●Currest research
１．Thin film thermoelectric materials
Thermoelectric materials can directly convert thermal energy into electrical energy, and can generate electricity using the Seebeck effect, in which a voltage (thermal electromotive force) is generated when a temperature difference is applied to the material. Thin-film thermoelectric materials, in particular, are expected to be used as a stand-alone power source for Internet of Things (IoT) sensors because they can generate power in a small space, although the amount of power generated is small.
To obtain high thermoelectric properties, interface-controlled nanostructures are very effective. I have been controlling thermoelectric properties by nanostructures for Si-based materials at Osaka University as shown below. Currently, I am working on nanostructured epitaxial thin films of Mg-based Zintl phase compounds with the aim of controlling thermoelectric properties.
●Previous research
１．Nanostructured thermoelectric materials
・Epitaxial Si thin films containing nanodots (at Osaka Univ.)
Epitaxial Si thin films containing nanodots were fabricated by molecular beam epitaxy using ultrathin SiO2 film technique to simultaneously control carriers (electrons) responsible for electrical conduction and phonons responsible for thermal conduction. Furthermore, the strain and defects can be controlled by changing the type of nanodots and the surface orientation of the substrate, and the effects of these on the thermoelectric properties of Si have been clarified.
[1] S. Sakane, et al., J. Vac. Sci. Technol. A 35(4), 041402 (2017).
[2] S. Sakane, et al., Mater. Today Energy 13, 56-63 (2019).
[3] S. Sakane, et al., Appl. Phys. Lett. 115, 182104 (2019).
[4] S. Sakane, et al., Jpn. J. Appl. Phys. 59, SFFB01-1-5 (2020).
・Nanostructured bulk SiGe (at Osaka Univ.)
We have demonstrated for the first time that the thermoelectric power factor was improved in nanostructured bulk SiGe composites by controlling the temperature distribution (we call it thermal management).
[1] S. Sakane, et al., ACS Appl. Energy Mater. 3, 1235-1241 (2020).
[2] S. Sakane, et al., J. Mater. Chem. A 9, 4851-4857 (2021).
・Organic-Inorganic hybrid thin films (at Chuo Univ.)
Cu2Se nanowires were prepared for the first time using the photoreduction method, and it was shown that high thermoelectric properties were obtained by compositing them with PEDOT:PSS, a conductive polymer.
[1] S. Sakane, et al., ACS omega 7, 32101-32107 (2022).
２．Synthesis of Cu nanoparticles by photoreduction method
・Cu nanoparticle catalsts (at Chuo Univ.)
Cu nanoparticles were synthesized in zeolite pores by photoreduction method and we demonstrated highly efficient reaction for the oxidation of benzyl alcohol.
[1] S. Sakane, et al., ACS Omega accepted.
・Plasmonic heating of Cu nanoparticles
Cu nanoparticles synthesized by the photoreduction method were composited with PNIPAM, a thermo-responsive material. We demonstrated that local heating of Cu nanoparticles by localized surface plasmon resonance occurs when irradiated with visible light.
[1] S. Sakane, et al., Chem. Lett. 52, 582-585 (2023).