Collapsible and portable solar-driven directional backside evaporation–condensation system for highly efficient freshwater generation and collection

Solar-driven evaporation is a sustainable technology for freshwater production, yet its practical application is limited by (1) water vapor accumulation on the evaporator surface reduces sunlight absorption efficiency, (2) low clean water collection efficiency (<50 %), and (3) complex, non-portable designs. Herein, a collapsible and portable solar-driven evaporation–condensation (EC) system featuring cone array microstructures is developed to enable efficient directional backside evaporation and freshwater collection. The system incorporates a lightweight, retractable frame for enhanced portability, a hydrophilic nonwoven fabric for rapid water transport, and a CNTs/PDMS film with cone array microstructures to achieve high solar–thermal conversion and directional evaporation. Three sides of the system are equipped with pure PDMS films featuring cone arrays to facilitate efficient vapor condensation and water collection via the Laplace pressure gradient. Under 1 sun irradiation, the system demonstrates an impressive evaporation rate of 3.61 kg m −2  h −1 and a freshwater collection efficiency of ∼72 %, representing a 50 % improvement over traditional EC systems. A large-scale prototype produces 16.53 L m −2  day −1 of clean water, sufficient to meet the daily needs of 8 individuals. This portable, scalable, and low-cost EC system offers a practical and sustainable solution for freshwater recycling in outdoor or rural areas, addressing global water scarcity with minimal environmental impact.