Polyacrylamide Microparticles-Assembled Hydrogel with Mitigated Inhomogeneous Deformation for Efficient Photovoltaic Cooling

Hydrogel-based evaporative cooling has emerged as a promising passive strategy for thermal management in photovoltaic (PV) systems. However, conventional bulk hydrogels suffer from severe structural deformation and limited water storage capacity, hindering their long-term performance in practical applications. Herein, we developed a polyacrylamide microparticle-assembled hydrogel (MPH) formed through the self-assembly of dehydrated microparticles triggered by water absorption. The as-reconstructed hydrogels establish dynamic interparticle interfaces via physical entanglements, facilitating rapid polymer chain mobility and local structural reorganization during hydration and dehydration. The flexible structure of the MPH mitigates drying-induced stress and reduces undesirable inhomogeneous deformation, ensuring sustained thermal contact between the hydrogel and the PV panel throughout evaporation. Meanwhile, the dynamic network enhances water molecule mobility and improves the water absorption capacity. Leveraging the fast water uptake of the MPH, we engineered a water-fed cooling system integrating a capillary-driven layer for a continuous water supply. The system achieved a significant temperature drop of 26 °C under an intense heat flux of 1000 W/m² and demonstrated sustained cooling performance compared to natural convection. This work presents a novel material strategy for efficient and durable thermal management in solar energy applications.