[14a-B12-1~11] 22.1 Joint Session M "Phonon Engineering"

▲ [14a-B12-5] Thermoelectricity at Solid/Liquid Interface of Colloidal Quantum Dot Arrays

〇Satria Zulkarnaen Bisri¹, Maria Ibanez^2,3, Sunao Shimizu¹, Maksym Kovalenko^2,3, Yoshihiro Iwasa^1,4 (1.RIKEN-CEMS, 2.ETH Zurich, 3.EMPA, 4.Univ. Tokyo)

Keywords:colloidal quantum dots, nanocrystals, thermoelectric

Nanostructuring is one of the most promising way to overcome the challenges to develop high performance thermoelectric materials. One of the most important feature of colloidal quantum dots (QDs) in this respect is the formation of quasi-atomic discrete energy levels resulting from the quantum confinement effect, beneficial for thermoelectric. On the other hands, well-ordered tightly-bonded monolayers of solid assemblies of nanoscale QDs might be transparent for electrons to diffuse, but with large amount of boundaries for phonons to scatter. This would lead to the decoupling of electronic and thermal conductivity. While so far the most common approach to utilize colloidal QDs for thermoelectricity is limited as material sources for hot-pressed nanocomposite pellets and relies much on metal intercalation to enhance its electrical conductivity, exploitation of the quantum confinement effect has yet to be explored. Through the interfacing between metal-chalcogenide colloidal QD arrays and ionic liquid, we demonstrate the measurement of high value of Seebeck coefficient reaching orders of mV/K at room temperature, stems from the interplay of field-induced doping by voltage-gated ionic liquid and the preserved discrete energy levels in the well-ordered QD arrays.