimide/graphene oxide composites

A series of novel multicolored near-infrared electrochromic polyimide (PI)-based composites with graphene oxide (GO) were prepared by using in situ polymerization. The prepared PI/GO composites are readily soluble in many organic solvents, and display outstanding thermal resistance, stably electrochromic characteristics, high coloration efficiency, short switching time, and anodic electrochromic behavior. Scanning electron microscope and transmission electron microscopy showed a good and uniform dispersion of the GO sheets in the PI matrix. The surface of the composites contains hydrophilic functional groups such as C-O and CO, which have been characterized by X-ray photoelectron spectroscopy. The typical, stable photoelectrical response showed that there was electron transfer in the interior of composites film under illumination, and the electrochemical impedance spectra result was consistent with the photoelectrical response. The different content of GO played a pivotal role in the electron transfer and regulated the conductivity of the composites. The work functions were obtained by KPFM measurements, and the work function is increasing with the contents increasing of GO in the composites. The properties prove that the composite is multipurpose material which will cater for photoelectric conversion and electrochromic application.