Дисертації з теми "Luminescent property"

付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム
京都大学
新制・課程博士
博士(工学)
甲第23227号
工博第4871号
京都大学大学院工学研究科高分子化学専攻
(主査)教授 田中 一生, 教授 秋吉 一成, 教授 古賀 毅
学位規則第4条第1項該当
Doctor of Philosophy (Engineering)
Kyoto University
DGAM

Dans cette thèse, la synthèse, les propriétés et les applications de verres contenant des quantum dots (QDs) de chalcogénure ont été étudiées. Des verres contenant des QDs à base de chalcogénure de plomb (PbSe ou PbS) ont été préparés. Leurs propriétés optiques et leurs applications potentielles ont été explorées en combinaison avec le co-dopage aux ions Tm3+. De plus, sur la base de ces résultats, des verres contenant des QDs de ZnS ou de ZnSe, sans plomb, ont été préparés avec succès. Leurs performances luminescentes ont été encore améliorées par dopage avec des ions de métaux de transition représentés ici par le nickel. Ces résultats jettent les bases pour l’amélioration des propriétés optiques de verres contant des QDs à base de chalcogénure de plomb et aussi pour le développement de verres aux QD sans métaux lourds et donc plus respectueux de l’environnement. Bien que des améliorations futures soient possibles et nécessaires pour des applications réelles, ces verres aux QDs de chalcogénure, développés dans ce travail, présentent un potentiel d'applications dans les domaines des concentrateurs solaires luminescents, de l'anti-contrefaçon optique, de l'éclairage à semi-conducteurs et de la mesure optique de la température
In this dissertation, the synthesis, properties and applications of glasses containing chalcogenide quantum dots (QDs) have been studied. Multicomponent lead chalcogenide QDs glasses (containing PbSe or PbS QDs) were successfully prepared, and their optical properties and potential applications were explored in combination with rare earth Tm3+ ion doping. In addition, based on the results, lead-free and environmentally friendly chalcogenide QDs glasses (containing ZnS or ZnSe QDs) were successfully prepared, and its luminescent performance was further improved by doping with transition metal nickel ions. These results lay the foundation for the improvement of optical properties of lead-based chalcogenide QDs and for the development of environmentally friendly heavy metal-free chalcogenide QDs glasses. Although future improvements are possible and necessary for practical applications, these chalcogenide QDs glasses developed in this work have application potential in the fields of luminescent solar concentrators, optical anti-counterfeiting, solid-state lighting, and optical temperature sensing

The research summarized in this dissertation is aimed at the design and exploratory synthesis, characterization, and property investigation of lanthanide-based functional materials. The substances prepared in this work, including small molecular complexes and nanostructured particles, are of fundamental scientific interest as well as practical significance due to the unique chemical and physical properties of the lanthanide elements. Envisioned applications include their uses as light-emitting materials in modern display technology, optical amplifiers, and high-density magnetic recording media. This research seeks to develop general methods for directing the formation of lanthanide materials, particularly as a means of influencing the physical properties of such materials. These efforts are elaborated in distinct yet related projects.In Chapter 2, exploratory synthesis, structural characterization, and photo-physical investigation of adducts of lanthanide β-diketonates with a tridentate neutral ligand, TPTZ are described.In Chapter 3, analogous studies utilizing p,p'-disubstituted bipyridine and phenathroline type bidentate neutral ligands are detailed. The structures of the complexes have been established by single crystal X-ray diffraction. Compositional and structural differences among the various complexes are caused by different structural and electronic properties of the ligands and overall steric compactness of the coordination sphere. Red and green luminescence characteristics of Eu(III) and Tb(III) ions are observed for the corresponding complexes, upon UV excitation, consistent with the well-established ligand-mediated energy transfer and light emission mechanism.In Chapter 4, the electroluminescence properties of various europium complexes are evaluated for their potential as emissive materials in organic light-emitting diodes.The synthesis and characterization of Er-doped LaPO4 nanoparticles are described in Chapter 5 together with the preparation and studies of hybrid nanocomposites composed of nanoparticle-doped sol-gels. A single-mode waveguide system was fabricated, wherein Er-doped nanoparticles solubilized in a sol-gel matrix has shown promising performance in propagating light signals (1.54 µm) without significant optical losses.In Chapter 6, synthesis, electron microscopic characterization and magnetic studies of crystalline Sm(III)- and Eu(III)-doped Fe3O4 nanoparticles are detailed. Magnetic studies suggest the ferromagnetic behavior of the lanthanide-doped Fe3O4 nanoparticles at room temperature and therefore, the significant effects of lanthanide doping.

