Nanomaterials

Research

10 pages, 4886 KiB

Open AccessArticle

Tailoring the Size and Shape of ZnO Nanoparticles for Enhanced Performance of OLED Device

by Nikita Khairnar, Hyukmin Kwon, Sangwook Park, Hayoon Lee and Jongwook Park

Nanomaterials 2023, 13(21), 2816; https://doi.org/10.3390/nano13212816 - 24 Oct 2023

Cited by 7 | Viewed by 2584

We synthesized zinc oxide nanoparticles (ZnO NPs) by meticulously controlling both temperature and reaction times, allowing us to fine-tune their crystalline properties, morphology, and particle dimensions. This analysis confirmed the existence of a mixture of rod and sphere shapes (ZnO-I), including rod-shaped NPs [...] Read more.

We synthesized zinc oxide nanoparticles (ZnO NPs) by meticulously controlling both temperature and reaction times, allowing us to fine-tune their crystalline properties, morphology, and particle dimensions. This analysis confirmed the existence of a mixture of rod and sphere shapes (ZnO-I), including rod-shaped NPs with an average size of 14.8 nm × 5.2 nm and spherical NPs with an average diameter of 5.27 nm. We subsequently incorporated these synthesized ZnO NPs into organic light-emitting diode (OLED) devices for red, green, and blue colors, utilizing them as the electron injection layer through a solution-based process. The green OLED device using ZnO-I exhibited a promising current efficiency of 4.02 cd/A and an external quantum efficiency of 1.47%. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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15 pages, 4364 KiB

Open AccessArticle

Effects of the Donor Unit on the Formation of Hybrid Layers of Donor-Acceptor Copolymers with Silver Nanoparticles

by Věra Cimrová, Sangwon Eom, Veronika Pokorná, Youngjong Kang and Drahomír Výprachtický

Nanomaterials 2023, 13(12), 1830; https://doi.org/10.3390/nano13121830 - 9 Jun 2023

Cited by 1 | Viewed by 1779

Abstract

Donor-acceptor (D-A) copolymers containing perylene-3,4,9,10-tetracarboxydiimide (PDI) electron-acceptor (A) units belonging to n-type semiconductors are of interest due to their many potential applications in photonics, particularly for electron-transporting layers in all-polymeric or perovskite solar cells. Combining D-A copolymers and silver nanoparticles (Ag-NPs) can further [...] Read more.

Donor-acceptor (D-A) copolymers containing perylene-3,4,9,10-tetracarboxydiimide (PDI) electron-acceptor (A) units belonging to n-type semiconductors are of interest due to their many potential applications in photonics, particularly for electron-transporting layers in all-polymeric or perovskite solar cells. Combining D-A copolymers and silver nanoparticles (Ag-NPs) can further improve material properties and device performances. Hybrid layers of D-A copolymers containing PDI units and different electron-donor (D) units (9-(2-ethylhexyl)carbazole or 9,9-dioctylfluorene) with Ag-NPs were prepared electrochemically during the reduction of pristine copolymer layers. The formation of hybrid layers with Ag-NP coverage was monitored by in-situ measurement of absorption spectra. The Ag-NP coverage of up to 41% was higher in hybrid layers made of copolymer with 9-(2-ethylhexyl)carbazole D units than in those made of copolymer with 9,9-dioctylfluorene D units. The pristine and hybrid copolymer layers were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, which proved the formation of hybrid layers with stable Ag-NPs in the metallic state with average diameters <70 nm. The influence of D units on Ag-NP diameters and coverage was revealed. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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12 pages, 3205 KiB

Open AccessArticle

Towards Unbiased Fluorophore Counting in Superresolution Fluorescence Microscopy

by Oskar Laitenberger, Timo Aspelmeier, Thomas Staudt, Claudia Geisler, Axel Munk and Alexander Egner

Nanomaterials 2023, 13(3), 459; https://doi.org/10.3390/nano13030459 - 23 Jan 2023

Cited by 3 | Viewed by 1797

Abstract

With the advent of fluorescence superresolution microscopy, nano-sized structures can be imaged with a previously unprecedented accuracy. Therefore, it is rapidly gaining importance as an analytical tool in the life sciences and beyond. However, the images obtained so far lack an absolute scale [...] Read more.

With the advent of fluorescence superresolution microscopy, nano-sized structures can be imaged with a previously unprecedented accuracy. Therefore, it is rapidly gaining importance as an analytical tool in the life sciences and beyond. However, the images obtained so far lack an absolute scale in terms of fluorophore numbers. Here, we use, for the first time, a detailed statistical model of the temporal imaging process which relies on a hidden Markov model operating on two timescales. This allows us to extract this information from the raw data without additional calibration measurements. We show this on the basis of added data from experiments on single Alexa 647 molecules as well as GSDIM/dSTORM measurements on DNA origami structures with a known number of labeling positions. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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18 pages, 23743 KiB

Open AccessArticle

Spectral Engineering of Hybrid Biotemplated Photonic/Photocatalytic Nanoarchitectures

by Gábor Piszter, Krisztián Kertész, Dávid Kovács, Dániel Zámbó, Zsófia Baji, Levente Illés, Gergely Nagy, József Sándor Pap, Zsolt Bálint and László Péter Biró

Nanomaterials 2022, 12(24), 4490; https://doi.org/10.3390/nano12244490 - 19 Dec 2022

Cited by 5 | Viewed by 1561

Abstract

Solar radiation is a cheap and abundant energy for water remediation, hydrogen generation by water splitting, and CO₂ reduction. Supported photocatalysts have to be tuned to the pollutants to be eliminated. Spectral engineering may be a handy tool to increase the efficiency [...] Read more.

