Tsuji Laboratory

Japanese

Research: Nanomaterials & Self-Organization

Nanotechnology brings innovations widely to information/communication, energy/enviroment, and bio/medicals by adding novel functions to materials by controlling their structures at nanometer-scale. We are trying to establish the base of materials nanotechnology.

Let us think about the future clean energy systems. For large-scale electric power generation by solar cells, efficient use of high purity silicon is the key so that we are trying to improve the efficiency several-ten times by making single-crystalline balls or thin films. Transparent electrodes are important for both solar cells (yielding electricity from light) and displays & lightings (generating lights from electricity), and we will replace current electrodes using rare-elements with carbon nanotubes. We are developing energy-conservation displays & lightings by using nanotube field emitters. Nanotube-silicon hybrids are promissing to realize Li ion batteries of larger capacities for (hybrid) electric vehicles, and nanotube-polymer hybrids are promissing to make lightweight vehicles & airplanes. In this way, nanotechnology can bring innovations widely even if elements are confined to just carbon and silicon, and contributes to sustainable technological society.

But nanomaterials can never be made in macro-scale if we artificially manipulate each atoms/molecules. Self-organization, i.e. spontaneous formation of materials from numerous atoms/molecules, is the key. We are trying to fundamentally understand the processes of chemical reactions of atoms/molecules, formation of nanostructures, and evolution of higher-order structures through both experiments and numerical simulations.

We are also actively conducting industry-academia joint projects to realize practical applications by utilizing these nanomaterials technologies.


Silicon Materials | Nanocarbons | Organic/Inorganic/Hybrids | Colloid System Infrastructure

Silicon Materials

Single-crystalline silicon realized semiconductor industry. But it is leading solar cells at the same time. But the processes originate from semiconductor device fabrication so that their cost is too high and scale is too small for solar cell fabrication. We are developing single-crystalline balls or thin films to improve the efficiency of silicon usage by several-ten times. We are also developing a new chemical route for feedstock production of high purity silicon.
Silicon changes its band structure when their size decreases to nanometer-scale. We are trying to apply silicon nanoparticles to bio-markers for medical diagnostics.
  • SHEN, Peng (D3): Fabrication process of silicon nanoparticles by plasma CVD method.
  • OHTA, Seiichi (D2): Application of fluorescent silicon nanoparticles into cellular imaging.
  • LEE, Jungho (D2): Developement of silicon-based high capacity anodes for lithium ion battery.
  • JIN, Kentaro (M2): Application of HIT structure to ball silicon solar cells.
  • YAMAGUCHI, Kohei (M2): Production of needle-like silicon crystals by zinc-reduction of tetrachlorosilane and laser annealing.
  • HIROTA, Kosuke (M1): Fabrication of single-crystalline silicon thin films by rapid vapor deposition and epitaxial lift-off methods.
  • OHTAKE, Hidenori (RS): Photoluminescence mechanism of silicon nanoparticles produced by plasma CVD method.
  • TSUTSUMI, Naoya (B4):
  • YAMURA, Kentaro (B4):

Sherical Silicon Solar Cells


Full-Color PL of Si-QDs by PE-CVD

Organic/Inorganic/Hybrids

As explained above, silicon and carbon nanomaterials realize various functions. And their hybrids further enrich the variety of functions.
Thin film technology is crucial for applying various materials to electronic devices. We are studying crystal growth processes and developing wiring technologies of metal thin films. We are also studying crystal growth processes of organic semiconducting thin films for thin-film transistors & luminescence devices.
  • YAMAGUCHI, Masahiro (D3): Self-organization in organic thin films.
  • OKU, Keisuke (D3): Structure control of low molecular organic semiconducting thin films via solution process.
  • IWAMURO, Norito (M1): Crystallization process and crystallinity evaluation of organic materials.
  • TANABE, Hajime (B4):

Luminescence from structure-controlled organic conductors


c-Axis oriented L10-FePt magnetic nanoparticles

Colloid System Infrastructure

Although actural fabrication processes of materials are largely dependent on substance properties, we can fundamentally study the structure evolution keeping the influence of substance properties unchanged by using standard substances.
When we understand the mechanism common for substances, we can conduct simulations commonly. Such simulations enable analysis at time & spatial scales which is difficult by experiments. We are developing a simulation infrastructure of dispersion/aggregation of colloids under flow/drying environment, which are important in various applications such as inks, cosmetics, foods, medicals.
In addition, safety & risk of nanomaterials is also important. We are developing an infrastructure systematically evaluating nanomaterials properties as well as their fabrication processes.
  • NAKATSU, Hiroaki (D3): Mechanical properties of drop-casted nanoparticle films.
  • EIHA, Noriko (D2): Gelation mechanism of nanoparticle suspensions.
  • NIKAIDO, Fumiya (D2): Bimodal distributions appearing in aggregate sizes of silica nanoparticles.
  • SUGIURA, Akihiko (B4): Crack formation mechanism in particle films coated-dried from concentrated suspensions.
Please clik here and here for details.

Free/ Hindered Settling of Silica Particles


Modeling of Colloidal Nanoparticles in Fluid

Past Ph. D. Theses

Past Master Theses

Past Bachelor Theses


Yamaguchi Laboratory&Tsuji Laboratory Department of Chemical System Engineering
School of Engineering, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan