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Literatura académica sobre el tema "Infrared nanocrystals"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Infrared nanocrystals"

Della Gaspera, Enrico, Noel W. Duffy, Joel van Embden, Lynne Waddington, Laure Bourgeois, Jacek J. Jasieniak y Anthony S. R. Chesman. "Plasmonic Ge-doped ZnO nanocrystals". Chemical Communications 51, n.º 62 (2015): 12369–72. http://dx.doi.org/10.1039/c5cc02429c.

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SHUBERT, V. ALVIN y STEVEN P. LEWIS. "SIZE-DEPENDENCE OF INFRARED SPECTRA IN NIOBIUM CARBIDE NANOCRYSTALS". International Journal of Modern Physics C 23, n.º 08 (agosto de 2012): 1240001. http://dx.doi.org/10.1142/s0129183112400013.

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Niobium carbide nanocrystals of ~1:1 stoichiometry have recently been observed for particle sizes ranging from Nb4C4 to Nb50C50 . Infrared (IR) spectroscopic measurements show that a new band of IR vibrational modes appears with increasing particle size at Nb9C9 . Using density-functional theory, we show that the vibrational modes in the new band involve structural features present only in nanocrystals with three or more atomic layers in every direction. The Nb9C9 nanocrystal is right at this structural threshold.

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Lhuillier, Emmanuel. "Narrow band gap nanocrystals for infrared cost-effective optoelectronics". Photoniques, n.º 116 (2022): 54–57. http://dx.doi.org/10.1051/photon/202211654.

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Infrared optoelectronics is driven by epitaxially grown semiconductors and the introduction of alternative materials is often viewed with some suspicion until the newcomer has demonstrated a high degree of viability. Infrared nanocrystals have certainly reached this degree of maturity switching from the demonstration of absorption by chemists to their integration into increasingly complex systems. Here, we review some of the recent developments relative to the integration of nanocrystal devices in the 1-5 µm range.

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Saez Cabezas, Camila A., Gary K. Ong, Ryan B. Jadrich, Beth A. Lindquist, Ankit Agrawal, Thomas M. Truskett y Delia J. Milliron. "Gelation of plasmonic metal oxide nanocrystals by polymer-induced depletion attractions". Proceedings of the National Academy of Sciences 115, n.º 36 (20 de agosto de 2018): 8925–30. http://dx.doi.org/10.1073/pnas.1806927115.

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Gelation of colloidal nanocrystals emerged as a strategy to preserve inherent nanoscale properties in multiscale architectures. However, available gelation methods to directly form self-supported nanocrystal networks struggle to reliably control nanoscale optical phenomena such as photoluminescence and localized surface plasmon resonance (LSPR) across nanocrystal systems due to processing variabilities. Here, we report on an alternative gelation method based on physical internanocrystal interactions: short-range depletion attractions balanced by long-range electrostatic repulsions. The latter are established by removing the native organic ligands that passivate tin-doped indium oxide (ITO) nanocrystals while the former are introduced by mixing with small PEG chains. As we incorporate increasing concentrations of PEG, we observe a reentrant phase behavior featuring two favorable gelation windows; the first arises from bridging effects while the second is attributed to depletion attractions according to phase behavior predicted by our unified theoretical model. Our assembled nanocrystals remain discrete within the gel network, based on X-ray scattering and high-resolution transmission electron microscopy. The infrared optical response of the gels is reflective of both the nanocrystal building blocks and the network architecture, being characteristic of ITO nanocrystals’ LSPR with coupling interactions between neighboring nanocrystals.

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Li, Xinke, Fangtian You, Hongshang Peng y Shihua Huang. "Synthesis and Near-Infrared Luminescent Properties of NaGdF4:Nd3+@NaGdF4 Core/Shell Nanocrystals with Different Shell Thickness". Journal of Nanoscience and Nanotechnology 16, n.º 4 (1 de abril de 2016): 3940–44. http://dx.doi.org/10.1166/jnn.2016.11818.

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The near-infrared to near-infrared (NIR-to-NIR) photoluminescence of nanocrystals has outstanding advantages in biological imaging. NaGdF4:Nd3+ core nanocrystals and NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals with different shell thicknesses were synthesized by a simple solvothermal method. The obtained nanocrystals were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The phase of all nanocrystals is hexagonal. NaGdF4:Nd3+ core nanocrystals have an average size of 6 nm. By controlling core–shell ratio for 1:2 and 1:3, we obtained NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals with average sizes of 10 nm and 11 nm, respectively. When excited at 808 nm, strong NIR emission was observed. The emission peaks at ∼860 nm, ∼1060 nm and ∼1330 nm correspond to the transitions from the 4F3/2 statetothe 4I9/2, 4I11/2 and 4I13/2 state of Nd3+ ions, respectively. The emission intensity of NaGdF4:Nd3+@NaGdF4 core/shell nanocrystals is stronger than that of the core. The intensity increases with the increase of shell thickness. The shell improves the luminous efficiency by reducing surface defects. The decay time of Nd3+ emission in NaGdF4:Nd3+@NaGdF4 core/shell nanocrystal is longer than that in NaGdF4:Nd3+ core, indicating that the shell isolates effectively the emitting ions (Nd3+)from the quenching defects. With the increase of shell thickness, the decay time becomes longer. Within a certain range of shell thickness, thicker shell can protect the emitting Nd3+ ions on the surface of core nanocrystals more effectively.

