Thèses sur le sujet « Porosi luminescenti »

L'attività di ricerca si è occupata della progettazione, sintesi e caratterizzazione di materiali porosi. Diverse linee di ricerca sono state perseguite. Materiali porosi per l'assorbimento selettivo e lo stoccaggio di gas. Le proprietà di una serie di polimeri porosi organici sono state studiate attraverso misure di assorbimento di gas e misure di risonanza magnetica nucleare dello stato solido in presenza di una fase gassosa per comprendere la natura delle interazioni tra le molecole ospiti e le pareti dei canali. In particolare, si è verificata l'elevata energia di interazione tra le molecole di anidride carbonica e gruppi amminici alifatici che genera un'efficiente trasferimento di magnetizzazione tra gli idrogeni del gruppo amminico e il carbonio dell'anidride carbonica. Polimeri iper-reticolati porosi e polimeri organici porosi sono stati studiati mediante assorbimento di metano ad alta pressione (fino a 180 bar) per possibili applicazioni per lo stoccaggio di gas naturale in presenza di reticoli porosi (ANG). Durante il periodo all'estero presso il Bernal Institute sotto la supervisione del Prof. M.J. Zaworotko mi sono occupato dello sviluppo di una serie di framework metallo-organici che presentano flessibilità strutturale. In presenza di un opportuno gas o vapore i reticoli sintetizzati danno luogo a una transizione di fase tra una fase compatta e una fase porosa in maniera repentina. Questo meccanismo è attualmente molto studiato per le possibili applicazioni nell'ambito dello stoccaggio e separazione dei gas. Reticoli metallo-organici contenenti rotori molecolari. Due nuovi reticoli porosi metallo-organici sono stati sviluppati e le loro proprietà di assorbimento e termiche sono state caratterizzate. Inoltre, i due sistemi contengono un rotore molecolare molto mobile anche alle basse temperature come dimostrato da esperimenti di risonanza magnetica nucleare dello stato solido. Materiali porosi per applicazioni nella fotonica. Sono stati sintetizzati alcuni materiali organici covalenti contenenti difenilantracene. Questi campioni presentano elevata resa quantica di fotoluminescenza. In dispersione e in presenza di un sensibilizzatore opportuno questi materiali danno vita ad un fenomeno di up-conversion dovuto all'annichilazione di tripletto con efficienze fino al 15 %. Inoltre, legando chimicamente il sensibilizzatore al reticolo poroso è possibile ottenere dei sistemi per up-conversion autonomi. Infine, nanocristalli di reticoli metallo-organici porosi sono stati cresciuti e le loro proprietà di foto- e radioluminescenza sono state investigate approfonditamente. Inoltre, questi cristalli, dispersi all'interno di una matrice polimerica, sono stai utilizzati per sviluppare degli innovativi scintillatori ibridi per la rivelazione di raggi x e gamma.<br>The research activity focused on the design, synthesis and characterization of porous organic and hybrid materials. Porous materials for selective gas adsorption and storage. Tailored porous organic frameworks bearing different functional groups have been investigated via gas adsorption analyses and in situ spectroscopic techniques to understand the interaction between the guest phase and the primary adsorption sites installed on pore walls. Specifically, aliphatic amines interact strongly with carbon dioxide molecules resulting in an isosteric heat of adsorption as high as 54 kJ/mol at low loading and this close-contact interaction has been characterized with 2D heterocorrelated NMR sppectroscopy. Hyper.crosslinked polymers and porous organic frameworks have been synthetized and their performance towards high pressure (up to 180 bar) methane adsorption have been evaluated to assess their potential applications in adsorbed natural gas technology (ANG). During a period at Bernal institute (Limerick, Ireland) under the supervision of Prof. M. J. Zaworotko, I developed novel switching metal-organic frameworks that display guest-induced phase transitions between close phases and a porous open phase. During the close to open phase transitions the coordination sphere of the zinc cations inside the structures changes from a square pyramidal to a tetrahedral geometry. Moreover, the threshold pressure for gas adsorption can be manipulated through a mixed-linker approach. These materials are currently investigated for applications in gas storage and separation. Metal-organic frameworks with intrinsic dynamics. Metal organic frameworks built up with rigid aliphatic linkers have been developed and their adsorptive and thermal properties fully characterized. These materials display ultra-fast rotational dynamic even at very low temperature. An in-depth solid state NMR study has been conducted to understand the fast rotation of the organic strut and the influence of guest species hosted inside the pores on its dynamic. Organic and hybrid materials for photonic applications. Emitting porous aromatic frameworks (ePAFs) nanoparticles containing highly fluorescent diphenylanthracene moieties have been developed. This materials display high photoluminescence quantum yield and a fast exciton diffusion inside the amorphous framework. When these nanoparticles are suspended in a solution of a suitable sensitizer the mixture display highly efficient sensitized triplet-triplet annihilation up-conversion with quantum yield up to 15 %. Moreover, PAFs with integrated sensitizers (i-ePAFs) display sensitized up-conversion working as an autonomous nanodevice. Metal-organic frameworks with diphenylanthracene units and zirconium oxo-hydroxo clusters have been developed and their luminescence and radioluminescence have been characterized. These nanocrystals have been embedded in polymeric matrixes to generate efficient and innovative scintillating materials with fast response for x-ray and gamma-ray detection.

Orientador: Vitor Baranauskas<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação<br>Made available in DSpace on 2018-07-25T01:27:47Z (GMT). No. of bitstreams: 1 Chang_DahgeChiadin_D.pdf: 9826585 bytes, checksum: 5734a3b6b43a08b7eb8b54729d1abb13 (MD5) Previous issue date: 1999<br>Resumo: Foi realizado um estudo de caracterização do silício poroso luminescente feito por corrosão eletroquímica visando sua cobertura com diamante. Foram utilizados eletrólitos com misturas de HF/H2O e de HF/C2H5OH/H2O em diferentes proporções, diferentes tempos de corrosão e com densidades de corrente entre 10 mA.cm-2 a 30 mA.cm-2. A morfologia do silício poroso foi analisada por microscopia de força atômica dentro do próprio meio líquido para estudo quantitativo da variação da porosidade com os parâmetros da anodização. Os filmes de silício poroso foram recobertos com diamante depositado em diferentes temperaturas e tempos. Observamos que a estrutura de silício poroso/diamante apresenta luminescência na temperatura ambiente mas não pudemos identificar se a forma gausssiana da luminescência é devida ao silício poroso ou ao diamante<br>Abstract: A study of the properties of anodically etched porous silicon was made prior to and following its coating with diamond. Mixtures of HF/H2O and of HF/C2H5OH/H2O were used as electrolytes in different proportions, for different corrosion times and with current densities in the range of 10 mA.cm-2 to 30 mA.cm-2. The porous silicon morphology was analyzed in-situ (liquid-phase) by atomic force microscopy to study of the variation of the porosity with the anodization parameters. The porous silicon films were covered with diamond deposited at different temperatures and times. It was observed that the porous silicon/diamond structure presents room temperature photoluminescence but it was not possible to determine whether the gausssian shape of the luminescence spectra was due to the porous silicon or to the diamond coating<br>Doutorado<br>Doutor em Engenharia Elétrica