ZnO based materials, such as Zn1-xTMxO (TM = Mn, Co, Cu) nanopowders, were synthesised by a Sol gel route to investigate their properties in three fields: catalysis, optics and magnetism. These materials were characterised by complementary techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and UV-Vis Spectroscopy. The fine structure and electronic properties of these nanomaterials were studied by X-ray Absorption Spectroscopy (XAS) and Electron Paramagnetic Resonance (EPR). These techniques give site, element and chemical specific measurements which allow a better understanding of the interplay and role of each element in the functionality of the system. The catalytic performance of undoped and Cu-doped ZnO nanosystems were tested with respect to the Methanol Steam Reforming (MSR) reaction. Contrary to what is generally accepted in literature, the results obtained in this study demonstrate that ZnO also plays a prominent role in this catalytic process. The structure–activity relationship of ZnO and copper-doped ZnO catalysts described in this work give an insight into the effective function of each component which is vital to enable the rational design of improved catalysts. The luminescence properties of the doped Zn1-xTMxO nanopowders were investigated with X-ray Excited Optical Luminescence (XEOL) techniques: these experiments provided a better understanding of the relationship between the electronic structure of the systems and their properties. Results showed how it is possible to manipulate the luminescence of ZnO grown by Sol gel by modifying synthesis conditions – i.e. the annealing temperature and the nature and concentration of the transition metal ion. Finally, preliminary results were presented on the materials' magnetic properties, obtained by SQUID (Superconducting Quantum Interference Devices) magnetometry, where the coexistence of different contributions has been detected. Even though further characterisation is still needed, this study is a step towards the determination of the nature of magnetic interactions in such systems, of which there has been considerable debate in the scientific community.
Materiali a base di ZnO, in particolare nano-polveri di Zn1-xTMxO (TM = Mn, Co, Cu), sono stati sintetizzati via Sol gel per studiarne le proprietà in tre diversi campi applicativi quali la catalisi, l’ottica ed il magnetismo. Tali materiali sono stati caratterizzati utilizzando diverse tecniche, complementari tra loro, quali X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) e UV-Vis Spectroscopy. X-ray Absorption Spectroscopy (XAS) ed Electron Paramagnetic Resonance (EPR) vengono invece impiegate per studiare le proprietà elettroniche e di struttura fine delle nano-polveri. Tali caratterizzazioni si sono dimostrate fondamentali per la comprensione delle proprietà del sistema ed, in particolare, per cercare di identificare le interazioni sussistenti tra struttura, composizione, morfologia dei materiali e la loro capacità di espletare una determinata funzionalità. Nano-polveri di ZnO tal quali e drogate con ioni rame vengono testate come catalizzatori nella reazione di Steam Reforming del metanolo. I risultati ottenuti in questo studio dimostrano il ruolo attivo dell’ossido di zinco nel processo catalitico, contrariamente a quanto solitamente accettato in letteratura. La relazione sussistente tra struttura-attività nei catalizzatori a base di ZnO permette di ottenere informazioni circa l’effettiva funzione di ogni componente, aspetto di estrema importanza per la progettazione razionale di catalizzatori con elevate performance. Le proprietà di luminescenza dei sistemi drogati Zn1-xTMxO vengono studiate mediante spettroscopia X-ray Excited Optical Luminescence (XEOL); tali esperimenti forniscono una migliore comprensione del rapporto che sussiste tra la struttura elettronica dei sistemi in esame e le loro proprietà di emissione. I risultati mostrano come sia possibile modulare la luminescenza di ZnO prodotto via Sol gel modificando le condizioni di sintesi – i.e. temperatura di trattamento, natura e concentrazione del metallo di transizione utilizzato come drogante. Infine, risultati preliminari sulle proprietà magnetiche dei materiali ottenuti mediante SQUID magnetometer (Superconducting Quantum Interference Devices) hanno rivelato la coesistenza di diversi contributi magnetici. Nonostante ulteriori caratterizzazioni siano sicuramente necessarie, questo studio si è rivelato un passo avanti verso una comprensione della natura delle interazioni magnetiche in tali sistemi, da tempo causa di vivace dibattito nella comunità scientifica.

碩士
國立中山大學
材料與光電科學學系研究所
103
First chapter: Tetraphenylthiophene (TP) with aggregation-enhanced emission (AEE) property was used as terminal fluorophore of the water-soluble poly(γ-propargyl-L-glutamate) (PPLG)-based polymers of TP-PPLG-g-MEO2. In this study, we research various TP-PPLG-g-MEO2 affect aggregation of luminescence. In water, when concentration of TP-PPLG-g-MEO2 achieve CMC, TP-PPLG-g-MEO2 will aggregation to nanoparticle and suddenly increasing emission, and when heating over LCST, TP-PPLG-g-MEO2 will contract and also enhance emission. We use TP-PPLG-g-MEO2 “salt out effect” property to probe salt in water, salt have interaction with side chain MEO2 and peptide main chain to make TP-PPLG-g-MEO2 contract together and change secondary structure to b-sheet conformation to enhance emission. In the strong alkaline media, TP-PPLG-g-MEO2 backbone change to random coil conformation that break intramolecular hydrogen bonding and loss LCST property, TP-PPLG-g-MEO2 become is a micelle like structure, core was hydrophobic TP and shell was hydrophilic polypeptide and particle size about 500nm measure by DLS. In random coil conformation, chain end hydrophobic TP have strong aggregation than in the a-helical and have strong aggregation emission peak. At last, we use TP-PPLG-g-MEO2 to detect BSA. When TP-PPLG-g-MEO2 mixture with BSA, TP-PPLG-g-MEO2 will fall in to BSA and separate to decrease TP-PPLG-g-MEO2 aggregation and emission. Second chapter: We synthesis polypeptide contain TPA pendent by click reaction. The resulting PPLG-g-TPA contains the crystalline TPA side groups, Tm about 145 oC and is therefore high Tg materials with the desired AIE activity. Due to side chain TPA, PPLG-g-TPA have piezofluorochromic property that have two color between crystal and amorphous state. The lone pair electrons of nitrogen atom in TPA side groups inherit PPLG-g-TPA the sensitivity toward acid HCl and metal ions. Emission of PPLG-g-TPA was progressively decreased upon increasing the amounts of HCl and metal ions in the solutions that can be acid or metal ions sensor.

