Perovskites have heated up the clean energy world with high-efficiency solar cells. Now researchers have made a hybrid perovskite that blocks heat better than any other dense solid. The material could be printed or sprayed to make a rigid thin film, making it easy to coat surfaces to create a heat barrier (Sci. Adv. 2026, DOI: 10.1126/sciadv.aee5269).
Materials with low thermal conductivity find many uses on Earth and in space. They insulate buildings, protect pipelines, keep batteries safe, and blanket electronics and other components in spacecraft.
No material that exists can prevent heat flow completely. Ceramics and plastics work well for many applications. Porous foams and aerogels are far better heat insulators because the air pockets within them act as speedbumps to heat flow. But these airy materials are soft or fragile, which makes them challenging to use in applications.
“What we offer is a new mechanism in a new class of materials that haven’t been explored extensively before,” says Jun Liu, a mechanical engineer at North Carolina State University.
Liu, physicist Dali Sun of NCSU, chemist Wei You of the University of North Carolina at Chapel Hill, Jun Zhou of Nanjing Normal University, and colleagues worked with hybrid organic-inorganic perovskites, the same class of materials that is being commercialized for solar cells. The materials have a layered structure, which inherently provides insulation because heat does not pass easily across the interfaces between the layers.
Their chemical makeup also offers several ways to tune their properties, Sun says. They are made of a positively charged organic group; a smaller cation, usually lead or tin; and a negatively charged ion.
For the organic group, people have previously used compounds with carbon-carbon chains or benzene rings. Liu, Sun, and colleagues instead used azobenzene ethyl ammonium, which contains two rings connected by nitrogen double bonds. The resulting perovskite, azobenzene ethyl ammonium lead iodide, has a disordered crystalline structure.
“And those disorders can move; they are dynamic disorders,” Liu explains. The molecules move so the distance between layers change or the rings twist, scattering energy and suppressing heat transfer, he says.
A 150 nm thick film of the material has a thermal conductivity of only 0.04 W m–1 K–1, close to that of foams and aerogels, while being stiffer than those materials and most plastics. “Once it’s painted, it is very rigid. On houses, coating one layer would provide mechanical support while providing thermal insulation,” Sun says. You could also spray coat the insulating film on batteries, solar panels, or telescopes.
The applications could go much further, says Jonathan Malen, a mechanical engineer at Carnegie Mellon University. The materials could be paired with others with higher thermal conductivity to route heat as desired, which would be useful for heat management in electronic devices. “The design rules could also lead to a new class of organic-hybrid thermoelectric materials that convert heat into electricity with no moving parts.”
While the use of lead is a concern, it should be possible to swap lead with tin. “Such changes to the chemistry impact optoelectronic performance for solar cells,” Malen says, but could be acceptable if the goal is to design rigid, insulating materials.
