Roles of Cu in the Enhanced Thermoelectric Properties in Bi0.5Sb1.5Te₃.

Feng Hao,Lidong Chen,Xun Shi,Hongyi Chen,Qingfeng Song,Dudi Ren,Ping Lu,Pengfei Qiu

doi:10.3390/ma10030251

Feng Hao, Lidong Chen + Show 6 more

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https://doi.org/10.3390/ma10030251

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Abstract

Recently, Cu-containing p-type Bi0.5Sb1.5Te3 materials have shown high thermoelectric performances and promising prospects for practical application in low-grade waste heat recovery. However, the position of Cu in Bi0.5Sb1.5Te3 is controversial, and the roles of Cu in the enhancement of thermoelectric performance are still not clear. In this study, via defects analysis and stability test, the possibility of Cu intercalation in p-type Bi0.5Sb1.5Te3 materials has been excluded, and the position of Cu is identified as doping at the Sb sites. Additionally, the effects of Cu dopants on the electrical and thermal transport properties have been systematically investigated. Besides introducing additional holes, Cu dopants can also significantly enhance the carrier mobility by decreasing the Debye screen length and weakening the interaction between carriers and phonons. Meanwhile, the Cu dopants interrupt the periodicity of lattice vibration and bring stronger anharmonicity, leading to extremely low lattice thermal conductivity. Combining the suppression on the intrinsic excitation, a high thermoelectric performance—with a maximum thermoelectric figure of merit of around 1.4 at 430 K—has been achieved in Cu0.005Bi0.5Sb1.495Te3, which is 70% higher than the Bi0.5Sb1.5Te3 matrix.

Highlights

IntroductionDue to the low efficiency of traditional energy conversion technologies, more than 60% of the total energy is dissipated as waste heat, with the temperatures ranging from ambient temperature to over 1000 ◦ C [1]
Utilizing energy in high-efficiency and ecofriendly ways is an urgent task in modern society.due to the low efficiency of traditional energy conversion technologies, more than 60% of the total energy is dissipated as waste heat, with the temperatures ranging from ambient temperature to over 1000 ◦ C [1]
Due to the low efficiency of traditional energy conversion technologies, more than 60% of the total energy is dissipated as waste heat, with the temperatures ranging from ambient temperature to over 1000 ◦ C [1]

Summary

Introduction

Due to the low efficiency of traditional energy conversion technologies, more than 60% of the total energy is dissipated as waste heat, with the temperatures ranging from ambient temperature to over 1000 ◦ C [1]. Thermoelectric (TE) materials can realize a direct conversion between heat and electricity with the characters of high reliability and zero pollution, and provide an alternative choice to use the energy more efficiently [2]. The energy conversion efficiency of a TE material is governed by the figure of merit zT = S2 σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity [3]. In order to maximize energy conversion efficiency, a large S, a high σ, and a low κ are required to obtain a high zT.

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