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Ницук, Ю. А., М. И. Киосе, Ю. Ф. Ваксман, В. А. Смынтына y И. Р. Яцунский. "Оптические свойства нанокристаллов CdS, легированных цинком и медью". Физика и техника полупроводников 53, n.º 3 (2019): 381. http://dx.doi.org/10.21883/ftp.2019.03.47291.8982.

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AbstractCadmium-sulfide nanocrystals are produced by the colloidal method. Doping with zinc and copper is conducted during nanocrystal growth. The optical absorption and photoluminescence spectra are studied. The maximum concentration of the optically active copper impurity is determined from a shift of the fundamental absorption edge to lower energies. It is shown that the long-wavelength luminescence of CdS and CdS:Zn nanocrystals is defined by optical transitions at donor–acceptor pairs. In CdS:Cu nanocrystals, optical absorption and photoluminescence in the visible spectral region are defined by recombination transitions involving the ground state of $${\text{Cu}}_{{{\text{Zn}}}}^{{2 + }}$$ ions. The infrared absorption and photoluminescence of CdS:Cu quantum dots are defined by intracenter transitions within $${\text{Cu}}_{{{\text{Zn}}}}^{{2 + }}$$ ions.

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Zhang, Xinhai, Qiuling Chen y Shouhua Zhang. "Ta2O5 Nanocrystals Strengthened Mechanical, Magnetic, and Radiation Shielding Properties of Heavy Metal Oxide Glass". Molecules 26, n.º 15 (26 de julio de 2021): 4494. http://dx.doi.org/10.3390/molecules26154494.

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In this study, for the first time, diamagnetic 5d0 Ta5+ ions and Ta2O5 nanocrystals were utilized to enhance the structural, mechanical, magnetic, and radiation shielding of heavy metal oxide glasses. Transparent Ta2O5 nanocrystal-doped heavy metal oxide glasses were obtained, and the embedded Ta2O5 nanocrystals had sizes ranging from 20 to 30 nm. The structural analysis of the Ta2O5 nanocrystal displays the transformation from hexagonal to orthorhombic Ta2O5. Structures of doped glasses were studied through X-ray diffraction and infrared and Raman spectra, which reveal that Ta2O5 exists in highly doped glass as TaO6 octahedral units, acting as a network modifier. Ta5+ ions strengthened the network connectivity of 1–5% Ta2O5-doped glasses, but Ta5+ acted as a network modifier in a 10% doped sample and changed the frame coordination units of the glass. All Ta2O5-doped glasses exhibited improved Vicker’s hardness, magnetization (9.53 × 10−6 emu/mol), and radiation shielding behaviors (RPE% = 96–98.8%, MAC = 32.012 cm2/g, MFP = 5.02 cm, HVL = 0.0035–3.322 cm, and Zeff = 30.5) due to the increase in density and polarizability of the Ta2O5 nanocrystals.

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Chen, Yi Chuan, Yue Hui Hu, Xiao Hua Zhang, Feng Yang, Hai Jun Xu, Xin Hua Chen y Jun Chen. "Structure and Properties of Doped ZnO Nanopowders Synthesized by Methanol Alcoholysis Method". Advanced Materials Research 287-290 (julio de 2011): 1406–11. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1406.

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Pured ZnO, Al doped ZnO and Al-In co-doped ZnO nanopowders were synthesized by the methanol alcoholysis method at 130 °C. Structure, morphology and optical properties of ZnO nanopowders were characterized using X-ray diffraction, Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Photoluminescence (PL) spectra. The results show that ZnO nanopowders can be obtained in methanol solution at low temperature (130 °C). TEM images show that Al doped ZnO nanocrystals grow along the [002] axis quicker than other axes. FTIR spectra show that ZnO nanocrystals synthesized by the methanol alcoholysis include a little organic impurity. PL spectrums reveal that pure ZnO and doped ZnO nanocrystals have a blue band emission at 440 nm and a green band emission at 520 nm and 530 nm, respectively. Compared with the pure ZnO nanocrystal, the Al doping improves the luminescent properties.

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Feng, Bin, Feng Teng, Ai-Wei Tang, Yan Wang, Yan-Bing Hou y Yong-Sheng Wang. "Synthesis and Optical Properties of L-Cysteine Hydrochloride-Stabilized CdSe Nanocrystals in a New Alkali System". Journal of Nanoscience and Nanotechnology 8, n.º 3 (1 de marzo de 2008): 1178–82. http://dx.doi.org/10.1166/jnn.2008.18168.

