- Optical spectroscopy of semiconductors and nanostructures
- Magnetic van der Waals materials
- Thin-film solar cell materials

1993 ~ 1995Postdoctoral Fellow, Harvard University
1995 ~ 1997 Postdoc, National Renewable Energy Laboratory
1997 ~ 1999 Senior Scientist, National Renewable Energy Laboratory
1999 ~ present Assistant Professor, Associate Professor, Professor, Sogang University
2014 ~ 2017 Vice President for Budget and Planning, Sogang University
2015 ~ 2016 President, Korean Graphene Society
2016 ~ 2020 Chair, Division of Applied Physics, the Korean Physical Society
2021 ~ 2022 Chair, Committee on International Activities, the Korean Physical Society
2021 ~ 2023 Vice President for Research and Director of Sogang University Research & Business Development (R&BD) Foundation, Sogang University
2023 ~ present Dean of Graduate School, Sogang University

2013 National R&D 100, ICT and Future Planning
2019 Outstanding research achievement award, The Korean Physical Society
2022 Korea Science Award