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Overview of My Research Area
Selected Research Highlights
Highlighting the Photodegradation Pathways
and Impacts in 2D Halide Perovskites
Highlighting the Photodegradation Pathways
and Impacts in 2D Halide Perovskites
Although 2D perovskites show excellent environmental stability, their light vulnerability has remained unclear. By systematically illuminating PEA₂PbI₄ films under different wavelengths and conditions, we revealed critical photodegradation pathways affecting their morphology, chemistry, and optical properties.
[Journal of Physics: Energy 5.2 (2023): 024011 ]
Defect Passivation and Energy Level Tuning of 2D Halide Perovskites via Surface Acceptor Doping
Defect Passivation and Energy Level Tuning of 2D Halide Perovskites via Surface Acceptor Doping
Degradation in 2D perovskites is often accompanied by Pb⁰ defects, which compromise their properties and applications. Recognizing their electron-rich nature, we employed surface doping with molecular acceptors to suppress these defects and remove existing Pb⁰ species. PES confirmed the elimination of metallic states and the induction of p-type doping, providing energetic insight into the phenomena.
[Applied Physics Reviews 10.4 (2023)]
We are now preparing to report complementary results from donor doping.
Band Gap and Exciton Binding Energy Modulation by Dielectric Environment in 2D Perovskites:
Proposal of an Extended Keldysh Model
Band Gap and Exciton Binding Energy Modulation by Dielectric Environment in 2D Perovskites:
Proposal of an Extended Keldysh Model
The unique multiple quantum well structure of 2D perovskites induces both quantum and dielectric confinement. Dielectric properties governed by organic spacers strongly influence not only the band gap but also the exciton binding energy. To clarify their impact, we performed systematic UPS and low-energy IPES measurements supported by DFT. To better predict exciton binding energies, we proposed an extended Keldysh model, which reproduced the experimental observations with remarkable accuracy.
[Submitted recently]
Notable Research Experience
Investigated photodegradation mechanisms in 2D halide perovskites using various laser sources and multiple characterization techniques (UPS, XPS, AFM, SEM, PL). (First-author, paper published.)
Performed vacuum deposition of p- and n-type dopants and in-situ PES measurements to investigate defect passivation feasibility and doping mechanisms in 2D halide perovskites, with additional verification using multiple techniques.
(First-author, paper published (p-type results); additional first-author paper in preparation (n-type results).)Elucidated bandgap modulation in 2D halide perovskites under varying dielectric environments using PES and Low-Energy IPES, and determined exciton binding energy from the difference with the optical bandgap. Proposed an extended version of the Keldysh model.
(First-author, paper submitted.)Probed structural information of 2D halide perovskites using synchrotron-based X-ray absorption (NEXAFS) and scattering (GIWAXS) techniques, and identified differences induced by variations in organic moieties.
(First-author, paper in preparation).Investigated the effects of localized strain on the electronic structure of transition metal dichalcogenide monolayer flakes using nano-ESCA, SPEM, and nano-probe JV techniques.
(First-author, paper in preparation).Identified energy level changes induced by quadrupole effects arising from the orientation of conjugated polymers, analyzed using UPS, GIWAXS, and DFT.
(First-author, paper in preparation).Observed the reversible color change of halide perovskites under varying humidity, and confirmed that it originated from structural changes using in-situ GIWAXS.
(Second author, paper in preparation).Revealed the direct impact of oxidation state changes at NbOx-based device interfaces on performance by combining surface etching via GCIB with XPS analysis.
(Second author, paper submitted).Proposed a high-quality thin-film synthesis method for 2D transition metal dichalcogenolate AgSePh, characterized its fundamental properties using multiple techniques.
(Second author, paper submitted, patent application filed with the Korean Intellectual Property Office).Investigated energy level alignment at the interface between transition metal dichalcogenides and organic molecules in 2D MOSFETs using a self-developed electrostatics-based simulation code.
(Contributing author, paper published; simulation principles referenced from Nat. Commun. 5, 4174 (2014)).Engaged in in numerous additional collaborative research activities beyond those listed above.
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