A synergy of strain loading and laser radiation in determining the high-performing electrical transports in the single Cu-doped SnSe microbelt

A synergy of strain loading and laser radiation in determining the high-performing electrical transports in the single Cu-doped SnSe microbelt

Semiconducting microbelts are key components of the thermoelectric micro-devices, and their electrical transport properties play significant roles in determining the thermoelectric performance. Here, we report heavily Cu-doped single-crystal SnSe microbelts as potential candidates employed in thermoelectric micro-devices, fabricated by a facile solvothermal route. The considerable Cu-doping concentration of ~11.8 % up to the solubility contributes to a high electrical conductivity of ~416.6 S m-1 at room temperature, improved by one order of magnitude compared with pure SnSe (38.0 S m-1). Meanwhile, after loading ~1 % compressive strain and laser radiation, the electrical conductivity can be further improved to ~601.9 S m-1 and ~589.2 S m-1, respectively, indicating great potentials for applying to thermoelectric micro-devices. Comprehensive structural and compositional characterizations indicate that the Cu+ doping state provides more hole carriers into the system, contributing to the outstanding electrical conductivity. Calculations based on first-principle density functional theory reveal that the heavily doped Cu lowers the Fermi level down into the valence bands, generating holes, and the 1 % strain can further reduce the bandgap, strengthening the ability to release holes, and, in turn, leading to such an excellent electrical transport performance. This study fills the gaps of finding novel materials as potential candidates employed in the thermoelectric micro-devices and provides new ideas for micro/nanoscale thermoelectric material design.

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