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Water-soluble CdSe nanocrystals were synthesized in a new alkali system at lower temperatures by using L-cysteine hydrochloride as a stabilizer and Na2SeSO3 as a selenium source to enable the synthesis of CdSe nanocrystals in a wider range of pHvalues. The CdSe nanocrystal powder was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. We systematically investigated the effect of synthesis conditions on the optical properties of the L-cysteine hydrochloride-stabilized CdSe nanocrystals, and found that different sizes of CdSe nanocrystals can be obtained by changing the pHvalue, the molar ratio of L-cysteine hydrochloride to Cd2+, or the refluxing time. The emission maxima of the obtained CdSe nanocrystals can be tuned in a wider range from 477 to 575 nm by changing the pHvalue from 7 to 13. We observed an obvious blue-shift of the absorption and photoluminescence peak position by varying the molar ratio of L-Cys to Cd2+ from 3.5:1 to 2:1 at the same pHvalue. The size of the obtained nanocrystals increased and the full width at half maximum became narrower as reflux time increased. Transmission electron microscopy images indicate that the as-prepared CdSe nanocrystals have a good dispersion, which means that L-cysteine hydrochloride can control the grouping of CdSe nanocrystals excellently as a stabilizer in the new alkali system.

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Fermi, Andrea, Mirko Locritani, Gabriele Di Carlo, Maddalena Pizzotti, Stefano Caramori, Yixuan Yu, Brian A. Korgel, Giacomo Bergamini y Paola Ceroni. "Light-harvesting antennae based on photoactive silicon nanocrystals functionalized with porphyrin chromophores". Faraday Discussions 185 (2015): 481–95. http://dx.doi.org/10.1039/c5fd00098j.

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Silicon nanocrystals functionalized with tetraphenylporphyrin Zn(ii) chromophores at the periphery perform as light harvesting antennae: excitation of the porphyrin units in the visible spectral region yields sensitized emission of the silicon nanocrystal core in the near infrared with a long lifetime (λ_max= 905 nm,τ= 130 μs). This result demonstrates that this hybrid material has a potential application as a luminescent probe for bioimaging.

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Tesis sobre el tema "Infrared nanocrystals"

Geyer, Scott Mitchell. "Science and applications of infrared semiconductor nanocrystals". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62053.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2010.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 149-158).
In this work we study several applications of semiconductor nanocrystals (NCs) with infrared band gaps. In the first half, we explore the physics of two systems with applications in NC based photovoltaics. The physics of mixed films of CdTe and CdSe NCs is studied in chapter 2 as a model for NC based bulk heterojunction photovoltaics. We demonstrate that the presence of an active electron trap on the CdTe dramatically reduces the electron mobility in mixed films. The trapping state is linked to oxidation of the CdTe NCs. A cadmium oleate treatment is shown to reduced the oxidation rate. In chapter 3, we present a method to switch the carrier type of InAs NCs deposited in a thin film from p-type to n-type by the addition of cadmium. This provides a stable pre-deposition technique to control the NC carrier type and is a step towards pn homojunction based NC devices. We discuss the role that surface passivation and substitution doping may play in determining the carrier type. The second half explores the use of NCs for photodetector applications. Chapter 4 presents our efforts to move from a single pixel, proof of principle PbS NC infrared detector to a large area infrared imaging camera. A method to control the resistivity of the NC film through oxidation and re-treatment with ethanedithiol is presented. This allows for integration of our NC film with existing read out technology. The noise spectrum is shown to be dominated by 1/f noise and the dependence of the noise on the bias and channel length is determined. The detectivity is found to be determined by the carrier lifetime and dark current carrier density. In chapter 5, we demonstrate efficient UV-IR dual band detectors based on luminescent down conversion. In this design, NCs absorb UV light and re-emit the light in the infrared band of an InGaAs detector. The high quantum yields of infrared nanocrystals and unique absorption profile are shown to provide a significant advantage over organic dyes. The bandwidth of the detectors is measured and the effect of the down conversion layer on the spatial resolution is characterized.
by Scott Mitchell Geyer.
Ph.D.

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Liyanage, Geethika Kaushalya. "Infrared Emitting PbS Nanocrystals through Matrix Encapsulation". Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1403953924.

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Kriegel, Ilka. "Near-infrared plasmonics with vacancy doped semiconductor nanocrystals". Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-164558.

