Multilayered Poly(<i>p</i>‑phenylenevinylene)/Reduced Graphene Oxide Film: An Efficient Organic Current Collector in an All-Plastic Supercapacitor

This article describes the preparation, using layer-by-layer deposition techniques, of an all-solid-state flexible in-plane supercapacitor based on a poly­(ethylene terephthalate) (PET) substrate, laminated with two strata of ultrathin multilayer films composed of 30 polyaniline (PANi)/reduced graphene oxide (RGO) bilayers and 30 poly­(<i>p</i>-phenylenevinylene) (PPV)/RGO bilayers. The influence of the (PPV/RGO)₃₀ stratum on the electrochemical properties of the (PANi/RGO)₃₀/(PPV/RGO)₃₀ film (denoted P30) (<i>d</i> = 90.1 nm) supported on a PET was evaluated and compared to the corresponding influence of the (PANi/RGO)₅₃ film (denoted P53) (<i>d</i> = 91.5 nm). The volumetric capacitance of P30 at a discharge current of 20 A/cm³ (957 F/cm³) was much higher than that obtained from P53 (733 F/cm³), indicating that the (PPV/RGO)₃₀ film performed well as a current collector. Furthermore, an all-solid-state flexible in-plane EC assembled with P30 electrodes in parallel mode (denoted EC30) exhibited an outstanding volumetric capacitance (152 F/cm³ at 20 A/cm³) with a high energy density (9.4 mW h/cm³) and power density (6.5 W/cm³), compared to EC53 (assembled with P53). The electron-transfer resistance of the P30 electrode corresponded to only 59% of the P53’s value (1.53 vs 2.60 kΩ cm²). The high capacitance of EC30 was attributed to the low internal resistance of P30, which resulted from the presence of additional in-plane electrical pathways in the electrode. The enhanced transport led to 85% capacitance retention by EC30 (69% for EC53) after a 1000 charge/discharge cycles test. The series resistance variations (Δ<i>R</i>/<i>R</i>₀) of EC30 also indicated good electromechanical durability in the device, with a 5.0% increase in the resistance (contrasted with a 10.8% increase in EC53) over 1000 bending cycles at a minimum radius of 5 mm. The excellent electrochemical properties of EC30 may potentially meet the requirements for miniaturized electrodes in the manufacture of flexible, lightweight, mechanically durable microelectronic applications