Optoelectronic Materials

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Nanomaterials nanomaterials	5.719	7.4	2011	12.7 Days	2600 CHF
Polymers polymers	4.967	6.6	2009	12.4 Days	2400 CHF
Applied Sciences applsci	2.838	4.5	2011	14.9 Days	2300 CHF
Crystals crystals	2.670	3.6	2011	11.6 Days	2000 CHF
Electronic Materials electronicmat	-	-	2020	14.6 Days	1000 CHF

Open AccessArticle

Nonradiative Energy Transfer in Bi₂O₃/Tm₂O₃ Powders under IR Excitation at Liquid Nitrogen Temperature

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Dmitry A. Artamonov

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Anna V. Tsibulnikova

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Vasily A. Slezhkin

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Alexey S. Kozhevnikov

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Ilia G. Samusev

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Ivan I. Lyatun

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Valery V. Bryukhanov

Crystals 2023, 13(3), 534; https://doi.org/10.3390/cryst13030534 - 20 Mar 2023

Viewed by 490

Abstract

The presented work shows the study of energy transitions in the NIR and visible regions in the system of Bi₂O₃ and Tm₂O₃ powders. Mechanisms of upconversion luminescence and NIR luminescence between two Bi³⁺ and Tm³⁺ [...] Read more.

The presented work shows the study of energy transitions in the NIR and visible regions in the system of Bi₂O₃ and Tm₂O₃ powders. Mechanisms of upconversion luminescence and NIR luminescence between two Bi³⁺ and Tm³⁺ ions at T = 80 K accompanied with nonradiative energy transfer through the vibrational levels were investigated under IR photoexcitation. The absorption bands of the samples on the reflection spectra were examined in the visible region. The values of the emission cross-section parameters were calculated for the Bi₂O₃/Tm₂O₃ complexes. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Trapped Carrier Recombination in Sb₂Se₃ Polycrystalline Film

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Crystals 2023, 13(3), 406; https://doi.org/10.3390/cryst13030406 - 27 Feb 2023

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Abstract

Sb₂Se₃ has recently emerged as a promising material for optic-electronic applications. In this work, trapped carrier recombination in Sb₂Se₃ was investigated by joint use of time-resolved microwave conductivity (TRMC) and photoluminescence (PL) spectroscopy. trapped carrier thermal excitation [...] Read more.

Sb₂Se₃ has recently emerged as a promising material for optic-electronic applications. In this work, trapped carrier recombination in Sb₂Se₃ was investigated by joint use of time-resolved microwave conductivity (TRMC) and photoluminescence (PL) spectroscopy. trapped carrier thermal excitation into the continuous band was observed in TRMC kinetics. Based on the exponential band tail model, the depth of the trap state, where trapped carriers are released into a continuous band, was estimated to range from 33.0 meV to 110.0 meV at room temperature. Temperature-varying TRMC and PL were further employed to study the influence of temperature on the trapped carrier recombination. Negative thermal quenchings of PL intensity and quantity of thermal emission carriers were observed and can be well explained by the thermal excitation of deep trapped carriers into shallow trap states and the continuous band. Two thermal activation energies of 12.5 meV and 304.0 meV were also revealed. This work is helpful for understanding the trapped carrier recombination process in polycrystalline Sb₂Se₃ film. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Abnormal Domain Growth during Polarization Reversal in Lithium Niobate Crystal Modified by Proton Exchange

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Crystals 2023, 13(1), 72; https://doi.org/10.3390/cryst13010072 - 01 Jan 2023

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Abstract

The results of an experimental study of the abnormal domain structure kinetics in lithium niobate single crystals with a surface layer modified by soft proton exchange are presented. Domain switching in a wide field range allowed two qualitatively different types of domain structure [...] Read more.

