Effect of Zn on nanoscale quaternary Cu2ZnSnS4thin film electrodes for high performance supercapacitors

•Absorber layer of Cu2ZnSnS4thin films were deposited with different Zn concentration by SILAR method.•SEM and AFM images reveal uniform spherical like particles distribution, rough surface of the film, and the range of the particle size is 18.2 to 146 nm.•Optimized film has been examined by photo-electrochemical technique and the efficiency was obtained as 1.678%.•This obtained maximum specific capacitance is 165.04 f g−1at 1 A g−1.•Binder free optimized Cu2ZnSnS4thin film electrode has exhibit maximum energy density of 5.73 Wh Kg−1and power density of 3124.99 W Kg−1.