Luminescent materials find numerous applications in recent times and have enriched human lives in several different ways. From display and lighting technologies to security, sensing and biological investigations, luminescent organic compounds have become indispensible and often preferred over their inorganic counterparts. The versatility of organic materials arises from their comparative low costs, ease of fine-tuning, low toxicity and the possibility to develop flexible devices. Even until very recent times, the investigations and usage of organic luminescent materials were mostly limited to solution-state properties. However, with progress of available characterisation techniques and parallel development of their usage in solid-state devices and other applications (e.g. security, forensics, sensing etc.), significantly greater attention has been paid to the development and investigations of solid-state emissive organic materials. In solid-state applications, apart from the molecular properties of any given material, their cumulative i.e. bulk physical properties are of even greater importance. Thus, investigations of structure-property relationships in organic luminescent compounds to understand their molecular and bulk properties are of fundamental interest. In this thesis, NPI (1,8-naphthalimide) and BODIPY (boron-dipyrromethene) dyes were investigated to provide a broad overview of their structure-property correlations. Among commonly encountered organic luminescent materials, NPIs and BODIPYs have emerged as two broad classes of luminescent organic compounds, finding applications as functional luminescent materials in various fields. However, lack of understanding for controlling the cumulative emissive properties of these compounds has limited their usage as active solid-state emitters in various applications. This thesis presents several new insights into the molecular and bulk emissive properties of these two classes of luminescent dyes (NPIs and BODIPYs). The contents of the six chapters contained in this thesis are summarised below. Chapter 1 summarises the available understanding of the basic concepts of photoluminescence and the design strategies to develop solid-state luminescent and AIE (aggregation-induced emission) active materials. This chapter also emphasises in the basic nature of the NPI and BODIPY compounds, their substitution patterns and their inherent characteristics and touches upon the relatively unexplored properties of NPI and BODIPY based materials. The importance and scope of the work reported in the thesis is outlined at the end of the chapter. Chapter 2 describes a detailed investigation of a series of seven (4-oxoaryl substituted) NPI compounds (1-7) providing an insight into the molecular and cumulative photophysical behaviour of these compounds. The low ICT characteristics of the NPIs, coupled with the twisted geometry, facilitated solid-state luminescence in these materials. The solution and solid-state luminescent properties of these compounds can be directly correlated to their structural rigidity, nature of substituents and solid-state intermolecular interactions (e.g. π-π stacking, C-H•••O interactions etc.). The solid-state crystal structures of the NPI siblings are profoundly affected by the pendant substituents. All of the NPIs (1-7) show antiparallel dimeric π-π stacking interactions in the solid-state which can further extend in parallel, alternate, orthogonal or lateral fashion depending on the steric and electronic nature of the C-4′ substituents. Structural investigations including Hirsfeld surface analysis methods reveal that while strongly interacting systems show weak to moderate emission in their condensed states, weakly interacting systems show strong emission yields under the same conditions. The nature of packing and extended structures also affects the emission colors of the NPIs in the solid-state. DFT computational studies were utilized to understand the molecular and cumulative electronic behavior of the NPIs. Apart from the investigation of solid-state luminescence, other functional potentials of these NPIs were also explored. One of the compounds (i.e. 4) shows chemodosimetric response towards aqueous Hg(II) species with a ‘turn-on’ response. Also, depending on the molecular flexibility of the compounds, promising AIEE (aggregation-induced emission enhancement) features were observed in these NPIs. Later (in Chapter 3), we developed a systematic investigation in a series of purely organic NPIs, restricting various parameters, to attain a thorough understanding of such AIEE properties. Chapter 3 describes a detailed experimental and computational study in order gain an insight into the AIE (aggregation-induced emission) and AIEE mechanisms in NPI compounds. Systematic structural perturbation was used to fine tune the luminescence properties of three new 1,8-naphthalimides (8-10) in solution and as aggregates. The NPIs (8-10) show blue emission in solution state and the fluorescence quantum yields depend on their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to result in quenching of fluorescence. In contrast, upon aggregation (in THF:H2O mixtures), two of the NPIs show aggregation-induced-emission-enhancement (AIEE). The NPIs also show moderately high solid-state emission quantum yields (~10-12.7 %). The AIEE behaviors of the NPIs depend on their molecular rigidity and nature of intermolecular interactions. The NPIs (8-10) show different extents of intermolecular (π-π and C-H•••O) interactions in their solid-state structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that only an optimal balance of structural flexibility and intermolecular communication is the effective recipe for achieving AIEE characteristics in these NPIs. Chapter 4 presents the design, synthesis and detailed investigations and potential applications of a series of NPI-BODIPY dyads (11-13). The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges and the compounds only differ structurally with respect to methyl substitutions on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in these molecular dyads (11- 13). Dyads 11-13 show dual emission in solution state originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibility of the systems. The dyads also show significant AIES (Aggregation-Induced-Emission Switching) features upon formation of nano-aggregates in THF-H2O mixtures with visual changes in emission from green to red color. Whereas the flexible and aggregation prone system (i.e. compound 11) shows aggregation-induced enhancement of emission, rigid systems with less favorable intermolecular interactions (i.e. compound 12-13) show aggregation-induced quenching of emission. The emission-intensity vs. the structural-flexibility correlations were found to be reverse in solution and aggregated states. Photophysical and structural investigations suggest that the intermolecular interactions (e.g. π-π stacking etc.) play major role in controlling emission of these compounds in aggregated states. Similar trends were also observed in the solid-state luminescence of these compounds. The applications of the luminescent dyads 11-13 as live-cell imaging dyes was also investigated. Chapter 5 describes investigations of photophysical properties of a series of six BODIPY dyes (14-19) in which there is a systematic alteration of a common -C6H4Si(CH3)3 substituent. Inrelated constitutional isomers, the systematic increment of steric congestion and lowering of molecular symmetry around the BODIPY core result in a steady increment of solution and solid- state fluorescence quantum yields. The increasing fluorescence quantum yields (solution, solid state) with increasing steric congestions show that the molecular free rotation and aggregation-induced fluorescence quenching of BODIPYs can be successfully suppressed by lowering the flexibility of the molecules. Photophysical and DFT investigations reveal that the electronic band gap in any set of these constitutional isomers remain almost similar. However, the crystal structures of the compounds reveal that the solid-state colour and quantum yields of the compounds in solid-state are also related to the nature of intermolecular interactions. Chapter 6 demonstrates the use of DFT computational methods to understand the effect of alkyl groups in governing the basic structural and electronic aspects of BODIPY dyes. As demonstrated in Chapter 4 and Chapter 5, apparently electronically inactive alkyl groups can be of immense importance to control the overall photophysics of BODIPYs. In this context, a systematic strategy su was utilized considering all possible outcomes of constitutionally-isomeric molecules to understand the effects of alkyl groups on the BODIPY molecules. Four different computational methods were employed to ascertain the unanimity of the observed trends associated with the molecular properties. In line with experimental observations, it was found that alkyl substituents in BODIPY dyes situated at 3/5-positions effectively participate in stabilization as well as planarization of such molecules. Screening of all the possible isomeric molecular systems was used to understand the individual properties and overall effects of the typical alkyl substituents in controlling several basic properties of such BODIPY molecules.

