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19 pages, 9849 KiB

Open AccessArticle

Detection, Characterization and Modeling of Localized Defects and Thermal Breakdown in Photovoltaic Panels from Thermal Images and IV Curves

by Nekane Azkona, Alvaro Llaria, Octavian Curea and Federico Recart

Electron. Mater. 2022, 3(2), 154-172; https://doi.org/10.3390/electronicmat3020014 - 01 Apr 2022

Cited by 4 | Viewed by 2286

Abstract

In this work, a defective commercial module with a rounded IV characteristic is analyzed in detail to identify the sources of its malfunction. The analysis of the module includes thermography images taken under diverse conditions, the IV response of the module obtained without [...] Read more.

In this work, a defective commercial module with a rounded IV characteristic is analyzed in detail to identify the sources of its malfunction. The analysis of the module includes thermography images taken under diverse conditions, the IV response of the module obtained without any shadow, and shadowing one cell at a time, as recommended by the IEC 61215 Standard. Additionally, a direct measurement of the IV characteristic and resistance of single cells in the panel has been conducted to verify the isolation between the p and n areas. In parallel, theoretical cell and module behaviors are presented. In this frame, simulations show how cell mismatch can be the explanation to the rounded IV output of the solar panel under study. From the thermal images of the module, several localized hot spots related to failing cells have been revealed. During the present study, thermal breakdown is seen before avalanche breakdown in one of the cells, evidencing a hot spot. Not many papers have dealt with this problem, whereas we believe it is important to analyze the relationship between thermal breakdown and hot spotting in order to prevent it in the future, since hot spots are the main defects related to degradation of modern modules. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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14 pages, 4671 KiB

Open AccessFeature PaperArticle

Vis and NIR Diffuse Reflectance Study in Disordered Bismuth Manganate—Lead Titanate Ceramics

by Andrzej Molak, Anna Z. Szeremeta and Janusz Koperski

Electron. Mater. 2022, 3(1), 101-114; https://doi.org/10.3390/electronicmat3010010 - 25 Feb 2022

Cited by 4 | Viewed by 2132

Abstract

This work shows a correlation between light reflectance, absorption, and morphologies of series of bismuth manganate–lead titanate, (1 − x) BM–x PT, (x = 0.00, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24, 1.00) ceramics composite. Low reflectance in the Vis-NIR range [...] Read more.

This work shows a correlation between light reflectance, absorption, and morphologies of series of bismuth manganate–lead titanate, (1 − x) BM–x PT, (x = 0.00, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24, 1.00) ceramics composite. Low reflectance in the Vis-NIR range corresponds to ‘black mirror’ features. The modified Kubelka-Munk function applied to measured visible-near infrared (Vis-NIR) diffuse reflectance enabled the estimation of the energy gaps magnitude of the order of 1.0–1.2 eV for BM-PT. Histograms of grains, obtained using a scanning electron microscope, enabled finding the correlation between grains size, reflectance magnitude, and PT content. The magnitude of energy gaps was attributed to electronic structure bands modified by crystal lattice disorder and oxygen vacancies. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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8 pages, 1344 KiB

Open AccessArticle

25,000 fps Computational Ghost Imaging with Ultrafast Structured Illumination

by Hongxu Huang, Lijing Li, Yuxuan Ma and Mingjie Sun

Electron. Mater. 2022, 3(1), 93-100; https://doi.org/10.3390/electronicmat3010009 - 24 Feb 2022

Cited by 5 | Viewed by 2554

Abstract

Computational ghost imaging, as an alternative photoelectric imaging technology, uses a single-pixel detector with no spatial resolution to capture information and reconstruct the image of a scene. Due to its essentially temporal measurement manner, improving the image frame rate is always a major [...] Read more.

