Development of stable and optically active composite film that can show efficient supercapacitor activity is a challenging research interest in material science. A polymer nanocomposite film composed of a green synthesised graphene quantum dot (GQD, G) doped polyacrylonitrile (PAN) and polyaniline (PANI) systems, designated as PAN-PANI@G, have been prepared. The critical loading concentration of prepared composite and its effect on the physicochemical, optical and electrical analysis were systematically studied in detail. PAN-PANI@G composite showed an appreciable electrical conductivity (2.362 x 10(-6) S m(-1)) and optical absorbance at A lambda(max) similar to 270 nm. Physicochemical characterizations by XRD, FTIR and TEM analysis reveal chemical interaction between the individual components via intermolecular hydrogen bonding. Analysed particle size of GQD in the polymer membrane was found to be about two times lesser than that of the pure GQD highlighting synergic interaction between the individual GQD and PAN/PANI matrix. A specific capacitance value of the polymer composites that have been modified on screen-printed carbon electrode were tested by cyclic voltammetric and galvanostatic charge-discharge techniques in 0.1 M H2SO4 solution. Calculated supercapacitor values at an applied current density, 670 mA g(-1)- are in a range of 105-587 F g(-1) cm(-2) which are approximately 2-1300 times higher than the values reported for polypyrrole and polyaniline based polymer composite film in the literature. As a preliminary extension of this study, the optimal PAN/PANI@G nanocomposite of GQD loading, 1.5 wt% was extended to prototype supercapacitor cell application in combination with a dilute solution of NaCl along with suitable conducting plates. When 3 V DC power was supplied for 4 min, the prototype cell produced an operating voltage of 1.4 V for 1 h of operating time. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.