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Plasmonics with heavily doped semiconductor nanocrystals (NCs) is an emerging field in NC science. However, impurity doping of NCs remains far from trivial and is, as yet, dominated by a low chemical control over the incorporated dopant atoms. An appealing alternative is vacancy doping, where the formation of vacancies in the structure is responsible for an increased carrier density and elegantly circumvents the issues related to impurity doping. Due to high carrier densities of around 10^21cm^(-3) localized surface plasmon resonances (LSPRs) in the near infrared (NIR) are expected, and as such highlighted to close the gap between conventionally doped NCs and noble metal nanoparticles. Copper chalcogenide NCs, namely copper sulfide (Cu2-xS), copper selenide (Cu2-xSe), and copper telluride (Cu2-xTe), are an attractive example of vacancy doped semiconductor NCs, with spectra dominated by intense NIR resonances. Within this study thorough experimental evidence has been given to prove the plasmonic nature of those NIR resonances. By presenting typical plasmonic characteristics, such as refractive index sensitivity of the LSPR, its intrinsic size dependence, plasmon dynamics, or interparticle plasmon coupling, the LSPRs in copper chalcogenide NCs have unambiguously been identified. The chemical nature of vacancy doping turns out to deliver an additional, highly attractive means of control over the LSPR in vacancy doped copper chalcogenide NCs. Through chemical tailoring of the copper vacancy density via controlled oxidation and reduction, as shown in this study, a reversible tuning of the LSPR over a wide range of frequencies in the NIR (1000-2000 nm) becomes feasible. This highlights copper chalcogenide NCs over conventional plasmonic materials. Notably, the complete suppression of the LSPR uncovers the excitonic features present only in the purely semiconducting, un-doped NCs and reveals the unique option to selectively address excitons and highly tunable LSPRs in one material (bandgap Eg~1.2 eV). As such, copper chalcogenide NCs appear to hold as an attractive material system for the investigation of exciton plasmon interactions. Indeed, a quenching of the excitonic transitions in the presence of the developing LSPR is demonstrated within this work, with a full recovery of the initial excitonic properties upon its suppression. A theoretical study on the shape dependent plasmonic properties of Cu2-xTe NCs reveals a deviation from the usual Drude model and suggests that the carriers in vacancy doped copper chalcogenide NCs cannot be treated as fully free. On the other hand, the Lorentz model of localized oscillators appears to account for the weak shape dependence, as observed experimentally, indicating an essential degree of localization of the carriers in vacancy doped copper chalcogenide NCs. Taken together, this work delivers a huge step toward the complete optical and structural characterization of plasmonic copper chalcogenide NCs. The advantages of semiconductor NC chemistry have been exploited to provide access to novel plasmonic shapes, such as tetrapods that have not been feasible to produce so far. A precise size, shape and phase control presents the basis for this study, and together with a thorough theoretical investigation delivers important aspects to uncover the tunable plasmonic properties of vacancy doped copper chalcogenide NCs.

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Panthani, Matthew George. "Colloidal Nanocrystals with Near-infrared Optical Properties| Synthesis, Characterization, and Applications". Thesis, The University of Texas at Austin, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3572875.

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Colloidal nanocrystals with optical properties in the near-infrared (NIR) are of interest for many applications such as photovoltaic (PV) energy conversion, bioimaging, and therapeutics. For PVs and other electronic devices, challenges in using colloidal nanomaterials often deal with the surfaces. Because of the high surface-to-volume ratio of small nanocrystals, surfaces and interfaces play an enhanced role in the properties of nanocrystal films and devices.

Organic ligand-capped CuInSe₂ (CIS) and Cu(In_XGa_1-X)Se2 (CIGS) nanocrystals were synthesized and used as the absorber layer in prototype solar cells. By fabricating devices from spray-coated CuInSe nanocrystals under ambient conditions, solar-to-electric power conversion efficiencies as high as 3.1% were achieved. Many treatments of the nanocrystal films were explored. Although some treatments increased the conductivity of the nanocrystal films, the best devices were from untreated CIS films. By modifying the reaction chemistry, quantum-confined CuInSe_XS_2-X (CISS) nanocrystals were produced. The potential of the CISS nanocrystals for targeted bioimaging was demonstrated via oral delivery to mice and imaging of nanocrystal fluorescence.

The size-dependent photoluminescence of Si nanocrystals was measured. Si nanocrystals supported on graphene were characterized by conventional transmission electron microscopy and spherical aberration (Cs)-corrected scanning transmission electron microscopy (STEM). Enhanced imaging contrast and resolution was achieved by using Cs-corrected STEM with a graphene support. In addition, clear imaging of defects and the organic-inorganic interface was enabled by utilizing this technique.

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Lox, Josephine F. L., Zhiya Dang, Volodymyr Dzhagan, Daniel Spittel, Beatriz Martín-García, Iwan Moreels, Dietrich R. T. Zahn y Vladimir Lesnyak. "Near-Infrared Cu-In-Se-Based Colloidal Nanocrystals via Cation Exchange". ACS Publications, 2019. https://tud.qucosa.de/id/qucosa%3A36557.

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We developed a three-step colloidal synthesis of near-infrared active Cu-In-Se (CISe)/ZnS core/shell nanocrystals (NCs) via a sequential partial cation exchange. In the first step binary highly copper deficient Cu2‒xSe NCs were synthesized, followed by a partial cation exchange of copper to indium ions yielding CISe NCs. In order to enhance the stability and the photoluminescence (PL) properties of the NCs, a subsequent ZnS shell was grown, resulting in CISe/ZnS core/shell NCs. These core/shell hetero-NCs exhibited a dramatic increase in size and a restructuring to trigonal pyramidal particles. The reaction parameters, e.g. the Cu:Se-ratio, the temperature and the time were carefully tuned enabling a distinct control over the size and the composition of the NCs. By varying only the size of the CISe/ZnS NCs (from 9 to 18 nm) the PL spectra could be tuned covering a wide range with maxima from 990 nm to 1210 nm. Thus, in these experiments we demonstrate a clear dependence of the optical properties of these materials on their size and extend the PL range of CISe-based nanoparticles further to the infrared part of the spectrum. Furthermore, the relatively large size of these NCs allows their detailed structural analysis via electron microscopy techniques, which is particularly challenging in the case of small particles and especially important to relate the size, composition and crystal structure to their optoelectronic properties.

