Multiscale Microstructures and Carrier-Phonon Decoupling in BiCuSeO-CDs Composites.
basic_science · Level V
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- Record sourced from PubMed, PMID 40442052.
- Also identified by DOI 10.1021/acs.nanolett.5c01160.
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Abstract
Owing to the carrier-phonon coupling, the majority of thermoelectric materials such as BiCuSeO adopt the strategy of sacrificing carrier mobility and thermal properties to improve the electrical performance so as to enhance the <i>zT</i> value. In response, we innovatively introduce carbon dots (CDs) as a nanophase and efficiently synthesize Bi<sub>0.88</sub>Ca<sub>0.06</sub>Pb<sub>0.06</sub>CuSeO-CDs composites, attenuating the carrier-phonon coupling while realizing the structure optimization on the multiscale. The addition of CDs improves the electrical performance (PF<sub><i>max</i></sub> = 883.99 μW m<sup>-1</sup> K<sup>-2</sup>), and CDs introduce multiscale defects that strongly scatter phonons across multiple frequencies, drastically reducing the lattice thermal conductivity to 0.14 W m<sup>-1</sup> K<sup>-1</sup>. The BCPCSO-0.15 wt % CDs achieve a record <i>zT</i> value of 1.82 at 873 K, representing a 61.97% enhancement of the BCPCSO matrix, with an average <i>zT</i> value reaching 1.11. This research offers an economical, efficient, and scalable approach to improve thermoelectric performance of BiCuSeO, offering a novel pathway for performance optimization of other structurally similar thermoelectric materials.