Recent Advances in Luminescent Nanomaterials for LEDs

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanoelectronics, Nanosensors and Devices".

Deadline for manuscript submissions: closed (20 February 2023) | Viewed by 4765

Special Issue Editor

Department of Microelectronic Science and Engineering, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
Interests: luminescent materials and their applications in white-LED; optical thermometry; photocatalysis

Special Issue Information

Dear Colleagues,

Light-emitting diodes (LEDs), composed of a commercial near-ultraviolet (NUV) chip and luminescent materials, have been widely investigated, owing to their admirable advantages such as high brightness, energy saving, small size, long durability, etc. Currently, to obtain luminescent material-based LEDs, several methods, such as combining a blue chip with yellow-emitting phosphors and utilizing a NUV or blue chip to excite multicolor phosphors, have been proposed. Evidently, the electroluminescence properties of packaged LEDs are greatly dependent on the performance of luminescent materials, and although plenty have been developed for LEDs, they still suffer some shortages, such as a high cost, narrow absorption range, unsatisfying efficiency, and harsh synthetic conditions, limiting their vivid applications. Thereby, more efforts should be carried out to develop novel luminescent materials as, currently, there is an increasing interest in them on account of their unique features (i.e., intense luminescence behaviors and controllable particle size and shape) and promising applications in LEDs.

This Special Issue aims to display the current state-of-the-art in the utilization of luminescent nanomaterials for LEDs, including the utilization of a special technique to modify the performance of luminescent materials and the development of new kinds of reaction technologies to prepare luminescent nanomaterials. We invite authors to contribute original research and review articles covering the current progress on luminescent nanomaterials for LEDs. Potential topics include, but are not limited to:

  • Rare-earth ion-doped luminescent nanomaterials for LEDs;
  • Self-activated luminescent nanoparticles for LEDs;
  • Transition metal ion-doped luminescent nanomaterials for LEDs;
  • Organic or inorganic luminescent nanomaterials for LEDs;
  • Quantum dots for LEDs.

Dr. Peng Du
Guest Editor

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Keywords

  • phosphors
  • photoluminescence
  • rare-earth ions
  • nanoparticles
  • luminescent nanomaterials
  • LEDs
  • upconversion

Published Papers (4 papers)

