High‐Ranged ZT Value Promotes Thermoelectric Cooling and Power Generation in n‐Type PbTe

Abstract

Excellent thermoelectric cooling and power generation are simultaneously realized in an n‐type PbTe‐based thermoelectric material. The cooling temperature difference (ΔT) of ≈15.6 K, maximum power density of ≈0.4 W cm−2 and conversion efficiency of ≈1.5% with TC = 295 K and TH = 765 K can be obtained in a single‐leg device composed of PbTe‐30%SnSe‐1.5%Cu. This advanced thermoelectric performance in n‐type PbTe‐30%SnSe‐1.5%Cu mainly originates from its high‐ranged ZT value achieved through optimizing its bandgap, carrier density, and microstructure. The bandgap in PbTe is first reduced by SnSe alloying to facilitate the carrier transport properties at low temperature range (300–573 K). With further tuned carrier density, the average power factor increases from ≈10.2 µW cm−1 K−2 in Pb0.985Sb0.015Te‐30%SnSe to ≈16.2 µW cm−1 K−2 in PbTe‐30%SnSe‐1.5%Cu at 300–773 K. Moreover, microstructure observation reveals high‐density dislocations in PbTe‐30% SnSe‐1.5% Cu, which can dramatically suppress the room‐temperature lattice thermal conductivity from ≈2.21 Wm−1 K−1 in Pb0.985Sb0.015Te to ≈0.53 Wm−1 K−1 in PbTe‐30%SnSe‐1.5%Cu. As a result, a room‐temperature ZT value of ≈0.7 and high average ZT value (ZTave) of ≈0.98 can be obtained in PbTe‐30%SnSe‐1.5%Cu at 300–573 K, which makes its performance comparable to the commercial n‐type Bi2Te3‐based thermoelectric material.

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

“…6b ). Moreover, the down-and-up tendency in temperature-dependent electrical conductivity and Seebeck coefficient indicates the dynamic doping behavior of Cu interstitials in lead chalcogenides as proved in our previous works 20 , 42 , 43 . Benefiting from the Cu interstitial doping, the power factor in Pb 1.02 Se 0.72 Te 0.20 S 0.08 - x %Cu ( x = 0–0.40) is obviously enhanced in the whole-temperature range.…”

Realizing high-ranged thermoelectric performance in PbSnS2 crystals

“…However, our results show that the carrier concentration has an obvious decreasing trend with temperature rising, indicating that the cation vacancies may be excited or electrons may be redistributed among the multiple conduction bands at higher temperatures 46 . To verify this, we compare the temperature-dependent behavior of Hall carrier mobility μ H and weighted mobility μ W (a mobility includes the effective mass m * of electronic density of states, and is widely used in thermoelectric systems to evaluate the carrier transport behavior) 3 , 38 , 47 , 48 , as shown in Fig. 2d .…”

“…The thorny problems of energy shortage and environmental pollution have been challenging the sustainable development. Thus, thermoelectric materials have gained increasing attention because they provide an alternative way of energy utilization by realizing the direct and reversible conversion between heat and electricity 1 – 3 . The efficiency of thermoelectric devices depends on the material’s dimensionless figure of merit, ZT = S 2 σT /( κ lat + κ ele ), where S , σ , S 2 σ , T , κ lat and κ ele represent Seebeck coefficient, electrical conductivity, power factor, absolute temperature, lattice thermal conductivity and electronic thermal conductivity, respectively.…”

Solid-state cooling: thermoelectrics

“…Additionally, strategies for improving carrier mobility have been attempted to realize better TE cooling in various systems, such as textured Bi 2 Te 3 -based alloys 125,126 and defect-modulated PbTe. 19…”

“…5,13–18 However, there are still some problems to be solved before their large-scale commercialization. Moreover, recent research revealed that the traditional mid-temperature PbQ (Q = Te, Se, S) systems also possess extraordinary TE performance near room temperature with extremely high carrier mobility, 19 demonstrating great potential as new TE cooling materials, with practical devices to be further constructed.…”