Orientadores : Vitor Baranauskas, Alfredo Carlos Peterlevitz<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação<br>Made available in DSpace on 2018-07-29T02:19:41Z (GMT). No. of bitstreams: 1 Tosin_MarceloCarvalho_D.pdf: 2129034 bytes, checksum: 39ff2fe9e6e37b45b74c5731f165aca3 (MD5) Previous issue date: 2001<br>Doutorado

Hidróxidos duplos lamelares (LDHs) são uma classe materiais lamelares com fórmula química [M_(1-x)^II M_x^III (OH)_2 ] [A^(n-)]_(x/n).yH_2 O (onde M^II e M^III são metais di e trivalentes, respectivamente) formados pelo empilhamento de camadas positivamente carregadas de hidróxidos metálicos intercaladas por espécies aniônicas A^(n-). Este trabalho descreve uma estratégia inédita para a produção de nanotubos de LDHs autossuportados (Ø 20 nm e comprimentos >= 100 nm) através da coprecipitação de Zn^(2+), Al^(3+) e Eu^(3+) em pH controlado e sua auto-organização sobre micelas cilíndricas do surfactante Plurônico® P-123. A subsequente extração destes agentes estruturantes através de lavagem com metanol resulta em uma rede de nanotubos cilíndricos, ocos e interconectados, formados pela deposição de multicamadas de hidróxidos duplos intercalados pela molécula sensibilizadora ácido benzeno-1,3,5-tricarboxílico (ácido trimésico, BTC). A combinação de Eu3+ nas camadas de hidróxidos e BTC no meio interlamelar resulta em nanotubos com propriedades luminescentes, demonstrando de maneira notável como modificações químicas e morfológicas nos LDHs podem levar ao remodelamento das suas propriedades físico-químicas e consequentemente direcionar suas aplicações de maneira desejável.<br>Layered double hydroxides are a class of lamellar compounds with chemical formula [M_(1-x)^II M_x^III (OH)_2 ] [A^(n-)]_(x/n).yH_2 O (with M^II and M^III being di and trivalent metals, respectively) that are formed by the stacking of positively charged mixed-valence metal hydroxide sheets intercalated by anionic species A^(n-). This work describes a new strategy for the synthesis of self-supporting mesoporous LDH nanotubes (Ø 20 nm and length >= 100 nm) by coprecipitation of Zn^(2+), Al^(3+) and Eu^(3+) around non-ionic worm-like micelles of Pluronic® P-123 in controlled pH. Subsequent extraction of the structure-directing agent with methanol results in a network of interconnected, well-defined, multi-walled and hollow cylindrical LDH nanotubes intercalated by the sensitizing ligand BTC (1,3,5-benzenetricarboxilate). The combination of Eu^(3+) in the hydroxide layers and BTC in the interlayers results in nanotubes with luminescence properties in a notable demonstration on how chemical and morphological changes in LDHs can lead to materials with tuned physico chemical properties that can be tailored towards a range of applications.

Ce travail décrit la synthèse et la caractérisation physico-chimique de nanocomposites hybrides obtenus par imprégnation en voie liquide de bétâ-dicétonates d'Europium dans des silices mésoporeuses structurées aux tensio-actifs de type MCM-48 et MCM-41, post-fonctionnalisées ou non. La caractérisation des matériaux par ICP, spectroscopie électronique, diffraction des rayons X, thermogravimétrie, isothermes d'adsorption d'azote, RMN, spectroscopies UV-Vis et IR a permis de confirmer et de quantifier l'incorporation des complexes dans les pores de ces réseaux de silice. Les propriétés de photoluminescence de ces hybrides ont été également évaluées et les mécanismes gouvernant les interactions entre les parties organiques et inorganiques analysés dans le cadre de la théorie de Judd-Ofelt. Des conclusions sont avancées pour le design de systèmes hybrides hautement luminescents pour des températures d'usage de 60-70°C, généralement rédhibitoires pour les complexes organiques seuls

A contactless method using a novel design of the experimental cell for formation of porous silicon with morphological gradient is reported. Fabricated porous silicon layers show a large distribution in porosity, pore size and depth along the radius of the samples. Symmetrical arrangements of morphology gradient were successfully formulated radially on porous films and the formation was attributed to decreasing current density radially inward on the silicon surface exposed to Triton (R) X-100 containing HF based etchant solution. Increasing the surfactant concentration increases the pore depth gradient but has a reverse effect on the pore size distribution. Interestingly, when dimethyl sulfoxide was used instead of Triton (R) X-100 in the etchant solution, no such morphological gradients were observed and a homogeneous porous film was formed.

Les nouveaux morph-génétiques poreux matériaux ont des potentielles applications dans les domaines de séparation et purification des matières, de l’adsorption sélective, de la fonction optique et de la conception de capteurs. Mais il est difficile de fabriquer ce genre de matériau par les techniques traditionnelles. Du fait de la diversité de ces matériaux, les structures bois morph-génétiques poreuses sont complexes et sont formées par les organismes eux-mêmes (morph-transformation génétique). Inspiré par cette transformation macro-biologique, la technologie morph-transformation génétique peut être utilisée dans la fabrication de ses nouveaux matériaux morph-génétiques poreux. Le but de notre recherche est la mise au point des nouvelles méthodes de fabrication des matériaux morph-génétique à partir de biomodèles oxydes de structure poreuse du bois, d’étudier leurs propriétés optiques et de détection de gaz de bois-modèle spécifiques. Dans le présent travail, le biomodèle oxyde de fer, l'oxyde de nickel et l'oxyde de zinc avec les structures morph-génétique du bois sont fabriqués en utilisant la technologie de morph-transformation génétique. Les processus physiques et chimiques de transformation sont analysés et les paramètres de fabrication sont optimisés. Le règlement d'oxydes de microstructures par divers processus de paramètres sont établi. La valeur numérique dans multi échelles de structures poreuses d'oxydes est analysée et les propriétés optiques et de détection de gaz des matériaux morph-génétique poreux sont exploitées dans ce travail<br>Hierarchical porous materials have displayed important researching and application values at the fields of separation and purification, selective adsorption, optical function, and sensor design etc. Some preparation methods have been designed to fabricate porous materials. But these traditional methods have to use specific equipments and complicated techniques, and obtained porous materials have single pore size distributions with single functions. The morph-genetic transformation technology is a simple processing technology to fabricate re-fined hierarchical porous materials using organ-isms as template. The organisms in nature are the perfect unities of highly delicate structures and effectively complex functions through mil-lions of years of evolution and natural survival law, which prepare plentiful structural tem-plates for hierarchical porous materials. In the present work, wood-templated Fe2O3, ZnO and NiO with hierarchical porous structures were fabricated through replication wood’s morphology and structure. The synthetic mechanism was studied to optimize the parameters of morph-genetic technology, and wood-templated oxides with wood’s structures were fabricated successfully. The porous structures in multi-scales, the optical properties and the gas sensing properties of wood-templated oxides were researched in detail