Computational ghost imaging, as an alternative photoelectric imaging technology, uses a single-pixel detector with no spatial resolution to capture information and reconstruct the image of a scene. Due to its essentially temporal measurement manner, improving the image frame rate is always a major concern in the research of computational ghost imaging technology. By taking advantage of the fast switching time of LED, an LED array was developed to provide a structured illumination light source in our work, which significantly improves the structured illumination rate in the computational ghost imaging system. The design of the LED array driver circuit presented in this work makes full use of the LED switching time and achieves a pattern displaying rate of 12.5 MHz. Continuous images with 32 × 32 pixel resolution are reconstructed at a frame rate of 25,000 fps, which is approximately 500 times faster than what a universally used digital micromirror device can achieve. The LED array presented in this work can potentially be applied to other techniques requiring high-speed structured illumination, such as fringe 3D profiling and array-based LIFI. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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11 pages, 2350 KiB

Open AccessArticle

Magnetization of Magnetically Inhomogeneous Sr₂FeMoO_6-δ Nanoparticles

by Gunnar Suchaneck, Nikolai Kalanda, Marta Yarmolich, Evgenii Artiukh, Gerald Gerlach and Nikolai A. Sobolev

Electron. Mater. 2022, 3(1), 82-92; https://doi.org/10.3390/electronicmat3010008 - 08 Feb 2022

Cited by 1 | Viewed by 2156

Abstract

In this work, we describe the magnetization of nanosized SFMO particles with a narrow size distribution around ca. 70 nm fabricated by the citrate-gel technique. The single-phase composition and superstructure ordering degree were proved by X-ray diffraction, the superparamagnetic behavior by magnetization measurements [...] Read more.

In this work, we describe the magnetization of nanosized SFMO particles with a narrow size distribution around ca. 70 nm fabricated by the citrate-gel technique. The single-phase composition and superstructure ordering degree were proved by X-ray diffraction, the superparamagnetic behavior by magnetization measurements using zero-field cooled and field-cooled protocols, as well as by electron magnetic resonance. Different contributions to the magnetic anisotropy constant and the temperature dependence of the magnetocrystalline anisotropy are discussed. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 6427 KiB

Open AccessArticle

Synthesis and Physical Properties of Iridium-Based Sulfide Ca_1−xIr₄S₆(S₂) [x = 0.23–0.33]

by Michael Vogl, Martin Valldor, Roman Boy Piening, Dmitri V. Efremov, Bernd Büchner and Saicharan Aswartham

Electron. Mater. 2022, 3(1), 41-52; https://doi.org/10.3390/electronicmat3010004 - 11 Jan 2022

Viewed by 2321

Abstract

We present the synthesis and characterization of the iridium-based sulfide Ca_1−xIr₄S₆(S₂). Quality and phase analysis were conducted by means of energy-dispersive X-ray spectroscopy (EDXS) and powder X-ray diffraction (XRD) techniques. Structure analysis reveals a [...] Read more.

We present the synthesis and characterization of the iridium-based sulfide Ca_1−xIr₄S₆(S₂). Quality and phase analysis were conducted by means of energy-dispersive X-ray spectroscopy (EDXS) and powder X-ray diffraction (XRD) techniques. Structure analysis reveals a monoclinic symmetry with the space group C 1 2/m 1 (No. 12), with the lattice constants a = 15.030 (3) Å, b = 3.5747 (5) Å and c = 10.4572 (18) Å. Both X-ray diffraction and EDXS suggest an off-stoichiometry of calcium, leading to the empirical composition Ca_1−xIr_4.0S₆(S₂) [x = 0.23–0.33]. Transport measurements show metallic behavior of the compound in the whole range of measured temperatures. Magnetic measurements down to 1.8 K show no long range order, and Curie–Weiss analysis yields θ_CW = −31.4 K, suggesting that the compound undergoes a magnetic state with short range magnetic correlations. We supplement our study with calculations of the band structure in the framework of the density functional theory. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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14 pages, 4196 KiB

Open AccessArticle

Defect- and H-Free Stoichiometric Silicon Carbide by Thermal CVD from the Single Source Precursor Trisilacyclohexane

by Alain E. Kaloyeros, Jonathan Goff and Barry Arkles

Electron. Mater. 2022, 3(1), 27-40; https://doi.org/10.3390/electronicmat3010003 - 10 Jan 2022

Cited by 6 | Viewed by 2533

Abstract

Stoichiometric silicon carbide (SiC) thin films were grown using thermal chemical vapor deposition (TCVD) from the single source precursor 1,3,5-trisilacyclohexane (TSCH) on c-Si (100) substrates within an optimized substrate temperature window ranging from 650 to 850 °C. X-ray photoelectron spectroscopy (XPS) and Fourier [...] Read more.

