High‐Voltage Energy Harvesting and Storage System for Internet of Things Indoor Application

Abstract

On the path toward independence from fossil fuels, solar energy is the most promising solution, but it needs a robust and reliable storage system to face its intrinsic fluctuations due to location, day cycle, and weather. The integration between energy harvesting and storage (H&S) technologies is a must toward clean energy production, and it becomes even more appealing considering the possibility of producing electricity not only from direct sunlight but also from diffuse light and indoor illumination. Herein, a dye‐sensitized solar module (DSSM) developed to harvest indoor illumination and directly store it into an electrical double‐layer capacitor (EDLC) is presented. Five series‐connected dye‐sensitized solar cells are fabricated on the same substrate and the module is integrated with a high‐voltage EDLC. The integrated device is characterized under indoor light sources such as light emitting diodes and fluorescent lamps. The results show one of the highest efficiencies ever reported for a high‐voltage DSSM under indoor illumination (16.27%), the largest voltage window ever reported for an indoor H&S device based on DSSM and EDLC—up to 3 V—and an overall photoelectric conversion and storage efficiency of 9.73% under indoor illumination.