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Research

9 pages, 6727 KiB  
Article
Quantum Cutting in KGd(CO3)2:Tb3+ Green Phosphor
by Dechuan Li, Jian Qian, Lei Huang, Yumeng Zhang and Guangping Zhu
Nanomaterials 2023, 13(2), 351; https://doi.org/10.3390/nano13020351 - 15 Jan 2023
Cited by 3 | Viewed by 1523
Abstract
Phosphors with a longer excitation wavelength exhibit higher energy conversion efficiency. Herein, quantum cutting KGd(CO3)2:Tb3+ phosphors excited by middle-wave ultraviolet were synthesized via a hydrothermal method. All the KGd(CO3)2:xTb3+ phosphors remain [...] Read more.
Phosphors with a longer excitation wavelength exhibit higher energy conversion efficiency. Herein, quantum cutting KGd(CO3)2:Tb3+ phosphors excited by middle-wave ultraviolet were synthesized via a hydrothermal method. All the KGd(CO3)2:xTb3+ phosphors remain in monoclinic structures in a large Tb3+ doping range. In the KGd(CO3)2 host, 6D3/2 and 6I17/2 of Gd3+ were employed for quantum cutting in sensitizing levels. The excited state electrons could easily transfer from Gd3+ to Tb3+ with high efficiency. There are three efficient excited bands for quantum cutting. The excited wavelengths of 244, 273, and 283 nm correspond to the transition processes of 8S7/26D3/2 (Gd3+), 8S7/26I17/2 (Gd3+), and 7F65F4 (Tb3+), and the maximum quantum yields of KGd(CO3)2:Tb3+ can reach 163.5, 119, and 143%, respectively. The continuous and efficient excitation band of 273–283 nm can well match the commercial 275 nm LED chip to expand the usage of solid-state light sources. Meanwhile, the phosphor also shows good excitation efficiency at 365 nm in a high Tb3+ doping concentration. Therefore, KGd(CO3)2:Tb3+ is an efficient green-emitting phosphor for ultraviolet-excited solid-state light sources. Full article
(This article belongs to the Special Issue Recent Advances in Luminescent Nanomaterials for LEDs)
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11 pages, 3241 KiB  
Article
Room-Temperature Synthesis of Highly-Efficient Eu3+-Activated KGd2F7 Red-Emitting Nanoparticles for White Light-Emitting Diode
by Yongqiang Zhong, Qian Wu, Jiujun Zhu, Peiqing Cai and Peng Du
Nanomaterials 2022, 12(24), 4397; https://doi.org/10.3390/nano12244397 - 09 Dec 2022
Cited by 4 | Viewed by 1153
Abstract
Luminescent materials with high thermal stability and quantum efficiency are extensively desired for indoor illumination. In this research, a series of Eu3+-activated KGd2F7 red-emitting nanoparticles were prepared at room temperature and their phase structure, morphology, luminescence properties, as [...] Read more.
Luminescent materials with high thermal stability and quantum efficiency are extensively desired for indoor illumination. In this research, a series of Eu3+-activated KGd2F7 red-emitting nanoparticles were prepared at room temperature and their phase structure, morphology, luminescence properties, as well as thermal stability, have been studied in detail. Excited by 393 nm, the resultant nanoparticles emitted bright red emissions and its optimal status was realized when the Eu3+ content was 30 mol%, in which the concentration quenching mechanism was triggered by electric dipole–dipole interaction. Through theoretical analysis via the Judd–Ofelt theory, one knows that Eu3+ situates at the high symmetry sites in as-prepared nanoparticles. Moreover, the internal and extra quantum efficiencies of designed nanoparticles were dependent on Eu3+ content. Furthermore, the studied nanoparticles also had splendid thermal stability and the corresponding activation energy was 0.18 eV. Additionally, via employing the designed nanoparticles as red-emitting constituents, a warm white light-emitting diode (white-LED), which exhibits low correlated color temperature (4456 K), proper luminous efficiency (17.2 lm/W) and high color rendering index (88.3), was developed. Our findings illustrate that Eu3+-activated KGd2F7 nanoparticles with bright red emissions are able to be used to promote the performance of white-LED. Full article
(This article belongs to the Special Issue Recent Advances in Luminescent Nanomaterials for LEDs)
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8 pages, 2426 KiB  
Article
Optical Properties and Concentration Quenching Mechanism of Er3+ Heavy Doped Gd2(MoO4)3 Phosphor for Green Light-Emitting Diode
by Dongyu Li, Bing Xu, Zhen Huang, Xiao Jin, Zhenghe Zhang, Tingting Zhang, Deng Wang, Xuping Liu and Qinghua Li
Nanomaterials 2022, 12(20), 3641; https://doi.org/10.3390/nano12203641 - 17 Oct 2022
Cited by 2 | Viewed by 1235
Abstract
Upconversion materials capable of converting low-energy excitation photons into high-energy emission photons have attracted considerable interest in recent years. However, the low upconversion luminescence seriously hinders the application of upconversion phosphors. Heavy lanthanide doping without concentration quenching represents a direct and effective method [...] Read more.
Upconversion materials capable of converting low-energy excitation photons into high-energy emission photons have attracted considerable interest in recent years. However, the low upconversion luminescence seriously hinders the application of upconversion phosphors. Heavy lanthanide doping without concentration quenching represents a direct and effective method to enhance the emission intensity. In this study, Er3+ heavy doped Gd2(MoO4)3 phosphor with a monoclinic phase was prepared by a sol–gel process. Under excitation at 976 nm, Gd2(MoO4)3:Er3+ phosphor emitted remarkably intense green emission, and Er3+ concentration up to 20 mol% did not cause concentration quenching. Here, we discuss the upconversion mechanism and concentration quenching. When the Er3+ concentration was in the range of 30–60 mol%, the concentration quenching was governed by the electric dipole–dipole interaction, and when the concentration was greater than 60 mol%, the concentration quenching was controlled by the exchange interactions. The result provides a schematic basis for identifying a phosphor host with heavy lanthanide doping. Full article
(This article belongs to the Special Issue Recent Advances in Luminescent Nanomaterials for LEDs)
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14 pages, 8049 KiB  
Article
Synthesis and Luminescence Properties of Eu2+-Doped Sr3MgSi2O8 Blue Light-Emitting Phosphor for Application in Near-Ultraviolet Excitable White Light-Emitting Diodes
by Chou-Yuan Lee, Chia-Ching Wu, Hsin-Hua Li and Cheng-Fu Yang
Nanomaterials 2022, 12(15), 2706; https://doi.org/10.3390/nano12152706 - 06 Aug 2022
Cited by 5 | Viewed by 1439
Abstract
In this study, [Sr0.99Eu0.01]3MgSi2O8 phosphors were sintered at 1200–1400 °C for 1–5 h by using the solid-state reaction method. The crystallinity and morphology of these phosphors were characterized through X-ray diffraction analysis and field-emission [...] Read more.
In this study, [Sr0.99Eu0.01]3MgSi2O8 phosphors were sintered at 1200–1400 °C for 1–5 h by using the solid-state reaction method. The crystallinity and morphology of these phosphors were characterized through X-ray diffraction analysis and field-emission scanning electron microscopy, respectively, to determine their luminescence. The photoluminescence properties, including the excitation and emission properties, of the prepared phosphors were investigated through fluorescence spectrophotometry. The α-Sr2SiO4, Sr2MgSi2O7, and Sr3MgSi2O8 phases coexisted in the [Sr0.99Eu0.01]3MgSi2O8 phosphors, which were synthesized at low temperatures. The particles of these phosphors had many fine hairs on their surface and resembled Clavularia viridis, which is a coral species. Transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the fine hairs contained the Sr2SiO4 and Sr2MgSi2O7 phases. However, when the [Sr0.99Eu0.01]3MgSi2O8 phosphors were sintered at 1400 °C, the Sr3MgSi2O8 phase was observed, and the Eu2+-doped Sr3MgSi2O8 phase dominated the only broad emission band, which had a central wavelength of 457 nm (blue light). The emission peaks at this wavelength were attributed to the 4f65d1–4f7 transition at the Sr2+(I) site, where Sr2+ was substituted by Eu2+. The average decay time of the synthesized phosphors was calculated to be 1.197 ms. The aforementioned results indicate that [Sr0.99Eu0.01]3MgSi2O8 can be used as a blue-emitting phosphor in ultraviolet-excited white light-emitting diodes. Full article
(This article belongs to the Special Issue Recent Advances in Luminescent Nanomaterials for LEDs)
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