Anthraquinone-functionalized polyurethane designed for polymer electrochromic and electrical memory applications

Novel electroactive functional polyurethane PU(IPDI-AQ-EG) with anthraquinone moiety in the backbone is synthesized and characterized. Due to the stable redox behaviors from spectroelectrochemical tests, PU(IPDI-AQ-EG) film is used to prepare electrochromic device with ITO/PU(IPDI-AQ-EG)/gel electrolyte/ITO structure, which shows well-behaved electrochromic properties with obvious color contrast when applied the external potentials from 0 to − 2.0 V. Moreover, electrical memory devices with configuration of ITO/PU(IPDI-AQ-EG)/Al are successfully fabricated via convenient spin-coating process. Current–voltage sweeps between the two electrodes indicate this type of device exhibits typical resistive switching performance with the function of flash memory. The devices can operate at low threshold voltages (write voltage of − 2.7 V and erase voltage of + 2.8 V) with a high ON/OFF current ratio up to 105. The retention time of both conductivity states can be maintained as long as 3000 s without obvious deterioration. It has been demonstrated that the anthraquinone group serving as good electron-withdrawing site in the polymer backbone has a strong influence on the resistive switching characteristics. Preliminary results reveal that the obtain polyurethane PU(IPDI-AQ-EG) is a promising multi-functional material that can be applied in both polymeric electrochromic and memory devices.