Stoichiometric silicon carbide (SiC) thin films were grown using thermal chemical vapor deposition (TCVD) from the single source precursor 1,3,5-trisilacyclohexane (TSCH) on c-Si (100) substrates within an optimized substrate temperature window ranging from 650 to 850 °C. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that the as-deposited films consisted of a Si-C matrix with a Si:C ratio of ~1:1. FTIR and photoluminescence (PL) spectrometry studies showed that films deposited ≥ 750 °C were defect- and H-free within the detection limit of the techniques used, while ellipsometry measurements yielded an as-grown SiC average refractive index of ~2.7, consistent with the reference value for the 3C-SiC phase. The exceptional quality of the films appears sufficient to overcome limitations associated with structural defects ranging from failure in high voltage, high temperature electronics to 2-D film growth. TSCH, a liquid at room temperature with good structural stability during transport and handling as well as high vapor pressure (~10 torr at 25 °C), provides a viable single source precursor for the growth of stoichiometric SiC without the need for post-deposition thermal treatment. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 3173 KiB

Open AccessArticle

p-Type Iodine-Doping of Cu₃N and Its Conversion to γ-CuI for the Fabrication of γ-CuI/Cu₃N p-n Heterojunctions

by Argyris Tilemachou, Matthew Zervos, Andreas Othonos, Theodoros Pavloudis and Joseph Kioseoglou

Electron. Mater. 2022, 3(1), 15-26; https://doi.org/10.3390/electronicmat3010002 - 10 Jan 2022

Cited by 8 | Viewed by 3479

Abstract

Cu₃N with a cubic crystal structure is obtained in this paper by the sputtering of Cu under N₂ followed by annealing under NH₃: H₂ at 400 °C, after which it was doped with iodine at room temperature [...] Read more.

Cu₃N with a cubic crystal structure is obtained in this paper by the sputtering of Cu under N₂ followed by annealing under NH₃: H₂ at 400 °C, after which it was doped with iodine at room temperature resulting into p-type Cu₃N with hole densities between 10¹⁶ and 10¹⁷ cm⁻³. The Cu₃N exhibited distinct maxima in differential transmission at ~2.01 eV and 1.87 eV as shown by ultrafast pump-probe spectroscopy, corresponding to the M and R direct energy band gaps in excellent agreement with density functional theory calculations, suggesting that the band gap is clean and free of mid-gap states. The Cu₃N was gradually converted into optically transparent γ-CuI that had a hole density of 4 × 10¹⁷ cm⁻³, mobility of 12 cm²/Vs and room temperature photoluminescence at 3.1 eV corresponding to its direct energy band gap. We describe the fabrication and properties of γ-CuI/TiO₂/Cu₃N and γ-CuI/Cu₃N p-n heterojunctions that exhibited rectifying current-voltage characteristics, but no photogenerated current attributed to indirect recombination via shallow states in Cu₃N and/or deep states in the γ-CuI consistent with the short (ps) lifetimes of the photoexcited electrons-holes determined from transient absorption–transmission spectroscopy. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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14 pages, 1060 KiB

Open AccessFeature PaperArticle

Attaining Low Lattice Thermal Conductivity in Half-Heusler Sublattice Solid Solutions: Which Substitution Site Is Most Effective?

by Rasmus Tranås, Ole Martin Løvvik and Kristian Berland

Electron. Mater. 2022, 3(1), 1-14; https://doi.org/10.3390/electronicmat3010001 - 05 Jan 2022

Cited by 1 | Viewed by 2844

Abstract

Low thermal conductivity is an important materials property for thermoelectricity. The lattice thermal conductivity (LTC) can be reduced by introducing sublattice disorder through partial isovalent substitution. Yet, large-scale screening of materials has seldom taken this opportunity into account. The present study aims to [...] Read more.

