Integrated all-silicon thin-film power electronics on flexible sheets for ubiquitous wireless charging stations based on solar-energy harvesting

With the explosion in the number of battery-powered portable devices, ubiquitous powering stations that exploit energy harvesting can provide an extremely compelling means of charging. We present a system on a flexible sheet that, for the first time, integrates the power electronics using the same thin-film amorphous-silicon (a-Si) technology as that used for established flexible photovoltaics. This demonstrates a key step towards future large-area flexible sheets which could cover everyday objects, to convert them into wireless charging stations. In this work, we combine the thin-film circuits with flexible solar cells to provide embedded power inversion, harvester control, and power amplification. This converts DC outputs from the solar modules to AC power for wireless device charging through patterned capacitive antennas. With 0.5-2nF transfer antennas and solar modules of 100cm2, the system provides 47-120μW of power at 11-22% overall power-transfer efficiency under indoor lighting.