LAUSR

Abstract Ytterbium sulfide (Yb2S3), graphene oxide (GO), and graphene oxide/ytterbium sulfide (GO/Yb2S3) composite thin films were synthesized by binder-free successive ionic layer adsorption and reaction (SILAR) method. Formation of Yb2S3, GO and GO/Yb2S3 composite thin films was confirmed by XRD and XPS techniques. Surface morphology and particle size of these films were observed through FE-SEM and TEM analyses. All thin films showed hydrophilic nature. The Yb2S3, GO and GO/Yb2S3 composite thin films exhibited the maximum specific capacitance of 181, 193 and 376 F g−1, respectively in 1 M Na2SO4 electrolyte at scan rate of 5 mV s−1. The flexible solid state supercapacitor (FSS-SSC) symmetric device was fabricated with GO/Yb2S3 composite electrodes as an anode and a cathode and a flexible solid state asymmetric supercapacitor (FSS-ASC) device were fabricated with GO/Yb2S3 as an anode and MnO2 as a cathode electrode with the PVA-Na2SO4 gel electrolyte. The FSS-SSC device showed specific capacitance 58 F g−1, energy density 23 Wh kg−1 and power density 0.43 kW kg−1. The FSS-ASC device showed specific capacitance 92 F g−1, energy density 42 Wh kg−1 and power density 0.84 kW kg−1. Both FSS-SSC and FSS-ASC devices showed coulombic efficiency of 88 and 79% for 10,000 GCD cycles, respectively. The FSS-ASC device showed better performance than the FSS-SSC device. The FSS-ASC device showed better performance than the FSS-SSC device.