CsPbBr ₃ Perovskite Nanocrystals for Photo-Electrochemical Supercapacitor Applications

Photosupercapacitors have been developed to enhance specific capacitance and also for constructing self-charging supercapacitors. As lead-halide perovskite nanocrystals (PNCs) possess better properties than their bulk structure due to unique optoelectronic properties, they can be considered a suitable electrode material for photosupercapacitor applications. In this work, CsPbBr 3 is prepared and its electrochemical performance under incident UV radiation is investigated. CsPbBr 3 PNCs achieved a high specific capacitance of 1154 mF g –1 (69.24 mF cm –2 ) at 5 mV s –1, which is increased by 4% (1200 mF g –1 ) after UV light exposure. Furthermore, the fabricated symmetric device is measured to have a high energy density of 7.1 mW h kg –1 at 843.5 mW kg –1 of power density after UV light exposure with 80% capacitance retention. The symmetric device showed a 10% increase in the capacitance values upon introduction of UV light. The increased specific capacitance is found to be a consequence of the increase in charge-carrier concentration, which improves ion insertion/absorption compared to the dark condition and is shown through analysis of the UV absorption spectra and ab initio calculations performed through density functional theory. Hence, CsPbBr 3 nanocrystals exhibit enhanced electrochemical performance under UV light and can be a viable candidate for next-generation photosupercapacitor applications.