Дисертації з теми "Nanomaterials- Semiconductors"
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Cozzarini, Luca. "Nanomaterials based on II-VI Semiconductors." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7359.
Повний текст джерелаThis thesis describes: (i) synthesis and characterization of colloidal nanocrystals of II-VI semiconductor compounds; (II) development of two novel materials using such nanocrystals as “building blocks”: (IIa) a nanocrystals/polymer composite, to be used as phosphor in LED-based lighting devices; (IIb) an inorganic, nano-structured multiphase material, showing a promising geometry as an electronic intermediate band material. Different typologies of nanocrystals (single-phase, alloyed or core-shells) were successfully synthesized using air-stable, safe reagents. Their optical properties (absorption spectrum, fluorescence wavelength and fluorescence quantum yield) were mapped as function of different parameters. Good results in engineering optical properties were achieved by: (a) changing size and/or composition in single-phase nanocrystals; (b) tuning shell composition and thickness and/or mutually diffusing one material into the other in multi-phase nanocrystals. The influence of different surface ligands on optical properties and on solubility in different media was also studied. Nanocrystal/polymer composite lenses were obtained from nanocrystals with desired fluorescence wavelength and quantum yield, mixed in an appropriate solvent with polymer pellets. The mixture was drop casted or tape casted on a solid substrate, obtaining solid, transparent lenses after solvent evaporation. A nano-structured, all-inorganic material (composed of semiconducor nanocrystals embedded into a wider bandgap semiconductor) was obtained through self-assembly and densification of colloidal core-shells nanocrystals. The realization of this composite supracrystal was achieved via a multi-step process: (i) colloidal synthesis of core-shell nanocrystals; (ii) surface ligands exchange; (iii) assembly; (iv) heat treatment. Evolution of the optical properties during heat treatment suggests that it is possible to sinter the shell material without altering the internal nano-heterostructure, if temperature and time of the treatment are controlled properly.
In questa tesi sono descritti: (I) la sintesi colloidale e la caratterizzazione di nanocristalli di semiconduttori II-VI; (II) lo sviluppo, utilizzando i suddetti nanocristalli quali “unità da costruzione”, di due materiali innovativi: (IIa) un composito nanocristalli/polimero, da usare come fosforo in dispositivi per illuminazione basati su LED; (IIb) un materiale inorganico nano-strutturato multifase, con una geometria promettente quale materiale a banda elettronica intermedia. Differenti semiconduttori II-VI sono stati sintetizzati in forma di nanocristalli (monofasici, in forma di lega o in struttura di tipo “core-shell”) usando reagenti sicuri e stabili in atmosfera. Le loro proprietà ottiche (spettro di assorbimento, lunghezza d’onda di fluorescenze e resa quantica di fluorescenza) sono state mappate in funzione di numerosi parametri. Sono stati raggiunti ottimi risultati nel controllo delle proprietà ottiche sia in nanocristalli a fase singola (modificandone le dimensioni o la composizione chimica) che in nanocristalli multifase (regolandone la composizione e lo spessore della “shell”, nonché mutualmente diffondendo un materiale nell’altro). È stata anche studiata l’influenza di differenti leganti superficiali sulle proprietà ottiche e sulla solubilità dei nanocristalli in differenti solventi. Lenti composite di nanocristalli/polimero sono state ottenute a partire da nanocristalli aventi la lunghezza d’onda e la resa quantica di fluorescenza desiderate, mescolandoli con pellet di polimero in solventi appropriati. La miscela è stata depositata su un supporto, tramite drop casting o tape casting, ottenendo lenti solide trasparenti dopo l’evaporazione del solvente. Un materiale inorganico nano strutturato (costituito da nanocristalli di semiconduttore racchiusi all’interno di un secondo materiale semiconduttore a bandgap maggiore) è stato ottenuto tramite l’autoassemblaggio e la densificazione di nanocristalli core-shell sintetizzati con procedure di chimica colloidale. La realizzazione di suddetto sovra-cristallo si è svolta in più fasi: (i) sintesi colloidale; (ii) sostituzione dei leganti superficiali; (iii) assemblaggio; (iv) trattamento termico. I risultati derivanti dallo studio dell’evoluzione delle proprietà ottiche durante il trattamento termico suggeriscono che sia possibile sinterizzare il materiale della shell senza alterare la nano-eterostruttura interna, se la temperatura e il tempo del trattamento sono scelti opportunamente.