Dans ce travail, nous avons etudie certains aspects du mecanisme de la luminescence du silicium poreux. La particularite de l'approche a ete le suivi simultane de l'intensite, des temps de vie et de la forme du declin de la pl en fonction des plusieurs parametres tels que: la temperature, le niveau d'oxydation anodique et l'intensite d'excitation. Nous decrivons la structure poreuse comme un ensemble de cristallites de dimensions nanometriques, interconnectees par des ponts de silicium ou de silice. Le premier niveau excite dans ces cristallites est localise, les porteurs se retrouvant confines dans un point quantique. Par contre, les niveaux excites superieurs sont etendus sur plusieurs cristallites, les porteurs etant confines dans un fil quantique. Pour des temperatures plus petites que 250k, nous avons conclu que les porteurs sont localises et une description de la dynamique de recombinaison limitee par l'effet tunnel est valable dans toute cette gamme des temperatures. A plus hautes temperatures, le changement de la forme du declin et la forte decroissance de l'intensite de la pl ont ete associes a une delocalisation progressive des porteurs par activation thermique. Dans ce cadre, l'evolution contraire, enregistree au cours de l'oxydation anodique du silicium poreux, est assimilee a une localisation progressive des porteurs par l'accroissement des barrieres de potentiel du a l'oxydation des ponts reliant les cristallites. Le dernier volet de ce travail comporte une etude de l'evolution de l'intensite de la pl en fonction de l'intensite d'excitation. La saturation de la pl, detectee dans un regime de fortes intensites d'excitation, a ete attribuee a une intensification de la recombinaison auger. La meme explication est ensuite utilisee pour justifier la diminution du rendement de luminescence dans un regime de forte injection electrique

Submitted by Guilherme Arroyos null (guiarroyos@gmail.com) on 2018-03-20T14:13:03Z No. of bitstreams: 1 DISSERTAÇÃO DE MESTRADO GUILHERME ARROYOS.pdf: 8526991 bytes, checksum: f3c3ac9d633deb1a24a357f7c55b9819 (MD5)<br>Rejected by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br), reason: Prezado Guilherme Arroyos, Solicitamos que realize a correção na submissão seguindo a orientação abaixo: Inclusão da Ficha Catalográfica no trabalho. Agradecemos a compreensão. on 2018-03-23T14:03:32Z (GMT)<br>Submitted by Guilherme Arroyos null (guiarroyos@gmail.com) on 2018-03-23T14:10:47Z No. of bitstreams: 1 DISSERTAÇÃO DE MESTRADO FINAL.pdf: 8591215 bytes, checksum: 599b8b89fcdc4e3ee1ee1be2261729c1 (MD5)<br>Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-03-23T17:23:06Z (GMT) No. of bitstreams: 1 arroyos_g_me_araiq_int.pdf: 8520705 bytes, checksum: 750f8f7bf0f7ffed7bba14f02afd5cf0 (MD5)<br>Made available in DSpace on 2018-03-23T17:23:06Z (GMT). No. of bitstreams: 1 arroyos_g_me_araiq_int.pdf: 8520705 bytes, checksum: 750f8f7bf0f7ffed7bba14f02afd5cf0 (MD5) Previous issue date: 2018-03-07<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Segundo a IUPAC, MOFs (Metal-Organic Frameworks) são definidos como polímeros de coordenação com uma estrutura aberta contendo cavidades potencialmente vazias. As MOFs podem ser sintetizadas utilizando íons lantanídeos como centros metálicos (LnMOFs) e por essa razão, apresentam luminescência somada às demais propriedades desta classe de materiais porosos. Dentro desse contexto, o objetivo deste trabalho foi a obtenção de LnMOFs visando aplicação na área de sensoriamento químico via luminescência. Os compostos foram sintetizados a partir dos cloretos de térbio (III), európio (III) e samário (III) hexahidratados (precursores metálicos) e dos ligantes ácidos malônico e 3,5-pirazoldicarboxílico. Os compostos de térbio e ligantes foram sintetizados em diferentes pHs, sendo que os valores iguais a 2, 4 e 5 conduziram a formação dos materiais TBM2, TBM4 e TBM5, respectivamente. Os sólidos de európio e samário foram sintetizados em pH igual a 5 (compostos EUM5 e SMM5, respectivamente). As sínteses foram realizadas utilizando micro-ondas e estufa solvotérmica. As amostras TBM4 e TBM5 obtidas via micro-ondas se organizam na forma de partículas com tamanhos entre 0,5 - 2 μm e morfologia esférica. Ensaios de caracterização demonstraram que se tratava do mesmo composto, exceto uma maior rugosidade nas partículas do TBM5. A cristalinidade do material foi baixa devido ao curto tempo de síntese, no entanto utilizando síntese solvotérmica (mais lenta) foi possível aumentar a cristalinidade. Há bandas características de ambos os ligantes na espectroscopia vibracional no infravermelho, assim como os deslocamentos de bandas ocasionados pela coordenação ao íon metálico. O composto apresentou boa estabilidade térmica, iniciando sua decomposição na temperatura de 455 °C. O material também apresentou intensa emissão de luz verde quando exposto à radiação ultravioleta. Esta propriedade de luminescência foi utilizada para os testes de sensoriamento de gás carbônico e íons cobre (II), apresentando variações na intensidade de emissão após exposição aos analitos. Após exposição ao CO2, a intensidade de luminescência aumentou, enquanto que após exposição ao Cu2+ a intensidade diminuiu, conforme a concentração. O composto EUM5 apresentou baixa intensidade de luminescência e o SMM5 não apresentou emissão de luz. O composto TBM2 via síntese solvotérmica foi obtido na forma de monocristais luminescentes. A técnica de difração de raios-X de monocristal elucidou a estrutura do material, onde foi possível observar que o ligante ácido malônico não coordenou neste caso. Foi investigada ainda nesse trabalho a influência da rota sintética e de alguns parâmetros experimentais (concentração dos reagentes, uso de modulador de coordenação) no tipo de produto formado.<br>According to IUPAC, MOFs (Metal-Organic Frameworks) are coordination polymers with an open structure containing potentially empty voids. MOFs can be synthesized using lanthanide ions as metal centers (LnMOFs) and therefore have luminescence added to the other properties of this porous materials class. In this context, the objective of this work was to obtain LnMOFs for chemical sensing application via luminescence. The compounds were synthesized from terbium (III), europium (III) and samarium (III) chlorides hexahydrates (metal precursors) and the malonic and 3,5-pyrazoledicarboxylic acid linkers. The compounds with terbium plus linkers were synthesized at different pHs, with values of 2, 4 and 5 leading to the formation of TBM2, TBM4 and TBM5 materials, respectively. The europium and samarium solids were synthesized at pH = 5 (compounds EUM5 and SMM5, respectively). The syntheses were microwave and solvothermic assisted. The TBM4 and TBM5 samples via microwave-assisted synthesis are organized in the form of particles with sizes between 0.5 - 2 μm and spherical morphology. Characterization tests showed both are the same compound, except for a greater roughness in the TBM5 particles. The crystallinity of the material was low due to the short synthesis time; however, by using solvothermic-assisted synthesis (slower) it was possible to increase the crystallinity. There are characteristic bands of both ligands in the infrared vibrational spectroscopy, as well as band displacements caused by coordination to the metal ion. The compound presented good thermal stability, initiating its decomposition at the temperature of 455.7 °C. The material also showed intense green light emission when exposed to ultraviolet radiation. This luminescence property was investigated for the carbon dioxide and copper (II) sensing tests, showing variations in emission intensity after exposure to analytes. After exposure to CO2, the intensity of luminescence increased, while after exposure to Cu2+ the intensity decreased, depending on the concentration. The compound EUM5 showed low luminescence intensity and SMM5 did not show emission. The TBM2 compound obtained via solvothermic synthesis organized itself in the form of luminescent single crystals. The single crystal X-ray diffraction technique elucidated the structure of the material, where it was possible to observe that the malonic acid binder did not coordinate in this case. The influence of the synthetic route and some experimental parameters (reagent concentration, use of coordination modulator) on the type of product were also investigated.

