Fig. 1: Overview of the passive cooling unit.

a Schematic representation of self-recovering passive cooling unit utilizing the chain reaction of water desorption (primary latent cooling) and dissolution of ammonium nitrate in water (secondary endothermic reaction cooling) integrated with photovoltaic (PV) cell. b Cooling power during electricity generation in response to solar radiation. c Cooling principle considering internal composition during the day. d Self-recovering process during the night.