Low thermal conductivity is an important materials property for thermoelectricity. The lattice thermal conductivity (LTC) can be reduced by introducing sublattice disorder through partial isovalent substitution. Yet, large-scale screening of materials has seldom taken this opportunity into account. The present study aims to investigate the effect of partial sublattice substitution on the LTC. The study relies on the temperature-dependent effective potential method based on forces obtained from density functional theory. Solid solutions are simulated within a virtual crystal approximation, and the effect of grain-boundary scattering is also included. This is done to systematically probe the effect of sublattice substitution on the LTC of 122 half-Heusler compounds. It is found that substitution on the three different crystallographic sites leads to a reduction of the LTC that varies significantly both between the sites and between the different compounds. Nevertheless, some common criteria are identified as most efficient for reduction of the LTC: The mass contrast should be large within the parent compound, and substitution should be performed on the heaviest atoms. It is also found that the combined effect of sublattice substitution and grain-boundary scattering can lead to a drastic reduction of the LTC. The lowest LTC of the current set of half-Heusler compounds is around 2 W/Km at 300 K for two of the parent compounds. Four additional compounds can reach similarly low LTC with the combined effect of sublattice disorder and grain boundaries. Two of these four compounds have an intrinsic LTC above ∼15 W/Km, underlining that materials with high intrinsic LTC could still be viable for thermoelectric applications. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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8 pages, 2477 KiB

Open AccessEditor’s ChoiceArticle

Self-Absorption Analysis of Perovskite-Based Luminescent Solar Concentrators

by Yujian Sun, Yongcao Zhang, Yuxin Li and Yilin Li

Electron. Mater. 2021, 2(4), 545-552; https://doi.org/10.3390/electronicmat2040039 - 10 Dec 2021

Viewed by 2665

Abstract

Luminescent solar concentrators (LSCs) are considered promising in their application as building-integrated photovoltaics (BIPVs). However, they suffer from low performance, especially in large-area devices. One of the key issues is the self-absorption of the luminophores. In this report, we focus on the study [...] Read more.

Luminescent solar concentrators (LSCs) are considered promising in their application as building-integrated photovoltaics (BIPVs). However, they suffer from low performance, especially in large-area devices. One of the key issues is the self-absorption of the luminophores. In this report, we focus on the study of self-absorption in perovskite-based LSCs. Perovskite nanocrystals (NCs) are emerging luminophores for LSCs. Studying the self-absorption of perovskite NCs is beneficial to understanding fundamental photon transport properties in perovskite-based LSCs. We analyzed and quantified self-absorption properties of perovskite NCs in an LSC with the dimensions of 6 in × 6 in × 1/4 in (152.4 mm × 152.4 mm × 6.35 mm) using three approaches (i.e., limited illumination, laser excitation, and regional measurements). The results showed that a significant number of self-absorption events occurred within a distance of 2 in (50.8 mm), and the photo surface escape due to the repeated self-absorption was the dominant energy loss mechanism. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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9 pages, 916 KiB

Open AccessEditor’s ChoiceArticle

Batteryless Electronic System Printed on Glass Substrate

by Peter Andersson Ersman, Jessica Åhlin, David Westerberg, Anurak Sawatdee, Patrik Arvén and Mikael Ludvigsson

Electron. Mater. 2021, 2(4), 527-535; https://doi.org/10.3390/electronicmat2040037 - 03 Nov 2021

Cited by 1 | Viewed by 3478

Abstract

Batteryless hybrid printed electronic systems manufactured on glass substrates are reported. The electronic system contains a sensor capable of detecting water, an electrochromic display, conductors, a silicon chip providing the power supply through energy harvesting of electromagnetic radiation, and a silicon-based microcontroller responsible [...] Read more.

Batteryless hybrid printed electronic systems manufactured on glass substrates are reported. The electronic system contains a sensor capable of detecting water, an electrochromic display, conductors, a silicon chip providing the power supply through energy harvesting of electromagnetic radiation, and a silicon-based microcontroller responsible for monitoring the sensor status and the subsequent update of the corresponding display segment. The silicon-based components were assembled on the glass substrate by using a pick and place equipment, while the remainder of the system was manufactured by screen printing. Many printed electronic components, often relying on organic materials, are sensitive to variations in environmental conditions, and the reported system paves the way for the creation of electronic sensor platforms on glass substrates for utilization in see-through applications in harsh conditions. Additionally, this generic hybrid printed electronic sensor system also demonstrates the ability to enable autonomous operation through energy harvesting in future smart window applications. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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16 pages, 4239 KiB

Open AccessArticle

A Novel Method to Significantly Improve the Mechanical Properties of n-Type Bi_(1−x)Sb_x Thermoelectrics Due to Plastic Deformation

by Nikolay Sidorenko, Yaakov Unigovski, Zinovi Dashevsky and Roni Shneck

Electron. Mater. 2021, 2(4), 511-526; https://doi.org/10.3390/electronicmat2040036 - 02 Nov 2021

Viewed by 2214

Abstract

A unique method was developed to significantly improve the strength of Bi_(1−x)Sb_x single crystals, the most effective thermoelectric (TE) materials in the temperature range from 100 to 200 K due to their plastic deformation by extrusion. After plastic [...] Read more.

