Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

Abstract

Dramatic enhancements in the figure of merit have been obtained in bulk thermoelectric materials by doping, band engineering, and nanostructuring. Especially, in p-type thermoelectrics, high figure of merits near 2.0 have been reported in a few papers through the reduction in lattice thermal conductivity and the advancement in power factors. However, there exists no report on the n-type systems showing high figure of merits because of their intrinsically low Seebeck coefficients. Here, we demonstrate that a nanostructured bulk n-type thermoelectric material that was assembled by sintering spinodally decomposed lead chalcogenide nanoparticles having a composition of PbSe0.5Te0.5 reaches a high figure of merit of 1.85. The spinodally decomposed nanoparticles permit our thermoelectric material to have extremely low lattice thermal conductivity and a high power factor as a result of nanostructuring, electronic optimization, insertion of an impurity phase and phase change in local areas. We propose that this interesting concept would be one of the promising approaches that overcome limitation arising from the fact that most parameters in the figure of merit are closely correlated.

Synergistic Regulation of Phonon and Electronic Properties to Improve the Thermoelectric Performance of Chalcogenide CuIn1−xGaxTe2:yInTe (x = 0–0.3) with In Situ Formed Nanoscale Phase InTe

“…[55] When calculating the electronic parts (κ e ) according to the equation κ e = LσT, the Lorenz numbers L were estimated using the formula L = 1.5 + exp(−|α|/116), [56] (where L is in 10 −8 W Ω K −2 and α in µV K −1 ). The thermal diffusivities were measured using TC-1200RH with an uncertainty of <10.0%.…”

High Performance Thermoelectric Materials: Progress and Their Applications

“…Over the years, various strategies have been applied to improve ZT values in a range of TE materials, [2,[85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100] in which the most effective approaches are to improve the electrical transport properties via optimizing n [1,111] and band engineering, [44,49,[112][113][114] that can decouple σ and S and simultaneously increase their values, for achieving overall high S 2 σ. On the other hand, through nanostructure engineering, [4,16,[115][116][117] κ can be effectively reduced without sacrificing the electrical transport of TE materials, [48,73,118] so that enhanced ZT can be ultimately achieved.…”

“…However, it is very hard to keep every parameter increasing without harming the efficiency when multiple strategies are applied, so tremendous efforts are still required to further push the ZT close to the theoretical limit. After all the fundamental explorations, the future development of TE materials should lie in the synergetic optimization . In any given materials systems, their electrical transport properties should be manipulated by optimizing the n , and/or band engineering, while κ should be reduced by nanostructure engineering, hierarchical structuring, defect engineering, increasing the porosity, or grain boundary engineering .…”

Probing of Thermal Transport in 50 nm Thick PbTe Nanocrystal Films by Time-Domain Thermoreflectance

“…53 Smaller thermal conductivities have been reported for PbTe nanowires, 1.3 W m -1 K -1 , 54 and PbSeTe nanoparticles. 55…”