Ce travail est consacre aux mecanismes de conduction du silicium poreux en contact avec un electrolyte liquide conducteur, ainsi qu'a l'etude du comportement de la luminescence sous polarisation. La premiere partie presente les principales caracteristiques de la luminescence du silicium poreux ainsi que les differents modeles qui ont ete proposes pour en expliquer les mecanismes. La deuxieme partie est consacree a la description des methodes experimentales utilisees pour la fabrication des couches poreuses et l'etude de leurs proprietes de photo et d'electroluminescence. Dans une troisieme partie, les mecanismes de conduction du silicium poreux ont ete etudies. Il a ete montre que ces derniers etaient determines par les flux d'ions et d'electrons en provenance de l'electrolyte et du substrat de silicium ainsi que par la cinetique d'echange de charges a l'interface silicium-electrolyte. Un modele quantitatif a ete developpe qui rend bien compte de l'etat de peuplement de la couche poreuse en porteurs libres et permet d'interpreter la presence ou l'absence d'electroluminescence. Une quatrieme partie est consacree aux phenomenes d'extinction de la luminescence sous l'action d'une polarisation electrique. Elle a permis de degager des arguments decisifs en faveur d'un mecanisme base sur l'effet auger. Enfin, dans une derniere partie situee en annexe, un certain nombre de resultats experimentaux complementaires sont presentes. Il s'agit d'une part du comportement electrochimique d'electrodes de silicium poreux dont les pores ont ete tapisses de germanium, et d'autre part de l'etude de l'influence des traitements thermiques sur la luminescence du silicium poreux.

