A light harvesting supercapacitor and a method of preparing the light harvesting supercapacitor is disclosed. The light harvesting supercapacitor includes a transparent conducting substrate, an active layer including TiO2 nanoparticles and polyaniline (PAM) nanoparticles disposed on the transparent conducting substrate, an electrolyte layer including a solid separator soaked with an electrolyte comprising polyvinyl alcohol and at least one ionic material selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, an alkali metal phosphate salt, an alkali metal sulfate salt, an alkali metal hydroxide, an alkali metal halide, and a mixture of a halogen and an alkali metal halide disposed on the active layer, a carbon electrode disposed on the electrolyte layer, and a metal layer disposed on the activated carbon electrode. The light harvesting supercapacitor of the present disclosure can be used in a photovoltaic device.