XXIV Ciclo
1983
Tassi, Nancy Gattuso. "Manipulation of organic nanomaterials." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 51 p, 2008. http://proquest.umi.com/pqdweb?did=1459918081&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Повний текст джерелаZhang, Shaolin. "Wide band gap nanomaterials and their applications." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41758225.
Повний текст джерелаBerestok, Taisiia. "Assembly of colloidal nanocrystals into porous nanomaterials." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663275.
Повний текст джерелаEsta tesis se centra en la síntesis coloidal de nanocristales (NCs), en la exploración de su química de superficie y en su ensabanado en nanomateriales porosos funcionales. Para demostrar la versatilidad de aplicación de dichas estructuras, en este estudio se han considerado NCs de distintos tipos de materiales: metales (Au), óxidos metálicos (CeO2, TiO2, Fe2O3), calcogenuros metálicos (In2S3, ZnS, PbS, CuGaS2,Cu2ZnSnSe4) y sus materiales compuestos. El trabajo se dividió en dos bloques. En el primero se desarrolló y optimizó la síntesis de NCs de óxidos y calcogenuros metálicos y se evaluó su potencial para aplicaciones de catálisis y fotocatálisis. Se investigó en profundidad la síntesis de NCs de CeO2, poniendo énfasis en controlar su morfología. Se consiguió producir NCs de CeO2 de forma controlada (esférica, octapodo ramificado, cúbico ramificado y romboidal) y con tamaño controlado (7-45 nm). Asimismo, se obtuvieron NCs de Cu2ZnSnSe4 con una fina distribución de tamaños y composición controlada. En el segundo bloque se establecieron y estudiaron procedimientos para fabricar nanomateriales porosos mono- o multicomponentes a partir del ensamblado de NCs. Se desarrolló una estrategia basada en el ajuste de la química de superficie de NCs de óxidos metálicos (CeO2, Fe2O3,TiO2) y de calcogenuros metálicos (In2S3, CuGaS2-ZnS) que permitió su ensamblaje controlado en estructuras porosas de tipo gel y aerogel. En el caso de los óxidos metálicos, se determinó que el ensamblado se inicia con la adición de un epóxido a NCs funcionalizados con glutamina, causando la gelación. La desorción oxidativa de ligandos basada en la formación de enlaces calcogenuro-calcogenuro se propuso como mecanismo de gelación en calcogenuros mono- (In2S3) y multicomponente (CuGaS2-ZnS). Se investigó el impacto del empleo de distintos ligandos en la eficiencia foto-electrocatalítica de NCs en forma coloidal, ensamblados en geles y soportados en sustratos. Se desarrolló y estudió el ajuste de la química de superficie de NCs para la obtención de ensamblajes multicomponente mediante interacción electrostática de coloides en suspensión. El mecanismo de gelación fue investigado al detalle para materiales compuestos de NCs de oxido metálico (CeO2) con NCs de óxido de calcogenuro (PbS-CeO2) y metálicos (Au-CeO2). Los aerogeles de Au-CeO2 demostraron potencial para la oxidación de CO.
Zhang, Shaolin, and 張少林. "Wide band gap nanomaterials and their applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41758225.
Повний текст джерелаYu, Zhang. "Solution Processed Chalcogenide Nanomaterials for Thermoelectric Application." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/670923.