La conception de nouveaux matériaux fonctionnels a une longue histoire. Durant les deux dernières décennies, le domaine des polymères organiques et inorganiques a attiré l'attention des chercheurs. Plus important encore, les matériaux poreux tels que les Metal Organic Frameworks (MOFs), en anglais, Covalent Organic Frameworks (COFs), en anglais, ainsi que des polymères de coordination poreux sont maintenant étudiés de manière intensive en raison de leurs applications potentielles, comprenant le stockage de gaz, la séparation de gaz, la catalyse et la détection. D'un autre côté, les polymères contenant du Pt ont montré l'application potentielle dans les cellules solaires et les diodes électroluminescentes. Le mémoire est divisé en trois sections principales présentant des résultats nouveaux. Dans la première section, le chapitre 2 traite essentiellement de la formation de polymères de coordination (CP) avec des sels CuX (X = Cl, Br, I) et trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), soit dans le PrCN ou PhCN. Les polymères résultants sont soit 2D (bidimensionel) ou 1D (unidimensionel). Cependant, en presence de PrCN ou de PhCN, le CP 2D obtenu avec le CuBr n'a pas incorporé de solvant dans ses espaces vides. D'autre part, le CP 2D et le reste des CP 1D obtenus avaient soit des molécules de solvant de cristallisation dans leurs cavités ou coordonnés au cuivre sur la chaîne. Les unités cuivre-halogénures étaient soit des rhomboïdes Cu2X2 ou le cubane Cu4I4. Leurs mesures photophysiques en présence et en l'absence de molécules de solvant de cristallisation ont été effectuées. En outre, la porosité du CP a été évaluée par BET (N2 à 77 K). Le vapochromisme du CP 2D sans solvant et des CP 1D ont été étudiés, ainsi que les mesures de sorption du CO2 ont été effectuées. De plus, nous avons utilisé CuCN et L1 dans MeCN pour former de nouveaux CP’s. Ceci est rapporté dans la deuxième section, le chapitre 3. Le CP obtenu était inattendu : L1 s’est rompu et du cyanure CN‾ s’est coordonné sur le Pt. Ceci a conduit à la formation d’un CP 1D zigzag. Généralement, les CP sont formés avec L1 via des liens Cu-S ou/et Cu([éta]2-C≡C), mais pas dans le cas du CuCN qui lui forme une chaîne 1D (CuCN)n où le L1 rompu se lie avec cette chaîne via un lien Cu-N. Les propriétés photophysiques et de stabilité thermique ont été étudiées. La troisième section (Chapitre 4) traite d'une exploration des CP formés par la reaction des sels CuX (X = Cl, Br, I) et le trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) ou le trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) dans du MeCN afin de trouver des tendances. L'utilisation de L1 a donné lieu à un CP 2D ou 1D CPs avec le MeCN piégé à l'intérieur des cavités, il y a de l’espace vide. L2 a conduit uniquement à des CP 1D sans molecules de solvant de cristallisation. Des analyses thermogravimétriques, photophysique et des mesures d’adsorption de gaz (uniquement pour ceux avec du solvant) ont été étudiées.<br>Abstract: The design of new functional materials has a long history. For the past two decades, the field of organic and inorganic polymers has attracted attention of researchers. More importantly, porous materials such as Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) as well as porous coordination polymers are now being intensively studied due to their potential applications including gas storage, gas separations, catalyst and sensing. On another hand, Pt-containing polymers have shown potential applications in solar cells and light emitting diodes. The masters’ thesis is mainly divided into three main sections presenting new results. In the first section; Chapter 2 mainly discusses the formation of coordination polymers with CuX salts (X= Cl, Br, I) and trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1), in either PrCN or PhCN. The resulting polymers obtained were 2D (bidimensional) CPs or 1D (unidimensional) CPs in all cases. However, 2D CPs obtained when CuBr salt is used by either using PrCN or PhCN did not incorporate the solvents in their cavities. On the other hand, the 2D CP and the rest of 1D CPs obtained had either the crystallization molecules in the cavities or coordinated to the copper cluster. The copper-halide clusters were either the rhomboids Cu2X2 fragments or the step cubane Cu4I4. The photophysical measurements in the presence and absence of solvent crystallization molecules were performed. In addition, the porosity of the CPs was evaluated by adsorption isotherms. The vapochromism of the solvent-free 2D and 1D CPs were investigated as well as CO2 sorption measurements were perfomed. Furthermore, we then attempted to use CuCN and L1 in MeCN which is reported in the second section as Chapter 3. The obtained CP was unexpected as L1 broke and a cyanide (CN‾) ion coordinated to the Pt atom leading to the formation of zigzag 1D CP. The coordination bonds Cu-S or/and Cu([eta]2-C≡C) were generally observed with L1, but not in the CuCN case. Instead a 1D chain of (CuCN)n was made and the broken L1 now binds the chain via a Cu-N bond. The photophysical and thermal stability properties were studied. Lastly, the third section, Chapter 4 deals with a potential predictability of CP formation by using CuX salts (X= Cl, Br, I) and either trans-[p-MeSC6H4C≡C-Pt(PMe3)2-C≡CC6H4SMe] (L1) or trans-[p-MeSC6H4C≡C-Pt(PEt3)2-C≡CC6H4SMe] (L2) in MeCN as the solvent. The use of L1 resulted in either 2D or 1D CPs with the MeCN trapped inside of the cavities while L2 resulted in 1D CPs without MeCN being present in their cavities. The thermogravimetric, photophysical as well as gas sorption measurements (only for those with crystalisation molecules) were perfomed.

Cette thèse porte sur l’élaboration et la caractérisation de nanostructures luminescentes dopées avec des terres rares qui peuvent être utilisées pour détecter la présence de gaz tels que le monoxyde d’azote. Le silicium cristallin est choisi comme substrat car il est le semi-conducteur de référence en microélectronique. Il est cependant un mauvais émetteur de lumière en raison de sa bande interdite indirecte. Obtenir des propriétés optiques à partir de ce matériau, notamment d’émission, est un challenge et un enjeu très important pour l’industrie de l’optoélectronique et pour les télécommunications optiques. Le confinement quantique de porteurs de charge dans des nanostructures de silicium a permis d’obtenir une émission radiative à température ambiante. Une alternative pour obtenir une émission optique exploitable est de coupler ce matériau avec des ions émetteurs de lumière. Dans ce travail, des complexes contenant des ions de terres rares ont été greffés sur la surface du silicium. Ces derniers sont très intéressants en optique car ils présentent des raies d’émission intenses à des longueurs d’ondes qui ne sont que peu modifiées par leur environnement. Afin d’élaborer ces matériaux hybrides inorganiques/organiques, différentes étapes ont été développées et optimisées au cours de ce travail. Pour fixer les ions à la surface du silicium, il est tout d’abord nécessaire d’oxyder celle-ci de manière à ce qu’elle présente des groupements réactifs. Une deuxième étape consiste à ajouter un aminosilane, l’APTES, qui permet le lien entre le complexe et la surface de silice. La fonction silane permet le greffage à la silice et le film formé présente des fonctions amines libres (-NH2) qui peuvent réagir avec une fonction acide carboxylique. Il est ensuite nécessaire "d’emprisonner" les ions de lanthanides dans un ligand, le DOTAGA. Celui-ci présente 4 fonctions acides carboxyliques pouvant complexer l’ion de terre rare. Une 5ème fonction acide carboxylique reste libre et peut interagir avec une fonction amine, ce qui permet une fixation covalente du complexe. Les complexes de lanthanides (Tb, Eu, Ce, Yb et Nd) ainsi formés sont luminescents. Il est montré qu’une fois greffés sur le silicium plan, les complexes à base de Tb, Eu et Ce présentent une émission radiative importante alors que ceux à base d’Yb et de Nd sont peu luminescents. Des résultats similaires sont obtenus sur silicium poreux. Enfin, l’effet de l’environnement sur les échantillons synthétisés est étudié afin de montrer qu’ils sont des candidats intéressants pour détecter rapidement et réversiblement de faibles quantités de NO, qui est un gaz toxique, incolore et inodore<br>This thesis is about the synthesis and characterization of luminescent nanostructures doped with rare earth ions that can be used as sensor for gases such as nitrogen monoxide (NO). Crystalline silicon, which is used as a substrate here, is a poor light emitter because of its indirect gap. It is challenging for the microelectronic and optical telecommunications industries to obtain optical properties, including emission, from this material. Thanks to quantum confinement in silicon nanostructures, a radiative emission can be obtained at room temperature. A possible way to enhance these properties is to modify the surface in such a way that it becomes optically active. In this work, complexes containing luminescent elements as lanthanides were grafted on the silicon surface. These elements are very interesting for optical applications because the wavelength of their emission peaks is almost independent of the environment and an emission from the blue to the near infrared can be obtained, depending on the rare earth. To produce inorganic/organic hybrid materials, different steps were developed and optimized during this work. So as to attach the rare-earth based complexes to the silicon surface, that surface is oxidized in order to generate reactive groups like silanols. A second required step is the functionalization of the surface by an aminosilane (APTES) which enables to link the silica surface and the complexes. To fix the optically active ions, it is necessary to complex the lanthanide ions with a ligand (DOTAGA) that can react with the ammine group to create a covalent bound of the complex. In this work, it is shown that the synthesized lanthanide complexes (Tb, Eu, Ce, Yb and Nd) are optically active and that after grafting on the silicon surface, Tb, Eu and Ce based complexes have a strong luminescence while Yb and Nd based complexes are weakly active. The same type of results are obtained when the complexes are grafted on porous silicon. Moreover, the effect of the environment, in particular a nitrogen oxide one, is studied on these samples in order to check whether they can be used as NO sensors

