Thermoelectric Performance of Surface-Engineered Cu<sub>1.5-<i>x</i></sub>Te-Cu<sub>2</sub>Se Nanocomposites.
basic_science · Level V
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- Record sourced from PubMed, PMID 37071412.
- Also identified by DOI 10.1021/acsnano.3c00495.
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Abstract
Cu<sub>2-<i>x</i></sub>S and Cu<sub>2-<i>x</i></sub>Se have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, Cu<sub>2-<i>x</i></sub>Te, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, <i>zT</i>, particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of Cu<sub>1.5-<i>x</i></sub>Te-Cu<sub>2</sub>Se nanocomposites by consolidating surface-engineered Cu<sub>1.5</sub>Te nanocrystals. This surface engineering strategy allows for precise adjustment of Cu/Te ratios and results in a reversible phase transition at around 600 K in Cu<sub>1.5-<i>x</i></sub>Te-Cu<sub>2</sub>Se nanocomposites, as systematically confirmed by in situ high-temperature X-ray diffraction combined with differential scanning calorimetry analysis. The phase transition leads to a conversion from metallic-like to semiconducting-like TE properties. Additionally, a layer of Cu<sub>2</sub>Se generated around Cu<sub>1.5-<i>x</i></sub>Te nanoparticles effectively inhibits Cu<sub>1.5-<i>x</i></sub>Te grain growth, minimizing thermal conductivity and decreasing hole concentration. These properties indicate that copper telluride based compounds have a promising thermoelectric potential, translated into a high dimensionless <i>zT</i> of 1.3 at 560 K.