Band Engineering of the Second Phase to Reach High Thermoelectric Performance in Cu<sub>2</sub> Se-Based Composite Material.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36772897.
- Also identified by DOI 10.1002/adma.202210345.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Hitherto, Cu<sub>2</sub> 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 Cu<sub>2</sub> Se<sub>0.88</sub> S<sub>0.06</sub> Te<sub>0.06</sub> has a highly similar electronic band structure to the Cu<sub>2</sub> Se matrix, which results in high carrier mobility and power factor in Cu<sub>2</sub> Se-based composite materials. Additionally, the dispersed second-phase Cu<sub>2</sub> Se<sub>0.88</sub> S<sub>0.06</sub> Te<sub>0.06</sub> , dislocations, and nanograins are observed in the Cu<sub>2</sub> Se/5 wt% Cu<sub>2</sub> Se<sub>0.88</sub> S<sub>0.06</sub> Te<sub>0.06</sub> 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 Cu<sub>2</sub> Se in this work and comparable to the recently reported p-type Cu<sub>2</sub> Se with outstanding performance.