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Nanoscale Interface Control for Highly-Luminescent Nanophosphors : 고효율 나노형광체를 위한 나노 계면 제어
DC Field | Value | Language |
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dc.contributor.advisor | 박병우 | - |
dc.contributor.author | 정대룡 | - |
dc.date.accessioned | 2017-07-13T05:38:04Z | - |
dc.date.available | 2017-07-13T05:38:04Z | - |
dc.date.issued | 2013-02 | - |
dc.identifier.other | 000000010308 | - |
dc.identifier.uri | https://hdl.handle.net/10371/117908 | - |
dc.description | 학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2013. 2. 박병우. | - |
dc.description.abstract | Nanophosphors have been extensively investigated during the last decade due to their size dependent physical properties which is different from the bulk materials. For display devices, nanophosphors have potential advantages over traditional micron-sized phosphors. Nanophosphors offer higher packing densities, lower scattering of light, and quantum-size effect. However, nanoparticles have generally showed poor luminescence efficiency, due to the surface adsorbates and defects in nanocrystals.
Therefore, I have studied on the nanoscale interface modification to develop highly-luminescent nanoparticles. Two fundamental factors are crucial for the novel properties of semiconductor nanoparticles. The first is the large surface to volume ratio: The surface states are likely to trap electrons and/or holes, and induce the nonradiative recombination of these charge carriers, leading to the reduction in the luminescent and photovoltaic efficiency. The second approach is taking advantage of the surface-plasmon resonance from metal nanostructures to semiconductors. The interaction of semiconductor nanoparticles with surface plasmons has an enhanced emission by electromagnetic-field amplications, and also has a suppression of emission by the energy transfer between semiconductor and metal nanoparticles. The PL enhancement of CdS nanoparticles by surface-plasmon resonance (Chap. 2, 3, 4), the surface-passivation effects by UV irradiation with oxygen bubbling (Chap. 5), and the photoluminescence enhancement using Li-addition (Chap. 6) will be introduced. Especially, to examine the influence of metal nanoparticles on the photoluminescence of semiconductors, colloidal mixtures of CdS and Au nanoparticles were prepared with different CdS/Au fractions. Compared to the cadmium-sulfide nanocrystals (quantum efficiency 9%), the CdS/Au mixtures showed enhanced luminescence properties (quantum efficiency 18%). The existence of an optimum ratio of metal to semiconductor nanoparticles for the photoluminescence intensity indicates that interactions between the metal and semiconductor nanoparticles induced by surface-plasmon resonance occur constructively at appropriate distances. In order to explain the origin of PL enhancement of CdS nanoparticles, a calculation was carried out for spherical Au nanoparticles with which the field enhancement by Au nanoparticles is found to insufficient to improve the PL quantum efficiency. In this respect, the PL enhancement can be understood in terms of increased radiative recombination rates due to surface plasmon resonance between the excitons in semiconductor nanoparticles and the electron plasma in metal nanoparticles, as confirmed by time-resolved PL. | - |
dc.description.tableofcontents | Abstract 1
List of Figures 6 List of Tables 14 Chap. 1. Overviews 15 1.1. General Introduction to Luminescent Materials 15 1.2. The d-d Transitions for Mn Ions 19 1.3. Radiative/Nonradiative Recombination 21 1.4. Nanophosphors 22 1.5. Surface Passivation by Inorganic 27 1.6. Surface-Plasmon Resonance 29 1.7. References 33 Chap. 2. Photoluminescence Enhancement in CdS Nanoparticles by Surface-Plasmon Resonance 34 2.1. Introduction 34 2.2. Experimental Section 35 2.3. Results and Discussion 37 2.4. Conclusions 49 2.5. Future Work 49 2.6. References 50 Chap. 3. Photoluminescence Enhancement of CdS Nanoparticles by Surface-Plasmon Resonance from Au/SiO2 nanocomposites 52 3.1. Introduction 52 3.2. Experimental Section 54 3.3. Results and Discussion 55 3.4. Conclusions 66 3.5. Future Work 66 3.6. References 67 Chap. 4. Brief Theoretical Investigation of Photoluminescence Enhancement by Surface-Plasmon Resonance 69 4.1. Introduction 69 4.2. Results and Discussion 70 4.3. Conclusions 79 4.4. Future Work 79 4.5. References 80 Chap. 5. Surface-Passivation Effects on the Photoluminescence Enhancement in ZnS:Mn Nanoparticles by UV Irradiation with Oxygen Bubbling 82 5.1. Introduction 82 5.2. Experimental Section 83 5.3. Results and Discussion 84 5.4. Conclusions 100 5.5. Future Work 100 5.6. References 101 Chap. 6. Highly-Luminescent Surface-Passivated ZnS:Mn Nanoparticles by a Simple One-Step Synthesis 103 6.1. Introduction 103 6.2. Experimental Section 104 6.3. Results and Discussion 105 6.4. Conclusions 119 6.5. Future Work 119 6.6. References 120 List of Publications and Presentations 122 | - |
dc.format | application/pdf | - |
dc.format.extent | 4695065 bytes | - |
dc.format.medium | application/pdf | - |
dc.language.iso | en | - |
dc.publisher | 서울대학교 대학원 | - |
dc.title | Nanoscale Interface Control for Highly-Luminescent Nanophosphors | - |
dc.title.alternative | 고효율 나노형광체를 위한 나노 계면 제어 | - |
dc.type | Thesis | - |
dc.contributor.AlternativeAuthor | Dae-Ryong Jung | - |
dc.description.degree | Doctor | - |
dc.citation.pages | 130 | - |
dc.contributor.affiliation | 공과대학 재료공학부 | - |
dc.date.awarded | 2013-02 | - |
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