Research

We are challenging to realize such novel electronic devices by the studies elucidating unique interactions in organic solids and applying the findings to the device functions with the knowledge of solid-state physics, electronics, surface science, polymer physics, and molecular science. The left-side panel is a poster showing our on-going studies (click to enlarge).

One unique point of this laboratory is to develop original research tools, such as the world’s only characterization techniques and thin-film fabrication instruments, for the elucidation of materials properties coming from nano-structures in organic materials. Theoretical calculations are also used to elucidate molecular-scale mechanisms that cannot be clarified only by experiments.

Another unique point is to develop entirely new device applications that are not just follow-ups of somebody’s works. We totally propose and demonstrate which material properties of what kind of materials we should use, how the device structure should be, and how to fabricate such devices to obtain a novel function.


Research Projects

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 aids of advanced measurement techniques, theoretical physics, and computational chemistry.
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

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.
Hierarchical structure and band-edge profile of pentacene thin films

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)
Functional structures for photovoltaic conversion in plastic solar cells

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 the terahertz (THz) waves, aiming at the realization of flexible THz imaging devices that utilize the band-edge potential fluctuation in organic thin films.
An image of a baggage check with the rollable THz-wave imaging device

Original characterization techniques

  • Atomic-Force-Microscope Potentiometry (AFMP)
  • Four-Point-Probe Field-Effect Transconductance Method (FPP-FET)
  • in-situ Field-Effect Thermally-Stimulated-Current Method (FE-TSC)
  • in-situ Thermo-Power Measurement System for Organic Thin-Films
  • Thermo-Power Measurement System for Organic Powder Materials
  • THz-Time Domain Spectometer for Gate-Modulation Spectroscopy of Organic Transistors

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