The results of an experimental study of the abnormal domain structure kinetics in lithium niobate single crystals with a surface layer modified by soft proton exchange are presented. Domain switching in a wide field range allowed two qualitatively different types of domain structure evolution to be revealed: (1) the traditional growth of hexagonal domains in fields higher than 21.5 kV/mm and (2) the abnormal growth of stripe domains oriented along the Y crystallographic directions in the field range from 3.8 to 21.5 kV/mm. The stripe domains had a width up to 4 µm and depth up to 30 µm. It was shown that the time dependence of the total length of stripe domains could be analyzed in terms of the modified Kolmogorov–Avrami approach, taking into account the transition from the one-dimensional β-model to the one-dimensional α-model. The possibility of the controllable creation of a quasi-periodic structure of stripe domains with an average period of 5 µm by a two-stage polarization switching process was demonstrated. The formation and growth of stripe domains were considered in terms of the kinetic approach to the evolution of the domain structure as a result of the domain walls’ motion under inefficient screening conditions caused by the presence of a modified surface layer. The abnormally low threshold fields were attributed to a presence of a “built-in” field facilitating switching, created by a composition gradient induced by soft proton exchange. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array

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Nanomaterials 2022, 12(21), 3880; https://doi.org/10.3390/nano12213880 - 03 Nov 2022

Viewed by 717

Abstract

Nanorod array and planar green-emission InGaN/GaN multi-quantum well (MQW) LEDs were fabricated by lithography, nano-imprinting, and top–down etching technology. The defect-pinning effect of the nanostructure was found for the first time. The ratio of the bright regions to the global area in the [...] Read more.

Nanorod array and planar green-emission InGaN/GaN multi-quantum well (MQW) LEDs were fabricated by lithography, nano-imprinting, and top–down etching technology. The defect-pinning effect of the nanostructure was found for the first time. The ratio of the bright regions to the global area in the panchromatic CL images of green MQW samples increased from 30% to about 90% after nano-fabrication. The overall luminous performance significantly improved. Throughout temperature-dependent photoluminescence (TDPL) and time-resolved PL (TRPL) measurements, the migration and recombination of carriers in the MQWs of green LEDs were analyzed. It was proved that nanostructures can effectively prevent carriers from being captured by surrounding nonradiative recombination centers. The overall PL integral intensity can be enhanced to above 18 times. A much lower carrier lifetime (decreasing from 91.4 to 40.2 ns) and a higher internal quantum efficiency (IQE) (increasing from 16.9% to 40.7%) were achieved. Some disputes on the defect influence were also discussed and clarified. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Wafer-Scale Fabrication of Silicon Film on Lithium Niobate on Insulator (LNOI)

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Crystals 2022, 12(10), 1477; https://doi.org/10.3390/cryst12101477 - 18 Oct 2022

Cited by 1 | Viewed by 1203

Abstract

Hybrid integration of silicon photonics with lithium niobate (LN) devices provides a promising route to enable an excellent modulation performance in silicon photonic integrated circuits. To realize this purpose, a substrate containing a Si film on an LNOI substrate, called Si on the [...] Read more.

Hybrid integration of silicon photonics with lithium niobate (LN) devices provides a promising route to enable an excellent modulation performance in silicon photonic integrated circuits. To realize this purpose, a substrate containing a Si film on an LNOI substrate, called Si on the LNOI structure, was analyzed and fabricated. The mode propagation properties in the Si-on-LNOI structure were simulated in detail and a vertical adiabatic coupler (VAC) between the Si waveguide and LN waveguide was simulated to help in the determination of the dimension of this structure. A 4-inch wafer-scale Si on an LNOI hybrid structure was fabricated through the ion-cut process. This structure has a single-crystalline quality, high thickness uniformity, smooth surface, and sharp bonding interface, which are practical for realizing low loss and high coupling efficiency. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessCommunication

Modified Fabrication of Perovskite-Based Composites and Its Exploration in Printable Humidity Sensors

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Polymers 2022, 14(20), 4354; https://doi.org/10.3390/polym14204354 - 16 Oct 2022

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Abstract

Organic perovskites are promising optoelectronic semiconductor materials with photoelectric applications. It is known that the luminescence of perovskites is highly sensitive to hydron molecules due to its low moisture resistance of crystal structure, indicating its potential application on humidity-sensing. Herein, a novel perovskite-based [...] Read more.