A unique method was developed to significantly improve the strength of Bi_(1−x)Sb_x single crystals, the most effective thermoelectric (TE) materials in the temperature range from 100 to 200 K due to their plastic deformation by extrusion. After plastic deformation at room temperature under all-round hydrostatic compression in a liquid medium, n-type Bi–Sb polycrystalline solid solutions show a significant increase in mechanical strength compared to Bi–Sb single crystals in the temperature range from 300 to 80 K. The significantly higher strength of extruded alloys in comparison with Bi–Sb single crystals is associated with the development of numerous grains with a high boundary surface as well as structural defects, such as dislocations, that accumulate at grain boundaries. Significant stability of the structure of extruded samples is achieved due to the uniformity of crystal plastic deformation under all-round hydrostatic compression and the formation of the polycrystalline structure consisting of grains with the orientation of the main crystallographic directions close to the original single crystal. The strengthening of Bi–Sb single crystals after plastic deformation allows for the first time to create workable TE devices that cannot be created on the basis of single crystals that have excellent TE properties, but low strength. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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7 pages, 358 KiB

Open AccessFeature PaperArticle

Structural, Electronic, and Optical Properties of p-Type Semiconductors Cu₂O and ZnRh₂O₄: A Self-Consistent Hybrid Functional Investigation

by Daniel Fritsch

Electron. Mater. 2021, 2(4), 504-510; https://doi.org/10.3390/electronicmat2040035 - 01 Nov 2021

Cited by 2 | Viewed by 2753

Abstract

The p-type semiconductors Cu

_{2}

O and ZnRh

_{2}

O

_{4}

have been under investigation for potential applications as transparent conducting oxides. Here, we re-evaluate their structural, electronic, and optical properties by means of first-principles calculations employing density functional theory and a [...] Read more.

The p-type semiconductors Cu

_{2}

O and ZnRh

_{2}

O

_{4}

have been under investigation for potential applications as transparent conducting oxides. Here, we re-evaluate their structural, electronic, and optical properties by means of first-principles calculations employing density functional theory and a recently introduced self-consistent hybrid functional approach. Therein, the predefined fraction

α

of Hartree–Fock exact exchange is determined self-consistently via the inverse of the dielectric constant

ε_{\infty}

. The structural, electronic, and optical properties will be discussed alongside experimental results, with a focus on possible technological applications. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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9 pages, 2906 KiB

Open AccessArticle

Theoretical Prediction of Heterogeneous Integration of Dissimilar Semiconductor with Various Ultra-Thin Oxides and 2D Materials

by Md Nazmul Hasan, Chenxi Li, Junyu Lai and Jung-Hun Seo

Electron. Mater. 2021, 2(4), 495-503; https://doi.org/10.3390/electronicmat2040034 - 11 Oct 2021

Cited by 1 | Viewed by 2694

Abstract

In this paper, we build a numerical p-n Si/GaAs heterojunction model using quantum-mechanical tunneling theory with various quantum tunneling interfacial materials including two-dimensional (2D) materials such as hexagonal boron nitride (h-BN) and graphene, and ALD-enabled oxide materials such as HfO₂, Al [...] Read more.

In this paper, we build a numerical p-n Si/GaAs heterojunction model using quantum-mechanical tunneling theory with various quantum tunneling interfacial materials including two-dimensional (2D) materials such as hexagonal boron nitride (h-BN) and graphene, and ALD-enabled oxide materials such as HfO₂, Al₂O₃, and SiO₂. Their tunneling efficiencies and tunneling currents with different thicknesses were systematically calculated and compared. Multiphysics modeling was used with the aforementioned tunneling interfacial materials to analyze changes in the strain under different temperature conditions. Considering the transport properties and thermal-induced strain analysis, Al₂O₃, among three oxide materials, and graphene in 2D materials are favorable material choices that offer the highest heterojunction quality. Overall, our results offer a viable route in guiding the selection of quantum tunneling materials for a myriad of possible combinations of new heterostructures that can be obtained with an ultra-thin tunneling intermediate layer. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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13 pages, 4053 KiB

Open AccessArticle

One-Step Cost-Effective Growth of High-Quality Epitaxial Ge Films on Si (100) Using a Simplified PECVD Reactor

by Jignesh Vanjaria, Venkat Hariharan, Arul Chakkaravarthi Arjunan, Yanze Wu, Gary S. Tompa and Hongbin Yu

Electron. Mater. 2021, 2(4), 482-494; https://doi.org/10.3390/electronicmat2040033 - 10 Oct 2021

Viewed by 2803

Abstract

Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low [...] Read more.

Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH₄) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (>10⁻⁶ Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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16 pages, 2332 KiB

Open AccessArticle

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

by Bhupendra Pratap Singh, Samiksha Sikarwar, Kamal Kumar Pandey, Rajiv Manohar, Michael Depriester and Dharmendra Pratap Singh

Electron. Mater. 2021, 2(4), 466-481; https://doi.org/10.3390/electronicmat2040032 - 08 Oct 2021

Cited by 14 | Viewed by 3711

Abstract

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response [...] Read more.

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (T

_{N I}

) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to

π

-

π

electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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9 pages, 1516 KiB

Open AccessArticle

High Rectification Ratio in Polymer Diode Rectifier through Interface Engineering with Self-Assembled Monolayer

by Khaoula Ferchichi, Sebastien Pecqueur, David Guerin, Ramzi Bourguiga and Kamal Lmimouni

Electron. Mater. 2021, 2(4), 445-453; https://doi.org/10.3390/electronicmat2040030 - 01 Oct 2021

Cited by 7 | Viewed by 3331

Abstract

In this work, we demonstrate P3HT (poly 3-hexylthiophene) organic rectifier diode both in rigid and flexible substrate with a rectification ratio up to 10⁶. This performance has been achieved through tuning the work function of gold with a self-assembled monolayer of [...] Read more.

In this work, we demonstrate P3HT (poly 3-hexylthiophene) organic rectifier diode both in rigid and flexible substrate with a rectification ratio up to 10⁶. This performance has been achieved through tuning the work function of gold with a self-assembled monolayer of 2,3,4,5,6-pentafluorobenzenethiol (PFBT). The diode fabricated on flexible paper substrate shows a very good electrical stability under bending tests and the frequency response is estimated at more than 20 MHz which is sufficient for radio frequency identification (RFID) applications. It is also shown that the low operating voltage of this diode can be a real advantage for use in a rectenna for energy harvesting systems. Simulations of the diode structure show that it can be used at GSM and Wi-Fi frequencies if the diode capacitance is reduced to a few pF and its series resistance to a few hundred ohms. Under these conditions, the DC voltages generated by the rectenna can reach a value up to 1 V. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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18 pages, 3810 KiB

Open AccessArticle

Metal–Insulator Transition in Doped Barium Plumbates

by Andreza M. Eufrasio, Ian Pegg, Amrit Kafle, Winnie Wong-Ng, Qingzhen Huang and Biprodas Dutta

Electron. Mater. 2021, 2(3), 428-444; https://doi.org/10.3390/electronicmat2030029 - 16 Sep 2021

Cited by 1 | Viewed by 2765

Abstract

Solid solutions in the Ba(Pb_1−xSr_x)O_3−z system were prepared by aliovalent substitution of Pb⁴⁺ by Sr²⁺ ions to investigate the effect of cation stoichiometry on thermal and electrical properties as x was varied between 0 [...] Read more.

Solid solutions in the Ba(Pb_1−xSr_x)O_3−z system were prepared by aliovalent substitution of Pb⁴⁺ by Sr²⁺ ions to investigate the effect of cation stoichiometry on thermal and electrical properties as x was varied between 0 and 0.4, in the temperature range 300–523 K. The starting compound, barium plumbate (BaPbO₃), has a perovskite structure and is known to exhibit metallic conductivity due to an overlap of the O2p nonbonding and the Pb–O spσ antibonding band, which is partially filled by the available electrons. The large difference in the ionic radii between the Pb⁴⁺ and Sr²⁺ ions introduces significant strain into the (Pb/Sr)O₆ octahedra of the perovskite structure. Additionally, charged defects are created on account of the different oxidation states of the Pb⁴⁺ and Sr²⁺ ions. Evidence of a metal to insulator transition (MIT) of the Mott–Hubbard type has been observed at a critical concentration of Sr²⁺ ions. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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15 pages, 4085 KiB

