State-of-the-art Electronic Engineering of Emerging PVs for Indoor IoT Applications

The Internet of Things (IoT) consists of a vast network of web-enabled smart gadgets, such as sensors, detectors, remote actuators, and radio frequency identification (RFID) devices, which are small devices that gather, transmit, and process data obtained from their surroundings via embedded systems. However, powering these devices over the past decades has posed a challenge due to the explosive growth of the IoT device ecosystem, which has reached billions of units. Efficient and reliable energy harvesting circuits are designed to make indoor, low-power IoT devices energy-autonomous under scarce illumination. This approach eliminates replaceable batteries and the workforce required for IoT device maintenance. This progress report explores how indoor energy harvesting is made to be self-sustainable by using both established and emerging photovoltaics (PVs), such as silicon (Si), dye-sensitized solar cells (DSSCs), organic photovoltaics (OPVs), and perovskite solar cells (PSCs). Optimizing system designs is crucial to maximizing indoor energy harvesting and utilization from available light sources. Thus, simulations, experimental setups that use off-the-shelf components, and chip prototypes are all employed to verify the operation and performance of the energy harvesting system. While a few articles cover all aspects of complete indoor energy harvesting systems, many sources concentrate solely on specific aspects such as PV materials, maximum power point tracking (MPPT), or energy storage (batteries, supercapacitors (SC)), and the low power consumption of the system. This review explores energy harvesting systems from devices to electronic circuits, offering a comprehensive perspective on their potential and focuses on bridging PV materials and low-power electronic design with IoT application needs. Highlighting examples of self-powered IoT applications operating under indoor illumination gives readers a broader understanding of how emerging PV technologies can enable sustainable IoT solutions. Future research should explore novel materials for higher performance, scalable fabrication methods and development of advanced MPPT algorithms to enhance self-powered IoT applications.