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Xiang, Hengyang. "Colloidal nanocrystals applied for short-wave infrared photodetectors with fast response". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS423.

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L'infrarouge à ondes courtes (SWIR) désigne généralement les photons dans la plage de longueurs d'onde allant de 1 à 3 micromètres. Les applications dans cette fenêtre de longueur d'onde exploitent divers avantages tels qu’une grande longueur de pénétration dans le tissu biologique, la couverture spectrale pour la vision nocturne atmosphérique et l'énergie d'excitation caractéristique de certains modes de vibration moléculaire. Les photodétecteurs SWIR sont donc les composants technologiques essentiels pour la communication optique, la détection de gaz dans l’environnement, le biodiagnostic et la vision nocturne passive. Les technologies SWIR actuelles reposent principalement sur des semi-conducteurs composés à faible bande interdite, tels que InGaAs, InSb, PbS et HgCdTe. Alors que les photodétecteurs SWIR classiques présentent une excellente détectivité, ils sont coûteux (en raison de la croissance requise par l'épitaxie) et / ou présentent un risque environnemental car impliquant des éléments hautement toxiques. Par conséquent, des efforts continus en matière de recherche et de développement concernant des systèmes de matériaux alternatifs et des méthodes de fabrication permettant d'élargir le champ des applications de la photodétection SWIR sont en cours. Ces dernières années, de nombreux nouveaux matériaux ont été proposés, notamment les nanocristaux de phosphore noir, de graphène, de MoS2 et de PbS colloïdal. Ils sont très prometteurs en termes de fonctionnement à des fréquences de modulation élevées et avec une excellente sensibilité. Cependant, certains inconvénients les éloignent toujours du marché: processus de production difficile (faible reproductibilité), non-adaptabilité à la fabrication à grande échelle, préoccupations de sécurité lors de la production en usine (en raison de l’utilisation d’éléments hautement toxiques). Alternativement, les nanoparticules colloïdales traitées en solution, telles que les nanorods d’or colloïdal (Au NR) et les nanoparticules fonctionnant par up-conversion (UCNP), présentent des caractéristiques intéressantes permettant de surmonter ces inconvénients: capacité de synthèse et de production à grande échelle et à faible coût, haute stabilité, faible toxicité biologique et bonne absorption optique des photons SWIR. Cette thèse a pour objectif d'appliquer ces nanoparticules colloïdales à la fabrication de photodétecteurs SWIR et d’étudiere des possibilités d’application dans le domaine de la photodétection. Quelques photodétecteurs SWIR (Au-NRs / Thermistance, photodétecteur Au-NRs / Pt et photodétecteur UCNPs / Polymers) ont été développés dans ce travail, montrant une sensibilité élevées. De plus, la fabrication de ces dispositifs est un procédé peu coûteux et évolutif vers la production de masse au niveau de la fois à la synthèse des matériaux et de la fabrication des composants, et ouvre une nouvelle voie sur le marché de la prochaine génération de photodétecteurs
Short-wave infrared (SWIR) typically refers to the photons in the wavelength range from 1 to 3 micrometers. Applications in this wavelength window exploit various advantages such as long penetration length in biological tissue, spectral coverage of the atmospheric nightglow, and the characteristic excitation energy of certain molecular vibration modes. SWIR photodetectors are thus the key technological components to achieve optical communication, environmental gas sensing, biodiagnostics, and passive night vision. Current SWIR technologies mainly rely on low-bandgap compound semiconductors, such as InGaAs, InSb, PbS, and HgCdTe. While classical SWIR photodetectors exhibit excellent detectivity, they are costly (due to epitaxial growth requirement) and/or environment unfriendly involving highly toxic elements. There are, therefore, continuous research and development efforts for alternative material systems and fabrication methods to expand the scope of applications of SWIR photodetection. In recent years, many new materials have been proposed, including black phosphorus, graphene, MoS2, and colloidal PbS nanocrystals. They show great promise in terms of operation at high modulation frequencies or high sensitivity. But some disadvantages still keep them away from the market: rigorous production process (poor reproducibility), non-adaptability to scale-up fabrication, manufactory safety and security concerns (due to the use of highly toxic elements). Alternatively, solution-processed colloidal nanoparticles, such as colloidal gold nanorods (Au NRs) and upconversion nanoparticles (UCNPs), exhibit interesting characteristics possible to overcome these disadvantages: capability of scaling-up synthesis, solution-processability adaptable to low-cost fabrication, high stability, low biological toxicity, and good optical absorption for SWIR photons. This PhD thesis aims to apply these colloidal nanoparticles to fabricate SWIR photodetectors and verifies their possibilities for new generation of photodetection. A few SWIR photodetectors (Au-NRs/Thermistor, Au-NRs/Pt photodetector and UCNPs/Polymers photodetector) were developed in this work, showing high responsivity and sensitivity. In addition, the preparation of these devices is a low-cost and scalable up to mass production process both in the materials synthesis and device fabrication, opening a new and convenient path to the next-generation SWIR photodetectors

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Livache, Clément. "Quantum-conﬁned nanocrystals for infrared optoelectronics : carrier dynamics and intraband transitions". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS216.

