Contents Abstract………………………………………….…………………………………....I Contents…………………………………………………………………………….IV List of Tables……………………………………………………………………....VII List of Figures…………………………………………………………..….……..VIII Chapter 1 Introduction…………………………………………………………….....1 1.1 Self-Assembly………………………………………………………………3 1.2 Self-assembly of Block Copolymers………………………………………..5 1.3 Development of Nanopatterning Technology………………………………8 1.3.1 Top-down method………………………………………………………9 1.3.2 Button-up method……………………………………………………..11 1.4 Nanopatterning from the self-assembly of Block Copolymer…………….12 1.4.1 Surface-induced Orientation………………………………………….14 1.4.2 Temperature Gradient-induced Orientation…………………………..15 1.4.3 Crystallization-induced Orientation…………………………………..16 1.4.4 Shear-induced Orientation…………………………………………….17 1.4.5 Evaporation of Solvent-induced Orientation…………………………18 1.5 Introduction of Semiconductor……………………………………………19 1.5.1 Bulk Semiconductors: Three-dimensional System…………………...20 1.5.2 Low-dimensional System…………………………………………….22 1.5.3 Mechanism for Lighting……………………………………………...24 1.6 Quantum Confinement Effect in Semiconductor………………………….25 1.6.1 Crystal Size Effects on Exciton Energies in Semiconductor…………25 1.6.2 Crystal Shape Effects on Exciton Energies in Semiconductor……….28 1.7 Electronic and Optical Properties of CdS Nanocrystal……………………30 1.8 Application of organic nanopatterning…………………………………….31 1.8.1 Nanoreactor Matrix…………………………………………………...31 1.8.2 Mixing of Inorganic/BCP Hybrid System…………………………….32 1.8.3 Pore-filling of Light-emitting Materials into Template……………….33 Chapter 2 Objectives………………………………………………………………..51 Chapter 3 Experimental Details.................................................................................53 3.1 Instruments...................................................................................................53 3.2 Experimental Section...................................................................................53 3.3 The Principles of Instruments……………………………………………..59 Chapter 4 Results and Discussion…………………………………………………..64 4.1 Pore-filling by wetting……………………………………………………...64 4.2 Pore-filling by air-block releasing………………………………………….68 4.3 Pore-filling by directed capillary force……………………………………..70 4.4 Optical properties of CdS nanocrystals in templates……………………….71 4.4.1 Templated nanocrystals by air-block releasing……………………….72 4.4.2 Templated nanocrystals by directed capillary force…………………..73 4.5 Quantum effect of light-emitting polymers in templates…………………...75 Chapter 5 Conclusion…………………………………………………………….…87 Chapter 6 Future Works………………………………………………………….…90 Chapter 7 References…………………………………………………………….…92 List of Tables Table 1 Varieties of synthesized PS-PLLA block copolymers having HC microstructures..….....................................................................................................63 List of Figures Figure 1.1 Examples of static self-assembly. (a) Crystal structure of a ribosome. (b) Self-assembled peptideamphiphile nanofibers. (c) An array of millimeter sized polymeric plates assembled at a water/perfluorodecalin interface by capillary interactions. (d) Thin film of a nematic liquid crystal on an isotropic substrate. (e) Micrometersized metallic polyhedra folded from planar substrates. (f) A three-dimensional aggregate of micrometer plates assembled by capillary forces…36 Figure 1.2 Examples of dynamic self-assembly. (a) An optical micrograph of a cell with fluorescently labeled cytoskeleton and nucleus; microtubules ~ 24 nm in diameter) are colored red. (b) Reaction-diffusion waves in a Belousov-Zabatinski reaction in a 3.5-inch Petri dish. (c) A simple aggregate of three millimeter-sized, rotating, magnetized disks interacting with one another via vortex-vortex interactions. (d) A school of fish. (e) Concentric rings formed by charged metallic beads 1 mm in diameter rolling in circular paths on a dielectric support. (f) Convection cells formed above a micropatterned metallic support. The distance between the centers of the cells is ~ 2 mm………………………………………….37 Figure 1.3 (a) Schematic phase diagram showing the various ‘classical’ BCP morphologies adopted by non-crystalline linear diblock copolymer. The blue component represents the minority phase and the matrix, majority phase surrounds it. (b) Schematic of morphologies for linear ABC triblock copolymer. A