Flexible Metal-Free Memory Electronic Made of π-Conjugation-Interrupted Hyperbranched Polymer Switch and Reduced Graphene Oxide Electrodes

A flexible metal-free flash memory device with reduced graphene oxide films as electrodes and diarylfluorene-based π-conjugation-interrupted hyperbranched polymers (CIHPs) as active switches is reported. Two CIHPs, named PCzPF and PCzPF-PF, are synthesized via BF₃•Et₂O-catalyzed fluorenol’s Friedel–Crafts reaction, where the PCzPF-PF is designed by the decoration of hindrance functional groups, i.e., bulky 9-phenyl-fluorenyl (PF) moieties, at the end-groups of PCzPF. Both of the two CIHPs exhibit excellent solubility and thermal stability. The PCzPF-based device exhibits no switching effect while the PCzPF-PF-based device shows a flash type memory effect, indicating the incorporation of PF groups plays a critical role in realizing electrically bistable behaviors. In particular, the optimized memory exhibits a high ON/OFF ratio of > 3.0 × 10³, long retention time of up to 1.2 × 10⁴ s, and high mechanical stability. This work opens a new avenue for metal-free memory electronics through a low-cost and full-solution process approach.