Solar radiation is a cheap and abundant energy for water remediation, hydrogen generation by water splitting, and CO₂ reduction. Supported photocatalysts have to be tuned to the pollutants to be eliminated. Spectral engineering may be a handy tool to increase the efficiency or the selectivity of these. Photonic nanoarchitectures of biological origin with hierarchical organization from nanometers to centimeters are candidates for such applications. We used the blue wing surface of laboratory-reared male Polyommatus icarus butterflies in combination with atomic layer deposition (ALD) of conformal ZnO coating and octahedral Cu₂O nanoparticles (NP) to explore the possibilities of engineering the optical and catalytic properties of hybrid photonic nanoarchitectures. The samples were characterized by UV-Vis spectroscopy and optical and scanning electron microscopy. Their photocatalytic performance was benchmarked by comparing the initial decomposition rates of rhodamine B. Cu₂O NPs alone or on the butterfly wings, covered by a 5 nm thick layer of ZnO, showed poor performance. Butterfly wings, or ZnO coated butterfly wings with 15 nm ALD layer showed a 3 to 3.5 times enhancement as compared to bare glass. The best performance of almost 4.3 times increase was obtained for the wings conformally coated with 15 nm ZnO, deposited with Cu₂O NPs, followed by conformal coating with an additional 5 nm of ZnO by ALD. This enhanced efficiency is associated with slow light effects on the red edge of the reflectance maximum of the photonic nanoarchitectures and with enhanced carrier separation through the n-type ZnO and the p-type Cu₂O heterojunction. Properly chosen biologic photonic nanoarchitectures in combination with carefully selected photocatalyst(s) can significantly increase the photodegradation of pollutants in water under visible light illumination. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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10 pages, 3654 KiB

Open AccessCommunication

Anion-Exchange Blue Perovskite Quantum Dots for Efficient Light-Emitting Devices

by Wei-Kuan Hung, Yi-Hsun Tseng, Chun-Cheng Lin, Sih-An Chen, Chih-Hung Hsu, Chen-Feng Li, Yen-Ju Chen and Zong-Liang Tseng

Nanomaterials 2022, 12(22), 3957; https://doi.org/10.3390/nano12223957 - 10 Nov 2022

Cited by 5 | Viewed by 2508

Abstract

In this study, blue perovskite quantum dots (PQDs) were prepared using didodecyldimethylammonium bromide (DDAB), which can passivate surface defects caused by the loss of surface ligands and reduce particle size distribution. After the passivation of DDAB, blue CsPbCl_xBr_3−x PQDs dispersed [...] Read more.

In this study, blue perovskite quantum dots (PQDs) were prepared using didodecyldimethylammonium bromide (DDAB), which can passivate surface defects caused by the loss of surface ligands and reduce particle size distribution. After the passivation of DDAB, blue CsPbCl_xBr_3−x PQDs dispersed in n-octane produced a more compact and uniform PQD thin film than the non-passivated ones. The resulting device showed a stabile lifetime, and an EL peak of 470 nm and a maximum EQE of 1.63% were obtained at an operating voltage of 2.6 V and a current density of 0.34 mA/cm². This work aims to provide a simple method to prepare blue-emitting PQDs and high-performance PQD-based light-emitting devices. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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10 pages, 1065 KiB

Open AccessArticle

Raman Fingerprint of Interlayer Coupling in 2D TMDCs

by Yang Pan and Dietrich R. T. Zahn

Nanomaterials 2022, 12(22), 3949; https://doi.org/10.3390/nano12223949 - 9 Nov 2022

Cited by 9 | Viewed by 3571

Abstract

Vertical stacking of two-dimensional (2D) homo- and heterostructures are intriguing research objects, as they are essential for fundamental studies and a key towards 2D device applications. It is paramount to understand the interlayer coupling in 2D materials and to find a fast yet [...] Read more.

