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Rational Electronic and Structural Designs Advance BiCuSeO Thermoelectrics
Author(s) -
Gu Yan,
Shi XiaoLei,
Pan Lin,
Liu WeiDi,
Sun Qiang,
Tang Xiao,
Kou LiangZhi,
Liu QingFeng,
Wang YiFeng,
Chen ZhiGang
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202101289
Subject(s) - materials science , crystallite , condensed matter physics , fermi level , doping , anisotropy , figure of merit , thermoelectric effect , density functional theory , thermoelectric materials , band gap , power factor , thermal conductivity , spark plasma sintering , optoelectronics , composite material , thermodynamics , metallurgy , ceramic , optics , computational chemistry , electron , power (physics) , chemistry , physics , quantum mechanics
In this work, a record high thermoelectric figure‐of‐merit ZT of 1.6 ± 0.2 at 873 K in p‐type polycrystalline Bi 0.94 Pb 0.06 CuSe 1.01 O 0.99 by a synergy of rational band manipulation and novel nanostructural design is reported. First‐principles density functional theory calculation results indicate that the density of state at the Fermi level that crosses the valence band can be significantly reduced and the measured optical bandgap can be enlarged from 0.70 to 0.74 eV by simply replacing 1% O with 1% Se, both indicating a potentially reduced carrier concentration and in turn, an improved carrier mobility and a boosted power factor up to 9.0 µW cm −1 K −2 . Meanwhile, comprehensive characterizations reveal that under Se‐rich condition, Cu 2 Se secondary microphases and significant lattice distortions triggered by Pb‐doping and Se‐substitution can be simultaneously achieved, contributing to a reduced lattice thermal conductivity of 0.4 W m −1 K −1 . Furthermore, a unique shear exfoliation technique enables an effective grain refinement with higher anisotropy of the polycrystalline pellet, leading to a further improved power factor up to 10.9 µW cm −1 K −2 and a further reduced lattice thermal conductivity of 0.30 W m −1 K −1 , which gives rise to record high ZT .