A Complete Fully Thin-Film PV Harvesting and Power-Management System on Plastic With On-Sheet Battery Management and Wireless Power Delivery to Off-sheet Loads

Large-area electronics enables the creation of systems with transformational capabilities and form factors. Through the ability to integrate thin-film photovoltaics, batteries, and active transistors, complete power-management subsystems addressing a wide range of applications can also be created. We present, for the first time, a fully flexible system integrating amorphous silicon (a-Si) solar modules with Li-ion thin-film batteries and circuits that are based on a-Si thin-film transistors for battery management and wireless power delivery. A fabricated prototype of the entire system on a plastic sheet is demonstrated. Using a 240 cm(2) solar module under indoor lighting conditions (similar to 400 mu W/cm(2)), the system is measured to provide 1) dc power (similar to 1 mW) to on-sheet loads and 2) ac power (similar to 10 mW) to off-sheet loads through wireless transmission. Four Li-ion batteries are used for on-sheet energy storage with a battery-management system ensuring discharging at permissible levels, while imposing minimal off-state current (<360 nA).