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Romero M, Sánchez-Valencia JR, Lozano G, Míguez H. Effect of the effective refractive index on the radiative decay rate in nanoparticle thin films. NANOSCALE 2023; 15:15279-15287. [PMID: 37676237 DOI: 10.1039/d3nr03348a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
In this work, we theoretically and experimentally study the influence of the optical environment on the radiative decay rate of rare-earth transitions in luminescent nanoparticles forming a thin film. We use electric dipole sources in finite-difference time-domain simulations to analyze the effect of modifying the effective refractive index of transparent layers made of phosphor nanocrystals doped with rare earth cations, and propose a correction to previously reported analytical models for calculating the radiative decay rate. Our predictions are tested against an experimental realization of such luminescent films, in which we manage to vary the effective refractive index in a gradual and controllable manner. Our model accurately accounts for the measurements attained, allows us to discriminate the radiative and non-radiative contributions to the time-resolved photoluminescence, and provides a way to rationally tune the spontaneous decay rate and hence the photoluminescence quantum yield in an ensemble of luminescent nanoparticles.
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Affiliation(s)
- Manuel Romero
- Institute of Materials Science of Seville, Spanish National Research Council - University of Seville, C. Américo Vespucio 49, 41092, Seville, Spain.
| | - Juan Ramón Sánchez-Valencia
- Institute of Materials Science of Seville, Spanish National Research Council - University of Seville, C. Américo Vespucio 49, 41092, Seville, Spain.
| | - Gabriel Lozano
- Institute of Materials Science of Seville, Spanish National Research Council - University of Seville, C. Américo Vespucio 49, 41092, Seville, Spain.
| | - Hernán Míguez
- Institute of Materials Science of Seville, Spanish National Research Council - University of Seville, C. Américo Vespucio 49, 41092, Seville, Spain.
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Viaña JM, Romero M, Lozano G, Míguez H. Nanoantennas Patterned by Colloidal Lithography for Enhanced Nanophosphor Light Emission. ACS APPLIED NANO MATERIALS 2022; 5:16242-16249. [PMID: 36466302 PMCID: PMC9706497 DOI: 10.1021/acsanm.2c03258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/18/2022] [Indexed: 06/17/2023]
Abstract
Transparent coatings made of rare-earth doped nanocrystals, also known as nanophosphors, feature efficient photoluminescence and excellent thermal and optical stability. Herein, we demonstrate that the optical antennas prepared by colloidal lithography render thin nanophosphor films with a brighter emission. In particular, we fabricate gold nanostructures in the proximity of GdVO4:Eu3+ nanophosphors by metal evaporation using a mask made of a monolayer of polymer beads arranged in a triangular lattice. Optical modes supported by the antennas can be controlled by tuning the diameter of the polymer spheres in the colloidal mask, which determines the shape of the gold nanostructure, as confirmed by numerical simulations. Confocal microscopy reveals that metallic antennas induce brighter photoluminescence at specific spatial regions of the nanophosphor film at targeted frequencies as a result of the coupling between gold nanostructures and nanophosphors. Patterning of nanophosphor thin layers with arrays of metallic antennas offers an inexpensive nanophotonic solution to develop bright emitting coatings of interest for color conversion, labeling, or anti-counterfeiting.
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Ngo TT, Cabello-Olmo E, Arroyo E, Becerro AI, Ocaña M, Lozano G, Míguez H. Highly Versatile Upconverting Oxyfluoride-Based Nanophosphor Films. ACS APPLIED MATERIALS & INTERFACES 2021; 13:30051-30060. [PMID: 34142553 PMCID: PMC8251696 DOI: 10.1021/acsami.1c07012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/02/2021] [Indexed: 05/26/2023]
Abstract
Fluoride-based compounds doped with rare-earth cations are the preferred choice of materials to achieve efficient upconversion, of interest for a plethora of applications ranging from bioimaging to energy harvesting. Herein, we demonstrate a simple route to fabricate bright upconverting films that are transparent, self-standing, flexible, and emit different colors. Starting from the solvothermal synthesis of uniform and colloidally stable yttrium fluoride nanoparticles doped with Yb3+ and Er3+, Ho3+, or Tm3+, we find the experimental conditions to process the nanophosphors as optical quality films of controlled thickness between few hundreds of nanometers and several micrometers. A thorough analysis of both structural and photophysical properties of films annealed at different temperatures reveals a tradeoff between the oxidation of the matrix, which transitions through an oxyfluoride crystal phase, and the efficiency of the upconversion photoluminescence process. It represents a significant step forward in the understanding of the fundamental properties of upconverting materials and can be leveraged for the optimization of upconversion systems in general. We prove bright multicolor upconversion photoluminescence in oxyfluoride-based phosphor transparent films upon excitation with a 980 nm laser for both rigid and flexible versions of the layers, being possible to use the latter to coat surfaces of arbitrary shape. Our results pave the way toward the development of upconverting coatings that can be conveniently integrated in applications that demand a large degree of versatility.
