Dissolvable photovoltaic cells on hydrogel

Solar energy is potentially the largest source of renewable energy for providing electrical power for human society. However, significant advances are required to make photovoltaic technologies have a low-carbon footprint in manufacture, be environmentally friendly at the end of their lives through recyclability, and be biodegradable. Here we report dissolvable organic photovoltaic devices based on poly(2-hydroxyethyl methacrylate), which show equal power conversion efficiency to their glass substrate-based counterparts. We use a novel method of including smectic liquid crystal (7-dioctyl[1]benzothieno[3,2- b][1]benzothiophene, C8-BTBT) as a crystal phase regulator in the heterojunction donor:acceptor polymer system to maintain the disposable organic solar cell efficiency without pre- or post-thermal annealing. The results show strong promise not only for more sustainable solar-cell fabrication but also as disposable and biocompatible solar cells for self-powered (energy harvesting) wearable and biomedical devices.