Long Z, Wang Y, Sun X, Li Y, Zeng Z, Zhang L, Chen H. Band Engineering of the Second Phase to Reach High Thermoelectric Performance in Cu
2 Se-Based Composite Material.
Adv Mater 2023;
35:e2210345. [PMID:
36772897 DOI:
10.1002/adma.202210345]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/27/2022] [Indexed: 05/17/2023]
Abstract
Hitherto, Cu2 Se incorporated with a dispersed second phase shows extremely low thermal conductivity and excellent thermoelectric properties. However, the significant mismatch in electronic band structure between the second phases and the matrix often causes a deterioration of carrier mobility. In this work, based on density functional theory (DFT) calculations, the electronic band structure of the second phase is adjusted through doping S and Te. It is found that Cu2 Se0.88 S0.06 Te0.06 has a highly similar electronic band structure to the Cu2 Se matrix, which results in high carrier mobility and power factor in Cu2 Se-based composite materials. Additionally, the dispersed second-phase Cu2 Se0.88 S0.06 Te0.06 , dislocations, and nanograins are observed in the Cu2 Se/5 wt% Cu2 Se0.88 S0.06 Te0.06 product, which leads to a substantial reduction in the thermal conductivity. Finally, high figure of merit (zT) values of 2.04 (by Dulong-Petit heat capacity) and 2.34 (by Differential Scanning Calorimetry (DSC) measured heat capacity) are achieved at 850 K, which are about 65% higher than that of Cu2 Se in this work and comparable to the recently reported p-type Cu2 Se with outstanding performance.
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