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

Abstract

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 (ZTave) value at low-medium temperatures. Here, a high ZTave 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 ZTave 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 × 1016 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.

Defect Reconfiguration in Hole-Doped PbSe via Minute Te Doping for Significantly Enhanced Thermoelectric Performance

“…The same awkward situation has also been found in n-type PbSe, in which μ is only ∼20 cm 2 V –1 s –1 at 300 K on account of Pb vacancy scattering against carriers. , Incorporating extra metal atoms to occupy the remaining Pb vacancies is an effective and widely hired method to inhibit the Pb vacancies and recover μ. ,− For instance, Ge et al simultaneously improved the electron mobility to a splendid value of 635 cm 2 V –1 s –1 and electron concentration to an optimal value of ∼2.0 × 10 19 cm –3 via introducing excess Pb, thereby noticeably raising the electrical conductivity (σ) . Likewise, Qian et al obtained high μ and astonishingly low κ lat in n-type PbSe by, respectively, incorporating extra Cu, Zn, and Ni atoms. , Despite the clear efficiency of incorporating extra metal atoms in restraining Pb vacancies, interstitial metal atoms and secondary metallic phases can both produce extra electrons to neutralize the holes in p-type Sn-doped PbSe, causing degradation of σ.…”

“…The same awkward situation has also been found in n-type PbSe, in which μ is only ∼20 cm 2 V −1 s −1 at 300 K on account of Pb vacancy scattering against carriers. 17,18 Incorporating extra metal atoms to occupy the remaining Pb vacancies is an effective and widely hired method to inhibit the Pb vacancies and recover μ. 8,19−25 V −1 s −1 and electron concentration to an optimal value of ∼2.0 × 10 19 cm −3 via introducing excess Pb, thereby noticeably raising the electrical conductivity (σ).…”

Defect Chemistry Engineering Promotes the Dopability of Cu for an Extraordinary Thermoelectric Performance of Hole-Doped PbSe with Resonant States

“…As illustrated in Figure c, if we only include Cu i and Cu Pb point defects in the simulation, only ∼28% reduction of κ lat (from black dotted line to orange dotted line) can be obtained. Therefore, some other factors, for instance, dense dislocations and Cu 2 Se precipitates that are known to strongly impede heat conduction but are not involved in the above model, should account for the rest 17% reduction of κ lat (from orange dotted line to blue dotted line). , …”

“…Therefore, some other factors, for instance, dense dislocations and Cu 2 Se precipitates that are known to strongly impede heat conduction but are involved in the above model, should account for the rest 17% reduction of κ lat (from orange dotted line to blue dotted line). 60,61 It is worth noting that at temperatures above 623 K, there is an abrupt drop of κ lat , particularly for samples with higher Cu concentrations, as described in Figure 7b. This can be attributed to the dynamic migration of highly mobile Cu atoms from Cu 2 Se precipitates (fast ion conductors) to the interstitial sites of PbSe upon warming, which is akin to the case of Ag 2 Te precipitates in PbTe.…”

Catalyst-free physical vapor deposition of crystalline PbSe nanosheets for fabrication of high-performance photodetector

“…PbSe have attracted extensive attention due to their appropriate energy band structure and excellent light absorption capacity, which have broad application prospects in the field of photodetectors. [8][9][10] At present, the research on PbSe photodetector mainly focuses on large-area thin film growth and device fabrication. Although a lot of efforts have been paid on preparing PbSe nanostructures for miniaturized detectors.…”