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, CsPbBr3 is prepared and its electrochemical performance under incident UV radiation is investigated. CsPbBr3 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, CsPbBr3 nanocrystals exhibit enhanced electrochemical performance under UV light and can be a viable candidate for next-generation photosupercapacitor applications.