Enhanced Energy Density in All-in-One Device Integrating Si Solar Cell and Supercapacitor Using [BMIm]Cl/PVA Gel...

All-in-one systems integrating solar cells and supercapacitors have recently received significant attention because of their high efficiency and portability. Unlike conventional solar photovoltaics, which require external wiring to connect to a battery for energy storage, integrated devices with solar cells and supercapacitors share one electrode, eliminating wiring resistance and facilitating charge transfer. In this work, we designed and fabricated all-in-one devices by combining a silicon solar cell and a supercapacitor with polymer gel electrolytes. Our all-in-one devices incorporating H₃PO₄/PVA and [BMIm]Cl/PVA exhibited areal capacitances of 452.5 and 550 mF·cm ^-2 at 0.1 mA·cm^-2, respectively, following 100 s of photocharging. Notably, the [BMIm]Cl/PVA-based all-in-one device demonstrated significantly higher maximum energy density and power density compared to both the H₃PO₄/PVA-based all-in-one device and the values reported in literature. In addition, the cyclic photocharge/galvanostatic discharge process for the [BMIm]Cl/PVA-based all-in-one device represented consistent retention of areal capacitance, affirming its stability across charge-discharge cycles. After 100 s of photocharging, the [BMIm]Cl/PVA-based all-in-one device achieved a total energy efficiency of 1.85%, surpassing the 1.45% efficiency observed in the device using H₃PO₄/PVA. These results provide valuable insights for the design of self-charging all-in-one devices for portable and wearable applications.