| 초록 |
We concurrently alloy Te to the PbSe lattice and introduce excess Cu to its interstitial voids. The strong attraction between interstitial Cu and Te atoms in the lattice facilitates charge transfer from Cu atoms to the crystal matrix. It follows the increased carrier concentration without damaging its mobility and the consequently improved electrical conductivity. This interaction also increases effective mass of electron in the conduction band according to the first principle calculation results, thereby enhancing Seebeck coefficient. As a result, Cu0.005PbSe0.99Te0.01 exhibits record high average power factor of 27 μWcm-1K-2 over 400-773 K. The highly mobile intersitial Cu atoms also severely distort the local microstructure by displacing Pb atoms from the ideal octahedral sites. This markedly depresses minimum lattice thermal conductivity to ~0.2 Wm-1K-2. These multiple effects synergistically boosts ZT to ∼1.7 at 773 K with a high average ZT ~1.3 from 400 to 773 K. |
