Single-and Two-band Transport Properties Crossover in Bi_(2)Te_(3)Based Thermoelectrics  

Bi_(2)Te_(3)基热电材料的单带和双带传输特性转变

作　　者：MENG Yuting WANG Xuemei ZHANG Shuxian CHEN Zhiwei PEI Yanzhong 孟雨婷;王雪梅;章淑娴;陈志炜;裴艳中(同济大学材料科学与工程学院,跨学科材料研究中心,上海201804)

机构地区：[1]Interdisciplinary Materials Research Center,School of Materials Science and Engineering,Tongji University,Shanghai 201804,China

出　　处：《无机材料学报》2024年第11期1283-1291,共9页Journal of Inorganic Materials

基　　金：National Natural Science Foundation of China(T2125008,92263108,92163203,52102292,52003198);Shanghai Rising-Star Program(23QA1409300);Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-07-E00096)。

摘　　要：Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)Te_(3)focus on band and microstructure engineering.However,a clear understanding of the modulation of band structure and scattering through such engineering remains still challenging,because the minority carriers compensate partially the overall transport properties for the narrow-gap Bi_(2)Te_(3)at room temperature(known as the bipolar effect).The purpose of this work is to model the transport properties near and far away from the bipolar effect region for Bi_(2)Te_(3)-based thermoelectric material by a two-band model taking contributions of both majority and minority carriers into account.This is endowed by shifting the Fermi level from the conduction band to the valence band during the modeling.A large amount of data of Bi_(2)Te_(3)-based materials is collected from various studies for the comparison between experimental and predicted properties.The fundamental parameters,such as the density of states effective masses and deformation potential coefficients,of Bi_(2)Te_(3)-based materials are quantified.The analysis can help find out the impact factors(e.g.the mobility ratio between conduction and valence bands)for the improvement of thermoelectric properties for Bi_(2)Te_(3)-based alloys.This work provides a convenient tool for analyzing and predicting the transport performance even in the presence of bipolar effect,which can facilitate the development of the narrow-gap thermoelectric semiconductors.基于Peltier效应,Bi_(2)Te_(3)基合金被广泛应用于室温商用固态制冷。提高Bi_(2)Te_(3)室温热电性能的主流策略聚焦于能带和微结构工程。然而,少数载流子部分补偿了窄带隙半导体Bi_(2)Te_(3)在室温下的宏观输运特性(即双极效应),这使得人们深入理解能带结构、散射机制仍具挑战。本工作搜集了大量文献中Bi_(2)Te_(3)基热电材料的热电性能数据,通过同时考虑多数载流子和少数载流子贡献的双带模型模拟了Bi_(2)Te_(3)基热电材料在双极效应区域附近和远离双极效应区域的热电输运特性。在模拟过程中,将费米能级从导带过渡到价带以预测热电各项输运参数的变化情况,并且量化了Bi_(2)Te_(3)基热电材料的各项基本参数,如态密度有效质量、形变势系数等。该分析方法有助于找出提高Bi_(2)Te_(3)基合金热电性能的重要影响因素(如导带迁移率因子与价带迁移率因子的比值)。本工作为分析和预测材料在双极效应下的输运性能提供了一个方便的工具,为窄带隙热电半导体的发展提供了有利的条件。

关 键 词：thermoelectric material Bi_(2)Te_(3)-based alloy two-band model narrow-gap thermoelectric semiconductor 

分 类 号：TB64[一般工业技术—制冷工程]