Engineering

Metallurgy

Materials science

Control engineering

Thermal conductivity

Decoupling (probability)

Thermoelectric effect

Phonon

Seebeck coefficient

Thermoelectric materials

Thermodynamics

Physics

Condensed matter physics

Composite material

Figure of merit

Dimensionless quantity

Optoelectronics

Science

Thermoelectric materials allow for direct conversion between heat and electricity, offering the potential for power generation. The average dimensionless figure of merit ZTave determines device efficiency. N-type tin selenide crystals exhibit outstanding three-dimensional charge and two-dimensional phonon transport along the out-of-plane direction, contributing to a high maximum figure of merit Zmax of ~3.6 × 10-3 per kelvin but a moderate ZTave of ~1.1. We found an attractive high Zmax of ~4.1 × 10-3 per kelvin at 748 kelvin and a ZTave of ~1.7 at 300 to 773 kelvin in chlorine-doped and lead-alloyed tin selenide crystals by phonon-electron decoupling. The chlorine-induced low deformation potential improved the carrier mobility. The lead-induced mass and strain fluctuations reduced the lattice thermal conductivity. Phonon-electron decoupling plays a critical role to achieve high-performance thermoelectrics.

High thermoelectric performance realized through manipulating layered phonon-electron decoupling