Exceptionally High Average Power Factor and Thermoelectric Figure of Merit in n-type PbSe by the Dual Incorporation of Cu and Te

Abstract

Thermoelectric materials with high average power factor and thermoelectric figure of merit (ZT) has been a soughtafter goal. Here, we report new n-type thermoelectric system Cu x PbSe 0.99 Te 0.01 (x = 0.0025, 0.004, and 0.005) exhibiting recordhigh average ZT ∼ 1.3 over 400−773 K ever reported for n-type polycrystalline materials including the state-of-the-art PbTe. We concurrently alloy Te to the PbSe lattice and introduce excess Cu to its interstitial voids. Their resulting strong attraction facilitates charge transfer from Cu atoms to the crystal matrix significantly. It follows the increased carrier concentration without damaging its mobility and the consequently improved electrical conductivity. This interaction also increases effective mass of electron in the conduction band according to DFT calculations, thereby raising the magnitude of Seebeck coefficient without diminishing electrical conductivity. Resultantly, Cu 0.005 PbSe 0.99 Te 0.01 attains an exceptionally high average power factor of ∼27 μW cm −1 K −2 from 400 to 773 K with a maximum of ∼30 μW cm −1 K −2 at 300 K, the highest among all n-and p-type PbSe-based materials. Its ∼23 μW cm −1 K −2 at 773 K is even higher than ∼21 μW cm −1 K −2 of the state-of-the-art n-type PbTe. Interstitial Cu atoms induce the formation of coherent nanostructures. They are highly mobile, displacing Pb atoms from the ideal octahedral center and severely distorting the local microstructure. This significantly depresses lattice thermal conductivity to ∼0.2 Wm −1 K −1 at 773 K below the theoretical lower bound. The multiple effects of the dual incorporation of Cu and Te synergistically boosts a ZT of Cu 0.005 PbSe 0.99 Te 0.01 to ∼1.7 at 773 K.

Thermostructural and Elastic Properties of PbTe and Pb0.884Cd0.116Te: A Combined Low-Temperature and High-Pressure X-ray Diffraction Study of Cd-Substitution Effects

“…It is equally possible to investigate other, more complex systems, for example those with lessconventional doubly substituted cationic systems, such as Na 0.03 Eu 0.03 Pb 0.94 Te [112]. The joint cationic/anionic substitution (Pb,Cu)(Se,Te) system has also been studied, providing another example of a dual system [135]. Mixed bi-cationic-bi-anionic systems such as Na 0.03 Eu 0.03 Pb 0.94 Te 0.9 Se 0.1 [112] are the subject of studies as well.…”

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

“…Another successful example of this electronic level matching strategy can be found in Ref. [127], where a careful selection of CdS nanoinclusions in p-type PbSe allowed ZT ∼ 1.6 at 923 K. In addition, high average ZT over a wide temperature range was reported in PbSe based systems by tuning the electronic properties by nanostructuring [128]. In CuxPbSe0.99Te0.01 polycrystalline specimens, a record-high average ZT ~ 1.3 over the whole 400 K to 773 K range, has been reported.…”

Coherent Sb/CuTe Core/Shell Nanostructure with Large Strain Contrast Boosting the Thermoelectric Performance of n‐Type PbTe

“…[ 15,17 ] Successful application of Cu dynamic doping also results in quite exciting thermoelectric performance in PbSe based materials as recently reported. [ 31–34 ]…”

“…[15,17] Successful application of Cu dynamic doping also results in quite exciting thermoelectric performance in PbSe based materials as recently reported. [31][32][33][34] Inspired by the aforementioned strategies, we propose in this work to combine Sb addition and Cu 2 Te doping in order to realize simultaneous modulation on both electrical and thermal transport. The base material we choose is (PbTe) n -Sb 2 Te 3 (abbreviated as PST), for the purpose of constructing Van der Waals gap structures as reported in Ge-Bi-Te, [7,35] and Ge-Sb-Te [36][37][38][39] based thermoelectric materials.…”