Luminescent materials find numerous applications in recent times and have enriched human lives in several different ways. From display and lighting technologies to security, sensing and biological investigations, luminescent organic compounds have become indispensible and often preferred over their inorganic counterparts. The versatility of organic materials arises from their comparative low costs, ease of fine-tuning, low toxicity and the possibility to develop flexible devices. Even until very recent times, the investigations and usage of organic luminescent materials were mostly limited to solution-state properties. However, with progress of available characterisation techniques and parallel development of their usage in solid-state devices and other applications (e.g. security, forensics, sensing etc.), significantly greater attention has been paid to the development and investigations of solid-state emissive organic materials. In solid-state applications, apart from the molecular properties of any given material, their cumulative i.e. bulk physical properties are of even greater importance. Thus, investigations of structure-property relationships in organic luminescent compounds to understand their molecular and bulk properties are of fundamental interest. In this thesis, NPI (1,8-naphthalimide) and BODIPY (boron-dipyrromethene) dyes were investigated to provide a broad overview of their structure-property correlations. Among commonly encountered organic luminescent materials, NPIs and BODIPYs have emerged as two broad classes of luminescent organic compounds, finding applications as functional luminescent materials in various fields. However, lack of understanding for controlling the cumulative emissive properties of these compounds has limited their usage as active solid-state emitters in various applications. This thesis presents several new insights into the molecular and bulk emissive properties of these two classes of luminescent dyes (NPIs and BODIPYs). The contents of the six chapters contained in this thesis are summarised below. Chapter 1 summarises the available understanding of the basic concepts of photoluminescence and the design strategies to develop solid-state luminescent and AIE (aggregation-induced emission) active materials. This chapter also emphasises in the basic nature of the NPI and BODIPY compounds, their substitution patterns and their inherent characteristics and touches upon the relatively unexplored properties of NPI and BODIPY based materials. The importance and scope of the work reported in the thesis is outlined at the end of the chapter. Chapter 2 describes a detailed investigation of a series of seven (4-oxoaryl substituted) NPI compounds (1-7) providing an insight into the molecular and cumulative photophysical behaviour of these compounds. The low ICT characteristics of the NPIs, coupled with the twisted geometry, facilitated solid-state luminescence in these materials. The solution and solid-state luminescent properties of these compounds can be directly correlated to their structural rigidity, nature of substituents and solid-state intermolecular interactions (e.g. π-π stacking, C-H•••O interactions etc.). The solid-state crystal structures of the NPI siblings are profoundly affected by the pendant substituents. All of the NPIs (1-7) show antiparallel dimeric π-π stacking interactions in the solid-state which can further extend in parallel, alternate, orthogonal or lateral fashion depending on the steric and electronic nature of the C-4′ substituents. Structural investigations including Hirsfeld surface analysis methods reveal that while strongly interacting systems show weak to moderate emission in their condensed states, weakly interacting systems show strong emission yields under the same conditions. The nature of packing and extended structures also affects the emission colors of the NPIs in the solid-state. DFT computational studies were utilized to understand the molecular and cumulative electronic behavior of the NPIs. Apart from the investigation of solid-state luminescence, other functional potentials of these NPIs were also explored. One of the compounds (i.e. 4) shows chemodosimetric response towards aqueous Hg(II) species with a ‘turn-on’ response. Also, depending on the molecular flexibility of the compounds, promising AIEE (aggregation-induced emission enhancement) features were observed in these NPIs. Later (in Chapter 3), we developed a systematic investigation in a series of purely organic NPIs, restricting various parameters, to attain a thorough understanding of such AIEE properties. Chapter 3 describes a detailed experimental and computational study in order gain an insight into the AIE (aggregation-induced emission) and AIEE mechanisms in NPI compounds. Systematic structural perturbation was used to fine tune the luminescence properties of three new 1,8-naphthalimides (8-10) in solution and as aggregates. The NPIs (8-10) show blue emission in solution state and the fluorescence quantum yields depend on their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to result in quenching of fluorescence. In contrast, upon aggregation (in THF:H2O mixtures), two of the NPIs show aggregation-induced-emission-enhancement (AIEE). The NPIs also show moderately high solid-state emission quantum yields (~10-12.7 %). The AIEE behaviors of the NPIs depend on their molecular rigidity and nature of intermolecular interactions. The NPIs (8-10) show different extents of intermolecular (π-π and C-H•••O) interactions in their solid-state structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that only an optimal balance of structural flexibility and intermolecular communication is the effective recipe for achieving AIEE characteristics in these NPIs. Chapter 4 presents the design, synthesis and detailed investigations and potential applications of a series of NPI-BODIPY dyads (11-13). The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges and the compounds only differ structurally with respect to methyl substitutions on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in these molecular dyads (11- 13). Dyads 11-13 show dual emission in solution state originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibility of the systems. The dyads also show significant AIES (Aggregation-Induced-Emission Switching) features upon formation of nano-aggregates in THF-H2O mixtures with visual changes in emission from green to red color. Whereas the flexible and aggregation prone system (i.e. compound 11) shows aggregation-induced enhancement of emission, rigid systems with less favorable intermolecular interactions (i.e. compound 12-13) show aggregation-induced quenching of emission. The emission-intensity vs. the structural-flexibility correlations were found to be reverse in solution and aggregated states. Photophysical and structural investigations suggest that the intermolecular interactions (e.g. π-π stacking etc.) play major role in controlling emission of these compounds in aggregated states. Similar trends were also observed in the solid-state luminescence of these compounds. The applications of the luminescent dyads 11-13 as live-cell imaging dyes was also investigated. Chapter 5 describes investigations of photophysical properties of a series of six BODIPY dyes (14-19) in which there is a systematic alteration of a common -C6H4Si(CH3)3 substituent. Inrelated constitutional isomers, the systematic increment of steric congestion and lowering of molecular symmetry around the BODIPY core result in a steady increment of solution and solid- state fluorescence quantum yields. The increasing fluorescence quantum yields (solution, solid state) with increasing steric congestions show that the molecular free rotation and aggregation-induced fluorescence quenching of BODIPYs can be successfully suppressed by lowering the flexibility of the molecules. Photophysical and DFT investigations reveal that the electronic band gap in any set of these constitutional isomers remain almost similar. However, the crystal structures of the compounds reveal that the solid-state colour and quantum yields of the compounds in solid-state are also related to the nature of intermolecular interactions. Chapter 6 demonstrates the use of DFT computational methods to understand the effect of alkyl groups in governing the basic structural and electronic aspects of BODIPY dyes. As demonstrated in Chapter 4 and Chapter 5, apparently electronically inactive alkyl groups can be of immense importance to control the overall photophysics of BODIPYs. In this context, a systematic strategy su was utilized considering all possible outcomes of constitutionally-isomeric molecules to understand the effects of alkyl groups on the BODIPY molecules. Four different computational methods were employed to ascertain the unanimity of the observed trends associated with the molecular properties. In line with experimental observations, it was found that alkyl substituents in BODIPY dyes situated at 3/5-positions effectively participate in stabilization as well as planarization of such molecules. Screening of all the possible isomeric molecular systems was used to understand the individual properties and overall effects of the typical alkyl substituents in controlling several basic properties of such BODIPY molecules.