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Les nanocristaux colloïdaux sont des objets cristallins obtenus par voie chimique. Ces objets étant conﬁnés, leurs propriétés optiques dépendent de leur taille, et peuvent donc être ajustées à la demande. Les nanocristaux de tellurure de mercure et de séléniure de mercure possèdent notamment des propriétés d’absorption dans l’infrarouge: l’énergie de bande interdite (interbande) des nanocristaux de HgTe peut-être variée du SWIR au MWIR, tandis que les nanocristaux de HgSe, grâce à un auto-dopage électronique dégénéré, présentent des transitions intrabande ajustables du MWIR au LWIR. Un contrôle ﬁn de la chimie de surface de ces objets permet de les intégrer dans des dispositifs électroniques et de créer des détecteurs infrarouge à bas coût. Dans mon travail de thèse, je me suis intéressé à diﬀérentes manières de sonder la dynamique des porteurs dans ces dispositifs, soit via la mesure du photocourant, soit par des observations directes de la relaxation des porteurs photogénérés. A partir d’études sur la dynamique dans HgSe, j’ai identiﬁé les limitations apportées par le fort dopage de ces nanocristaux : le transport est dominé par la forte densité électronique, conduisant à des faibles performances pour la détection IR. En reprenant les concepts développés pour les hétérostructures de semi-conducteurs III-V, je propose diﬀérentes approches fructueuses pour découpler les propriétés optiques et le transport de charges dans des dispositifs de détection MWIR à base de nanocristaux de HgSe
Colloidal nanocrystals are crystalline objects grown by colloidal chemistry approaches. Thanks to quantum conﬁnement, their optical properties depend on their size, and can then be tuned accordingly. Using mercury selenide and mercury telluride, we grow infrared-absorbing nanocrystals. While HgTe nanocrystals interband gap can be tuned from the NIR to the MWIR, HgSe nanocrystals display self-doping and intraband transitions in the MWIR to LWIR. With a careful control of their surface chemistry, those nanocrystals can be integrated into electrical devices to create cheap infrared photodetectors. In my PhD work, I am interested in probing carrier dynamics in those devices using various time-resolved techniques, either based on photocurrent measurements or on direct observation of the photocarriers relaxation. From dynamic study of HgSe intraband devices, I identify the issue brought by the degenerative doping level of those nanocrystals: transport is driven by the doping of this material, resulting in very poor IR-sensing performances. By taking inspiration from the III-V semiconductor developments, I propose several successful approaches to uncouple optical and transport properties in HgSe-based, MWIR detectors

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Gencer, Imer Arife. "Si Nanocrystals In Sic Matrix And Infrared Spectroscopy Of In A Dielecric Matrix". Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611778/index.pdf.

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This study focuses on various aspects of nanocrystals embedded in a dielectric matrix. In the first part of this work, a new approach with the use of Fourier Transform Infrared spectroscopy (FTIR) in the nanocrystal analysis was developed and presented. Si and Ge nanocrystals embedded in SiO2 matrix were mainly studied. This new approach is based on the analysis of structural variations of SiO2 matrix during the formation of semiconductor nanocrystlas. It is shown that the chemical and structural variations of the host matrix are directly related to the precipitation of nanocrystals in it. This correlation provides valuable information about the presences of nanocrystals in the matrix. In the second part of this work, fabrication of SiC films with and without Si nanocrystals inclusions was studied. With this aim, stoichiometric SiC and Si rich SiC thin films were fabricated by using magnetron co-sputtering and Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques. For SiC films, the structural and optical analyses were performed. For Si rich SiC films, the formation conditions of Si nanocrystals were investigated. Post annealing studies were carried out to track the evolution of the SiC matrix and formation of Si nanocrystals at different temperatures. Chemical and structural properties of the SiC host matrix were investigated with FTIR spectroscopy. Optimum conditions for the fabrication of stoichiometric SiC layers were determined. The crystallography of the nanocrystals was investigated by X-Ray Diffraction (XRD). The variation of the atomic concentrations and bond formations were investigated with X-Ray Photoelectron Spectroscopy (XPS). Raman spectroscopy and Transmission Electron Microscopy (TEM) were used to verify the formation of Si nanocrystals. We have shown that both single and multilayer Si nanocrystals can be fabricated in the amorphous SiC matrix for applications such as light emitting diodes and solar cells.

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Kriegel, Ilka [Verfasser] y Jochen [Akademischer Betreuer] Feldmann. "Near-infrared plasmonics with vacancy doped semiconductor nanocrystals / Ilka Kriegel. Betreuer: Jochen Feldmann". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1046503316/34.