Повний текст джерелаLa ingeniería de nanomateriales a partir del procesado en solución es de particular interés para optimizar el rendimiento de los materiales y dispositivos termoeléctricos. . Esta tesis estáse centra en el diseño y el ensamblaje racional de nanomateriales termoeléctricos de alto rendimiento a través de procesado en solución. La tesis se divide en 5 capítulos. El Capítulo 1 aborda la introducción fundamental del enfoque sintético para producir nanomateriales funcionales. Los capítulos 2 y 3 presentan un método rápido y simple basado en soluciones para producir nanomateriales SnSe2 y SnSe con textura cristalográfica. Dado que los calcogenuros de estaño son materiales especialmente interesantes para la conversión de energía termoeléctrica, se sintetizaron nanoplacas SnSe y SnSe2 controlables por forma mediante una estrategia basada en tinta molecular para lograr una figura de mérito termoeléctrica sin precedentes por dopaje con Te/Cu. Ambos nanomateriales mostraron una textura cristalográfica significativa después del prensado en caliente, lo que dio como resultado unas propiedades de transporte de carga calor altamente anisotrópicas. Los capítulos 4 y 5 describen dos estrategias diferentes para producir nanocompuestos Bi2Te3-Cu2-xTe basados en la consolidación de nanoestructuras. La presencia de Cu2-xTe da como resultado un fuerte aumento del coeficiente de Seebeck. Este aumento está relacionado con el filtrado de los portadores de carga en función de su energía en las barreras de energía dentro de los dominios Bi2Te3 creados por la acumulación de electrones en las regiones cercanas a las uniones Cu2-xTe / Bi2Te3. En general, se obtiene una mejora significativa de la figura de mérito con nanocompuestos Bi2Te3-Cu2-xTe. Finalmente, en el último capítulo se presentan las principales conclusiones de esta tesis y algunas perspectivas para trabajos futuros.
Liu, Yu. "Bottom-up Engineering of Chalcogenide Thermoelectric Nanomaterials." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663274.
Повний текст джерелаLos nanocristales (NCs) coloidales tienen excelentes propiedades para diferentes aplicaciones, como la conversión de energía, la catálisis, los dispositivos electrónicos y optoelectrónicos, entre otros. Así mismo, la síntesis coloidal de NCs tiene ventajas en el control del tamaño, forma y composición a nivel de la nanoescala; las bajas temperaturas de reacción; y la no necesidad de equipos especializados. Este proyecto se concentra en el diseño racional y la ingeniería de materiales termoeléctricos (TE) nanoestructurados de alta eficiencia, usando la estrategia del ensamblado ascendente (bottom-up) de NCs coloidales. Primero, se diseñó una ruta de síntesis de bajo costo, alto rendimiento, con la cual, se obtuvieron NCs de AgSbSe2 y Cu3SbSe4. La optimización de la concentración de dopaje resultó en valores para la figura de mérito TE, ZT, de 1.10 a 640 K para AgSb0.98Bi0.02Se2, y de 1.26 at 673 K para Cu3Sb0.88Sn0.10Bi0.02Se4. El material con mejores propiedades se usó para la producción de un generador TE en forma de anillo, para acoplarlo a los tubos de escape de gases, obteniendo una potencia eléctrica de 1mW por elemento TE con una diferencia de temperatura de 160 °C. En la segunda parte, se presenta el trabajo de la producción de nanocopuestos de PbS-metal (Cu y Sn) usando un procedimiento versátil de mezcla de NCs. La función de trabajo del metal es capaz de inyectar electrones a la matriz intrínseca de PbS. El factor de potencia TE, se ve dramáticamente incrementado debido al aumento en la conductividad eléctrica en los nanocompuestos TE. Consecuentemente, el valor máximo de ZT se vio excepcionalmente incrementado por el doble del valor comparado con el material original PbS. Finalmente, se presenta el proceso de producción de materiales texturizados cristalográficamente, produciendo materiales tipo p BixSb2-xTe3 y tipo n Bi2Te3-xSex. Se controló la estequiometria durante el procesamiento en solución y la textura cristalográfica, por medio de la sinterización en fase líquida con un procedimiento de múltiples pasos de presión y relajación a una temperatura de 480°C. Los valores de la figura de mérito TE presentan el record de: ZT=1.83 a 420 K para Bi0.5Sb2.5Te3 y ZT=1.31 para Bi2Te2.7Se0.3 a 440 K.
Cress, Cory D. "Effects of ionizing radiation on nanomaterials and III-V semiconductor devices /." Online version of thesis, 2008. http://hdl.handle.net/1850/6278.
