Integration of solar cells with hierarchical CoSx nanonets hybrid supercapacitors for self-powered photodetection systems

We have developed a self-powered integration system consisting of a-Si:H solar cells as the energy generation device, CoSx hybrid supercapacitors (HSCs) as the energy storage device and ZnO photodetectors as the energy consumption device. The CoSx HSC plays a crucial role in determining the system performances. By elaborately designing hierachical 3D CoSx nanonets as the faradic electrode, the specific capacity reaches 225 mAh g(-1) at a current density of 0.6 A g(-1). The HSCs assembled with the CoSx faradic electrode and active carbon capacitive electrode have a high energy density of 32 Wh kg(-1), high power density of 6.61 kW kg(-1) and long-term cycling lifetime. The CoSx HSC can be charged to 0.85 V by the a-Si:H solar cell under AM 1.5 G illumination and serves as a stable power supply for driving ZnO photodetector. The CoSx HSC not only acts as a buffer to diminish the solar energy fluctuations, but also provides a strategy for designing self-powered detector systems. The integration system exhibits a stable photoelectric conversion, excellent storage characteristic and sensitive photoelectric response, verifying the feasibility and potential applications. This study is expected to offer a basic guideline for designing self-powered and environment-friendly systems.