Dual Interstitials Doping to Advance PbSe Thermoelectric at Wide Temperatures

Abstract

Abstract Interstitial doping has been widely verified in optimizing thermoelectric performance due to its carrier and phonon decoupling effect. To maximize the role of interstitial, this work develops a novel strategy of Pb and Cu dual interstitials doping in n-type Pb1.02Se-0.2%Cu, and a considerably improved average ZT value of 1.01 at 300–773 K can be achieved, which obviously outperforms previous single interstitial doped PbSe systems. Its superior thermoelectric performance mainly originates from optimally tuned carrier and phonon transport properties caused by synergy of Pb and Cu dual interstitials. Firstly, Pb and Cu dual interstitials in n-type Pb1.02Se-0.2%Cu can fully optimize temperature-dependent carrier density in the whole temperature range, from 1.27×1019 cm− 3 at 300 K to 3.90×1019 cm− 3 at 773 K, thus contributing to maximal power factor of 32.83 µW cm− 1 K− 2 and average power factor of 24.18 µW cm− 1 K− 2. Furthermore, Pb and Cu dual interstitials doping can cause hierarchical defects, including interstitials, vacancies, dislocations and precipitates, thus to largely lower the lattice thermal conductivity. As a result of the optimized electrical and thermal transport properties, the thermoelectric performance in n-type Pb1.02Se-0.2%Cu is largely enhanced at wide temperatures.