Organic perovskites are promising optoelectronic semiconductor materials with photoelectric applications. It is known that the luminescence of perovskites is highly sensitive to hydron molecules due to its low moisture resistance of crystal structure, indicating its potential application on humidity-sensing. Herein, a novel perovskite-based compound (PBC) with minimal defects was developed to promote the photoluminescence performance via optimization of the drying method and precursor constitutions. Perovskite materials with good structural integrity and enhanced fluorescence performance up to four times were obtained from supercritical drying. Moreover, the hydrophilic polymer matrix, polyethylene oxide (PEO), was added to obtain a composite of perovskite/PEO (PPC), introducing enhanced humidity sensitivity and solution processibility. These perovskite/PEO composites also exhibited long-term stability and manifold cycles of sensitivity to humidity owing to perovskite encapsulation by PEO. In addition, this precursor solution of perovskite-based composites could be fancily processed by multiple methods, including printing and handwriting, which demonstrates the potential and broaden the applications in architecture decoration, logos, trademarks, and double encryption of anti-fake combined with humidity. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

The First-Principle Study on Tuning Optical Properties of MA₂Z₄ by Cr Replacement of Mo Atoms in MoSi₂N₄

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Nanomaterials 2022, 12(16), 2822; https://doi.org/10.3390/nano12162822 - 17 Aug 2022

Cited by 1 | Viewed by 1777

Abstract

Recently, with the successful preparation of MoSi₂N_4, an emerging family of two-dimensional (2D) layered materials has been predicted with a general formula of MA₂Z₄ (M: an early transition metal, A: Si or Ge and Z: N, P, [...] Read more.

Recently, with the successful preparation of MoSi₂N_4, an emerging family of two-dimensional (2D) layered materials has been predicted with a general formula of MA₂Z₄ (M: an early transition metal, A: Si or Ge and Z: N, P, or As). In terms of this new type of 2D material, how to effectively tune its light absorption properties is unclear. We systematically discuss the effects of replacing Mo with Cr atoms on the lattice structure, energy bands, and light absorption properties of 2D monolayer MoSi₂N₄ using density functional theory (DFT) and the Vienna Ab initio Simulation Package (VASP). Additionally, the results show that the single replacement of the atom Cr has no significant effect on the lattice structure of the outermost and sub-outer layers but plays a major role in the accumulation of electrons. In addition, the 2D MoSi₂N₄, Mo_0.5Cr_0.5Si₂N₄, and CrSi₂N₄ all have effective electron–hole separation properties. In the visible region, as the excited state increases, the required excitation energy is higher and the corresponding wavelength of light is shorter. It was found that the ultraviolet (UV)–visible spectra are red-shifted when Cr atoms replace Mo atoms in MoSi₂N₄; when Cr atoms and Mo atoms coexist, the coupling between Cr atoms and Mo atoms achieves modulation of the ultraviolet (UV)–visible spectra. Finally, we reveal that doping M-site atoms can effectively tune the light absorption properties of MA₂Z₄ materials. These results provide a strategy for the design of new 2D materials with high absorption properties. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Study on Fluorescence Properties of Green-Blue Apatite

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Qicheng Yan

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Ziyuan Liu

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Ying Guo

Crystals 2022, 12(6), 866; https://doi.org/10.3390/cryst12060866 - 19 Jun 2022

Viewed by 1460

Abstract

The fluorescence phenomenon of apatite is an important feature. In this paper, three apatites with uniform transition from green to blue were selected, and the fluorescence color characteristics of the samples were observed under UV fluorescent lamp and DiamondView. With 3D fluorescence technology, [...] Read more.