Open AccessArticle

Highly Flexible Polyaniline-Based Implantable Electrode Materials for Neural Sensing/Stimulation Applications

by Nader Almufleh, Amani Al-Othman, Zaid Alani, Mohammad H. Al-Sayah and Hasan Al-Nashash

Electron. Mater. 2021, 2(3), 413-427; https://doi.org/10.3390/electronicmat2030028 - 14 Sep 2021

Cited by 6 | Viewed by 2592

Abstract

Implantable bioelectrodes have the potential to advance neural sensing and muscle stimulation, mainly in patients with peripheral nerve injuries. They function as the transducer at the interface between the damaged nerve and the muscle which is controlled by that nerve. This work reports [...] Read more.

Implantable bioelectrodes have the potential to advance neural sensing and muscle stimulation, mainly in patients with peripheral nerve injuries. They function as the transducer at the interface between the damaged nerve and the muscle which is controlled by that nerve. This work reports the fabrication and characterization of novel, low-cost, flexible bioelectrodes based on polyaniline (PANI) and supported with silicone polymer. The fabricated electrodes were evaluated for their electrical and mechanical characteristics. PANI was used as the main transducer component in this fabrication. The characterization methods included electrical conductivity, capacitive behavior, long-term electrical impedance, and mechanical evaluation. The results of the fabricated PANI-silicone-based samples displayed a bulk impedance of 0.6 kΩ with an impedance of 1.6 kΩ at the frequency of 1 kHz. Furthermore, the bioelectrodes showed a charge storage capacity range from 0.0730 to 4.3124 C/cm². The samples were stable when subjected to cyclic voltammetry tests. The bioelectrodes revealed very flexible mechanical properties as observed from the value of Young’s modulus (in the order of MPa) which was less than that of skin. Hence, the PANI-based bioelectrodes reported herein showed promising electrochemical characteristics with high flexibility. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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20 pages, 9286 KiB

Open AccessArticle

Sterically Stabilized Multilayer Graphene Nanoshells for Inkjet Printed Resistors

by Michael Orrill, Dustin Abele, Michael J. Wagner and Saniya LeBlanc

Electron. Mater. 2021, 2(3), 394-412; https://doi.org/10.3390/electronicmat2030027 - 14 Sep 2021

Cited by 1 | Viewed by 2598

Abstract

In the field of printed electronics, there is a pressing need for printable resistors, particularly ones where the resistance can be varied without changing the size of the resistor. This work presents ink synthesis and printing results for variable resistance, inkjet-printed patterns of [...] Read more.

In the field of printed electronics, there is a pressing need for printable resistors, particularly ones where the resistance can be varied without changing the size of the resistor. This work presents ink synthesis and printing results for variable resistance, inkjet-printed patterns of a novel and sustainable carbon nanomaterial—multilayer graphene nanoshells. Dispersed multilayer graphene nanospheres are sterically stabilized by a surfactant (Triton X100), and no post-process is required to achieve the resistive functionality. A surface tension-based adsorption analysis technique is used to determine the optimal surfactant dosage, and a geometric model explains the conformation of adsorbed surfactant molecules. The energetic interparticle potentials between approaching particles are modeled to assess and compare the stability of sterically and electrostatically stabilized multilayer graphene nanoshells. The multilayer graphene nanoshell inks presented here show a promising new pathway toward sustainable and practical printed resistors that achieve variable resistances within a constant areal footprint without post-processing. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 5422 KiB

Open AccessEditor’s ChoiceArticle

Structural and Electronic Properties of Small Perovskite Nanoparticles of the Form ABX₃ (A = MA, DEA, FA, GA, B = Pb, Sn, X = Cl, Br, I)

by Christos S. Garoufalis, Iosif Galanakis, Zaiping Zeng, David B. Hayrapetyan and Sotirios Baskoutas

Electron. Mater. 2021, 2(3), 382-393; https://doi.org/10.3390/electronicmat2030026 - 10 Aug 2021

Cited by 5 | Viewed by 3595

Abstract

Using a combination of first principles and semiempirical calculation, we explore the structural, electronic, and optical properties of a wide range of perovskite (

A B X_{3}

) nanoparticle of different size and composition. The variations of the

B X_{3}

backbone [...] Read more.

