Welcome to Tsuji Laboratory Website

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

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

HASEGAWA, Kei: Millimeter-scale growth of single-walled carbon nanotubes on substrates (2011).
UESAWA, Norihisa: Production of silicon materials using gas phase zinc reduction of silicon tetrachloride (2011).

SUGIME, Hisashi: Clarification of catalytic growth mechanism of single-walled carbon nanotubes and control of their synthesis (2010).

KUZUOKA, Yoshikazu: Photo-functional devices using poly p-phenylenevinylene derivatives (2008).
KAKEHI, Kazunori: Growth of single- and multi-walled carbon nanotubes catalized by sputter-deposited metal nanoparticles (2008).

KOMOTO, Atsushi: Unstabilization of semiconductor nanoparticle suspensions by light irradiation and oscillation in their fluorescence (2007).

Past Master Theses

OTOWA, Takuya: Mode transition between shear-thinning/thickening in colloidal suspensions (2011).
SEKIGUCHI, Kotaro: Instant implementation of carbon nanotube field emitters by pulse-current heating CVD (2011).
TAKANO, Soichiro: Direct fabrication of metal-free graphene films on substrates (2011).
NARITA, Eisuke: Crystallization of organic semiconductor films by laser annealing (2011).
HIRANO, Yoshihisa: Drying properties of colloidal suspensions and formation of particle structures (2011).
LEE, Kyu-Ha: Fabrication of dense FePt nanorod arrays by separation of sputtered polycrystalline films at their grain boundaries (2011).
KANG, Heunku: Fabrication of graphene from amorphous carbon by metal-induced crystallization and crystal growth mechanism (2011).

KETPREECHASAWAT, Suarpa: Self-organized networks of carbon nanotubes and their transparent conducting properties (2010).
PARK, Sang Wook: Sustainable centimeter-scale growth of carbon nanotubes (2010).

ARAKI, Yoshitomo: Improvement of energy conversion efficiency of concentrated spherical silicon solar cells (2010).
ISHITSUKA, Yoko: Gas-phase synthesis of single-walled carbon nanotubes by gas-suspended catalysts and their growth mechanism (2010).
OHTA, Seiichi: Shear induced change in alignment and function of endothelial cells (2010).
TSUJI, Yukie: Structural control of polycrystalline cobalt silicide thin films (2010).
NOMURA, Keisuke: Development of catalysts for low temperature growth of carbon nanotubes (2010).
MIYAOI, Kenichi: Evaluation of bio-hazard of nanomaterials by statistical analysis and in vitro experiments (2010).

OI, Yuki: Structural evolution and optical/electronical properties of coated thin films in organic semiconducting devices (2009).
OGINO, Yumi: Fabrication and performance evaluation of single-walled carbon nanotube filters for nanoparticle separation (2009).
OKU, Keisuke: Mode change of settling and aggregation mechanism in colloidal silica aqueous suspensions (2009).
SHIRAI, Takashi: Low temperature growth of carbon nanotubes and their dense growth by thin-film catalysts (2009).
NAKATSU, Hiroaki: Mechanical properties of drop-casted nanoparticle films (2009).
MANO, Ryohei: Aggregation and blocking in pressure-driven flow of dense colloidal suspension (2009).
MUNGAI, F. Kanyiri: Rapid epitaxial growth and lift-off process for fabrication of single-crystalline silicon thin films for solar cells (2009).
MOROKUMA, Shingo: Development of Si thin film anode for Li ion secondary battery (2009).

SHEN, Peng: Synthesis of Silicon Nanoparticles by Plasma CVD (2008).
WAKABAYASHI, Tomonori: Study on the self-organization process of nanoparticles in drying droplet of their suspension (2008).
ITO, Ryuhei: Seperate control of the gas-phase and catalytic reactions in catalytic CVD synthesis of carbon nanotubes (2008).
TAKASHIMA, Satoshi: Understanding of Cu deposition mechanism under chlorine atmosphere and developement of via-filling process (2008).
HASEGAWA, Kei: Rapid growth of single-walled carbon nanotubes on substrate by thermal CVD method (2008).
WADA, Kosuke: Photo-assembly of semiconductor nanoparticles (2008).

ONDA, Takuma: Flow-induced structure of dense colloidal suspension (2007).
UESAWA, Norihisa: Wet synthesis of Si nanoparticles and their characterization (2007).
OHSHIMA, Hiroshi: Synthesis and characterization of amorphous silica film showing phase transition from semiconductor to insulator (2007).
KUWAHARA, Yuichi: Fabrication of crystalline silicon thin films for solar cells by epitaxial lift-off method (2007).
SUGIME, Hisashi: Combinatorial screening of catalysts and basics and control of single-walled carbon nanotube growth (2007).
MASHIGE, Yoko: Structural evolution in photopolymers by self-organization (2007).
MORISHITA, Azusa: Grain boundary control of sputtered, magnetic FePt nanocrystalline thin films (2007).
YAMAGUCHI, Masahiro: Optical characteristic and device application of poly-phenylenevinylene derivatives (2007).

CAI, Yixin: Heterogeneous aggregation of nanoparticles during drying (2006).

Past Bachelor Theses

IWAMURO, Norito: Structures and properties of low molecular organic thin films formed by wet process (2011).
OHTAKE, Hidenori: Dispersion-aggregation states and optical properties of silicon nanoparticles (2011).
HIROTA, Kosuke (M1): Fabrication of single-crystalline silicon thin films for solar cells by rapid vapor deposition and epitaxial lift-off methods (2011).
MASUDA, Ryuya (M1): Fabrication and structural control of graphene by chemical vapor deposition using Cu thin film catalysts (2011).

ENDO, Midori: Quantitative evaluation of supersaturation ratio in wet-coated organic thin films during drying (2010).
SATO, Yoshikuni: Gas-phase synthesis of single-walled carbon nanotube seeds (2010).
JIN, Kentaro: Formation mechanism of network structures of nanoparticles (2010).
YAMAGUCHI, Kohei: Evolution mechanism of anisotropic refractory index in colloidal particle films (2010).

ITO, Takehiro: Simulation of string-shaped nanoparticle systems under flow (2009).
OTOWA, Takuya: Shear thickening mechanism of dense colloidal suspension under shear field" (2009).
SEKIGUCHI, Kotaro: Instant implementation of carbon nanotube field emitters by pulse-current heating (2009).
TAKANO, Soichiro: Developing a selective filling method of micro-pores (2009).
NARITA, Eisuke: Structure control and application to electronic devices of tetrabenzoporphyrin organic semiconducting thin films (2009).
HIRANO, Yoshihisa: Elucidation of secondary particle formation mechanism in drying droplet of nanoparticle suspensions (2009).

ARAKI, Yoshimoto: Development of granulation method of silicon balls for solar cells by laser heating (2008).
OHTA, Seiichi: Simulation of thin film formation by drying of colloidal nanorod suspensions" (2008).
TSUJI, Yukie: Understanding and controlling crystal growth of cobalt silicide thin films for electronic devices (2008).
NOMURA, Keisuke: Low temperature growth of carbon nanotubes by function-shared catalysts" (2008).
MATSUMOTO, Kaoru: Observation of crystallization process of spherical silicon during cooling" (2008).

OI, Yuki: Modeling of voltage-current characteristics in organic light-emitting devices" (2007).
OKU, Keisuke: Formation of bimodal size distribution during aggregation of colloids" (2007).
SAKURADA, Yuki: Dispersion and aggregation mechanism of colloidal nanoparticles in flow" (2007).
MOROKUMA, Shingo: Structural change of catalyst nanoparticles during carbon nanotube growth" (2007).