Повний текст джерелаHsieh, Chien-Wen. "Formation of composite organic thin film transistors with one-dimensional nanomaterials." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609276.
Повний текст джерелаBecerril-Garcia, Hector Alejandro. "DNA-Templated Nanomaterials." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1823.pdf.
Повний текст джерелаLee, Michael M. "Organic-inorganic hybrid photovoltaics based on organometal halide perovskites." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:9384fc54-30de-4f0d-86fc-71c22d350102.
Повний текст джерелаLeijtens, Tomas. "Charge transport in disordered semiconductors in solid state sensitized solar cells : influence on performance and stability." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:04b2a950-59f1-4a3b-bf99-1b7a4492f88b.
Повний текст джерелаBenaissa, Manel. "ÉLABORATION D'OXYDES DOPÉS DE TYPE DMS (semi-conducteurs magnétiques dilués) PAR ÉLECTRODÉPOSITION SOUS CHAMP MAGNÉTIQUE." Thesis, Reims, 2016. http://www.theses.fr/2016REIMS011/document.
Повний текст джерелаOur work focuses on the synthesis and characterization of doped oxides by electrodeposition method under magnetic field superimposition.The goal of this research presents two challenges, because it combines a study of electrochemical synthesis and obtaining materials with optical and magnetic properties. The materials which have been studied are manganese or cobalt doped copper (I) oxide on the one hand, and the copper doped zinc oxide in the other hand.Our goal is the elaboration of diluted magnetic oxides, and the study of their physical and chemical characterizations.Indeed, the effects of doping and of the magnetic field applied during the electrodeposition can provide interesting changes in morphology, texture, composition and optical and magnetic properties of the obtained materials
Kong, Liang. "Bismuth oxybromide-based photocatalysts for solar energy utilisation and environmental remediation." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c95ee3cc-b276-4c69-8b3f-eb60cc64e1c0.
Повний текст джерелаCheng, Cheng. "Semiconductor colloidal quantum dots for photovoltaic applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:07baccd0-2098-4306-8a9a-49160ec6a15a.
Повний текст джерелаEley, Clive William. "The rational design of photocatalytic semiconductor nanocrystals." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:ee29c922-857c-432a-8316-a7e04c822b1d.
Повний текст джерелаParkinson, Patrick. "Ultrafast electronic processes at nanoscale organic-inorganic semiconductor interfaces." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:e68168c6-bcc0-437d-9133-1bfaf955c80a.
Повний текст джерелаShpilevaya, Inga. "Surface characterisation and functional properties of modified diamond electrodes." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:55c8243f-3779-4bcc-878a-999a067cc9c4.
Повний текст джерелаLang, Volker. "Electrically detected magnetic resonance in semiconductor and carbon nanodevices." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:614ed1d1-0304-4356-8bd3-eb0ce7bd6c9d.
Повний текст джерелаZhao, Yixin. "Developing Nanomaterials for Energy Conversion." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270172686.
Повний текст джерелаBrent, John. "Exfoliation and synthesis of two-dimensional semiconductor nanomaterials." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/exfoliation-and-synthesis-of-twodimensional-semiconductor-nanomaterials(289ba930-19ff-4fae-8d84-e46560620c18).html.
Повний текст джерелаHolmes, Mark J. "Optical spectroscopy of wide bandgap semiconductor nanoscale structures." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:b8318654-dd3a-4875-8a8e-1e57d877b0f2.
Повний текст джерелаSugunan, Abhilash. "Photochemical and Photoelectric Applications of II-VI Semiconductor Nanomaterials." Licentiate thesis, KTH, Functional Materials, FNM, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12808.
Повний текст джерелаIn this work we investigated fabrication of semiconductor nanomaterials and evaluated their potential for photo-chemical and photovoltaic applications. We investigated two different II-VI semiconductor nanomaterial systems; (i) ZnO oriented nanowire arrays non-epitaxially grown from a substrate; and (ii) colloidal CdTe nanotetrapods synthesized by solution-based thermal decomposition of organo-metallic precursors. In both the cases our main focus has been optimizing material synthesis for improving potential applications based on photon-electron interactions.
