ds-Block Element-Enabled Cooperative Regulation of Electrical and Thermal Transport for Extraordinary N- and P-Type PbSe Thermoelectrics near Room Temperature

From a practical application perspective, achieving a high thermoelectric performance for both n and p types in one system is particularly desirable. Here, we provide a new strategy for incorporating the ds-block element(s) to realize an unprecedentedly high thermoelectric performance for both n-type and p-type PbSe near room temperature. The synergistic effects of the Cu interstitial and Cd alloying, including enhancing the effective mass by flattening the conducting band, maintaining a high carrier mobility by protecting the charge-conducting channel, and suppressing phonon transport via dislocations, enable a record high average ZT of 0.81 in the range of 300–523 K for n-type PbSe. Moreover, a record high average ZT of 0.67 in the range of 300–523 K is achieved in Ag-doped p-type PbSe due to (i) the cooperative optimization of the effective mass, carrier concentration, and mobility and (ii) the strengthened point defect scattering. Ultimately, a high theoretical conversion efficiency of 6.4%, which is comparable to that of commercial Bi2Te3, is thereby achieved in the thermoelectric module made of as-developed PbSe systems at ΔT = 223 K. Our work demonstrates that introducing the ds-block element(s) extends PbSe to near room temperature power generation application and makes as-developed materials very suitable for segmentation with other widely reported high-performance PbSe thermoelectrics working at intermediate temperature, which can be greatly significant for the application of a low-cost PbSe-based thermoelectric device across a broad temperature range.