| 초록 |
Highly efficient thermoelectric materials have attracted tremendous attention due to various technological applications such as power generation from waste heat and environmentally friendly refrigeration. Nano- and mesostructuring is widely used in thermoelectric (TE) materials. It introduces numerous interfaces and grain boundaries that scatter phonons and decrease thermal conductivity. Chemically synthesized nanoparticles have been recognized as the noble nano-scale building blocks for the preparation of bulk-scale nanostructured thermoelectric materials as well as studying the fundamental thermoelectric properties of nano-scale materials. For example, the nanostructured Bi2Te3 bulk materials prepared from colloidal Bi2Te3 nanoplates also exhibited very high electrical conductivity and low thermal conductivity, consequently enhancing ZT values higher than pure that of Bi2Te3 bulk. Furthermore, all-inorganic Bi NCs capped with Sb2Te3 ligands were used as an additive to BiSbTe ball-milled micro-particles. During heat treatment, NCs fill up the interfaces and voids between micro-particles and act as a “glue” joining grains in hot-pressed pellets or solution-processed thin films. The chemical design of the NC glue allowed for the selective enhancement or reduction of the majority carrier concentration near the grain boundaries, and thus resulted in doped or de-doped inter-faces in granular BiSbTe material. The pellets with engineered interfaces showed increased power factors and reduced thermal conductivities compared to the reference samples without NC glue. This resulted in enhanced ZT values well above 1. |
