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New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n‐type Mg 3 Sb 2 ‐Based Thermoelectric Materials
Author(s) -
Zhang Jiawei,
Song Lirong,
Borup Kasper Andersen,
Jørgensen Mads Ry Vogel,
Iversen Bo Brummerstedt
Publication year - 2018
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.201702776
Subject(s) - electronegativity , chalcogen , dopant , materials science , doping , thermoelectric effect , density functional theory , electron mobility , effective mass (spring–mass system) , chemical physics , computational chemistry , nanotechnology , crystallography , optoelectronics , thermodynamics , chemistry , organic chemistry , physics , quantum mechanics
n‐type Mg 3 Sb 1.5 Bi 0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n‐type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n‐type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing electronegativity difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing electronegativity difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on electronegativity is proposed to shed new light on n‐type doping in Zintl antimonides.