Title

Quasi-layered Crystal Structure Coupled with Point Defects Leading to Ultralow Lattice Thermal Conductivity in n-Type Cu2.83Bi10Se16

Abstract

Cu2.83Bi10Se16, a new n-type thermoelectric material, was synthesized via a high-temperature solid-state routine. The quasi-layered structure features of Cu2.83Bi10Se16 were established by a comprehensive study including variable-temperature single-crystal X-ray diffraction, synchrotron powder X-ray diffraction, DFT calculations, and resonant ultrasound spectroscopy. The structural relationship between Cu2.83Bi10Se16 and two previously reported compounds, Cu1.6Bi4.8Se8 and Cu1.78Bi4.73Se8, is addressed. The quasi-layered structure of Cu2.83Bi10Se16 coupled with point defects accounts for its ultralow lattice thermal conductivity. First-principles simulations predict that the electrical properties of Cu2.83Bi10Se16 are sensitive to Cu content, which is confirmed by the thermoelectric property measurements of Cu2.83-xBi10Se16 (x = 0, 0.1, and 0.2) samples. Through tuning the Cu content, Cu2.73Bi10Se16 shows the best performance due to the highest Seebeck coefficient combined with a moderate electrical conductivity, achieving zT = 0.42 at 775 K. This work proves that crystal structure engineering can achieve extremely low lattice thermal conductivity in crystalline solids.

Department(s)

Chemistry

Document Type

Article

DOI

https://doi.org/10.1021/acsaem.1c02154

Keywords

lattice thermal conductivity, quasi-layered structure, resonant ultrasound spectroscopy, selenides, thermoelectrics

Publication Date

1-1-2021

Journal Title

ACS Applied Energy Materials

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