Passive isothermal film with self-switchable radiative cooling-driven water sorption layer for arid climate applications.

Reducing substantial energy demand of active heating, ventilation, and air conditioning in arid climates is of paramount importance. Here, we develop a millimeter-scale passive isothermal film that maintains temperature near 25 °C without relying on energy consumption solely through natural phenomena. A radiative cooling unit comprising polydimethylsiloxane (PDMS) with diffraction grating and fused SiO/Ti/Ag film facilitates radiative cooling during daylight hours.

Self-recovering passive cooling utilizing endothermic reaction of NHNO/HO driven by water sorption for photovoltaic cell.

Power efficiency of photovoltaic cell is significantly affected by the cell temperature. Here, a self-recovering passive cooling unit is developed. The water-saturated zeolite 13X is coated on the back side of photovoltaic cell, and ammonium nitrate is dispersed as a layer to form a thin film.