Dimensional engineering to simultaneously enhance energy density and stability of MAPbBr₃-based photo-rechargeable ion capacitors

Integrated solar photovoltaic and energy storage devices have gained a lot of attention due to their ease of implementation in portable electronic devices and remote sensors for smart cities and IoTs. Although hybrid halide perovskites are widely used in solar photovoltaics, they can also be used in rechargeable batteries and supercapacitors. Due to the bi-functional properties and mixed electronic-ionic conductivity, halide perovskite-based photo-rechargeable supercapacitors do not need additional photovoltaic cells to charge them. However, the major challenge in halide perovskite-based photo-rechargeable supercapacitors is the photo-stability and overall charge/energy storage efficiency of these devices. In this article, we have demonstrated that by dimensional engineering, halide perovskite-based supercapacitors can be made photo-stable with improved energy conversion and storage efficiency. Field emission scanning electron microscopy image analysis of 2D/3D heterostructure perovskite electrodes indicates that the mixed phases create a porous flex-like structure at the interface as compared to that of its pure compact phase. An optimum device with 10% 2D perovskite and 90% 3D perovskite can have 50% higher energy storage efficiency under illumination over the pure phase of halide perovskites. We have achieved an overall photo charging efficiency of similar to 0.03% under 70 mW cm(-2) light illumination. The charging potential is 1190 mV which is one of the highest for any kind of photorechargeable ion capacitor.