The fluorescence phenomenon of apatite is an important feature. In this paper, three apatites with uniform transition from green to blue were selected, and the fluorescence color characteristics of the samples were observed under UV fluorescent lamp and DiamondView. With 3D fluorescence technology, combined with LA-ICP-MS, this paper aims to comprehensively test the fluorescence phenomenon of apatite to explore the relationship between apatite fluorescence and elements and analyze the fluorescence color characteristics. With the experiments mentioned above, this paper explores the fluorescent color characteristics of gemstones and their influencing factors to improve the color system of apatite. UV and DiamondView experiments show that with the change from green to blue, apatites show weak purple–red to strong pink–purple fluorescence. The 3D fluorescence test shows that the samples have two notable fluorescence emission peaks: (1) The fluorescence peak group composed of the double fluorescence peaks around 600 nm is generated by the excitation light source at 450 and 470 nm and a weaker fluorescence peak generated by the excitation at 400 nm; (2) The fluorescence emission peak of the sample gradually becomes prominent and the intensity increases significantly near the areas where the excitation wavelength is 280–330 nm and where the emission wavelength is 380 nm. According to the LA-ICP-MS test combined with the element properties, the fluorescence peak group (1) is mainly affected by Mn²⁺, Sm³⁺, and Pr³⁺, which emit orange fluorescence. The fluorescence emission peak (2) is caused by Ce³⁺, Eu³⁺, Dy³⁺, and Tb³⁺, which emit purple fluorescence. The mixing of the two fluorescent colors results in violet–pink fluorescence. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessFeature PaperArticle

Electrically Tunable Solution-Processed Transparent Conductive Thin Films Based on Colloidally Dispersed ITO@Ag Composite Ink

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Nanomaterials 2022, 12(12), 2060; https://doi.org/10.3390/nano12122060 - 15 Jun 2022

Cited by 3 | Viewed by 1238

Abstract

Silver (Ag) introduced colloidal Sn-doped In₂O₃ (ITO) ink for transparent conductive electrodes (TCEs) was prepared to overcome the limitation of colloidally prepared thin film; low density thin film, high resistance. ITO@Ag colloid ink was made by controlling the weight ratio [...] Read more.

Silver (Ag) introduced colloidal Sn-doped In₂O₃ (ITO) ink for transparent conductive electrodes (TCEs) was prepared to overcome the limitation of colloidally prepared thin film; low density thin film, high resistance. ITO@Ag colloid ink was made by controlling the weight ratio of ITO and Ag nanoparticles through ball-milling and fabricated using spin coating. These films were dried at 220 °C and heat-treated at 450–750 °C in an air atmosphere to pyrolyze the organic ligand attached to the nanoparticles. All thin films showed high crystallinity. As the thermal treatment temperature increased, films showed a cracked surface, but as the weight percentage of silver increased, a flattened and smooth surface appeared, caused by the metallic silver filling the gap between the nano-particles. This worked as a bridge to allow electrical conduction, which decreases the resistivity over an order of magnitude, from 309 to 0.396, and 0.107

Ω \cdot cm

for the ITO-220 °C, ITO-750 °C, and ITO@Ag (7.5 wt.%)-750 °C, respectively. These films also exhibited >90% optical transparency. Lowered resistivity is caused due to the inclusion of silver, providing a sufficient number of charge carriers. Furthermore, the work function difference between ITO and silver builds an ohmic junction, allowing fluent electrical flow without any barrier. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Femtosecond Laser Deposition of Germanium Selenide onto Silicon Platform at Different Substrate Temperatures

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Nanomaterials 2022, 12(12), 2003; https://doi.org/10.3390/nano12122003 - 10 Jun 2022

Viewed by 1054

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Germanium selenide (GeSe) thin films were fabricated by employing femtosecond pulsed-laser deposition (fs-PLD) on silicon (100) substrates at various substrate temperatures, ranging from 25 °C to 600 °C. The thin films’ surface morphology qualities and optical properties were studied by utilising transmission electron [...] Read more.

