NAIST Graduate School of Materials Science

Organic Electronics Laboratory

Staff & Contact
Educational StaffProf. Masakazu Nakamura
Associate Prof. Hiroaki Benten
Assistant Prof. Hirotaka Kojima
URLhttp://mswebs.naist.jp/LABs/greendevice/index_e.html

Let’s imagine electronic equipment that is easy to carry in a rolled state, a piece of fabric that generates electricity from the human body or a paper-like solar battery that generates electricity by choosing the most available light. Adding such unprecedented electronic functions onto various “surfaces”, human life will become more comfortable and prosperous. We are pursuing the realization of such novel electronic devices through studies elucidating unique interactions in organic solids and applying the findings to the device functions using knowledge of solid-state physics, electronics, surface science, polymer physics, and molecular science. Our laboratory utilizes unique approaches made possible by our original evaluation apparatus and theoretical calculations.

We determine individual research projects ranging from basic science to development of operable devices, depending on the interests and aptitudes of the students. We foster independent thinking and a top-level mindset necessary for a researcher through joint research with institutes in Japan and overseas. Thus, we aim to cultivate researchers with a broad knowledge of science and a keen interest toward industrial applications.

1. Creation of “soft” thermoelectric materials
We are attempting to create novel thermoelectric materials and innovative flexible thermoelectric generators to convert exhaust heat from the living environment and the human body into electricity. We have found that the thermal conductivity of a carbon nanotube composite decreases to 1/1000 by forming molecular junctions between nanotubes with a specially designed protein (Fig. 1). We are also trying to elucidate and control the Giant Seebeck Effect in organic semiconducting solids discovered in our laboratory (Fig. 2) with the aid of advanced measurement techniques, theoretical physics, and computational chemistry.
2. Elucidation of carrier transport mechanisms in organic semiconductors
We develop original characterization techniques, such as AFM Potentiometry, and perform studies to deepen understanding of the structure and the electronic functions of organic semiconductors.
3. Development of next-generation plastic solar cells
We develop next-generation solar cells based on semiconducting polymers. To elucidate the mechanisms that lead to photon-to-current energy conversion, functional structures of the photovoltaic layer have been visualized at the nanometer scale by conductive atomic force microscopy. (Fig. 3)
4. Development of flexible THz imaging devices using organic transistor structures
We are performing fundamental studies on the interaction of free carriers in organic field-effect transistors with terahertz (THz) waves, aiming at the realization of flexible THz imaging devices that utilize the band-edge potential fluctuation in organic thin films. (Fig. 4)

  • Fig. 1 A novel design of a thermoelectric nanocomposite using biomolecular junctions
  • Fig. 2 Conceptual diagram of the Giant Seebeck Effect: a specific current-heat flow interaction in organic solids
  • Fig. 3 Functional structures for photovoltaic conversion in plastic solar cells
  • Fig. 4 An image of a baggage check with the rollable THz-wave imaging device

1. H. Kojima et al., “Giant Seebeck effect in pure fullerene thin films”, Appl. Phys. Express 8 121301 (2015).
2. R. Matsubara et al., “Quantitative investigation of the effect of gate-dielectric surface treatments on limiting factors of mobility in organic thin-film transistors”, J. Appl. Phys. 118 175502 (2015).
3. M. Ito et al., “Enhancement of Thermoelectric Properties of Carbon Nanotube Composites by Inserting Biomolecules at Nanotube Junctions”, Appl. Phys. Express 7 065102 (2014).

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