Vertical stacking of two-dimensional (2D) homo- and heterostructures are intriguing research objects, as they are essential for fundamental studies and a key towards 2D device applications. It is paramount to understand the interlayer coupling in 2D materials and to find a fast yet precise characteristic signature. In this work, we report on a Raman fingerprint of interlayer coupling in 2D transition metal dichalcogenides (TMDCs). We observed that the out-of-plane

B_{2 g}

vibrational mode is absent when two monolayers form a vertical stack yet remain uncoupled but emerges after strong coupling. Using systematic Raman, photoluminescence (PL), and atomic force microscopy (AFM) studies of WSe

_{2}

/WSe

_{2}

homo-bilayers and MoSe

_{2}

/WSe

_{2}

hetero-bilayers, we conclude that the

B_{2 g}

vibrational mode is a distinct Raman fingerprint of interlayer coupling in 2D TMDCs. Our results propose an easy, fast, precise, and reliable measure to evaluate the interlayer coupling in 2D TMDCs. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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10 pages, 2897 KiB

Open AccessEditor’s ChoiceArticle

3D Polymer-Based 1 × 4 MMI Splitter

by Tomas Mizera, Peter Gaso, Dusan Pudis, Martin Ziman, Anton Kuzma and Matej Goraus

Nanomaterials 2022, 12(10), 1749; https://doi.org/10.3390/nano12101749 - 20 May 2022

Cited by 10 | Viewed by 2157

Abstract

Due to the increasing trend of photonic device miniaturisation, there is also an increased need for optical splitting in a small volume. We propose a smart solution to split light in three dimensions (3D). A 3D optical splitter based on multimode interference (MMI) [...] Read more.

Due to the increasing trend of photonic device miniaturisation, there is also an increased need for optical splitting in a small volume. We propose a smart solution to split light in three dimensions (3D). A 3D optical splitter based on multimode interference (MMI) for the wavelength of 1550 nm is here designed, simulated, fabricated and optimised for splitting at 1550 nm. We focus also on the possibility of its direct integration on an optical fibre. The design is focused on the use of 3D laser lithography based on the direct laser writing (DLW) process. The output characteristics are investigated by near-field measurement, where we confirm the successful 1 × 4 splitting on a 158 µm long MMI splitter. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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10 pages, 3642 KiB

Open AccessArticle

IP-Dip-Based SPR Structure for Refractive Index Sensing of Liquid Analytes

by Petra Urbancova, Dusan Pudis, Matej Goraus and Jaroslav Kovac, Jr.

Nanomaterials 2021, 11(5), 1163; https://doi.org/10.3390/nano11051163 - 29 Apr 2021

Cited by 10 | Viewed by 3400

Abstract

In this paper, we present a two-dimensional surface plasmon resonance structure for refractive index sensing of liquid analytes. The polymer structure was designed with a period of 500 nm and prepared in a novel IP-Dip polymer by direct laser writing lithography based on [...] Read more.

In this paper, we present a two-dimensional surface plasmon resonance structure for refractive index sensing of liquid analytes. The polymer structure was designed with a period of 500 nm and prepared in a novel IP-Dip polymer by direct laser writing lithography based on a mechanism of two-photon absorption. The sample with a set of prepared IP-Dip structures was coated by 40 nm thin gold layer. The sample was encapsulated into a prototyped chip with inlet and outlet. The sensing properties were investigated by angular measurement using the prepared solutions of isopropyl alcohol in deionized water of different concentrations. Sensitivity of 478–617 nm per refractive index unit was achieved in angular arrangement at external angle of incidence of 20°. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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13 pages, 3869 KiB

Open AccessArticle

Design and Fabrication of a Triple-Band Terahertz Metamaterial Absorber

by Jinfeng Wang, Tingting Lang, Zhi Hong, Meiyu Xiao and Jing Yu

Nanomaterials 2021, 11(5), 1110; https://doi.org/10.3390/nano11051110 - 25 Apr 2021

Cited by 52 | Viewed by 3290

Abstract

We presented and manufactured a triple-band terahertz (THz) metamaterial absorber with three concentric square ring metallic resonators, a polyethylene terephthalate (PET) layer, and a metallic substrate. The simulation results demonstrate that the absorptivity of 99.5%, 86.4%, and 98.4% can be achieved at resonant [...] Read more.

We presented and manufactured a triple-band terahertz (THz) metamaterial absorber with three concentric square ring metallic resonators, a polyethylene terephthalate (PET) layer, and a metallic substrate. The simulation results demonstrate that the absorptivity of 99.5%, 86.4%, and 98.4% can be achieved at resonant frequency of 0.337, 0.496, and 0.718 THz, respectively. The experimental results show three distinct absorption peaks at 0.366, 0.512, and 0.751 THz, which is mostly agreement with the simulation. We analyzed the absorption mechanism from the distribution of electric and magnetic fields. The sensitivity of the three peaks of this triple-band absorber to the surrounding is 72, 103.5, 139.5 GHz/RIU, respectively. In addition, the absorber is polarization insensitive because of the symmetric configuration. The absorber can simultaneously exhibit high absorption effect at incident angles up to 60° for transverse electric (TE) polarization and 70° for transverse magnetic (TM) polarization. This presented terahertz metamaterial absorber with a triple-band absorption and easy fabrication can find important applications in biological sensing, THz imaging, filter and optical communication. Full article

(This article belongs to the Special Issue Nanostructures for Advanced Photonic Devices)

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