We have studied the synthesis of vertically aligned ZnO nanowire arrays (NWA), by a wet chemical process on various substrates. The synthesis is based on epitaxial growth of ZnO seed-layer on a substrate in a chemical bath consisting of an aqueous solution of zinc nitrate and hexamethylenetetramine (HMT). We have suggested an additional role played by HMT during the synthesis of ZnO nanowire arrays. We have also extended this synthesis method to fabricate hierarchical nanostructures of nanofibers of poly-L-lactide acting as a substrate for the radially oriented growth of ZnO nanowires. The combination of high surface area of the nanofibrous substrate with the flexibility of the PLLA-ZnO hierarchical nanostructure enabled the proof-of-principle demonstration of a ‘continuous-flow’ water treatment system that could effectively decompose single and combination of known organic pollutants in water, as well as render common waterborne bacteria nonviable.
We have studied another chemical synthesis that is commonly used for size controlled synthesis of colloidal quantum dots, which was modified to obtain anisotropic nanocrystals mainly for CdE (E=S, Se, Te) compositions. In this work we demonstrate by use of oleic acid (instead of alkylphosphonic acids) it is possible to synthesize CdTe and CdSe nanotetrapods at much lower temperatures (~180 ºC) than what is commonly reported in the literature, with significantly different formation mechanism in the low-temperature reaction.
Finally, we have performed preliminary photoconduction measurements with CdTe nanotetrapods using gold ‘nanogap’ electrodes fabricated in-house, and obtain up to 100 times enhancement in current levels in the I–V measurements under illumination with a white light source.
QC20100607
Sugunan, Abhilash. "Fabrication and Photoelectrochemical Applications of II-VI Semiconductor Nanomaterials." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95410.
Повний текст джерелаQC 20120525
Mao, Baodong. "Synthesis and Property Characterization of Novel Ternary Semiconductor Nanomaterials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1334065821.
Повний текст джерелаWu, Fanxin. "Synthesis and characterization of semiconductor nanomaterials : PbS, CdS, and CdTe /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.
Повний текст джерелаYong, Chaw Keong. "Ultrafast carrier dynamics in organic-inorganic semiconductor nanostructures." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:b2efdc6a-1531-4d3f-8af1-e3094747434c.
Повний текст джерелаLiu, Jingjing. "Diluted Magnetic Semiconductor Nanomaterials Fabrication by a Chemical Vapor Deposition Method." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/426.
Повний текст джерелаNagy, Dávidné. "Visible light response semiconductor nanomaterials for heterogeneous photocatalysis in liquid phase." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33062.
Повний текст джерелаCONCA, ERIKA. "Preparation and investigation of new heterostructures for prospective energetic and biomedical applications." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266554.
Повний текст джерелаSushko, O. A., and О. М. Bilash. "Use of semiconductor nanomaterials for polycyclic aromatic hydrocarbons detection in water object." Thesis, B. Verkin Institute of Low Temperature Physics and Engineering, NASU, 2013. http://openarchive.nure.ua/handle/document/8874.
Повний текст джерелаShahine, Issraa. "A chemical route to design plasmonic-semiconductor nanomaterials heterojunction for photocatalysis applications." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0105/document.