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Affiliation(s)
| | | | - Encarnación Arroyo
- Instituto de Ciencia de Materiales
de Sevilla, Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla, Américo Vespucio 49, 41092, Sevilla, Spain
| | - Ana I. Becerro
- Instituto de Ciencia de Materiales
de Sevilla, Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla, Américo Vespucio 49, 41092, Sevilla, Spain
| | - Manuel Ocaña
- Instituto de Ciencia de Materiales
de Sevilla, Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla, Américo Vespucio 49, 41092, Sevilla, Spain
| | - Gabriel Lozano
- Instituto de Ciencia de Materiales
de Sevilla, Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla, Américo Vespucio 49, 41092, Sevilla, Spain
| | - Hernán Míguez
- Instituto de Ciencia de Materiales
de Sevilla, Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla, Américo Vespucio 49, 41092, Sevilla, Spain
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Hofmann CLM, Fischer S, Eriksen EH, Bläsi B, Reitz C, Yazicioglu D, Howard IA, Richards BS, Goldschmidt JC. Experimental validation of a modeling framework for upconversion enhancement in 1D-photonic crystals. Nat Commun 2021; 12:104. [PMID: 33397918 PMCID: PMC7782824 DOI: 10.1038/s41467-020-20305-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 11/23/2020] [Indexed: 11/15/2022] Open
Abstract
Photonic structures can be designed to tailor luminescence properties of materials, which becomes particularly interesting for non-linear phenomena, such as photon upconversion. However, there is no adequate theoretical framework to optimize photonic structure designs for upconversion enhancement. Here, we present a comprehensive theoretical model describing photonic effects on upconversion and confirm the model’s predictions by experimental realization of 1D-photonic upconverter devices with large statistics and parameter scans. The measured upconversion photoluminescence enhancement reaches 82 ± 24% of the simulated enhancement, in the mean of 2480 separate measurements, scanning the irradiance and the excitation wavelength on 40 different sample designs. Additionally, the trends expected from the modeled interaction of photonic energy density enhancement, local density of optical states and internal upconversion dynamics, are clearly validated in all experimentally performed parameter scans. Our simulation tool now opens the possibility of precisely designing photonic structure designs for various upconverting materials and applications. A theoretical framework to optimize photonic structure designs for upconversion enhancement is lacking. Here, the authors present a comprehensive theoretical model and confirm the model’s predictions by experimental realisation of 1D-photonic upconverter devices with large statistics and parameter scans.
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Affiliation(s)
- Clarissa L M Hofmann
- Fraunhofer Institute for Solar Energy Systems, Heidenhofstraße 2, 79110, Freiburg, Germany. .,Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
| | - Stefan Fischer
- Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, CA, 94305, USA
| | - Emil H Eriksen
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000, Aarhus, Denmark
| | - Benedikt Bläsi
- Fraunhofer Institute for Solar Energy Systems, Heidenhofstraße 2, 79110, Freiburg, Germany
| | - Christian Reitz
- Institute of Nanotechnology (INT), Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Deniz Yazicioglu
- Fraunhofer Institute for Solar Energy Systems, Heidenhofstraße 2, 79110, Freiburg, Germany.,Laboratory for Nanotechnology, Institute of Micro Systems Technology - IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 79110, Freiburg, Germany
| | - Ian A Howard
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.,Light Technology Institute (LTI), Karlsruhe Institute of Technology, Engesserstrasse 13, 76131, Karlsruhe, Germany
| | - Bryce S Richards
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.,Light Technology Institute (LTI), Karlsruhe Institute of Technology, Engesserstrasse 13, 76131, Karlsruhe, Germany
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Geng D, Cabello-Olmo E, Lozano G, Míguez H. Tamm Plasmons Directionally Enhance Rare-Earth Nanophosphor Emission. ACS PHOTONICS 2019; 6:634-641. [PMID: 31049366 PMCID: PMC6488127 DOI: 10.1021/acsphotonics.8b01407] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Indexed: 05/04/2023]
Abstract
Rare-earth-based phosphors are the materials on which current solid-state lighting technology is built. However, their large crystal size impedes the tuning, optimization, or manipulation of emitted light that can be achieved by their integration in nanophotonic architectures. Herein we demonstrate a hybrid plasmonic-photonic architecture capable of both channeling in a specific direction and enhancing by eight times the emission radiated by a macroscopically wide layer of nanophosphors. In order to do so, a slab of rare-earth-based nanocrystals is inserted between a dielectric multilayer and a metal film, following a rational design that optimizes the coupling of nanophosphor emission to collective modes sustained by the metal-dielectric system. Our approach is advantageous for the optimization of solid-state lighting systems.
