Topic Editors

Department of Chemical Engineering and Materials Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan
Lyon Institute of Nanotechnology, UMR 5270, INSA de Lyon, 69100 Villeurbanne, France

Optoelectronic Materials

Abstract submission deadline
closed (20 January 2023)
Manuscript submission deadline
closed (31 March 2023)
Viewed by
42631

Topic Information

Dear Colleagues,

Optoelectronic materials have been developed for almost a century since studies of their optical and electronic properties were first reported in the 1910s. In the 1960s and 1970s, interest in optoelectronic materials was intensified because of the discovery of electroluminescence in conducting polymers and molecular crystals. Moreover, there has been a real surge of interest in the organic and inorganic field of optoelectronic materials over the past 20 years because of significant improvements in material design and purification resulting in dramatic improvements in material performances. Currently, organic materials have received extensive attention for their applications in electronic and optoelectronic devices, such as light-emitting diodes (LEDs or OLEDs), photorefractive (PR) devices, sensors, solar cells, thin film transistors, etc. Of particular technological interest are low-cost solution-processed thin films that can be deposited on large areas and/or flexible substrates. The goals of this topic are to provide a balanced assessment of the current understanding of the physical mechanisms that determine the optoelectronic properties of high-performance organic materials, highlight the capabilities of various experimental techniques to characterize these materials, summarize the most important in-line device performance, and outline recent trends in further development of the field. This topic focuses on photoinduced processes and electronic properties for optoelectronic applications that rely on charge carrier photogeneration. Electronic applications (e.g., OFETs or spintronic devices) and optoelectronic applications (e.g., OLEDs) that do not rely on photogenerated charge generation, as well as photonic applications (e.g., exciton–photon coupling in microcavities) are also welcome to be published in this Topic. I cordially invite you to submit feature articles (or review papers) on the Topic “Optoelectronic Materials”. This Topic seeks original contributions focusing on the following (or related) subtopics:

  • Charge transport mechanisms in optoelectronic materials;
  • Synthesis of organic and inorganic materials for optoelectronic applications;
  • Theoretical and experimental methods in optoelectronic materials;
  • High-mobility conjugated polymers;
  • Photonic and electronic processes and interfacial phenomena in organic–inorganic hybrid materials;
  • Emerging materials for optoelectronics;
  • New insights of optical materials for optoelectronic applications.

Prof. Dr. Tzi-yi Wu
Dr. Ali Belarouci
Topic Editors

Keywords

  • optoelectronic performances of polymers
  • organic synthesis of optoelectronic polymers
  • synthesis of photoactive and electroactive polymers
  • conjugated polymers
  • organometallic polymers
  • molecular engineering of optoelectronic polymers
  • optical, electrochemical, and physicochemical characterizations of optoelectronic polymers

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Nanomaterials
nanomaterials
5.3 7.4 2010 13.6 Days CHF 2900
Polymers
polymers
5.0 6.6 2009 13.7 Days CHF 2700
Applied Sciences
applsci
2.7 4.5 2011 16.9 Days CHF 2400
Crystals
crystals
2.7 3.6 2011 10.6 Days CHF 2600
Electronic Materials
electronicmat
- - 2020 17 Days CHF 1000

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Published Papers (20 papers)