Germanium selenide (GeSe) thin films were fabricated by employing femtosecond pulsed-laser deposition (fs-PLD) on silicon (100) substrates at various substrate temperatures, ranging from 25 °C to 600 °C. The thin films’ surface morphology qualities and optical properties were studied by utilising transmission electron microscopy (TEM) and X-ray diffraction (XRD). The X-ray diffraction result signifies that the thin films deposited on the silicon at a substrate temperature below 400 °C were amorphous Ge-Se. In contrast, those grown at 400 °C and above exhibited crystallised peaks of Ge-Se orthorhombic and tetragonal structures. The deposition growth rate of the thin films was also found to decrease substantially with increasing substrate temperature. These results show that the fs-PLD process has great potential for fabricating good quality Ge-Se thin film. This technique could enable the manufacture of modern optoelectronic devices for applications in optical communication, sensing, and ovonic threshold switching for the high-density crossbar memory array. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Numerical Simulation of Solid–Liquid Interface of GaInSb Crystal Growth with Travelling Heater Method

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Crystals 2022, 12(6), 793; https://doi.org/10.3390/cryst12060793 - 31 May 2022

Viewed by 938

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The heat transfer and liquid phase convection during GaInSb crystal growth via the traveling heater method (with a seed) were investigated using numerical simulation to optimize the process parameters and shorten the experimental period in order to produce a high-quality crystal widely used [...] Read more.

The heat transfer and liquid phase convection during GaInSb crystal growth via the traveling heater method (with a seed) were investigated using numerical simulation to optimize the process parameters and shorten the experimental period in order to produce a high-quality crystal widely used to make various optoelectronic devices. There will be a phenomenon of “thermal impermeability” with an increase in crystal radii for the same furnace temperature profile. The maximum furnace temperature should display an increase of at least 1030 K to 1060 K in order to ensure the successful introduction of the seed with an increase of the crystal radius from 0.01 m to 0.03 m. The interface bending of the solid–liquid interface significantly increases with an increase of the crystal radius from 0.01 m to 0.02 m by about 50%, 67%, and 140%, corresponding to the maximum furnace temperatures 1030 K, 1040 K, and 1050 K, respectively. However, it decreases significantly when the maximum temperature increases from 1030 K to 1050 K, from 0.16 to 0.05, 0.2 to 0.105, and 0.24 to 0.12, corresponding to the crystal radii 0.01 m, 0.015 m, and 0.02 m, respectively. The maximum flow velocity of melt increases slightly with the furnace maximum temperature for the same radius, less than about 6%. However, it increases significantly with the increase of the radius from 0.01 m to 0.02 m, more than 68%. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Mechanically Contacted Distributed-Feedback Optical Microcavity

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Nanomaterials 2022, 12(11), 1883; https://doi.org/10.3390/nano12111883 - 31 May 2022

Viewed by 1081

Abstract

We report a construction of distributed-feedback (DFB) optical microcavities, which is realized through mechanical contact between a high-quality planar thin film of a polymeric semiconductor and a large-area homogeneous nanograting. Using poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] (F8BT) as the active medium for the planar layer, we [...] Read more.

We report a construction of distributed-feedback (DFB) optical microcavities, which is realized through mechanical contact between a high-quality planar thin film of a polymeric semiconductor and a large-area homogeneous nanograting. Using poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] (F8BT) as the active medium for the planar layer, we achieve strong amplified spontaneous emission from such a microcavity with a low threshold. This not only simplifies largely the fabrication techniques for DFB microcavities, but also avoids the unexpected chemical interactions during solution processing between the organic semiconductors and the nanograting materials. Furthermore, high-quality polymer thin films with high surface smoothness and high thickness homogeneity are employed without any modulations for constructing the microcavities. This also suggests new designs of microcavity light-emitting diodes, or even for realizing electrically pumped polymer lasers, simply by metallizing the dielectric nanogratings as the electrodes. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Shaping in the Third Direction; Fabrication of Hemispherical Micro-Concavity Array by Using Large Size Polystyrene Spheres as Template for Direct Self-Assembly of Small Size Silica Spheres

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Ion Sandu

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Claudiu Teodor Fleaca

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Florian Dumitrache

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Bogdan Alexandru Sava

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Polymers 2022, 14(11), 2158; https://doi.org/10.3390/polym14112158 - 26 May 2022

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Abstract

Silica and polystyrene spheres with a small size ratio (r = 0.005) form by sequential hanging drop self-assembly, a binary colloidal crystal through which calcination transforms in a silica-ordered concavity array. These arrays are capable of light Bragg diffraction and shape dependent optical [...] Read more.

