Highly Efficient and Stable All‐Weather Moisture Power Generation via Asymmetric Structured Color Photothermal Evaporation‐Induced Cotton Fabrics

Harvesting electrical energy from the ubiquitous water cycle to power flexible electronic devices is receiving increasing attention. However, the development of moisture-driven generators with high and stable power output remains a significant challenge. Here, we design a photothermal evaporation-driven moisture generator (PEMG) that modifies a cotton fabric with in situ polymerized pyrrole by a polydopamine (PDA)-structured color film to form an asymmetric photothermal temperature gradient. The PDA asymmetric photothermal layer not only effectively addresses the issue of insufficient sustained power generation caused by water adsorption saturation but also mitigates the unstable moisture gradient resulting from excessive water evaporation. CF@PPy@PDA (purple) achieved an open-circuit voltage (V_oc) of 0.74 V and a short-circuit current (I_sc) of 0.72 mA under 60% relative humidity (RH) and 1-sun illumination, respectively. White LED bulbs emit a steady stream of light for more than 24 h. Moreover, the V_oc of the PEMG (six units in series) reaches 1.18 V at an average solar intensity of 1000 W m^-2 and 43% RH, while the V_oc is 0.72 V at night (52% RH). Meanwhile, wearable systems designed with integrated PEMG units provide sufficient power supply for electronic devices under natural conditions.