Lattice Plainification Leads to High Thermoelectric Performance of P-Type PbSe Crystals

Thermoelectrics has applications in power generation and refrigeration. Since only commercial Bi₂Te₃ has a low abundance Te, PbSe gets attention. This work enhances the near-room temperature performance of p-type PbSe through enhancing carrier mobility via lattice plainification. Composition controlled and Cu-doped p-type PbSe crystals are grown through physical vapor deposition. Results exhibit an enhanced carrier mobility ≈2578 cm² V^-1 s^-1 for Pb_0.996Cu_0.0004Se. Microstructure characterization and density functional theory calculations verify the introduced Cu atoms filled Pb vacancies, realizing lattice plainification and enhancing the carrier mobility. The Pb_0.996Cu_0.0004Se sample achieves a power factor ≈42 µW cm^-1 K^-2 and a ZT ≈ 0.7 at 300 K. The average ZT of it reaches ≈0.9 (300-573 K), resulting in a single-leg power generation efficiency of 7.1% at temperature difference of 270 K, comparable to that of p-type commercial Bi₂Te₃. A 7-pairs device paired the p-type Pb_0.996Cu_0.0004Se with the n-type commercial Bi₂Te₃ shows a maximum cooling temperature difference ≈42 K with the hot side at 300 K, ≈65% of that of the commercial Bi₂Te₃ device. This work highlights the potential of p-type PbSe for power generation and refrigeration near room temperature and hope to inspire researchers on replacing commercial Bi₂Te₃.