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Geng G, Yu C, Li X, Yuan X. Variable 3'polyadenylation of Wheat yellow mosaic virus and its novel effects on translation and replication. Virol J 2019; 16:23. [PMID: 30786887 PMCID: PMC6383263 DOI: 10.1186/s12985-019-1130-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/13/2019] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Polyadenylation influences many aspects of mRNA as well as viral RNA. variable polyadenylation at the 3' end have been reported in RNA viruses. It is interesting to identify the characteristic and potential role of 3' polyadenylation of Wheat yellow mosaic virus (WYMV), which has been reported to contain two genomic RNAs with 3' poly(A) tails and caused severe disease on wheat in East Asia region. METHODS 3' RACE was used to identify sequences of the 3' end in WYMV RNAs from naturally infected wheat by WYMV. In vitro translation assay was performed to analyze effect of UTRs of WYMV with or without 3'polyadenylation on translation. In vitro replication mediated by WYMV NIb protein were performed to evaluate effect of variable polyadenylation on replication. RESULTS Variable polyadenylation in WYMV RNAs was identified via 3' RACE. WYMV RNAs in naturally infected wheat in China simultaneously present with regions of long, short, or no adenylation at the 3' ends. The effects of variable polyadenylation on translation and replication of WYMV RNAs were evaluated. 5'UTR and 3'UTR of WYMV RNA1 or RNA2 synergistically enhanced the translation of the firefly luciferase (Fluc) gene in in vitro WGE system, whereas additional adenylates had an oppositive effect on this enhancement on translation mediated by UTRs of WYMV. Additional adenylates remarkably inhibited the synthesis of complementary strand from viral genome RNA during the in vitro replication mediated by WYMV NIb protein. CONCLUSIONS 3' end of WYMV RNAs present variable polyadenylation even no polyadenylation. 3' polyadenylation have opposite effect on translation mediated by UTRs of WYMV RNA1 or RNA2. 3' polyadenylation have negative effect on minus-strand synthesis of WYMV RNA in vitro. Variable polyadenylation of WYMV RNAs may provide sufficient selection on the template for translation and replication.
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Affiliation(s)
- Guowei Geng
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University; Shandong Province Key Laboratory of Agricultural Microbiology, No 61, Daizong Street, Shandong Province Tai’an, 271018 People’s Republic of China
| | - Chengming Yu
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University; Shandong Province Key Laboratory of Agricultural Microbiology, No 61, Daizong Street, Shandong Province Tai’an, 271018 People’s Republic of China
| | - Xiangdong Li
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University; Shandong Province Key Laboratory of Agricultural Microbiology, No 61, Daizong Street, Shandong Province Tai’an, 271018 People’s Republic of China
| | - Xuefeng Yuan
- Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University; Shandong Province Key Laboratory of Agricultural Microbiology, No 61, Daizong Street, Shandong Province Tai’an, 271018 People’s Republic of China
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Geng D, Lozano G, Míguez H. Highly Efficient Transparent Nanophosphor Films for Tunable White-Light-Emitting Layered Coatings. ACS APPLIED MATERIALS & INTERFACES 2019; 11:4219-4225. [PMID: 30576105 PMCID: PMC6422321 DOI: 10.1021/acsami.8b17368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Bright luminescence in rare-earth (RE) nanocrystals, the so-called nanophosphors, is generally achieved by choosing a host that enables an effective excitation of the RE activator through charge or energy transfer. Although tungstate, molybdate, or vanadate compounds provide the aforementioned transfer, a comparative analysis of the efficiency of such emitters remains elusive. Herein, we perform a combined structural and optical analysis, which reveals that the tetragonal GdVO4 matrix gives rise to the highest efficiency among the different transparent nanophosphor films compared. Then, we demonstrate that by a sequential stacking of optical quality layers made of Eu3+- and Dy3+-doped nanocrystals, it is possible to attain highly transparent white-light-emitting coatings of tunable shade with photoluminescence quantum yields above 35%. Layering provides a precise dynamic tuning of the chromaticity based on the photoexcitation wavelength dependence of the emission of the nanophosphor ensemble without altering the chemical composition of the emitters or degrading their efficiency. The total extinction of the incoming radiation along with the high quantum yields achieved makes these thin-layered phosphors one of the most efficient transparent white converter coatings ever developed.
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