Les silsesquioxanes, famille de silice hybride organique-inorganique, peuvent s’organiser soit en structures moléculaires parfaitement définies soit en réseaux polymériques. Dans cette thèse, la préparation de ces structures diverses est réalisée comme suit : (1) synthèse de silsesquioxanes oligomériques organisés à l’échelle moléculaire à partir de précurseurs monosilylés (2) création de réseaux de silsesquioxanes organisés à l’échelle mésoscopique via des précurseurs organosilylés pontés.Premièrement, la synthèse de tetrasilsesquioxanes fonctionnels de type Janus qui comportent des fonctions luminescentes et complexantes sur des faces opposées, est décrite. Ces structures cycliques sur mesure seront utilisées pour la modification de la surface de nanoparticules de métal, propriété particulièrement attractive pour des applications en imagerie, détection ou catalyse… De même, des silsesquioxanes cages (T8, T10, T12 et le premier isomère de T18 isolé) dotés de groupes styryles sont également préparés et caractérisés. De plus, une cage T8 possédant un ion fluor encapsulé a été obtenue et a permis une étude inédite des interactions Si F. La fonctionnalisation et l’intégration de cette cage dans un réseau de silice sont explorés.Deuxièmement, l’organisation à l’échelle mésoscopique est étudiée avec un intérêt particulier pour la formation contrôlée de pores dans des réseaux de silsesquioxanes. Des organosilices mésoporeuses périodiques organisées à l’aide d’un tensioactif sont synthétisées en utilisant un unique organosilane ponté et en s’appuyant sur la répartition préférentielle du silane dans les différents domaines de la micelle selon son degré d’hydrolyse. D’autre part, des dendrimères polysilylés comportant des groupes dégradables sont préparés et leur capacité à créer des pores fonctionnels par clivage de la partie interne du dendrimère est démontrée<br>Silsesquioxanes, which are a family of organic-inorganic hybrid silicas, can organize either in carefully controlled structures or polymerized networks. In this thesis, we approach the synthesis of such versatile structures in the following: (1) from monosilylated precursors to prepare oligomeric silsesquioxanes organized at the molecular scale and (2) from bridged organosilane precursors to obtain silsesquioxane networks organized at the mesoscale.Firstly, the synthesis of well-defined functional Janus tetrasilsesquioxanes with luminescent and coordinating functions on opposite faces is described. These tailored cyclic structures will be used for the modification of metal nanoparticle surfaces, which is particularly attractive for various applications such as imaging, sensing, catalysis, etc. Similarly, styryl-functionalized cage silsesquioxanes, including T8, T10, T12 and the first isolated T18 isomer, are prepared and fully characterized. In addition, T8 silsesquioxane with fluoride encapsulated within the cage (T8-F) is also synthesized and characterized. For the first time, the Si-F interaction is investigated as well as the functionalization of the T8-F and its integration into silica networks.Secondly, organization at the mesoscale is investigated, with particular focus on the controlled formation of pores in silsesquioxane networks. Surfactant templated bimodal periodic mesoporous organosilicas are synthesized from an organosilane precursor with bridging organic units, taking advantages of preferential partitioning of silanes within the various domains of block copolymer surfactant micelles. In addition, polysilylated dendrimers bearing degradable groups are prepared and their ability to generate functionalized pores by cleavage of the inner part of the dendrimer was demonstrated

Les etudes presentees dans ce manuscrit portent sur la photo- (pl) et l'electro-luminescence (el) de couches de silicium poreux obtenu par attaque electrochimique de substrat de silicium monocristallin. La premiere partie presente les principales caracteristiques du materiau et la description de ses proprietes de luminescence accompagnee des differents modeles avances pour en expliquer les mecanismes, en s'attachant tout particulierement a celui du confinement quantique des porteurs dans les cristallites qui forment la couche poreuse, qui est le plus generalement retenu. La deuxieme partie decrit les differents montages experimentaux permettant la formation des couches poreuses et leurs caracterisations. Dans une troisieme partie, nous presentons les resultats obtenus lors de l'etude par spectroscopie infrarouge de l'influence des especes presentes en surface des cristallites de silicium sur la pl de la couche poreuse. Nous montrons que la desorption de l'hydrogene present en surface apres formation du materiau s'accompagne d'une diminution de l'intensite de pl. L'analyse de la composition chimique d'une couche poreuse oxydee electrochimiquement nous permet de mettre en evidence la conservation de la passivation par l'hydrogene au cours de ce traitement et de confirmer que l'augmentation du rendement quantique de l'emission associee a l'oxydation electrochimique peut etre attribuee a une meilleure localisation des porteurs photogeneres dans les cristallites. La quatrieme partie est consacree aux effets d'une polarisation electrique sur les phenomenes de luminescence. Ce travail a ete mene sur des couches nanoporeuses formees sur substrat de type n, polarisees par l'intermediaire d'un contact electrolytique. On observe une extinction selective, progressive (mais reversible) de la pl quand la polarisation cathodique est augmentee. Parallelement, l'el observee en presence d'une espece oxydante dans l'electrolyte subit un deplacement spectral vers le bleu. L'etude detaillee des differentes caracteristiques de ces deux phenomenes nous permet de montrer qu'ils resultent de l'injection selective des electrons depuis le substrat dans les cristallites de plus en plus confinees au fur et a mesure que la polarisation augmente. On verifie par ailleurs que ce caractere selectif disparait progressivement au cours de l'oxydation electrochimique de la couche poreuse. L'extinction de la pl et de l'el sous forte polarisation cathodique peut etre attribuee a la recombinaison non radiative des porteurs de charges par un mecanisme de type auger