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Chen, Yue Ph D. Massachusetts Institute of Technology. "Syntheses of biocompatible luminescent nanocrystals for visible and short-wave infrared imaging applications". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115798.

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Thesis: Ph. D. in Physical Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references.
The primary focus of this thesis is to synthesize biocompatible luminescent nanocrystals for visible and short-wave infrared (1-2 [mu]m, SWIR) imaging applications. Quantum dots (QDs) have been promising fluorescent probes for biomedical imaging due to their high quantum yield (QY), narrow photoluminescence spectra, and excellent photostability. However, challenges remain to be solved to transfer the as-synthesized hydrophobic QD to aqueous solutions while maintaining the high QY and a compact size. This study involves the design and synthesis of a novel ligand that can be introduced to the established QD synthesis, producing norbornene functionalized QDs that can be readily phase transferred into water via norbornene/tetrazine click chemistry, meanwhile allowing flexible functionalization of the QDs by incorporating a functional group on the hydrophilic chain. This ligand system can be applied to a variety of carboxylic-ligand-stabilized QDs, with emission spectra spanning the visible and the SWIR region. The resulting water-soluble QDs exhibit a high QY, a small hydrodynamic diameter (HD), and excellent colloidal stability and pH stability. Further in vitro cell labeling experiments using azido-functionalized QDs demonstrates their potential for cell targeting applications. As in vivo imaging in the SWIR range has further reduced background noise from tissue scattering compared to traditional visible and near infrared (0.7-1 tm, NIR) imaging, images of higher contrast and better resolution can be readily obtained. The next challenge is to develop SWIR emitters that have high quantum efficiency and minimal toxicity, which is of critical importance in order to promote this technology for clinical applications. Our study found that the emission of luminescent gold nanoclusters can be tuned from the visible to the SWIR region by proper selection of ligands and post ligand modifications. The SWIR-emitting gold nanoclusters have a good QY, a HD that is small enough that they exhibit a rapid renal clearance, and images taken in the SWIR region show better resolution of the blood vessels than in the NIR region.
by Yue Chen.
Ph. D. in Physical Chemistry

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Más fuentes

Libros sobre el tema "Infrared nanocrystals"

Chang, Tung-Wah Frederick. Luminescence and energy transfer excitation of infrared colloidal semiconductor nanocrystals: Y Tung-Wah Frederick Chang. 2006.

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Capítulos de libros sobre el tema "Infrared nanocrystals"

Sugimoto, Hiroshi y Minoru Fujii. "Near-infrared luminescent colloidal silicon nanocrystals". En Silicon Nanomaterials Sourcebook, 399–412. Boca Raton, FL: CRC Press, Taylor & Francis Group, [2017] | Series: Series in materials science and engineering: CRC Press, 2017. http://dx.doi.org/10.4324/9781315153544-19.

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Lhuillier, Emmanuel, Tung Huu Dang, Mariarosa Cavallo, Claire Abadie, Adrien Khalili, John C. Peterson y Charlie Gréboval. "Infrared Sensing Using Mercury Chalcogenide Nanocrystals". En Handbook of II-VI Semiconductor-Based Sensors and Radiation Detectors, 155–81. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-20510-1_7.

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Heitmann, Detlef y Can-Ming Hu. "Far-Infrared Spectroscopy of Low-Dimensional Electron Systems". En Quantum Materials, Lateral Semiconductor Nanostructures, Hybrid Systems and Nanocrystals, 103–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10553-1_5.

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Marciniak, Łukasz, W. Strek, A. Lukowiak, A. Bednarkiewicz, R. Wiglusz y D. Hreniak. "Infrared Induced White Anti-stokes Emission of LiYbP4O12 Nanocrystals". En NATO Science for Peace and Security Series B: Physics and Biophysics, 423–24. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5313-6_43.

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Nakajima, Atsushi, Minoru Fujii, Shinji Hayashi y Koji Kaya. "Visible and Infrared Photoluminescence from Deposited Germanium-Oxide Clusters and from Ge Nanocrystals". En Frontiers of Nano-Optoelectronic Systems, 303–17. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-010-0890-7_20.

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Ca, N. X., N. T. Hien, N. T. Luyen y P. M. Tan. "Near-Infrared Emitting Type-II CdTe/CdSe Core/Shell Nanocrystals: Synthesis and Optical Properties". En Advances in Engineering Research and Application, 398–407. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-04792-4_52.

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He, Ying, K. Ma, L. Bi, J. Y. Feng y Q. L. Wu. "Strong Near-Infrared Luminescence from NiSi₂-Passivated Silicon Nanocrystals Embedded in SiO_x Films". En Key Engineering Materials, 655–57. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.655.

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Pietryga, Jeffrey M., Jennifer A. Hollingsworth, Fudong Wang y William E. Buhro. "Mid-Infrared Emitting Lead Selenide Nanocrystal Quantum Dots". En Inorganic Syntheses: Volume 36, 198–202. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118744994.ch37.