Silica and polystyrene spheres with a small size ratio (r = 0.005) form by sequential hanging drop self-assembly, a binary colloidal crystal through which calcination transforms in a silica-ordered concavity array. These arrays are capable of light Bragg diffraction and shape dependent optical phenomena, and they can be transformed into inverse-opal structures. Hierarchical 2D and 3D super-structures with ordered concavities as structural units were fabricated in this study. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Study of Electronic and Transport Properties in Double-Barrier Resonant Tunneling Systems

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Nanomaterials 2022, 12(10), 1714; https://doi.org/10.3390/nano12101714 - 17 May 2022

Cited by 2 | Viewed by 1261

Abstract

Resonant tunneling devices are still under study today due to their multiple applications in optoelectronics or logic circuits. In this work, we review an out-of-equilibrium GaAs/AlGaAs double-barrier resonant tunneling diode system, including the effect of donor density and external potentials in a self-consistent [...] Read more.

Resonant tunneling devices are still under study today due to their multiple applications in optoelectronics or logic circuits. In this work, we review an out-of-equilibrium GaAs/AlGaAs double-barrier resonant tunneling diode system, including the effect of donor density and external potentials in a self-consistent way. The calculation method uses the finite-element approach and the Landauer formalism. Quasi-stationary states, transmission probability, current density, cut-off frequency, and conductance are discussed considering variations in the donor density and the width of the central well. For all arrangements, the appearance of negative differential resistance (NDR) is evident, which is a fundamental characteristic of practical applications in devices. Finally, a comparison of the simulation with an experimental double-barrier system based on InGaAs with AlAs barriers reported in the literature has been obtained, evidencing the position and magnitude of the resonance peak in the current correctly. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessEditor’s ChoiceArticle

High Luminous Efficacy Phosphor-Converted Mass-Produced White LEDs Achieved by AlN Prebuffer and Transitional-Refraction-Index Patterned Sapphire Substrate

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Nanomaterials 2022, 12(10), 1638; https://doi.org/10.3390/nano12101638 - 11 May 2022

Cited by 1 | Viewed by 1162

Abstract

Constant advance in improving the luminous efficacy (η_L) of nitride-based light-emitting diodes (LEDs) plays a critical role for saving measurable amounts of energy. Further development is motivated to approach the efficiency limit for this material system while reducing the costs. [...] Read more.

Constant advance in improving the luminous efficacy (η_L) of nitride-based light-emitting diodes (LEDs) plays a critical role for saving measurable amounts of energy. Further development is motivated to approach the efficiency limit for this material system while reducing the costs. In this work, strategies of using thin AlN prebuffer and transitional-refraction-index patterned sapphire substrate (TPSS) were proposed, which pushed up the efficiency of white LEDs (WLEDs). The AlN prebuffer was obtained through physical vapor deposition (PVD) method and TPSS was fabricated by dry-etched periodic silica arrays covered on sapphire. Devices in mass production confirmed that PVD AlN prebuffer was able to improve the light output power (φ_e) of blue LEDs (BLEDs) by 2.53% while increasing the productivity by ~8% through shortening the growth time. Additionally, BLEDs on TPSS exhibited an enhanced top η_ext of 5.65% in contrast to BLEDs on the conventional PSS through Monte Carlo ray-tracing simulation. Consequently, φ_e of BLEDs was experimentally enhanced by 10% at an injected current density (J_in) of 40 A/cm². A peak η_L of 295.2 lm/W at a J_in of 0.9 A/cm² and the representative η_L of 282.4 lm/W at a J_in of 5.6 A/cm² for phosphor-converted WLEDs were achieved at a correlated color temperature of 4592 K. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

High-Resolution Patterning of Organic Emitting-Layer by Using Inkjet Printing and Sublimation Transfer Process