碩士
國立臺北科技大學
有機高分子研究所
101
In this study, we prepared electrospun (ES) fiber from mulifunctional random copolymers of poly(HEMA-co-NMA-co-RhBAM). The moieties of HEMA, NMA and RhBAM were designed to the hydrophilic, chemical cross-linking (to ensure insolubility in aquesous), pH-responsive, respectively. The random copolymers were synthesized by free radical copolymerization of the above three kinds of moieties with the different mole ratio, and then prepared to form ES nanofibers using the different electronspinning parameters. It was observed that the variation of morphologies on different operated conditions from SEM. We explored the pH-responsive and photophysical properties of the ES fibers immersed in aqueous solvent with different pH value. The fluorescent emission of 580 nm was gradually increased with increasing concentration of pH from pH value of 7 to 2 for ES fibers due to the pH-responsive RhBAM moiety. In our study, we discovered the difference of efficiency for sensing on dissimilar ratio of the random copolymers. Due to the enhanced degree of cross-linking with increasing the NMA content, the cross-linked ES fibers of P2 have the unobvious swelling morphology. It resulted in the pH-sensing efficiency of P1 ES fibers are better than that of P2. The fluorescent intensity of P1 ES fiber exhibits around 90-fold enhancement at pH value of 2 while only 46-fold enhancement on P2 ES fiber. In addition, the ES fibers had a significant reversibility for pH-dependence and could be repeated for several times. Moreover, the ES fibers led a much better pH-response on the fiber morphology compared with the corresponding spin-coated film because of their high surface/volume. Above all results show that the multi-functional ES fiber have a potential in relative applications, such as filters, bio-sensor and sensory devices.

