Photo Ionic gelatin power source by Ion-gradient and photo redox pairs synchronization

Flexible photoelectric power sources are promising to power Internet-of-things sensors, freeing the limitations of wired power sources or batteries and enabling bio-integrated devices. Traditional photo power sources have to be integrated with energy storage modules since photovoltaic materials have an order of nanosecond lifetime for photogenerated charge carriers. Obtaining flexible, biocompatible power sources that can perform light harvesting and store energy simultaneously is still challenging. In this paper, inspired by natural ion gradient diffusion in organisms, we develop a novel photoelectric conversion mechanism that synchronizes the mechanism of photoinduced ion gradient diffusion and photo-REDOX pairs (I-PR), offering an ion-hydrogel-based flexible photo power source. Through the photochemical process of ammonium molybdate, the electric potential of the device is regulated by the altered ion gradient of gelatin hydrogel and the REDOX (/) pairs, to generate energy. In comparison with photovoltaic materials-based photo power sources, the carrier life is times longer than that of commercial solar cell, we can still obtain a considerable output power for milliseconds to thousands of seconds after the termination of the initial illumination. Additionally, reaping the benefits from I-PR, the open-circuit potential is independent of the power sources’ volume. The flexible hydrogel droplets support the fabrication of arbitrary and millimetre-scale structures. A single photo power source can generate an open-circuit potential of ~ 250 mV, even with a 20-fold reduction in volume to ~10 mm ³ . The reversible hydrogel network allows for the recovery and re-manufacturing of the photo power source, with a 61% potential retention rate after two cycles of recycling and re-manufacturing. We further demonstrate the flexible photo power source can stimulate the activity of biological tissue cells, regulate the expression of proliferative genes on demand and facilitate tissue wound repair. This ionic hydrogel opens a new avenue for flexible, battery-free, biocompatible devices.