combination of block sequence (ABC, ACB, BAC), composition and block molecular weights provides an enormous parameter space for the creation of new morphologies. Microdomains are colored as shown by the copolymer strand at the top, with monomer types A, B and C confined to regions colored blue, red and green, respectively. (Reprinted with permission from Physics Today. Copyright (1999) American Institute of Physics)……………………………………………………..38 Figure 1.4 (a) Topographic nanopattern (b) Chemical nanopattern………………..39 Figure 1.5 Photolithography………………………………………………………..39 Figure 1.6 Soft-lithography………………………………………………………...40 Figure 1.7 Sacnning probe lithography is electrically conducting AFM (or STM) tip that is operated in air is used to anodically oxidize selected regions of a sample surface………………………………………………………………………………40 Figure 1.8 Electron-lithography (EL)………………………………………………41 Figure 1.9 Schematic of the Lloyd’s mirror interferometer exposure system on the EUV beamline. The reflected beam from the mirror interferes with the direct beam at the substrate to produce the interference pattern. The fringe period is given byλ/(2 sinθ) where θ is the angle of incidence with the mirror…………………………….41 Figure 1.10 Diagrams showing structural evolution during the directional eutectic solidi®cation and epitaxial crystallization of the block copolymer from the crystallizable solvent. a, Homogeneous solution of PS-PE in BA between two glass substrates. b, Directional solidification forms crystals of α-BA coexisting with a liquid layer of more concentrated polymer. c, Second directional solidification, showing the eutectic liquid layer transforming into BA crystal (which grows on the pre-eutectic α-BA crystal) and an ordered lamellar block copolymer (β). d, Because of the highly asymmetric composition of the block copolymer and the epitaxial crystallization of the PE in contact with the BA substrate, the flat interfaces of vertically oriented lamellae are unstable, and spontaneously deform in order to achieve a more preferred interfacial curvature and allow epitaxial growth of PE. e, The layers transform into an array of vertically oriented, pseudohexagonally packed semicrystalline PE cylinders………………………………………………………..42 Figure 1.11 Schematic of the roll-caster used to generate macroscopically oriented films. Two independent, motorcontrolled, parallel rollers counterrotate at a constant frequency. The rollers are separated by a micrometer-controlled gap. A viscous block copolymer solution is introduced into the gap region and allowed to undergo microphase separation in the presence of the flow field. After slow evaporation of the solvent an oriented film preferentially forms on the stainlesssteel roller……….43 Figure 1.12 Plan-view bright-field TEM images of the as-cast OsO4-stained SBS thin films with inset Fourier transforms: (a) fast (~200 nL/s); (b) intermediate (~5 nL/s); (c) slow (~1.5 nL/s); (d) very slow (~0.2 nL/s)……………………………...43 Figure 1.13 The Schematic illustration of formation of PS-PLLA nanopattern prepared by spin coating……………………………………………………………44 Figure 1.14 Illustrations representing system dimensionality d: (a) bulk semiconductors, 3D; (b) thin films, layer structures, quantum wells, 2D; (c) linear chain structures, quantum wires, 1D; (d) clusters, colloids, microcrystallites, nanocrystallites, quantum dots, 0D…………………………………………………44 Figure 1.15 Densities N(E) of states for (a) 3D, (b) 2D, (c) 1D and (d) 0D systems (corresponding to ideal cases)………………………………………………………45 Figure 1.16 Exciton energies for cubic CdS in the form of a slab, wire and quantum dot of side Lz. The exciton parameters used were M=0.94m0, ε2=8.1, Eb=28meV…45 Figure 1.17 Schematic diagram of possible luminescence transitions for a CdS microcrystallite: CB, conduction band, VB, valence band…………………………46 Figure 1.18 The size regimes of semiconductors with different types of electrical states, from molecule, quantum dot to bulk form…………………………………..47 Figure 1.19a Predictions of simple particle-in-a-box models for the size dependences of the kinetic confinement energies of electrons and holes in corresponding……………………………………………………………………….48 Figure 1.19b The four highest occupied electronic states of CdSe quantum rods calculated with an empirical pseudopotential method with different aspect ratios...48 Figure 1.20 Nanoreactor use