博士
國立成功大學
資源工程學系碩博士班
97
Blue light emitting diode (LED) chip coated with a yellow yttrium aluminum garnet doped with cerium ions (YAG:Ce) phosphor has led to the commercial production of white LED. The advantages of good reliability, simple preparation, low cost and so on are the reasons why this YAG product has been popular on the market for a long time. This dissertation not only investigates the spherical YAG:Ce and YAG:Tb (terbium) phosphors granulated by a spray-drying method, but also studies the host transition from YAG to TbAG (terbium aluminum garnet) synthesized with the maximum replacement of yttrium ions in YAG. The effects of dopant concentration, temperature and atmosphere used in the synthesis and so forth on structure and property of the system are mainly studied in the dissertation as follows: 1. Pure YAG:Ce can be successfully synthesized without second phase through the pH control. The flux, sodium hydroxide (NaOH) solution, actually acts as an important role. In addition, the spherical particles granulated with the spray-drying method produce the homogeneous agglomerate of phosphors and consequently achieve more favorable photoluminescence (PL) properties in this study. 2. The factors, such as activator concentration, phase impurity, calcination term, and powder crystallinity dominate the PL properties of phosphors. Most of these products (YAG:Ce) are identified as YAG and CeO2 phases after calcination, showing higher emission intensity resulted from higher crystallinity and less defect of phosphor (calcined at 1500oC/8 h). On the contrary, the product with CeO2 is found to have lower emission intensity (Ce3+ doping content: 2.50 at.%), and therefore decrease the reliability and goodness of fit when refining its atomic parameters. 3. Tb3+ ions have a strong trend to transform into Tb4+ ions under an oxidizing environment, and Tb4+ is induced and obtained by incorporating magnesium (Mg2+) ions into YAG host in the study. MgO co-doping restrains the grain growth behavior than single-doped YAG:Tb phosphors. Furthermore, the decrease of PL intensity is mainly caused by Tb4+ ions and the defect of microstructure of phosphor, and the co-existence of Mg2+ and Tb4+ in the YAG matrix also results in some changes in crystal structure. 4. TbAG is the complete solid solution with the maximum replacement for Y ion in YAG. The Tb3+ concentration quenchings of PL and cathodoluminescence (CL) emission intensities with higher Tb doping levels are shown, and the suitable Tb3+ concentration is between 15 ~ 20 at.% in this work. The Tb3+ concentration is the most important factor in YAG/TbAG system in the study, influencing the microstructure of powder, reflective and fluorescent properties, energy transfer of excitation light, and crystal structure. 5. Theta-Al2O3 is replaced by alpha-Al2O3 as one of the starting materials in the system. In addition, NaOH solution is selected for the synthesis as comparing with hydrochloric acid (HCl). The crystal field splitting of Ce3+ in YAG/TbAG host and the lowering of Ce3+-O2- bond lengths are correlated with luminescent properties in this study. PL excitation (PLE) and PL spectra, and chromaticity diagram of Ce3+-garnet shift to a longer wavelength while the structures expand with the increasing content of Tb3+ ions. The Tb3+ ions (or TbAG) not only act as a non-radiative role, but bring the concentration quenching in the (Y/Tb)AG:Ce material. 6. The absorption and luminescence spectra of compounds in YAG-TbAG solid solution synthesized in a N2/H2 (nitrogen/hydrogen) are significantly different from those synthesized in air. The oxidation of Tb from 3+ to 4+ when synthesized in air is the key factor in the variation of spectra, and it also results in smaller lattice constants for the Tb-garnets. The inhomogeneous broadening effect obviously occurs in the phosphors synthesized in N2/H2, but it disappears in the air-prepared system. The concentration quenching is still found because of an excess of Tb3+ doping, at more than 20 at.%, in the system.

The thesis entitled “Local structure-property relationship in some selected Solid State Materials” mainly focuses on two fundamental topics: (a) evaluation of some standard global structural concepts in terms of local structure to provide a unique description of the crystal structure, and (b) the role of the crystal structure at different length-scales in controlling the properties in some selected materials.

The thesis entitled “Local structure-property relationship in some selected Solid State Materials” mainly focuses on two fundamental topics: (a) evaluation of some standard global structural concepts in terms of local structure to provide a unique description of the crystal structure, and (b) the role of the crystal structure at different length-scales in controlling the properties in some selected materials.

碩士
國立高雄應用科技大學
光電與通訊研究所
94
ZnS is a wide-gap (3.66 eV) II-VI compound semiconductor material and is commercially used as phosphor for electroluminescence devices. ZnS has good luminescence property, it is a candidate material for phosphors that emit visible light. The major and important applications of phosphor are in light sources, display devices, and high energy radiation detector. Two subjects on this thesis have been discussed. The first one is the synthesis of the traditional ZnS-based phosphors. The effect of preparation parameters, such as synthesis temperature, sintering time, dopants and doping concentration, on the luminescence characteristics of phosphor was studied. X-ray diffractometer (XRD), photoluminescence (PL), cathodeluminescence (CL) and scanning electron microscopy (SEM) were used to analyze the characterizations of crystalline structure, luminescence and microstructure of phosphor. From the XRD pattern, transformation temperature of the ZnS phosphor was determined. It was also found that the luminescence property of host lattice changed along with the amount of hexagonal phase. The higher the firing temperature, the higher the amount of hexagonal phase could be found. From photoluminescence and cathodeluminescence spectra, luminescence intensity related to the sintering temperature, doping concentration and sintering time were evaluated. When ZnS doped with Mn and Ce ion, a yellow-orange emission wavelength around 568 nm is observed. Increasing the doping concentration, the concentration quenching effect was observed. When the co-doping concentration is 0.9 mol%, sintering temperature is 1200℃ and sintering time is 1 hour, the optima emission efficiency of phosphor was achieved. The phosphor which was synthesized in the first subject was applied to the second subject subsequently. The ZnS-based phosphor used as the phosphor layer for electroluminescence device, which was prepared by screen-printing method. After the electrode was fabricated, a yellow-orange EL device was obtained.

