Quasi 2D Ruddlesden–Popper perovskite thin film electrode for supercapacitor application: Role of diffusion and capacitive process in charge storage mechanism

Abstract

Hybrid halide perovskites are the most widely explored materials in the photovoltaic field. Recently they have been investigated for energy storage applications owing to their unique conductivity. Most reports on supercapacitor applications of halide perovskites are based on Methyl ammonium lead iodide (MAPbI3) and Methyl ammonium lead bromide (MAPbBr3) compounds. These halides are prone to degradation owing to external environmental parameters. Hence, one must look for other stable alternative halides. In this scenario, materials that can yield significant results with better stability are Quasi 2D perovskites, which combine the properties of both 3D and 2D perovskites. We successfully synthesized and characterized 4-Fluorobenzylammine hydroiodide spacer cation-based quasi 2D perovskite in this study. A detailed study was carried out on the effect of the precursor concentration and annealing temperature on the morphology and vertical growth of quasi-2D perovskite. An in-depth analysis of these perovskites' graded, phase-segregated growth was performed. Furthermore, we prepared a composite electrode from a mixture of quasi-2D perovskite with acetylene carbon black to obtain better performance. Our results show a maximum specific capacitance of 8.67 F g−1 from Cyclic Voltammetry curves. Further from the Galvanostatic Charge Discharge (GCD) curves, we obtained a capacitance of 3.39 F g−1. It is the highest value obtained for perovskite thin-film based supercapacitor electrode. The material displayed a low charge transfer resistance indicating a better conducting property, and displayed energy and power density of 170 mWh kg−1 and 109 W kg−1, respectively. Further, the contribution of capacitance and diffusion limited process in the charge storage mechanism of these electrodes were quantified. The electrodes could retain 91% capacitance after working for 1000 cycles, emerging as potential energy storage material for the future.