Mon doctorat se focalise sur la synthèse, la caractérisation et les applications de matériaux poreux à base de silice, dioxyde de titane et zéolite. La silice poreuse, le dioxyde de titane et les zéolites ont été synthétisés en utilisant des méthodologies différentes. Des matériaux de silice fonctionnalisés ont été utilisés pour des applications en adsorption de colorant, ce qui est utile pour le traitement de l'eau. Un nouveau système réticulé et un nouveau dispositif ont été créés pour améliorer la capacité d'adsorption et pour le traitement d’une grande quantité d'eau. En tirant parti des pores, une nouvelle méthode de formation de clusters de Cu (0) a été établie. Les propriétés photophysiques ont été étudiées, en utilisant plusieurs sources de cuivre et différents matériaux poreux. L'utilisation du confinement pour la détection de petites molécules biologiques tels que les neurotransmetteurs a été démontrée. Plusieurs applications ont été développées sur la base de ces récepteurs de neurotransmetteurs artificiels. Un matériau de titane mésoporeux multifonctionnalisé a été utilisé pour les applications en biologie. En comparaison avec la silice, plus couramment utilisée, sa photoactivité pourrait apporter des avantages supplémentaires. Finalement, de nouveaux types de matériaux de type organotitanes hybrides ont été développés, et leurs propriétés photo-catalytiques ont été démontrées<br>My PhD research focus on the synthesis, characterization and applications of silica, titania and zeolite based porous materials. Porous silica, titania and zeolite have been synthesized using different methodologies. Functionalized silica materials have been used for dye adsorption application which is useful for water treatment. A new cross-linked system and device have been created to enhance the adsorption ability and for large quantity of water treatment. By taking advantage of the pores, new method for Cu(0) cluster formation have been established. The photophysics of the Cu(0) clusters reduced from different copper source in different porous materials has been investigated. The use of the confinement for sensing has been demonstrated for small bio molecules, such as neurotransmitters. Several applications have been developed based on this artificial neurotransmitter receptors. Multi-functionalized mesoporous titania material has been used for bio-applications. Compare to the widely used silica material, its photoactivity could bring extra advantages. Finally, new types of hybrid organotitanium materials have been developed and their photocatalytic properties have been investigated

Une organisation contrôlée de la porosité offre l'opportunité de combiner les avantages structuraux des macropores (diamètres supérieures à 50 nm), assurant l'intégrité et l'interconnectivité de l'ossature du matériau, avec ceux des pores plus étroits (méso- et micropores), déployant des surfaces spécifiques réactives importantes. L'élaboration de telles architectures, dites " hiérarchisées ", à l'échelle du laboratoire représente un véritable défi physico-chimique. Dans ce contexte, ce travail de thèse s'intéresse à l'élaboration de matériaux poreux fonctionnels avancés, s'inscrivant dans le concept de chimie intégrative, en combinant matière molle (mésophases lyotropes, émulsions directes concentrées, auto-assemblages organique-organique, etc.), procédé sol-gel, polymérisation organique et principe de l'empreinte " dure ". Dans une première approche générale, des monolithes hybrides macrocellulaires à base de silice ont été fonctionnalisés par greffage covalent post-synthèse ou par co-condensation de précurseurs organosilanes appropriés. Dès lors, l'encapsulation de complexes luminescents (ions europium), de catalyseurs métalliques piégés dans une phase liquide ionique supportée (sels ou nanoparticules de palladium), ou d'entités biologiques (enzymes hydrosolubles : lipases) a offert une modulation rationnelle des propriétés optiques, catalytiques ou biocatalytiques induites in fine. Dans une seconde approche générale, l'utilisation de monolithes de silice macrocellulaires comme empreintes dures " sacrificielles " a permis la genèse de composés carbonés poreux, associée à un contrôle structural sur plusieurs échelles. Dès lors, une surface spécifique développée et une porosité hiérarchisée, conjuguées à des propriétés intrinsèques opportunes (stabilités thermique et chimique, conductivité électrique), ont offert un large champ d'applications, comme électrodes pour systèmes de stockage de l'énergie électrochimique (batteries Li-ion et condensateurs à double couche électrochimique), sites de nucléation de borohydrures de lithium (LiBH4) pour le stockage de l'hydrogène, ou encore comme électrodes enzymatiques pour biopiles.

碩士<br>國立交通大學<br>電子研究所<br>82<br>The luminescence properties of porous Si and porous SiGe was studied in this thesis. The SiGe alloy and related heterostructures have been a subject of intensive research recently because of the possibility of fabracting high speed devices. The porous SiGe and SiGe/Si heterostructures, however, were never throughly studied before. In this thesis, various porous Si and SiGe alloy layers with different thickness and compositions were investigated. The luminescence behavior was correlated with the layer parameters. It was found that the PL line width decreases as the porous layer become thicker indicating quantum behavior. The emission peak shifts toward long wavelength in SiGe samples as Ge composition increases. In SiGe/Si heterostructures, the intensity of the luminescence from SiGe increase dramatically as a result of carrier confinement provided by the heterostructure. The aging behaviors of porous Si and porous SiGe were also studied. We found that the luminescence intensity of SiGe has a much faster degradation rate than Si. From FTIR measurement, we found that the Si-H bonds are much weaker in SiGe than in Si. The breakdown of the Si-H bonds causes the degradation of luminescence in porous SiGe.

The incorporation of three conjugated polymers: MEH-PPV, DP-PPV and DP10- PPV into porous alumina films on Al, Si and ITO substrates via an adsorption process is reported. The nature of this adsorption process involves bonding between Lewis acidic Al centres on the alumina and the Lewis basic polymer backbone. The MEH-PPV porous alumina hybrids was found to degrade rapidly upon the irradiation of UV-light (λext = 366 nm) in air but to a lesser extent in the dark and under nitrogen. Silanization of the pores by treatment with trimethylchlorosilane (TMS), phenyldimethylchlorosilane (PDMS) and octyldimethylchlorosilane (ODMS) resulted in lower MEH-PPV loading in porous alumina membranes (Anodisc 13) relative to the membranes with unmodified pore walls. In the fluorescence spectra, the intensity of the fluorescence from the Anodisc membranes containing MEH-PPV is higher than from MEH-PPV in silanized porous alumina. The Lewis acidic Al centres of the porous alumina in the silanized pores are screened from the Lewis basic polymer resulting in a lower fluorescence intensity. Within the silanes used, the absorbance intensity is in the order: TMS > ODMS, PDMS. Within the silanes, the difference in fluorescence intensities may be due to the size of the alkyl/aryl groups. The larger alkyl substituent in ODMS and the aryl group in PDMS may act to better screen the Lewis acidic Al than in the smaller alkyl group in TMS. In DP10-PPV, the unmodified porous alumina has a higher fluorescence intensity relative to the modified materials. This is attributed to the interactions between the pore walls and the polymer. The same screening effect that occurs for MEH-PPV is also observed for DP10-PPV. For DP10-PPV, the fluorescence intensities is in the order: PDMS > ODMS, TMS. This difference may arise from the favourable π-stacking interactions between the polymer and the PDMS silanized pores.

