Realizing high-performance thermoelectric modules through enhancing the power factor via optimizing the carrier mobility in n-type PbSe crystals

The limited availability of Te poses challenges for the widespread application of Bi2Te3-based thermoelectric modules. In this work, we explored the thermoelectric module potential of Te-free PbSe by elevating its power factor through crystal growth and slight-tuning vacancy and interstitial defects. The outcomes revealed a gradual increase in the carrier concentration and a high room-temperature carrier mobility of similar to 1750 cm(2) V-1 s(-1), leading to an enhanced power factor of similar to 37.4 mu W cm(-1) K-2 in Pb1.006Se+0.0016 Al crystals. We grew PbSe crystals to minimize the impact of grain boundaries on the charge carrier transport. Subsequently, n-type PbSe crystals were produced by introducing extra Pb to occupy the intrinsic Pb vacancies, effectively minimizing vacancy scattering. Following this, a minute quantity of small-sized Al (<= 2 parts per thousand) was introduced, revealing that these surplus Al atoms served as cationic dopants, substituting for Pb, while also occupying interstitial positions. The interstitial doping increases the carrier concentration while maintaining carrier mobility due to the distinct dimensions between the interstitial atoms and mean free path of electrons. The consistently improved power factor with the suppression of thermal conductivity brings about a significantly high ZT value over the whole temperature. Specifically, the ZT values of the Pb1.006Se+0.0016Al crystal reached similar to 0.5 at 300 K, similar to 1.5 at 673 K, and the average ZT (ZT(ave)) reached similar to 1.1 at 300-773 K. Ultimately, a single-leg power generation efficiency similar to 7.1% was achieved in Pb1.006Se+0.0016Al crystal and a 7-pair module reached a maximum temperature cooling difference similar to 51.2 K at the high temperature side T-h of 363 K. These results indicate the potential for developing a cost-effective and high-performance thermoelectric module utilizing PbSe.