碩士
國立成功大學
材料科學及工程學系碩博士班
97
In the present work, Yttrium aluminum garnet doped cerium (YAG:Ce) phosphors co-doped with Si4+ ions were synthesized by a solid-state method. The effect of co-dopant on the photoluminescence, microstructure and diffusion activation energy of YAG:Ce were studied systematically. The resulting materials were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR) and Photoluminescence. Those spectra reveal that by adding SiO2 to YAG:Ce precursor, the lattice constant decreases while vacancies are generate due to the co-dopant ions (Si4+) replaces in the place of Al3+ sites of YAG:Ce system. YAG:Ce phosphors with Y3+ dodecahedral site replaced by Ce3+ and diffused effectively as an activator, as a result the photoluminescence intensity increased about ~20-30%. From the literature, it was found that the addition of silica to YAG:Nd makes it possible to greatly improve the grain growth because of SiO2 inhibits exaggerated coalescence. From the SEM images of following samples YAG:Ce with 0~5wt% silica addition sintered by 980oC~1400oC/8hrs and YAG/YAG:Si sintered at 1650oC/8hrs, we observed that the grain growth is not obvious in the temperature range between 980oC~1100oC due to the insufficient temperature. As the temperature is higher than 1100oC, we can see the significant grain growth and the higher grain density of YAG due to the adding of SiO2 to the system YAG:Ce. In addition to that we also observed the different microstructures of grain distribution between YAG:Ce containing SiO2 and pure YAG:Ce. The analysis spectra confirms that the presence of Si4+, it was replaced in Al3+ sites of YAG:Ce, then the Ce3+ might be occupied the luminescence centre easily. As well as it proves that the enhancement of PL intensity of YAG:Ce containing with SiO2. By comparing the diffusivities of Ce3+ into YAG/YAG:Si bulk samples, we concluded that by adding the SiO2 to the system YAG:Ce, the PL intensity enhanced significantly due to the increasing the density of YAG and the diffusing of rare-earth element (Ce3+) through the grain boundaries.

碩士
國立高雄應用科技大學
電子工程系
98
In this study, the ZnWO4 phosphor was synthesized by sol-gel method. Zinc (Zn) and tungsten (W) compounds were used as source materials. From the evaluation of synthesis parameters of mixed temperature, aging time, standing time, sintering temperature and time, it is found that the synthesis parameters indeed affect the particle size and luminescence intensity of the phosphor. The characteristics of the phosphors synthesized by sol-gel method and solid state reaction were compared and discussed. Additionally, the electroluminescence device (ELD) was fabricated, in which the phosphor synthesized at optimal parameters was used as emission layer. The luminance and CIE coordinates of the ELD were measured.

碩士
國立中山大學
材料科學研究所
96
The powder phosphor of β-LiGaO2：Ce3+ 、β-LiGaO2：Eu3+ and γ-LiAlO2 were prepared by using the reagents of Ga2O3 (99.999%), Al2O3 (99.99％), Li2CO3 (99.999%), CeO2 (99.98%) and Eu2O3 (99.98%). Cerium and europium doped β-LiGaO2 respectively and europium doped γ-LiAlO2 phosphors were synthesized by the method of high temperature solid-state reaction. The Ga, Al, Li, Ce and Eu reagents were mixed according to the requisite stoichiometric ratios. The mixture was mixed thoroughly and sintered at requisite temperature in a tube furnace in atmosphere for several hours. Then the products were cooled down to room temperature and ground into powder to get the final product. The phase purity and crystallinity of the as-synthesized, cerium and europium doped β-LiGaO2 phosphors respectively and europium doped γ-LiAlO2 phosphors, were characterized using x-ray powder diffraction. The particle size and the morphology of the samples were analyzed by scanning electron microscopy. Luminescence properties of the β-LiGaO2 and the γ-LiAlO2 phosphor samples with different cerium doping and europium doping concentrations were studied. The photoluminescence spectra of cerium doped β-LiGaO2 showed a broad yellow-green light emission range from 450 to 640 nm with the peak at 519 nm. The strongest intensity peak of luminescence was found at 0.5 % cerium doping concentration synthesized at 1000℃. The photoluminescence spectra of europium doped β-LiGaO2 and γ-LiAlO2 showed the orange-red light emission range from 588 to 630 nm with the maximum peak at 612 nm. The strongest intensity peaks of luminescence were found respectively at 9 % and 7 % europium doping concentration synthesized at 1000℃.

