Solid-Solutioned Homojunction
Nanoplates with Disordered
Lattice: A Promising Approach toward “Phonon Glass Electron
Crystal” Thermoelectric Materials
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Abstract
The concept of “phonon glass electron crystal”
(PGEC)
was proposed in the mid-1990s to maximize the <i>ZT</i> value
for thermoelectric materials, based on its combined advantages of
low thermal conductivity as in a glass but high electricity as in
a well-ordered crystal. Although a great amount of research in complex
materials systems for achieving this concept has been done, a perfect
“PGEC” material has not been acquired yet. Herein, we
first put forward a solid-solutioned homojunction in high temperature
phase with disordered lattice, which possesses both high electrical
conductivity and low thermal conductivity, as an effective way to
optimize the low/mid-temperature thermoelectric property. As an example,
nonambient cubic phase AgBiSe<sub>2</sub> was successfully stabilized
to room temperature through the formation of a solid solution by Sb
incorporation for the first time, and furthermore, in situ formed
homojunctions on the surface of solid-solutioned nanoplates were also
first achieved through a simple colloidal method. A significant enhancement
of thermoelectric performance at low/mid-temperature was realized
through synergistical regulation on electronic and thermal transport.
As a result, compared to that of original AgBiSe<sub>2</sub> (<i>ZT</i> = 0.03 at 550 K), the <i>ZT</i> value of AgBi<sub>0.5</sub>Sb<sub>0.5</sub>Se<sub>2</sub> was increased to 0.51 at
550 K by the formation of a solid solution, and then further increased
to 1.07 at 550 K by the formation of solid-solutioned homojunction