Bismuth-based organometallic-halide perovskite photo-supercapacitor utilizing novel polymer gel electrolyte for hybrid energy harvesting and storage applications

The quest for a hybrid device that combines the functionalities of energy harvesting of solar cells and energy storage of supercapacitors is of great significance for smart electronics and wearable gadgets applications. Metal halide perovskite materials possess the unique dual properties of light absorption and capacitive charge storage. In this work, we fabricated MBI:CPH-G photo-supercapacitor using symmetric lead-free methylammonium bismuth triiodide (MBI) photo-capacitive electrodes. A novel polymer CPH-G gel electrolyte was sandwiched between the electrodes. Field emission scanning electron microscopy (FE-SEM) reveals the presence of nanopores on the structure of the MBI photo-capacitive material. The nanopores benefit the photo-supercapacitor by providing additional sites for electrolyte penetration into the MBI photo-capacitive electrodes. The CPH-G gel electrolyte functional groups were investigated by Fourier transform infrared spectroscopy (FT-IR), while its conductivity and voltage window were determined by electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV), respectively. The electrochemical energy storage performance of the MBI:CPH-G photo-supercapacitor under dark and light operating conditions was investigated using cyclic voltammetry (CV) and EIS. Modified Dunn's equation was developed, utilized to decouple the light-induced, capacitive-controlled and diffusion-controlled energy storage mechanisms. The dominance of capacitive-controlled mechanism was observed under dark working conditions, while light-induced mechanism was responsible for the highest contribution under light functioning condition. About 1275 % light-induced energy density enhancement was recorded for the MBI:CPH-G photo-supercapacitor. The device shows excellent cyclic charge-discharge stability, retaining 94.79 % of its initial capacitance after 5000 cycles.