아래와 같이 응집물질물리 세미나 일정을 안내드리니 많은 관심과 참석을 바랍니다

일시: 2026. 08. 19(수) 15시 30분

장소: 제1물리관 105호 대회의실

연사/소속: Hiromichi Ohta 교수 (Hokkaido University)

연제: Development of solid-state electrochemical thermaltransistors

초록: Precise control of device temperature is essential forpreventing electronic devices from malfunctioning or failing undervarying operating conditions and self-heating. In analogy tosemiconductor field-effect transistors, which electrically switchcurrent on and off, thermal transistors (or thermal switches) aredevices that electrically modulate heat flow and have emerged as apromising platform for active thermal management. The first thermaltransistor was theoretically proposed in 2014 using VO2 as theactive material, exploiting its structural phase transition frommonoclinic to tetragonal symmetry near 68 °C and the accompanyinginsulator-to-metal transition. However, this concept could not beexperimentally realized because pristine VO2 exhibits negligibleelectronic contributions to thermal conductivity. Subsequent studiesdemonstrated electrochemical thermal transistors, in which thermalconductivity is modulated by ion intercalation/deintercalation inlayered materials or by proton or oxide-ion insertion/extraction inmetal oxides. Other approaches, including field-effect devices basedon ferroelectric domain switching or self-assembled monolayers, andgap-type devices incorporating a low-thermal-conductivity air layer,have also been explored. Among these approaches, we focused on theelectrochemical concept because it offers scalability fromminiaturized devices to large-area architectures. However,previously reported electrochemical thermal transistors rely onliquid electrolytes, which pose challenges for practical integrationand long-term operation despite their room-temperaturefunctionality. To overcome this limitation, we developed anall-solid-state electrochemical thermal transistor based on a solidelectrolyte, eliminating the need for liquid components whileretaining electrically controlled heat-flow modulation. In thisseminar, I will introduce several thermal transistors including oursolid-state electrochemical thermal transistors using several oxidethin films grown on solid electrolyte.