A High-Performance Photocapacitor by Potential Energy Window Modulation Enabling a Coupling Efficiency of 95.8%

Abstract

With the development of the Internet of Things and wearable devices, flexible photocapacitors capable of both energy harvesting and storage have attracted significant attention. However, issues such as low overall conversion efficiency, poor stability, and low energy density in flexible devices urgently need to be addressed. In this work, a self-charging photocapacitor is designed by integrating a flexible quasi-solid-state supercapacitor with two silicon solar cells connected in series, and the matching conditions between photovoltaic conversion unit and energy storage unit are optimized. The best-performing photocapacitor achieve an coupling efficiency of 95.84%, a joule efficiency of 76.90%, and an overall conversion efficiency of 13.44%, with a high specific capacitance (149.3 mF cm−2) and an excellent energy density (19.3 mWh cm−2), along with great stability in photo-charging/dark-discharge cycles. This study provides new insights for the current research on flexible self-powered systems.

Keywords: Photocapacitor, Supercapacitor, Silicon solar cell, potential energy window, modulation