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Sugimoto, Hiroshi y Minoru Fujii. "Near-infrared luminescent colloidal silicon nanocrystals". En Silicon Nanomaterials Sourcebook, 399–412. CRC Press, 2017. http://dx.doi.org/10.1201/9781315153544-20.

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Tao, Ke, Kang Sun y Seok Ki Choi. "Upconversion nanocrystals for near-infrared-controlled drug delivery". En Photonanotechnology for Therapeutics and Imaging, 345–71. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-817840-9.00012-6.

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Actas de conferencias sobre el tema "Infrared nanocrystals"

Tisdale, William. "Surfaces of Infrared-Active PbS Nanocrystals and their Assemblies". En Internet Conference for Quantum Dots. València: Fundació Scito, 2020. http://dx.doi.org/10.29363/nanoge.icqd.2020.031.

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Camilo, Nilmar S., Djalmir N. Messias, Viviane Pilla, Anielle C. A. Silva, Noelio O. Dantas y Acácio A. Andrade. "CdS Nanocrystals in Glass Phosphate Matrix With High Photoluminescence Quantum Efficiency in Near Infrared". En Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.w4a.44.

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In this work the CdS nanocrystals (NC) photoluminescence quantum efficiency (η) was determined by thermal lens technique. Due the high NC diameter a near-infrared emission is observed and η was determined η ~ 60%.

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Apretna, T., S. Massabeau, N. Goubet, C. Greboval, S. Dhillon, E. Lhuillier y J. Mangeney. "Picosecond carrier dynamics in THz HgTe nanocrystals". En 2020 45th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2020. http://dx.doi.org/10.1109/irmmw-thz46771.2020.9370911.

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Diener, Joachim, Dmitri I. Kovalev, Gennadi Polisski y Frederick Koch. "Polarization properties of the luminescence from silicon nanocrystals". En Fifth International Conference on Material Science and Material Properties for Infrared Optoelectronics, editado por Fiodor F. Sizov. SPIE, 2001. http://dx.doi.org/10.1117/12.417772.

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Xu, F., X. Ma y S. G. Cloutier. "Highly efficient near-infrared electroluminescence devices based on PbS nanocrystals". En Frontiers in Optics. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/fio.2010.fthaa3.

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Livache, Clement, Bertille Martinez, Eva Izquierdo, Marion Dufour, Herve Cruguel, Sebastien Royer, Xian Zhen Xu, Sandrine Ithurria y Emmanuel Lhuillier. "Shape and confinement control in mid and far infrared nanocrystals". En SPIE OPTO, editado por Diana L. Huffaker y Holger Eisele. SPIE, 2017. http://dx.doi.org/10.1117/12.2250160.

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Stavarache, I., L. Nedelcu, V. S. Teodorescu, V. A. Maraloiu, I. Dascalescu y M. L. Ciurea. "GeSi Nanocrystals in SiO2 Matrix with Extended Photoresponse in Near Infrared". En 2018 International Semiconductor Conference (CAS). IEEE, 2018. http://dx.doi.org/10.1109/smicnd.2018.8539745.

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Ravanan, Fereshte, Hossein Roshan y Mohammad Hossein Sheikhi. "A Novel Low Voltage Near-Infrared Photodetector Based on Ag2S Nanocrystals". En 2020 28th Iranian Conference on Electrical Engineering (ICEE). IEEE, 2020. http://dx.doi.org/10.1109/icee50131.2020.9260989.

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Zajac, Vit, Petr Kuzel, Hynek Nemec, Christelle Kadlec, Katerina Kusova y Ivan Pelant. "THz photoconductivity in Si nanocrystals: Issues of (non)percolation". En 2013 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2013). IEEE, 2013. http://dx.doi.org/10.1109/irmmw-thz.2013.6665827.

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Apretna, T., S. Massabeau, N. Goubet, C. Greboval, S. Dhillon, F. Carosella, R. Ferreira, E. Lhuillier y J. Mangeney. "Terahertz emission from HgTe nanocrystals excited by femtosecond optical pulses". En 2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2021. http://dx.doi.org/10.1109/irmmw-thz50926.2021.9567449.

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Informes sobre el tema "Infrared nanocrystals"

Hollingsworth, Jennifer, Victoria Nisoli, Ekaterina Dolgopolova, Paul Bourdin, Andrew West, siyuan zhang, Matthew Schneider, Sergei Ivanov y Maiken mikkelsen. Near Infrared Plasmonic Properties in Spinel Metal Oxide Nanocrystals. Office of Scientific and Technical Information (OSTI), agosto de 2023. http://dx.doi.org/10.2172/1993209.

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Xu, Jian. Photonic Devices Based on Surface and Composition-Engineered Infrared Colloidal Nanocrystals. Fort Belvoir, VA: Defense Technical Information Center, enero de 2012. http://dx.doi.org/10.21236/ada559844.

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Cao, Xian-An. Depleted Nanocrystal-Oxide Heterojunctions for High-Sensitivity Infrared Detection. Fort Belvoir, VA: Defense Technical Information Center, julio de 2015. http://dx.doi.org/10.21236/ad1001326.

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