Повний текст джерелаHybrid heterojunctions composed of semiconductors and metallic nanostructures have perceived as a sustainable technology, due to their perfect effectiveness in improving, renovating, and enriching the properties of the integrated components. The cooperative coupling results in the variation of the system’s functional properties, by which the metal-generated surface plasmon resonance can enhance the charge separation, light absorption, as well as luminescence of the semiconductor. This phenomenon enables strong interactions with other photonic elements such as quantum emitters. These multifaceted functionalities arise from the synergic exciton-plasmon interaction between the linked units. Thereby, hybrid systems become suitable for various applications including: solar energy conversion, optoelectronic devices, light-emitting diodes (LED), photocatalysis, biomedical sensing, etc. Au-ZnO nanostructures have received growing interest in these applications, where the deposition of gold nanoparticles (GNPs) promotes the system’s response towards the visible region of the light spectrum through their surface plasmon resonance (SPR). Based on a specific size and purity of ZnO nanostructures, as well as the GNPs, and a definite inter-distance between the nanoparticles, the properties of the ZnO nanostructures are varied, especially the photoemission and photocatalytic ones. In this context, we have focused on the construction of size-tunable ZnO nanocrystals (NCs), then incorporated into GNPs solutions using a simple chemical way. This work is divided into two parts: the first is to perform synthesis of pure ZnO NCs having excellent UV photoluminescence. This was achieved through a low-temperature aqueous synthesis, resulting in rough and amorphous structures. The synthesis was followed by a post-thermal treatment in order to crystallize the obtained particles. The synthesis was followed by structural and optical studies (SEM, TEM, XRD, photoluminescence). The photocatalytic activities of ZnO NCs were studied through tailoring their ability to degrade the methylene blue (MB) dye. In addition, the relationship between ZnO structures, luminescence, and photocatalytic properties was explored in details. In the second step, the obtained ZnO NCs were added to gold nanoparticles of various sizes and volume fractions. The effective role of GNPs concerning their size, amount, and their capping molecule on the photoemission of the ZnO nanostructures was emphasized through the charge and/or energy transfer between the constituents in the hybrid system. In the same way, the systems photocatalytic activities were examined after coupling ZnO to GNPs. Further advancement in the integration of the ZnO NCs into PMMA polymer layers was featured in order to obtain large area template of homogenous ZnO properties. The PMMA-assembled ZnO nanoparticles could be promising substrates as catalysts for growing ZnO nanowires, metallic nanoparticles and hybrid nanomaterials
Aryal, Basu Ram. "Bottom-Up Fabrication and Characterization of DNA Origami-Templated Electronic Nanomaterials." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9041.
Повний текст джерелаNaik, A. J. T. "Hetero-junction and nanomaterial systems for metal oxide semiconductor based gas sensing." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1463687/.
Повний текст джерелаAl-Saadi, Ali. "Preparation and characterisation of encapsulation magnetic metal iron oxide nanoparticles." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:57bdcf38-9d45-48ab-a971-a2d60e2e4391.
Повний текст джерелаBidaud, Thomas. "Characterization of nanomaterials by cathodoluminescence for photovoltaic applications." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPAST010.
Повний текст джерелаThe recent development of photovoltaic devices makes use of materials with properties that may vary at the sub-micrometer scale, for instance nanowire-based III-V solar cells based or CdTe polycrystalline thin films. This thesis aims at developing new methods and techniques based on cathodoluminescence (CL) and time-resolved CL (TRCL) in order to probe material properties at the nanometer scale. A first part is devoted to CdTe polycrystalline thin films. The role of CdCl₂ annealing on the formation and passivation of defects in the grain interior and at the grain boundaries is analyzed by combining high-resolution CL maps at room- and low-temperature. The incorporation of Se at different concentrations and its effect on defect passivation and radiative efficiency of CdSeₓTe₁-ₓ thin films is investigated and correlated to macroscopic measurements (Voc, lifetimes). A second part is devoted to GaAs nanowires. The optical and transport properties of wurtzite (WZ) and zinc-blende (ZB) phases are compared in single nanowires, and radiative decay measurements are presented (τ(WZ)=0.55 ns et τ(ZB)=0.62 ns). N-doping obtained by incorporation of Te is determined quantitatively, and its homogeneity is studied in single nanowires by CL maps. We evidence doping levels up to n=3.3×10¹⁸ cm⁻³, and a doping gradient along nanowires. Finally, the passivation of GaAs nanowires by an AlGaAs or InGaP shell is characterized by CL measurement of the radiative intensity, diffusion length and lifetime of charge carriers. The techniques and methodologies presented in this thesis may be applied to a wide variety of semiconductor materials for photovoltaic or optoelectronic applications
Fairclough, Simon Michael. "Carrier dynamics within semiconductor nanocrystals." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:857f624d-d93d-498d-910b-73cce12c4e0b.
Повний текст джерелаJiang, Zhoufeng Jiang. "Zero-dimensional and two-dimensional colloidal nanomaterials and their photophysics." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522964027555741.
