Abstract

In this work, the thermoelectric properties of Bi2O2Se by Bi2Te2.7Se0.3 addition through liquid assisted shear exfoliation- restacking (LASE-R) process were studied. The results show that the Bi2Te2.7Se0.3 can alloy with Bi2O2Se and reduce the band gap, which introduce more electrons and improve the electrical conductivity of Bi2O2Se. Moreover, Bi2Te2.7Se0.3 addition act as a liquid phase sintering aids here, which can promote crystal growth and increase the sintering density of Bi2O2Se. Owing to the offset effect between |S| and σ, the absolute Seebeck coefficient |S| of all samples drops first and then rises with the increase of Bi2Te2.7Se0.3 content. Thus, the power factor is effectively improved. In addition, the lattice thermal conductivity is also suppressed to the nearly minimum theoretical limit, which should be attributed to the enhanced phonon-scattering by alloying. Therefore, a high figure of merit of 0.7 at 772 K was achieved for Bi2O2Se- 0.3 mol% Bi2Te2.7Se0.3.

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