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High Thermoelectric Performance in p‐type Polycrystalline Cd‐doped SnSe Achieved by a Combination of Cation Vacancies and Localized Lattice Engineering
Author(s) -
Shi Xiaolei,
Wu Angyin,
Feng Tianli,
Zheng Kun,
Liu Weidi,
Sun Qiang,
Hong Min,
Pantelides Sokrates T.,
Chen ZhiGang,
Zou Jin
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201803242
Subject(s) - materials science , spark plasma sintering , thermoelectric effect , vacancy defect , doping , crystallite , thermoelectric materials , condensed matter physics , dopant , valence (chemistry) , phonon scattering , density functional theory , thermal conductivity , optoelectronics , sintering , computational chemistry , thermodynamics , metallurgy , chemistry , physics , organic chemistry , composite material
Herein, a high figure of merit ( ZT ) of ≈1.7 at 823 K is reported in p‐type polycrystalline Cd‐doped SnSe by combining cation vacancies and localized‐lattice engineering. It is observed that the introduction of Cd atoms in SnSe lattice induce Sn vacancies, which act as p‐type dopants. A combination of facile solvothermal synthesis and fast spark plasma sintering technique boosts the Sn vacancy to a high level of ≈2.9%, which results in an optimum hole concentration of ≈2.6 × 10 19 cm −3 and an improved power factor of ≈6.9 µW cm −1 K −2 . Simultaneously, a low thermal conductivity of ≈0.33 W m −1 K −1 is achieved by effective phonon scattering at localized crystal imperfections, as observed by detailed structural characterizations. Density functional theory calculations reveal that the role of Cd atoms in the SnSe lattice is to reduce the formation energy of Sn vacancies, which in turn lower the Fermi level down into the valence bands, generating holes. This work explores the fundamental Cd‐doping mechanisms at the nanoscale in a SnSe matrix and demonstrates vacancy and localized‐lattice engineering as an effective approach to boosting thermoelectric performance. The work provides an avenue in achieving high‐performance thermoelectric properties of materials.