Ultralow Thermal Conductivity and High Thermoelectric Figure of Merit in Two-Dimensional Thallium Selenide

• Several selenides have been studied as potential thermoelectric materials in the past. Thermoelectric performance improves on reducing the dimension of the system. Following these notions, we studied three hexagonal two-dimensional phases of thallium selenide for promising thermoelectric performance by using first-principles techniques. Their dynamical and mechanical stabilities have been shown. The band gaps using different approximations of calculations have been reported and are in the range that can render these materials to show optimal thermoelectric performance. The lattice thermal conductivity is ultralow between 0.088 and 0.429 W m(-1) K-1 at 900 K. High thermoelectric performance has been predicted in the systems with the figure of merit reaching magnitudes of similar to 0.5-1.94 between 300 and 900 K. The high thermoelectric performance results from an ultralow thermal conductivity arising due to the strong lattice anharmonicity. These results can have significant impact on the synthesis of high performance thermoelectric materials based on thallium selenide.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

Nyckelord

low thermal conductivity

thermoelectric

high figure of merit

electronic structures

anharmonicity

phonon scattering

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