(6hb) Engineering Nanopores and Nanostructures of Atomically Thin Sheets and Carbon Nanotubes

Engineering optical properties of nanomaterials allow us to achieve the efficient process of light-material interaction and contribute to improving photochemical reaction and performance of photovoltaics and photodetector. Nanomaterials possess unique properties due to quantum confinement effects, which differs from bulk materials. In particular, quantum well and wire that consists of an atomically thin sheet, for instance, graphene, carbon nanotube, and other related materials, hold great promise for sensing, energy convergence, and other high-tech applications.

My past and current research focused on exploring and engineering physical and chemical properties of the one-dimensional (1D) carbon nanotube and other two-dimensional (2D) atomically thin sheets. My approach includes micro-spectroscopy for the 1D and 2D nanomaterials, which are engineered with photochemical reaction, stacking two different 2D sheets, and fabrication of electrical devices with nano- and micro-lithography. My automated homemade scanning probe spectroscopy has obtained thousands of spectra from individual nanostructures formed in 2D sheets and revealed their collective properties. I aim to translate their unusual characteristics into potential optoelectronic applications.

Postdoctoral Project:

“Characterization of Nanopore Structures in 2D Hexagonal Boron Nitride Using Scanning Probe Photoluminescence Spectroscopy”

“Optical Application of Archimedean Scroll Fiber based on 2D sheets/polymer composites”

PI: Michael S. Strano, Chemical Engineering, MIT

Ph.D. Dissertation:

“Behavior of Photocarrier in Atomically Thin Two-dimensional Semiconducting Materials for Optoelectronics”

PI: Kazunari Matsuda, Institute of Advanced Energy, Kyoto University

Fellowship:

2015-2017 JSPS Research Fellow, Japan Society for the Promotion of Science

Research Experience:

Advanced spectroscopy of 1D and 2D nanomaterials

Carbon nanotube solar cell

Optoelectronics of field effect transistor based on 2D sheets

Synthesis of 1D and 2D nanomaterials

Teaching Interests:

I believe that the role of the teacher in a learning environment is to get students motivated by helping them achieve their learning outcomes. From an engineering viewpoint, my ultimate goal of teaching is to enable students to define essential problems existing in the real world and solve them on their own. For them to achieve it, I am enthusiastic to share my knowledge and experience and to continue growing as a teacher. I will keep attentive to their feedback such as the quiz at the end of lectures and will analyze individual responses in each office hour after the lectures.

I will care classroom environment. For students to get motivated for the lecture, the instructor should help students have a sense of belonging in the classroom. To create an inclusive classroom environment, I believe the active learning can be an essential role. The method promotes students to think on their own, and the discussion in pairs facilitate them to work together so that all students will feel welcome.

Effective teaching facilitates students’ learning. My strategy for the effective teaching is to introduce active learning into my teaching. For example, showing a characteristic figure, I will let students in pairs discuss their observation in that figure and ask them to share their idea in front of other students. The active learning is beneficial for students to enhance their understanding and get them refreshed, which keeps them engaged in my teaching.

Future Direction:

As faculty, I will expand my research interests to magnetic properties of nanomaterials in addition to the optoelectronic properties that I have developed so far. I aim at using the nanomaterials as a probe of magnetic response. Since the nanostructures are exposed to environments, these could be sensitive probes. Nuclear magnetic resonance (NMR) and magnetic resonance imaging magnetic (MRI) are typical applications of magnetic properties in materials. I expect that engineering nanostructures of the carbon nanotube and 2D insulator sheets could allow us to manipulate magnetic properties, while the perfect crystals of them do not exhibit such magnetic response. I want to develop how to control the magnetic properties of the nanomaterials with my experience of modification of materials and advanced spectroscopy technique. As magnetic resonance sensor can probe physical parameters such as temperature, strain, and magnetic field as well as the chemical traces, this class of sensor could allow us to reveal unexplored properties. Likely examples are measuring local temperature of the living body in sub-micrometer resolution and visualization of the chemical reaction process, monitoring those physical and chemical parameters. Besides the sensing application, I am also interested in the application of the magnetic properties to quantum communication. Such magnets in the nanostructure could store quantum states for long time. Also the absorption and fluorescence of telecom wavelength of light in carbon nanotube are promising for the direction.

Teaching Experience:

Teaching certificate, MIT Kaufman Teaching Certificate Program

Guest Lecturer of Engineering Nanotechnology in Chemical Engineering at MIT for first-year graduate student

Mentor for one graduate student and one undergraduate student

Selected Publications:

*Son, Y.; *Kozawa, D.; Liu, A. T.; Koman, V. B.; Wang, Q. H.; Strano, M. S. A Study of Bilayer Phosphorene Stability under MoS₂ -Passivation. 2D Materials 2017, 4 (2), 025091. (*Equally contributed)

Kozawa, D.; Carvalho, A.; Verzhbitskiy, I.; Giustiniano, F.; Miyauchi, Y.; Mouri, S.; Castro Neto, A. H.; Matsuda, K.; Eda, G. Evidence for Fast Interlayer Energy Transfer in MoSe₂/WS₂ Heterostructures. Nano Letters 2016, 16 (7), 4087–4093.

Kozawa, D.; Kumar, R.; Carvalho, A.; Kumar Amara, K.; Zhao, W.; Wang, S.; Toh, M.; Ribeiro, R. M.; Castro Neto, A. H.; Matsuda, K.; Eda G. Photocarrier Relaxation Pathway in Two-Dimensional Semiconducting Transition Metal Dichalcogenides. Nature Communications 2014, 5, 4543.

Kozawa, D.; Miyauchi, Y.; Mouri, S.; Matsuda, K. Exploring the Origin of Blue and Ultraviolet Fluorescence in Graphene Oxide. The Journal of Physical Chemistry Letters 2013, 4 (12), 2035–2040.

Kozawa, D.; Hiraoka, K.; Miyauchi, Y.; Mouri, S.; Matsuda, K. Analysis of the Photovoltaic Properties of Single-Walled Carbon Nanotube/Silicon Heterojunction Solar Cells. Applied Physics Express 2012, 5 (4), 042304.