GaSb doping facilitates conduction band convergence and improves thermoelectric performance in n-type PbS

• Published in: Energy & environmental science 2023-04, Vol.16 (4), p.1676-1684
• Main Authors: Chen, Zixuan, Cui, Hong-Hua, Hao, Shiqiang, Liu, Yukun, Liu, Hui, Zhou, Jing, Yu, Yan, Yan, Qingyu, Wolverton, Christopher, Dravid, Vinayak P, Luo, Zhong-Zhen, Zou, Zhigang, Kanatzidis, Mercouri G
• Format: Article
• Language: English
• Subjects: Chalcogenides; Conduction; Conduction bands; Convergence; Doping; Figure of merit; Gallium antimonides; Lattice vibration; Phonons; Point defects; Power factor; Thermal conductivity; Thermoelectric materials; Valence band
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d3ee00183k

P-type lead chalcogenides have superior thermoelectric performance because they exhibit the energy convergence of several valence bands. However, despite the existence of two conduction bands, there has been no report about conduction band (CB) convergence for n-type counterparts because of the large energy difference between them. New strategies are required to manipulate the CBs if enhancing the electrical transport performance of n-type lead chalcogenides is to be achieved. PbS is a highly attractive member of the lead chalcogenides because of its high earth-abundance and low cost. Here, we report that the introduction of GaSb can successfully dope the PbS matrix with Ga and Sb atoms occupying the Pb site in its rock salt structure. GaSb doping leads to conduction band convergence and enlarged effective density of state mass for n-type PbS. This effect results in superior power factor and decreased lattice thermal conductivity caused by the soft phonon modes and point defect scattering of phonons. Consequently, a record-high average power factor PF avg of ∼20.4 μW cm −1 K −2 and figure of merit ZT avg of ∼0.84 in the temperature range of 400 K to 923 K were obtained, higher than any n- and p-type PbS-based thermoelectric materials. We improve n-type lead chalcogenides by adding GaSb to reduce lattice thermal conductivity and achieve conduction band convergence. This significantly enhances the thermoelectric performance of n-type PbS, making it comparable to its p-type counterpart.