| 초록 |
Here we report that PbSe0.998Br0.002-2%Cu2Se exhibits record high values of peak ZT ~1.8 at 723 K and average ZT ~1.1 at 300-873 K for PbSe thermoelectrics, rivaling the state-of-the-art n-type PbTe thermoelectrics. Cu2Se uniquely provides multiple desirable mechanisms synergistically enhancing the electrical and thermal transport properties for n-type PbSe thermoelectrics. It enlarges the band gap, flattens the edge of conduction band and increases the effective mass of charge carriers, leading to a substantially improved Seebeck coefficient for PbSe. The carrier concentration is concurrently increased with nearly no loss in carrier mobility, giving even increased electrical conductivity above ~423 K. The result is very high power factor ~21-26 μW cm-1K-2 over the wide range of temperature above 423 K. Cu2Se doping significantly reduces lattice thermal conductivity as low as ~0.4 Wm−1K−1 at 773 K, which can be attributed to enhanced phonon-phonon scattering and phonon softening. |
