Open AccessDegenerated Hole Doping and Ultra‐Low Lattice Thermal Conductivity in Polycrystalline SnSe by Nonequilibrium Isovalent Te Substitution
Author(s) -
He Xinyi,
Zhang Haoyun,
Nose Takumi,
Katase Takayoshi,
Tadano Terumasa,
Ide Keisuke,
Ueda Shigenori,
Hiramatsu Hidenori,
Hosono Hideo,
Kamiya Toshio
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202105958
Subject(s) - materials science , crystallite , thermoelectric effect , doping , phonon scattering , thermal conductivity , condensed matter physics , phonon , thermoelectric materials , selenide , ion , analytical chemistry (journal) , crystallography , optoelectronics , chemistry , thermodynamics , metallurgy , selenium , physics , organic chemistry , chromatography , composite material
Tin mono‐selenide (SnSe) exhibits the world record of thermoelectric conversion efficiency ZT in the single crystal form, but the performance of polycrystalline SnSe is restricted by low electronic conductivity ( σ ) and high thermal conductivity ( κ ), compared to those of the single crystal. Here an effective strategy to achieve high σ and low κ simultaneously is reported on p‐type polycrystalline SnSe with isovalent Te ion substitution. The nonequilibrium Sn(Se 1− x Te x ) solid solution bulks with x up to 0.4 are synthesized by the two‐step process composed of high‐temperature solid‐state reaction and rapid thermal quenching. The Te ion substitution in SnSe realizes high σ due to the 10 3 ‐times increase in hole carrier concentration and effectively reduced lattice κ less than one‐third at room temperature. The large‐size Te ion in Sn(Se 1− x Te x ) forms weak SnTe bonds, leading to the high‐density formation of hole‐donating Sn vacancies and the reduced phonon frequency and enhanced phonon scattering. This result—doping of large‐size ions beyond the equilibrium limit—proposes a new idea for carrier doping and controlling thermal properties to enhance the ZT of polycrystalline SnSe.