Dense dislocations enable high-performance PbSe thermoelectric at low-medium temperatures

Thermoelectric material is capable of realizing direct conversion between heat and electricity. Here, the authors obtain high thermoelectric performance in PbSe at low-medium temperatures by importing dense dislocations. PbSe-based thermoelectric materials exhibit promising ZT values at medium temperature, but its near-room-temperature thermoelectric properties are overlooked, thus restricting its average ZT (ZT(ave)) value at low-medium temperatures. Here, a high ZT(ave) of 0.90 at low temperature (300-573 K) is reported in n-type PbSe-based thermoelectric material (Pb1.02Se0.72Te0.20S0.08-0.3%Cu), resulting in a large ZT(ave) of 0.96 at low-medium temperatures (300-773 K). This high thermoelectric performance stems from its ultralow lattice thermal conductivity caused by dense dislocations through heavy Te/S alloying and Cu interstitial doping. The dislocation density evaluated by modified Williamson-Hall method reaches up to 5.4 x 10(16) m(-2) in Pb1.02Se0.72Te0.20S0.08-0.3%Cu. Moreover, the microstructure observation further uncloses two kinds of dislocations, namely screw and edge dislocations, with several to hundreds of nanometers scale in length. These dislocations in lattice can strongly intensify phonon scattering to minimize the lattice thermal conductivity and simultaneously maintain high carrier transport. As a result, with the reduced lattice thermal conductivity and optimized power factor in Pb1.02Se0.72Te0.20S0.08-0.3%Cu, its near-room-temperature thermoelectric performance is largely enhanced and exceeds previous PbSe-based thermoelectric materials.

Automated summary

The authors achieved high thermoelectric performance in low-medium temperature PbSe through the introduction of dense dislocations. The dislocation density reached a high level and two types of dislocations were observed in n-type PbSe-based thermoelectric material. These dislocations effectively reduced the lattice thermal conductivity while maintaining high carrier transport.