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11 pages, 3157 KiB  
Article
Nonradiative Energy Transfer in Bi2O3/Tm2O3 Powders under IR Excitation at Liquid Nitrogen Temperature
by Dmitry A. Artamonov, Anna V. Tsibulnikova, Vasily A. Slezhkin, Alexey S. Kozhevnikov, Ilia G. Samusev, Ivan I. Lyatun and Valery V. Bryukhanov
Crystals 2023, 13(3), 534; https://doi.org/10.3390/cryst13030534 - 20 Mar 2023
Viewed by 1056
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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10 pages, 1836 KiB  
Article
Trapped Carrier Recombination in Sb2Se3 Polycrystalline Film
by Tingting Tao, Jingting Shu, Yingnan Guo, Kai Wang, Xiaohui Zhao, Baolai Liang, Zhiqiang Li and Wei Dang
Crystals 2023, 13(3), 406; https://doi.org/10.3390/cryst13030406 - 27 Feb 2023
Viewed by 1272
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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10 pages, 3887 KiB  
Article
Abnormal Domain Growth during Polarization Reversal in Lithium Niobate Crystal Modified by Proton Exchange
by Evgeniy Savelyev, Andrey Akhmatkhanov, Mikhail Kosobokov, Hervé Tronche, Florent Doutre, Tommaso Lunghi, Pascal Baldi and Vladimir Shur
Crystals 2023, 13(1), 72; https://doi.org/10.3390/cryst13010072 - 01 Jan 2023
Cited by 2 | Viewed by 1195
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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12 pages, 1935 KiB  
Article
A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array
by Jinglin Zhan, Zhizhong Chen, Chuhan Deng, Fei Jiao, Xin Xi, Yiyong Chen, Jingxin Nie, Zuojian Pan, Haodong Zhang, Boyan Dong, Xiangning Kang, Qi Wang, Yuzhen Tong, Guoyi Zhang and Bo Shen
Nanomaterials 2022, 12(21), 3880; https://doi.org/10.3390/nano12213880 - 03 Nov 2022
Cited by 3 | Viewed by 1372
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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9 pages, 3016 KiB  
Article
Wafer-Scale Fabrication of Silicon Film on Lithium Niobate on Insulator (LNOI)
by Yang Chen, Xiaomeng Zhao, Zhongxu Li, Xinjian Ke, Chengli Wang, Min Zhou, Wenqin Li, Kai Huang and Xin Ou
Crystals 2022, 12(10), 1477; https://doi.org/10.3390/cryst12101477 - 18 Oct 2022
Cited by 2 | Viewed by 2297
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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10 pages, 1839 KiB  
Communication
Modified Fabrication of Perovskite-Based Composites and Its Exploration in Printable Humidity Sensors
by Meiting Peng, Fan Zhang, Liyong Tian, Longbin You, Jiayi Wu, Nanhua Wen, Yangfan Zhang, Yancheng Wu, Feng Gan, Hui Yu, Jing Zhao, Qi Feng, Fuqin Deng, Longhui Zheng, Yingzhu Wu and Ningbo Yi
Polymers 2022, 14(20), 4354; https://doi.org/10.3390/polym14204354 - 16 Oct 2022
Cited by 3 | Viewed by 2002
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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10 pages, 2296 KiB  
Article
The First-Principle Study on Tuning Optical Properties of MA2Z4 by Cr Replacement of Mo Atoms in MoSi2N4
by Yongsheng Li, Jiawei Li, Lingyu Wan, Jiayu Li, Hang Qu, Cui Ding, Mingyang Li, Dan Yu, Kaidi Fan and Huilu Yao
Nanomaterials 2022, 12(16), 2822; https://doi.org/10.3390/nano12162822 - 17 Aug 2022
Cited by 4 | Viewed by 3302
Abstract
Recently, with the successful preparation of MoSi2N4, 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 MoSi2N4, 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, Mo0.5Cr0.5Si2N4, 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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15 pages, 2556 KiB  
Article
Study on Fluorescence Properties of Green-Blue Apatite
by Qicheng Yan, Ziyuan Liu and Ying Guo
Crystals 2022, 12(6), 866; https://doi.org/10.3390/cryst12060866 - 19 Jun 2022
Cited by 1 | Viewed by 2852
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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16 pages, 5675 KiB  
Article
Electrically Tunable Solution-Processed Transparent Conductive Thin Films Based on Colloidally Dispersed ITO@Ag Composite Ink
by Yoo Lim Cha, Jeong-Hye Jo, Dong-Joo Kim and Sun Hee Kim
Nanomaterials 2022, 12(12), 2060; https://doi.org/10.3390/nano12122060 - 15 Jun 2022
Cited by 3 | Viewed by 1952
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·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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11 pages, 2388 KiB  
Article
Femtosecond Laser Deposition of Germanium Selenide onto Silicon Platform at Different Substrate Temperatures
by Kheir S. Albarkaty, Eric Kumi-Barimah, Jian Zhang, Zhiyong Yang and Gin Jose
Nanomaterials 2022, 12(12), 2003; https://doi.org/10.3390/nano12122003 - 10 Jun 2022
Cited by 2 | Viewed by 1580
Abstract
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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16 pages, 4709 KiB  
