Energy Harvesting and Storage with a High Voltage Organic Inorganic Photo-Battery for Internet of Things Applications

Integrated local energy harvesting and storage is a critical prerequisite for energy autonomy of distributed sensing arrays required for the implementation of the internet of things (IoT). In this context, the monolithic integration of solar cells with metallic lithium-based batteries into stacked high voltage photo-batteries allows to provide said energy autonomy, with the smallest possible footprint and the highest resource efficiency. However current photo-battery designs require additional electronics to control and match power output like maximum power point (MPP) tracking and overcharge protection. Herein a novel and compact monolithic photo-battery design is provided, advantageously combining an organic solar cell with a NMC 622 versus metallic lithium-based battery, matched in terms of VOC and cut-off voltage, thereby achieving photo-charging without any control electronics and energy release on demand at a very compact footprint of only 2.5 cm x 2.5 cm x 0.2 cm. Additionally, by applying a power profile simulating a temperature and humidity sensor over the course of a 24 h light and dark cycle, real world applicability of the photo-battery in this type of applications is demonstrated. The provided design of a mode II photo-battery combines an organic solar cell (OSC) with a NMC 622-based battery with a very compact footprint of only 2.5 cm x 2.5 cm x 0.2 cm, capable of delivering a discharge power of more than 1 mW with a nominal battery capacity of only 1.53 mAh, enabling truly energy autonomous small sensors.image (c) 2024 WILEY-VCH GmbH