Повний текст джерелаDooley, Chad Johnathan. "New Nanomaterials for Photovoltaic Applications: A Study on the Chemistry and Photophysics of II-VI Semiconductor Nanostructures." Thesis, Boston College, 2009. http://hdl.handle.net/2345/705.
Повний текст джерелаThis dissertation examines the chemistry and photophysics of semiconductor quantum dots with the intent of studying their capabilities and limitations as they pertain to photovoltaic technologies. Specifically, experiments are presented detailing the first time-resolved measurements of electron transfer in electronically coupled quantum rods. Electron transfer from the conduction band of CdTe was measured to occur on the 400 fs timescale (kET = 2.5 x 1012 s-1), more than 500x faster than previously believed. Additionally, the direct optical promotion of an electron from the valence band of CdTe was observed, occurring on the timescale of the pump pulse (~50 fs). Based on the determined injection rates, a carrier separation efficiency of > 90% has been calculated suggesting these materials are sufficient for use in solar energy capture applications where efficient carrier separation is critical. To this end, model photovoltaic cells were fabricated, and their power conversion efficiency and photon-to-current generation efficiency characterized. In devices based of CdSe and heteromaterial quantum rods we observed fill-factors on the order of 10-20% though with power conversion efficiencies of < 0.02%. It was discovered that using a high temperature annealing step, while critical to get electrochemically stable photoelectrodes, was detrimental to quantum confinement effects and likely removed any hQR specific capabilities. Additionally, a detailed study on the role of nucleotide triphosphate chemistry in stabilizing emissive CdS nanoparticles is presented. Specifically it was observed that in a neutral pH environment, GTP selectively stabilizes CdS quantum dots with diameters of ~4 nm while the other naturally occurring ribonucleotides do not yield emissive product. The selectivity is dependent on the presence of the nucleophilic N-7 electrons near a triphosphate pocket for Cd2+ complexation as well as an exocyclic amine to stabilize the resulting product particles. However, in an elevated pH environment, the nucleobase specificity is relaxed and all NTPs yield photo-emissive quantum dots with PLQEs as high as 10%
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Shao, Hui. "Functional nanomaterials derived from self-assembly of peptide hybrids and amino acid amphiphiles: from diseases to devices." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267225830.
Повний текст джерелаParala, Harish. "Precursor routes to selected metal and semiconductor nanomaterials crystals, composites, colloids of Au, GaN, InN, CdSe and TiO₂ /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96870901X.
Повний текст джерелаParala, Harish. "Precursor routes to selected metal and semiconductor nanomaterials crystals, composites, colloids of Au, GaN, InN, CdSe and TiO2 /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96870901X.
Повний текст джерелаFarzinpour, Pouyan. "DYNAMIC TEMPLATING: A NEW PATHWAY FOR THE ASSEMBLY OF LARGE-AREA ARRAYS OF PLASMONIC, MAGNETIC AND SEMICONDUCTOR NANOMATERIALS." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/280637.
Повний текст джерелаPh.D.
Substrate-based nanostructures are of great importance due to their applications in microelectronic devices, chemical sensors, catalysis and photovoltaics. This dissertation describes a novel fabrication technique for the formation of periodic arrays of substrate-based nanoparticles. The prescribed route, referred to as dynamic templating, requires modest levels of instrumentation consisting of a sputter coater, micrometer-scale shadow masks and a tube furnace. The route has broad applicability, having already produced periodic arrays of gold, silver, copper, platinum, nickel, cobalt, germanium and Au-Ag alloys on substrates as diverse as silicon, sapphire, silicon-carbide, and glass. The newly devised method offers large-area, high-throughput capabilities for the fabrication of periodic arrays of sub-micrometer and nanometer-scale structures and overcomes a significant technological barrier to the widespread use of substrate-based templated assembly by eliminating the need for periodic templates having nanoscale features. Because this technique only requires modest levels of instrumentation, researchers are now able to fabricate periodic arrays of nanostructures that would otherwise require advanced fabrication facilities.
Temple University--Theses
Lin, Yu-Pu. "Functionalization of two-dimensional nanomaterials based on graphene." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4727.
