Benzothiazole-conjugated perylene diimide/functionalized reduced graphene oxide composite electrode for flexible supercapacitors

The development of flexible devices based on organic small molecules (OSMs) will be a crucial advantage in modern portable and wearable electronic appliances. In this work, we investigate the energy storage capacity of benzothiazole functionalized perylene diimides such as 2,9-bis(6-methoxybenzo d thiazol-2-yl)anthra2,1,9-def:6,5,10-d'e'f' diisoquin oline-1,3,8,10(2H,9H)-tetraone (PDI-BTH1) and 2,9-bis(6-hydroxybenzo d thiazol-2-yl)anthra2,1,9-def:6,5,10-d'e'f' diisoquinoline-1,3,8,10(2H,9H)-tetraone (PDI-BTH2)-reduced graphene oxide (rGO) composite-based electrode materials. The PDI-BTH1/rGO and PDI-BTH2/rGO- based three-electrode supercapacitor (SC) device delivered excellent specific capacitance ( C sp ) of about 350 and 295.92 F g −1 at 1 A g −1 current density. The presence of the methoxy (–OCH 3 ) group in the organic molecular skeleton influences the C sp of the electrode in the SC device. Moreover, in two-electrode PDI-BTH1/rGO//PDI-BTH1/rGO symmetric supercapacitor devices at 0.5 A g −1 offers remarkable C sp of 321.08 F g −1 and outstanding energy density (ED) of 57.79 Wh kg −1 at 1079.37 W kg −1 power density (PD) with impressive cycling stability of 106.74% after 10000 gravimetric charging and discharging (GCD) cycles. Furthermore, the flexible device has been developed by depositing the PDI-BTH1/rGO electrode layer on graphite foil (GF). By assembling the PDI-BTH1/rGO//PDI-BTH1/rGO on a graphite foil (GF) surface in two-electrode flexible symmetric supercapacitor (FSSC) devices, the electrochemical performance was measured. The electrochemical studies showed that the FSSC device with its two structures with bending angles of 0° and 180° exhibits an excellent C sp of 66.40 mF cm −2 and 57.90 mF cm −2 , respectively, at 0.5 mA cm −2 . After 5000 GCD cycles, both the FSSC devices with 0° and 180° bending angles exhibited excellent cycling stability with 94.98% and 84.55% C sp retention. The flexible flat SSC device displayed ED of 11.95 μWh cm −2 at 1.66 mW cm −2 PD. Therefore, these FSSC devices represent significant potential for electronics.