Modulation doping enables ultrahigh power factor and thermoelectric ZT in n-type Bi2Te2.7Se0.3
Prof. Yang-Yuan Chen and Dr. Cheng-Lung Chen in collaboration with Prof. Te-Hsien Wang (NCHU) et al have reported a new strategy to boost up ZT in n-type Bi2Te2.7Se0.3 crystals near room temperature by a two-stage process, i.e., step 1: stabilizing Seebeck coefficient by CuI doping; step 2: boosting power factor by synergistically optimizing phonon and carrier transport via thermal-driven Cu intercalation in the vdW gaps. Theoretical Ab initio calculations disclose that these intercalated Cu atoms act as modulation doping and contribute conduction electrons of wavefunction spatially separated from the Cu atoms themselves, which simultaneously lead to large carrier concentration and high mobility. As a result, an ultra-high power factor and a highest average ZT=1.36 at 300-450 K are realized, which outperform all n-type bismuth telluride materials ever reported. The work offers a new approach in improving n-type layered TE materials. Results were published in Advanced Science, 2201353 (2022)
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WebSite: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202201353