碩士<br>大葉大學<br>電機工程學系<br>105<br>In this study, porous silicon flims are fabricated by electrochemical etching at room temperature. The silicon porosity was controlled by the dependence of current density etching of time. In the dependence of temperature, the energy gap is determined by photoluminescence measurement(PL). The surface morphology is analyzed by Scanning Electron Microscope(SEM) measurement. The electrical properties of porous silicon are measured by semiconductor devices parameter system. The influence of the different current density and different voltages in the band gap and the porosity are observed by setting 20 minutes etching time in the electric current from 1mA to 20mA. The variation of energy gap is about 0.16eV. The etching time is controlled from 5 minutes to 25 minutes at 5mA constant current. The shift of energy gap is about 0.11eV. Etching current density shows the blue-shift of the optical energy gap. The red-shift of energy gap is due to large porosity of porous silicon at the shorter etching time. The porous silicon energy gap is determined by temperature-dependent photoluminescence measurement(50K-300K).The activation energy of the porous silicon are figured out two characteristic features. The activation energy of below 200K is due to quantum tunneling effect. The activation energy is about 10.6meV at higher than 200K because of the influence of thermal effect.The electrical properties of porous silicon are measured by semiconductor devices parameter system. The result indicate that the porous silicon having the similar to schottky barrier diode in the negative bias. The reverse collapse voltage of -10.9V.

碩士<br>長庚大學<br>電子工程學系<br>100<br>Porous anodic alumina (PAA) film which produced by the anodization technique has a nano-scale porous structure in mass production and the pore height and diameter are controllable. This work aims to study effect of current density on luminescence properties of porous anodic alumina. Metal interlayer was observed to have significant influences on porous anodic alumina. We used highly pure Al film (about 2.0 μm) which was deposited on the p-type silicon substrate and coated with a Ti and W metal interlayer (about 300 nm) by radio frequency sputtering. The anodization was carried out in 0.3 M oxalic acid solution at 5 °C temperature, 40 V for about 50 nm pores in diameter. A layer of thin Ti and W film was sandwiched between a silicon substrate and an Al film to form the Al/Ti/Si and Al/W/Si structure. Current–time (I–t) curve was obtained on a recorder. The PAA/Ti/Si and PAA/W/Si had current density higher than AAO/Si. Further studies into the growth kinetics of porous layers which formed by anodization in oxalic acid under galvanostatic conditions have shown that the rate of growth of the oxide layer increases with increasing current density. From the XRD experiment consequence can discover that PAA of higher current density have more Aluminum oxide in the inside different substance structure. Besides, we get the consequence from analyzing PL experiment when a current density rise, the PL intensity of F+ center getting increase and that because during re-crystallize, oxygen will make up the oxygen vacancy of Aluminum oxide’s inside and reduce F+ defect.

碩士<br>國立交通大學<br>光電工程系所<br>93<br>We successfully employed rapid thermal oxidized porous silicon (PS) to create silicon nanocrystals (nc-Si). In order to observe the size and the characteristics, experiments on different samples were investigated via transmission electron microscope (TEM)、Raman scattering and photoluminescence. After that, we doped Er ions into silicon rich SiO2 (SRSO) structure and successfully observed the infrared photoluminescence at 1.54μm from Er ions. The relations between infrared photoluminescence and average size of nc-Si were discussed in this study. In this work, we controlled different current density to vary the silicon porosity. The different average size of nc-Si were formed by changing the silicon porosity and rapid thermal oxidization. We observe the red-shift of Raman scattering and the blue-shift of visible photoluminescence from the average size of nc-Si. The intensity of infrared photoluminescence at 1.54μm from Er ions would increase as the decreasing of the average size of nc-Si. This fact means that the Er ions are excited by energy transfer process from the excited nc-Si and the conversion efficiency has relations with the average size of nc-Si.

碩士<br>長庚大學<br>光電工程研究所<br>97<br>Porous anodic alumina (PAA) film produced by the anodization technique has a nanoscale porous structure in mass production and the pore height and diameter are controllable and was applied in the fabrication of visible spectral range optical devices. In order to characterize the luminescence properties, we have formed the self-ordered PAA films which evaporated onto silicon substrates. In this work, the anomalous luminescence properties of carrier confinement in PAA films have been investigated by introducing oxalic acid electrolyte into the anodization technique. The temperature-dependent photoluminescence (PL) spectra were measured to characterize the recombination mechanisms. From the PL spectra of PAA films, it has found the asymmetrical luminescence profile in the blue emission region. It was used the Gaussian function to divided into two subbands which originate in two kinds of different oxygen-deficient defect centers, i.e., F+ (oxygen vacancy with only one electron) and F (oxygen vacancy with two electrons) centers, respectively. The density of the F centers is the largest on the surface, followed by a gradual decrease with an increase in the pore wall depth and electrolyte concentration. However, it was observed the reverse trend of the F+ centers. In strong contrast to a commonly expected trend of uniformly reduced non-radiative recombination with decreasing the lattice temperature, anomalous low-temperature PL growing and declining is observed between the F and F+ centers. The theoretical models are invoked to corroborate the anomalous temperature behaviors. All the calculations are agreement with the experimental observations.

Binary oxides constitute an outstanding class of functional materials with potential applications in many fields such as catalysis, gas sensing, field emission, solar cells, photodetection, etc. Due to the difference in their physical/chemical properties, different oxides have been explored for different applications. For examples, SnO2, Cr2O3 and ZnO are being explored for gas sensing due to their high adsorption capacity for volatile gases, ZnO, Cu2O etc. are being explored in solar cells because of high adsorption coefficient in UV/visible region and so on. Various techniques are available for synthesis of binary oxides and tuning their properties. Most of the physical or chemical synthesis techniques are expensive, need high cost instruments and produces hazardous chemical waste. We need a simple, cost effective and ecofriendly techniques for the synthesis of binary oxides. In present work, a simple and facile thermal oxidation strategy has been employed for the synthesis of various binary oxides (Cu2O, GeO2 and ZnO). For example, CuO nanorods are obtained when Cu is heated around ~ 500 oC, which then heated in Ar atmosphere to obtain a film of porous Cu2O. Similarly, GeO2 with different morphologies and green-luminescent ZnO are obtained by controlling the reaction parameters. These oxides have then been explored for various applications including white light phosphors, catalysis for the degradation of dyes and non-contact thermometry. Overall, we present a thermal oxidation strategy for the synthesis of various binary oxides and explore potential applications in various fields.