topographic nanopatterning to promote inorganic or organic into nano-sacle by electrodeposition, sputtering, evaporation, chemical or physical vapor deposition…………………………………………………………..49 Figure 1.21 Schematic illustrating the capillary force (Fc) assembly mechanism at the vapor-suspension-substrate three-phase contact line. (Inset) Moving of the three-phase contact line is driven by evaporation in-house vacuum or by heating the solution to ~60 °C…………………………………………………………………..49 Figure 1.22 Schematic diagram of the setup used to drive negatively charged CdSe nanoparticles into diblock copolymer templates. Templates with nanopores or nanotrenches served used as the anode, and bare gold-coated silicon wafers served as the cathode………………………………………………………………………….50 Figure 4.1 The tapping-mode SPM height images of the nanopatterning morphology for spin-coated PS–PLLA thin films on glass slide at ambient temperature (a) before; (b) after hydrolysis………………………………………………………………….79 Figure 4.2 TEM mass-thickness images of hydrolyzed PS-PLLA templates immersed into Au solution (a) without and (b) with ultrasonic treatment for 30 min………………………………………………………………………………….79 Figure 4.3 TEM micrographs of pore-filling functional gold nanoparticles in hydrolyzed PS-PLLA templates after O2 plasma treatment with 75 Watt for 20 seconds……………………………………………………………………………...80 Figure 4.4 (a) The tapping-mode SPM height image of PS-PLLA template after hydrolysis 4 days and RuO4 staining for 30s. (b) Measured Contact angle image of H2O on stained PS template before and after RIE treatment with 20 Watt for 20 seconds……………………………………………………………………………...80 Figure 4.5 TEM micrographs of pore-filling functional gold nanoparticles in hydrolyzed PS-PLLA templates after O2 plasma treatment with 20 Watt and RuO4 staining for 30 seconds……………………………………………………………..81 Figure 4.6 (a) Air-extracting apparatus (b) Measured Contact angle image of H2O and methanol on PS templates……………………………………………………...81 Figure 4.7(a) TEM image of CdS nanocrystals into hexagon cylinder (HC) template by air-block releasing. (b) Electron-diffraction pattern of the CdS particles……….82 Figure 4.8 TEM images of nanoporous template generated from cylindrical PS-PLLS diblock copolymer thin film. After pore-filling of CdAc2 by directed capillary force and surface washing, the HC CdS structure was achieved by adding equivalent amounts of H2S for 2 hr from (a) methanol solvent; (b) aqueous solvent. Inset shows the electron diffraction pattern of the CdS nanoparticles……………...82 Figure 4.9(a) TEM image of CdS nanoparticles by spin coating of 0.48M CdAc2 methanol solution and exposing to H2S for 2 hours. (b) UV-vis absorption spectra of CdS solid state and pore-filling CdS into templates by air-block releasing………...83 Figure 4.10 (a) PL spectra of CdS solid state and pore-filling CdS into templates air-block releasing. (b) Schematic pictures of CdS solid state and pore-filling CdS into templates air-block releasing. (Exciting length at 450nm)…………………….83 Figure 4.11 (a) UV spectra of CdS solid state and nanoporous PS matrix/CdS by directed capillary force. (b) PL spectra of CdS solid state and nanoporous PS matrix/CdS by directed capillary force. (Exciting length at 450nm)……………….84 Figure 4.12 Confocal microscopy image of (a) pore-filling of CdS into template by air-block releasing. Inset: CdS solid state (b)pore-filling of CdS into template by direct capillary force (a)) exciting at 454nm and detected from 480nm~600nm…..84 Figure 4.13 (a) PL spectra of spin-coating polymer film and pore-filling light-emitting materials in hydrolyzed PS-PLLA template under air extracted after O2 plasma treatment with 20 Watt and RuO4 staining for 30 seconds. (b) Schematic pictures of spin-coating polymer film and light-emitting polymers in hydrolyzed PS-PLLA template by pore-filling method………………………………………....85 Figure 4.14(a) Bright field TEM image of light-emitting polymers in hydrolyzed PS-PLLA template using pore-filling method by air-block releasing. (b) HR-TEM images of light-emitting polymers in hydrolyzed PS-PLLA template by pore-filling method, along with spectra from EDX analysis……………………………………86 Figure 4.15 (a) FE-SEM images of light-emitting polymers in hydrolyzed PS-PLLA template by pore-filling method. (b) Elemental Br map obtained using EDX analysis with FE-SEM……………………………………………………………………….86