Theoretical study on surface properties of colloidal quantum dots and graphene = 콜로이드 양자점과 그래핀의 표면 특성에 대한 이론 연구

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In this thesis, we study surface chemistry of colloidal quantum dots and nanoscale friction of graphene by investigating their surface properties using first-principles density-functional theory calculations. For colloidal quantum dots, our calculation results show that cation-rich surfaces are necessary for proper ligand-surface coordination to be stabilized. In addition to ligand-surface coordination, the cation-rich surface stabilization is affected by steric hindrance between coordinating ligands. For IV-VI colloidal quantum dots, the steric hindrance between passivating ligands has influence on shape transition from oleate-capped octahedron to cuboctahedron truncated with (100) surface that prone to surface oxidation. The shape transition leads to size-dependent air-stability of IV-VI colloidal quantum dots. For graphene, we examine nanoscale friction properties of chemically modified graphene, epitaxial graphene on SiC(0001), and water-intercalated graphene on mica. By calculating elastic properties of graphene and investigating 3D/2D contact through first-principles calculations and contact mechanics theory, we find that nanoscale frictional energy of graphene is mainly dissipated by out-of-plane bending deformation of graphene and shear deformations between graphene and substrate. In addition, for water-intercalated graphene, we propose that the increased friction by water layer is attributed to phonon excitation enhancement and improved energy transfer based on calculated phonon properties.
Advisors
Kim, Yong-Hyunresearcher김용현researcher
Description
한국과학기술원 :나노과학기술대학원,
Publisher
한국과학기술원
Issue Date
2017
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 나노과학기술대학원, 2017.2,[vi, 75 p. :]

Keywords

Surface chemistry; Colloidal quantum dot; Nanoscale friction; Graphene; First-principles calculation; 표면화학; 콜로이드 양자점; 나노스케일 마찰력; 그래핀; 제일원리계산

URI
http://hdl.handle.net/10203/241741
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=675665&flag=dissertation
Appears in Collection
NT-Theses_Ph.D.(박사논문)
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