Повний текст джерелаIn order to promote 2D materials like graphene to their numerous applications, new methodsaltering their electronic and chemical properties have to be mastered. In this thesis, theprocesses of chemical doping and hydrogenation of monolayer graphene grown on SiC are investigated. Nitrogen atoms are successfully substituted in the graphene lattice using plasma-basedmethods. The bonding configurations of the incorporated N can be controlled via the nature and energy of exposing species and the thickness of the pristine graphene. An n-type doping, revealed by angle-resolved inverse photoemission spectroscopy (ARIPES), is found in most N-doped graphene and is assigned to the presence of graphitic-N. Hydrogenations of the buffer layer of graphene (BLG) on SiC at ambient or high temperatures saturate the remaining Si dangling bonds at BLG/SiC interface in two different ways, either by inducing additional C-Si bonds or by H intercalation. This results in 2D materials with distinct characters, an insulating, graphane-like H-BLG or a quasi-free-standing graphene, which may be used as a new concept for the engineering of graphene-based devices. The interactions between pi-conjugated molecules and the functionalized graphene are also investigated. The unoccupied states of molecules are altered by the presence of incorporated N, but the degradation of molecules due to low-energy electron exposure seems not enhanced by the doping nitrogen under the studied conditions. Nevertheless, the functionalization of graphene is demonstrated and its electronic and chemical properties are carefully studied, which should help to faster further applications employing functionalized graphene
Wu, Yimin A. "Towards large area single crystalline two dimensional atomic crystals for nanotechnology applications." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:bdb827e5-f3fd-4806-8085-0206e67c7144.
Повний текст джерелаDocampo, Pablo. "Electronic properties of mesostructured metal oxides in dye-sensitized solar cells." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:e97e90f9-47fe-4259-a462-c97f0bf81469.
Повний текст джерелаJiang, Ye. "Growth mechanism and surface chemistry of II-VI 2D nanomaterials." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS058.
Повний текст джерелаColloidal two-dimensional semiconductor nanocrystals such as nanoplatelets of cadmium chalcogenides, have emerged as a new class of nanomaterials due to their unique optical and electronic properties. These nanocrystals possess exciton confinement along one direction in analogy to quantum wells, with their thickness controlled at atomic level.Although colloidal two-dimensional nanoplatelets have been considered as potential candidates for the fabrication of optoelectronic devices, their formation mechanism e.g. zinc blende CdSe nanoplatelets is still under debate. Thereby this thesis first focuses on the study of CdSe nanoplatelets synthesis and size of the aliphatic chain in the carboxylate, paving the way to a better understanding of two-dimensional nanocrystals’ growth.Successively surface carboxylate ligands are investigated by NMR techniques which gives us an idea of how surface ligands are composed and relocated. Our study of ligand quantification on nanoplatelets’ surface appears to support the proposed effect from steric hinderance on NPLs growth. 13C-1H 2D correlation solid state NMR based on the dipolar interaction indicates that acetates and long alkyl chain carboxylates should be distributed homogenously on the surface of the CdSe NPLs. In the last part, I explore the possibility of improving the optical features of nanoplatelets synthesized from colloidal atomic-layer-deposition technique through optimizing both interior and surface structures by an annealing process
Mehdi, Aghaei Sadegh. "Electronic and Magnetic Properties of Two-dimensional Nanomaterials beyond Graphene and Their Gas Sensing Applications: Silicene, Germanene, and Boron Carbide." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3389.
Повний текст джерелаPournia, Seyyedesadaf. "Exploring the Photoresponse and Optical Selection Rules in the Semiconductor Nanowires, Topological Quantum Materials and Ferromagnetic Semiconductor Nanoflakes using Polarized Photocurrent Spectroscopy." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627666632280473.
Повний текст джерелаJakob, Matthias [Verfasser], Ulrich K. [Akademischer Betreuer] Heiz, Ulrich K. [Gutachter] Heiz, and Bernhard [Gutachter] Rieger. "Optical and Chiroptical Properties of Semiconductor and Noble Metal Nanomaterials / Matthias Jakob ; Gutachter: Ulrich K. Heiz, Bernhard Rieger ; Betreuer: Ulrich K. Heiz." München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1212178106/34.
Повний текст джерела