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Jun Yeub Lee

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Byeong-Kwon Ju

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Kwan Hyun Cho

Nanomaterials 2022, 12(9), 1611; https://doi.org/10.3390/nano12091611 - 09 May 2022

Viewed by 1454

Abstract

We implemented ultra-high resolution patterns of 2822 pixels-per-inch (PPI) via an inkjet printing and vacuum drying process grafted onto a sublimation transfer process. Co-solvented ink with a 1:1 ratio of N,N-dimethylformamide (DMF) to ortho-dichlrorobenzene (oDCB) was used, and the inkjet driving waveform was [...] Read more.

We implemented ultra-high resolution patterns of 2822 pixels-per-inch (PPI) via an inkjet printing and vacuum drying process grafted onto a sublimation transfer process. Co-solvented ink with a 1:1 ratio of N,N-dimethylformamide (DMF) to ortho-dichlrorobenzene (oDCB) was used, and the inkjet driving waveform was optimized via analysis of Ohnesorge (Oh)—Reynolds (Re) numbers. Inkjet printing conditions on the donor substrate with 2822 PPI microchannels were investigated in detail according to the drop space and line space. Most sublimation transferred patterns have porous surfaces under drying conditions in an air atmosphere. Unlike the spin-coating process, the drying process of inkjet-printed films on the microchannel has a great effect on the sublimation of transferred thin film. Therefore, to control the morphology, we carefully investigated the drying process of the inkjet-printed inks in the microchannel. Using a vacuum drying process to control the morphology of inkjet-printed films, line patterns of 2822 PPI resolution having a root-mean-square (RMS) roughness of 1.331 nm without voids were successfully fabricated. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessEditor’s ChoiceArticle

Characterizations of Single-Crystal Lithium Niobate Thin Films

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Crystals 2022, 12(5), 667; https://doi.org/10.3390/cryst12050667 - 06 May 2022

Cited by 2 | Viewed by 1858 | Correction

Abstract

Single-crystal lithium niobate thin films (lithium niobate on insulator, LNOI) are becoming a new material platform for integrating photonics. Investigation into the physical properties of LNOI is important for the design and fabrication of photonic devices. Herein, LNOIs were prepared by two methods: [...] Read more.

Single-crystal lithium niobate thin films (lithium niobate on insulator, LNOI) are becoming a new material platform for integrating photonics. Investigation into the physical properties of LNOI is important for the design and fabrication of photonic devices. Herein, LNOIs were prepared by two methods: ion implantation and wafer bonding; and wafer bonding and grinding. High-resolution X-ray diffraction (HRXRD) and confocal Raman spectroscopy were used to study the LNOI lattice properties. The full-width at half-maximum (FWHM) of HRXRD and Raman spectra showed a regular crystal lattice arrangement of the LNOIs. The domain inversion voltage and electro-optical coefficient of the LNOIs were close to those of LN bulk material. This study provides useful information for LNOI fabrication and for photonic devices in LNOI. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Evolution of Nanodomains and Formation of Self-Organized Structures during Local Switching in X-Cut LNOI

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Crystals 2022, 12(5), 659; https://doi.org/10.3390/cryst12050659 - 05 May 2022

Viewed by 1029

Abstract

The features of nanodomain growth during local switching in X-cut lithium niobate on insulator (LNOI) were comprehensively studied using the biased tip of a scanning probe microscope. The obtained results were discussed in terms of the kinetic approach. The revealed differences in domain [...] Read more.

