p‐Type Plastic Inorganic Thermoelectric Materials

Abstract Deformable thermoelectrics have great potential in self‐powered flexible or hetero‐shaped electronics. The exceptional room‐temperature plasticity recently discovered in several inorganic semiconductors makes it possible to develop new thermoelectric (TE) materials with both high performance and intrinsic deformability. Nonetheless, all the known plastic or ductile TE materials are n‐type semiconductors. It is urgent to explore p‐type counterparts for device design and fabrication. In this study, the first p‐type plastic inorganic TE material is reported. Via alloying Cu in n‐type plastic Ag 2 S 0.7 Se 0.3 to modulate the charged crystal defects, (Ag 1− x Cu x ) 2 S 0.7 Se 0.3 ( x = 0.7–0.8) can simultaneously realize good plasticity and p‐type conduction. Particularly, (Ag 0.2 Cu 0.8 ) 2 S 0.7 Se 0.3 with a hexagonal structure shows a maximum zT of 0.42 at 800 K. Via the introduction of Cu deficiencies, the good plasticity is well maintained while the maximum zT is greatly enhanced to 0.95 at 800 K, a record‐high value for plastic TE materials. This study is expected to accelerate the development of plastic TE semiconductors and full‐inorganic deformable TE devices for the application in hetero‐shaped power generators.