碩士
國立中山大學
材料與光電科學學系研究所
100
In this research, we used the zinc oxide (ZnO) which is die pressed and sintered for studying. We want to know the variations of microstructure and luminescence property when we doped 0.2 mol.% Al2O3 or Li2O to ZnO, or sintered under different atmospheres (high purity oxygen, high purity nitrogen, high purity argon). Using X-ray diffractometry (XRD), scanning electron microscope (SEM), and catholuminescence (CL) spectrometry equipped with a SEM to analyze the different samples. The all six samples’ crystal structure didn’t change via XRD. We investigated for the in-gap-level modification using the CL spectrometry. CL analysis results indicated that ZnO emitted UV light, visible light (blue, green, yellow light), and Near-infrared light emissions. The UV light emission was attributed to the two electronic transitions from the donor level of free exciton and Zn interstitial to valence band. The blue light (2.53 eV) emission was attributed to the donor level of oxygen vacancy-related defect. The green light emission was attributed to the electronic transition from the acceptor level of zinc vacancy-related defect.And the yellow light emission was attributed to the O interstitial and Li-related defects. The Near-infrared light may be attributed to the deep levels recombination.

碩士
國立高雄應用科技大學
電子工程系
97
In this study, the ZnO-based phosphor was synthesized by solid-state reaction method. Potassium (K), tungsten (W), lithium (Li) and gallium (Ga) compound were used as activators and fluxes. By understanding the different sintering temperature and time of phosphors on the impact properties; different frequency and time of abrasive powder particles on the surface of fluorescent patterns and structural characteristics of the luminescence; the experimental results from the synthesis parameters, we can see indeed phosphors will affect the wavelength and intensity of the luminescence. Finally, under the best conditions for the production of phosphors into electroluminescence to stimulate the production of optical components, to assess the power of fluorescent powder laser brightness, and color coordinates of the location. In addition, the fluorescent powder-ray laser measurement of the excitation source wavelength fixed at 325 nm, always visible light radiation dominated region.

碩士
國立交通大學
應用化學系所
96
Novel phosphors with compositions of A,B,C,D,E,F, LiAl5O8：Mn4+,and LiAlO2：Mn4+ were synthesized by solid state method. The crystal structure of host materials were found to retain after doping of rare earth ions by comparing X-ray data of the samples to those reported in database. Through the measurements of diffuse reflectance spectra for both doped and un-doped samples, we found that all of the optical emissions were resulted from the doped rare earth ions. We have also analyzed the structure of the hosts and relevant luminescence behaviors. In this research, rare-earth ions were found to substitute and enter the cation siteswith four to nine in coordination numbers. The emission wavelength werefound from 403 nm to 423 nm as in the case of Ce3+-doped phosphors showing a blue emission and 494 nm as in Eu2+-doped phosphors showing a green emission and 667 nm to 715 nm as in Mn4+-doped phosphors showing characteristically highly saturated red emission. Additionally, the C.I.E. chromaticity coordinates show that these phosphors emit hues including violet, blue, green, and red, respectively.

碩士
國立交通大學
應用化學系所
95
In this research we have synthesize nine different types of Eu2+-or Ce3+-doped phosphors with the compositions of Host：Eu2+(or Ce3+)　 (Host = A、B、C、D、E、F、G、H、I ) under a mildly reducing atmosphere. Each of these compounds was solely doped with Ce3+ or Eu2+,which are expected to substitute for the positions of Ca2+、Sr2+、Ba2+,respectively. By comparing X-ray data of the samples to those reported in database, we are sure that the crystal structures of hosts do not change after doping of 2% rare earth ions. Through the measurements of diffuse reflectance spectrum for both doped and un-doped samples, we found that all of the optical emissions were resulted from the doped rare earth ions. We have also analyzed the structure of the hosts and made attempts to correlate the luminescence behaviors and crystal structure. In this phosphors synthesized in this work, rare-earth ions were found to substitute and enter the cation sites with six to twelve coordination number. The emission wavelength were found to vary from 323 nm to 506 nm as in the case of Ce3+-doped phosphors and 398 nm to 657 nm as in Eu2+-doped phosphors. Additionally, the C.I.E. chromaticity coordinates show that these phosphors emit hues including violet, blue, aqua blue, green, yellow and orange.

碩士
國立中山大學
材料科學研究所
95
The method of coating near-ultraviolet light with phosphor powders is one of the main trends in the current development of white light-emitting diodes (LEDs). It a long time for the development of Ce3+ doped phosphor materials. The Ce3+ has one outer 4f1 electron. And this electron can be excited to 5d. The luminescence wavelength of Ce3+ doped phosphor materials different from the different host lattice. First part of this paper is about the growth of cerium doped LiGaO2 crystal by conventional Czochralski melt pulling method. The dose of cerium is 0.2ppm. The growth were operated in the ambient pressure, with the pull rate of 2.0 mm/hour and the rotation rate of 10~20 RPM. LiGaO2 crystal of 200 mm in length was grown under these conditions. We found a yellow to green peak on 505 nm from the measurement of photoluminescence spectra. It showed that LiGaO2 can emit phosphorescence by the doped of cerium. Second part of this paper is growth of Gallium nitride (GaN) thin films. GaN possess vast application potential in the fields of optoelectronics and microelectronics for its wide band gap, high thermal stability and high chemistry stability. GaN mostly grow on large lattice mismatch substrates, for the difficulty growth of GaN bulk single crystal and scarce of lattice match heteroepitaxial substrates. This result in great dislocation defects density in the GaN films. To lower the dislocation density of GaN films and improve the crystal quality is an important point of GaN research fields. In this study, the GaN thin films were grown on γ-LiAlO2(100) substrates by Chemical Vapor Deposition(CVD). We found that the growth direction and structure of GaN were influenced by growth parameter. The GaN（10-10） thin films were grown by the adjust of growth temperature and pressure.