The features of nanodomain growth during local switching in X-cut lithium niobate on insulator (LNOI) were comprehensively studied using the biased tip of a scanning probe microscope. The obtained results were discussed in terms of the kinetic approach. The revealed differences in domain growth in bulk LN and LNOI were attributed to the higher bulk conductivity of LNOI. The obtained influence of humidity on the shape and growth of isolated domains was attributed to the water meniscus. Analysis of the transition between the “forward growth” and “sideways growth” stages was performed by switching to the stripe electrode. A sand-glass-shaped domain was formed due to growth in the opposite direction after the domain touched the electrode. Stable periodical domain structures down to 300 nm were created and characterized in LNOI. Highly ordered comb-like domains of various alternating lengths, including four- and eight-fold increase periods, were produced by performing biased tip scanning along the Y axis. The obtained knowledge is important for the future development of nanodomain engineering methods in monocrystalline ferroelectric thin films on insulators. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessReview

Progress in Transparent Nano-Ceramics and Their Potential Applications

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Nanomaterials 2022, 12(9), 1491; https://doi.org/10.3390/nano12091491 - 27 Apr 2022

Cited by 12 | Viewed by 2355

Abstract

Transparent nano-ceramics have an important high-transmittance, material-integrating structure and function and a variety of potential applications, such as use in infrared windows, optical isolators, composite armors, intelligent terminal screens, and key materials of solid-state lasers. Transparent ceramics were originally developed to replace single [...] Read more.

Transparent nano-ceramics have an important high-transmittance, material-integrating structure and function and a variety of potential applications, such as use in infrared windows, optical isolators, composite armors, intelligent terminal screens, and key materials of solid-state lasers. Transparent ceramics were originally developed to replace single crystals because of their low fabricating cost, controllable shape, and variable composition. Therefore, this study reviews and summarizes the development trends in transparent nano-ceramics and their potential applications. First, we review the research progress and application of laser nano-ceramic materials, focusing on the influence of controllable doping of rare earth ions on thermal conductivity and the realization of large-scale fabrication technology. Second, the latest research progress on magneto-optical transparent nano-ceramics, mainly including terbium gallium garnet (Tb₃Ga₅O₁₂, TGG) ceramics and terbium aluminum garnet (Tb₃Al₅O₁₂, TAG) ceramics, are summarized, and their performance is compared. Third, the research progress of transparent armor nano-ceramic materials, represented by MgAl₂O₃ and Aluminum oxynitride (AlON), are reviewed. Lastly, the progress in electro-optical transparent nano-ceramics and scintillation transparent nano-ceramics is reported, and the influence of the material-fabrication process on electro-optic effect or luminous intensity is compared. Moreover, the effect of particle diameter on fabrication, the relationship between nano powder and performance, and different sintering methods are discussed. In summary, this study provides a meaningful reference for low-cost and sustainable production in the future. Full article

(This article belongs to the Topic Optoelectronic Materials)

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Open AccessArticle

Luminescent Color-Adjustable Europium and Terbium Co-Doped Strontium Molybdate Phosphors Synthesized at Room Temperature Applied to Flexible Composite for LED Filter

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Jae-Yong Jung

Crystals 2022, 12(4), 552; https://doi.org/10.3390/cryst12040552 - 15 Apr 2022

Cited by 4 | Viewed by 1548

Abstract

In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO₄ phosphor at room temperature. The samples prepared synthesized crystalline SrMoO₄ powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d₍₁₁₂₎ spacing [...] Read more.

In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO₄ phosphor at room temperature. The samples prepared synthesized crystalline SrMoO₄ powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d₍₁₁₂₎ spacing was changed by rare-earth doping. As the amount of rare earth added increased, a secondary phase appeared, and the structure changed. The synthesized SrMoO₄:Tb³⁺ phosphors showed a green light emission at 544 nm under 287 nm, SrMoO₄:Eu³⁺ phosphors showed a red light emission at 613 nm under 290 nm, and SrMoO₄:[Eu³⁺]/[Tb³⁺] phosphor showed a yellow-white light emission at 544 and 613 nm when excited at 287 nm. The synthesized phosphor exhibited a change in green and red luminescence intensity based on the amount of Eu³⁺ doped and showed strong red luminescence as the Eu³⁺ doping increased. To use the SrMoO₄:[Eu³⁺]/[Tb³⁺] phosphor with these characteristics in an LED color filter, a flexible composite prepared by mixing with PDMS showed green, red, and yellow-white emission under a UV-lamp. Full article

(This article belongs to the Topic Optoelectronic Materials)

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