[17a-Z17-1~11] 9.4 Thermoelectric conversion

▼ [17a-Z17-2] Thermoelectric Properties of Tungsten Oxide Films with 1D Atomic Defect Tunnels

〇(DC)GOWOON KIM¹, Bin Feng², Yu-Miin Sheu³, Sangkyun Ryu⁴, Hyoungjeen Jeen⁴, Yuichi Ikuhara², HaiJun Cho^1,5, Hiromichi Ohta^1,5 (1.IST-Hokkaido Univ., 2.Univ. Tokyo, 3.Natl Chia Tung Univ., 4.Pusan Natl Univ., 5.RIES-Hokkaido Univ.)

Keywords:Tungsten Oxide, Thermal conductivity, Thermopower

The coexistence of high electron conduction and low heat conduction is essentially important to realize efficient thermoelectric materials. Although introducing 0D point defects or 2D layers is known as an effective way to reduce the heat conduction, there is a dilemma that the electron conduction is also reduced due to that electrons and phonons are scattered simultaneously by impurities, defects, and boundaries. Here we show that introducing a 1D atomic defect tunnel which is epitaxially stabilized in oxygen deficient tungsten oxide WO_x films is an excellent solution to solve this dilemma. The thermal conductivity (κ) of the films drastically decreased from ~7 to ~1.5 W m⁻¹ K⁻¹ and the electrical conductivity (σ) in the in-plane direction of WO_x film dramatically increased from ~10⁻¹ to ~10³ S cm⁻¹ with increasing 1D defects. These results clearly indicate that high electron conduction and low heat conduction coexist in the oxygen-deficient tungsten oxide epitaxial films. The present finding would be useful to design efficient thermoelectric materials.