Article
Numerical Simulation of Solid–Liquid Interface of GaInSb Crystal Growth with Travelling Heater Method
by Pei Wang, Zheng Zhang, Xiang Li, Kainan Suo and Juncheng Liu
Crystals 2022, 12(6), 793; https://doi.org/10.3390/cryst12060793 - 31 May 2022
Cited by 1 | Viewed by 1399
Abstract
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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8 pages, 2341 KiB  
Article
Mechanically Contacted Distributed-Feedback Optical Microcavity
by Yue Liu, Miao Liu, Jingyun Hu, Jiajun Li and Xinping Zhang
Nanomaterials 2022, 12(11), 1883; https://doi.org/10.3390/nano12111883 - 31 May 2022
Cited by 1 | Viewed by 1601
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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15 pages, 6544 KiB  
Article
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
by Ion Sandu, Claudiu Teodor Fleaca, Florian Dumitrache, Bogdan Alexandru Sava, Iuliana Urzica, Iulia Antohe, Simona Brajnicov and Marius Dumitru
Polymers 2022, 14(11), 2158; https://doi.org/10.3390/polym14112158 - 26 May 2022
Cited by 4 | Viewed by 2068
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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19 pages, 1718 KiB  
Article
Study of Electronic and Transport Properties in Double-Barrier Resonant Tunneling Systems
by John A. Gil-Corrales, Juan A. Vinasco, Miguel E. Mora-Ramos, Alvaro L. Morales and Carlos A. Duque
Nanomaterials 2022, 12(10), 1714; https://doi.org/10.3390/nano12101714 - 17 May 2022
Cited by 3 | Viewed by 1887
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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12 pages, 3403 KiB  
Article
High Luminous Efficacy Phosphor-Converted Mass-Produced White LEDs Achieved by AlN Prebuffer and Transitional-Refraction-Index Patterned Sapphire Substrate
by Shuo Zhang, Meng Liang, Yan Yan, Jinpeng Huang, Yan Li, Tao Feng, Xueliang Zhu, Zhicong Li, Chenke Xu, Junxi Wang, Jinmin Li, Zhiqiang Liu and Xiaoyan Yi
Nanomaterials 2022, 12(10), 1638; https://doi.org/10.3390/nano12101638 - 11 May 2022
Cited by 1 | Viewed by 1637
Abstract
Constant advance in improving the luminous efficacy (ηL) 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 (ηL) 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 (φe) 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 ηext of 5.65% in contrast to BLEDs on the conventional PSS through Monte Carlo ray-tracing simulation. Consequently, φe of BLEDs was experimentally enhanced by 10% at an injected current density (Jin) of 40 A/cm2. A peak ηL of 295.2 lm/W at a Jin of 0.9 A/cm2 and the representative ηL of 282.4 lm/W at a Jin 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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12 pages, 4653 KiB  
Article
High-Resolution Patterning of Organic Emitting-Layer by Using Inkjet Printing and Sublimation Transfer Process
by Jun Yeub Lee, Byeong-Kwon Ju and Kwan Hyun Cho
Nanomaterials 2022, 12(9), 1611; https://doi.org/10.3390/nano12091611 - 09 May 2022
Cited by 2 | Viewed by 2172
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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9 pages, 3968 KiB  
Article
Characterizations of Single-Crystal Lithium Niobate Thin Films
by Qingyun Li, Honghu Zhang, Houbin Zhu and Hui Hu
Crystals 2022, 12(5), 667; https://doi.org/10.3390/cryst12050667 - 06 May 2022
Cited by 6 | Viewed by 2985 | 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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10 pages, 4641 KiB  
Article
Evolution of Nanodomains and Formation of Self-Organized Structures during Local Switching in X-Cut LNOI
by Boris Slautin, Anton Turygin, Elena Pashnina, Alla Slautina, Dmitry Chezganov and Vladimir Shur
Crystals 2022, 12(5), 659; https://doi.org/10.3390/cryst12050659 - 05 May 2022
Viewed by 1475
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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39 pages, 10849 KiB  
Review
Progress in Transparent Nano-Ceramics and Their Potential Applications
by Wuyi Ming, Zhiwen Jiang, Guofu Luo, Yingjie Xu, Wenbin He, Zhuobin Xie, Dili Shen and Liwei Li
Nanomaterials 2022, 12(9), 1491; https://doi.org/10.3390/nano12091491 - 27 Apr 2022
Cited by 19 | Viewed by 4140
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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11 pages, 3794 KiB  
Article
Luminescent Color-Adjustable Europium and Terbium Co-Doped Strontium Molybdate Phosphors Synthesized at Room Temperature Applied to Flexible Composite for LED Filter
by Jae-Yong Jung
Crystals 2022, 12(4), 552; https://doi.org/10.3390/cryst12040552 - 15 Apr 2022
Cited by 10 | Viewed by 2256
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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