CdSe Quantum Dots Enable High Thermoelectric Performance in Solution-Processed Polycrystalline SnSe

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Tin selenide (SnSe) is a promising thermoelectric material.
• Improving the thermoelectric performance of SnSe is crucial for energy harvesting applications.

Purpose of the Study:

• To enhance the thermoelectric performance of solution-processed polycrystalline SnSe.
• To investigate the effects of Ge and Cd codoping and CdSe quantum dots on SnSe's properties.

Main Methods:

• Solution processing to introduce CdSe quantum dots into Ge and Cd codoped SnSe.
• Microstructural characterization to confirm the presence of CdSe quantum dots.
• Ultraviolet photoelectron spectroscopy to analyze electronic structure modifications.
• Measurement of thermoelectric properties (Seebeck coefficient, electrical conductivity, thermal conductivity).

Main Results:

• A high figure of merit (ZT) of ≈2.0 was achieved in Ge and Cd codoped SnSe.
• CdSe quantum dots enhanced the density of states, leading to a larger Seebeck coefficient.
• Ge and Cd codoping optimized carrier concentration and improved electrical conductivity.
• CdSe quantum dots and lattice strain induced strong phonon scattering, resulting in ultralow lattice thermal conductivity.

Conclusions:

• Solution-processed polycrystalline SnSe with Ge and Cd codoping and CdSe quantum dots exhibits excellent thermoelectric performance.
• Microstructural manipulation, including quantum dot integration and lattice strain, is an effective strategy for designing advanced thermoelectric materials.