Using a combination of first principles and semiempirical calculation, we explore the structural, electronic, and optical properties of a wide range of perovskite (

A B X_{3}

) nanoparticle of different size and composition. The variations of the

B X_{3}

backbone structure considered include all possible combinations of the cations

B = P b, S n

and the anions

X = C l, B r, I

, while the interstitial cation A is either methylamonium (MA), or formamidinium (FA), or guanidine amine (GA), or dimethylamine (DEA). Our results indicate that the orientational disorder of the A moieties may affect the structural and electronic properties of the NPs while the optical properties exhibit a clear dependence on the NPs’ size and the types of B cations and X anions, but they are quite insensitive to the type of A cation. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 5353 KiB

Open AccessArticle

Bayesian Optimization of Hubbard U’s for Investigating InGaN Superlattices

by Maxim N. Popov, Jürgen Spitaler, Lorenz Romaner, Natalia Bedoya-Martínez and René Hammer

Electron. Mater. 2021, 2(3), 370-381; https://doi.org/10.3390/electronicmat2030025 - 05 Aug 2021

Cited by 1 | Viewed by 3214

Abstract

In this study, we undertake a Bayesian optimization of the Hubbard U parameters of wurtzite GaN and InN. The optimized Us are then tested within the Hubbard-corrected local density approximation (LDA+U) approach against standard density functional theory, as well as a hybrid functional [...] Read more.

In this study, we undertake a Bayesian optimization of the Hubbard U parameters of wurtzite GaN and InN. The optimized Us are then tested within the Hubbard-corrected local density approximation (LDA+U) approach against standard density functional theory, as well as a hybrid functional (HSE06). We present the electronic band structures of wurtzite GaN, InN, and (1:1) InGaN superlattice. In addition, we demonstrate the outstanding performance of the new parametrization, when computing the internal electric-fields in a series of [InN]

_{1}

–[GaN]

_{n}

superlattices (n = 2–5) stacked up along the c-axis. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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20 pages, 5488 KiB

Open AccessArticle

Activated Carbon from Corncobs Doped with RuO₂ as Biobased Electrode Material

by Viola Hoffmann, Catalina Rodriguez Correa, Saskia Sachs, Andrea del Pilar Sandoval-Rojas, Mo Qiao, Avery B. Brown, Michael Zimmermann, Jenny Paola Rodriguez Estupiñan, Maria Teresa Cortes, Juan Manuel Carlos Moreno Pirajan, Maria-Magdalena Titirici and Andrea Kruse

Electron. Mater. 2021, 2(3), 324-343; https://doi.org/10.3390/electronicmat2030023 - 02 Aug 2021

Cited by 4 | Viewed by 2899

Abstract

Bio-based activated carbons with very high specific surface area of >3.000 m² g⁻¹ (based on CO₂ adsorption isotherms) and a high proportion of micropores (87% of total SSA) are produced by corncobs via pyrolysis and chemical activation with KOH. The activated [...] Read more.

Bio-based activated carbons with very high specific surface area of >3.000 m² g⁻¹ (based on CO₂ adsorption isotherms) and a high proportion of micropores (87% of total SSA) are produced by corncobs via pyrolysis and chemical activation with KOH. The activated carbon is further doped with different proportions of the highly pseudocapacitive transition metal oxide RuO₂ to obtain enhanced electrochemical properties and tune the materials for the application in electrochemical double-layer capacitors (EDLC) (supercapacitors). The activated carbon and composites are extensively studied regarding their physico-chemical and electrochemical properties. The results show that the composite containing 40 wt.% RuO₂ has an electric conductivity of 408 S m⁻¹ and a specific capacitance of 360 Fg⁻¹. SEM-EDX, XPS, and XRD analysis confirm the homogenous distribution of partly crystalline RuO₂ particles on the carbon surface, which leads to a biobased composite material with enhanced electrochemical properties. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 1944 KiB

Open AccessArticle

Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films

by Esat Pehlivan, Claes G. Granqvist and Gunnar A. Niklasson

Electron. Mater. 2021, 2(3), 312-323; https://doi.org/10.3390/electronicmat2030022 - 27 Jul 2021

Cited by 2 | Viewed by 2865

Abstract

Tungsten oxide is a widely used electrochromic material with important applications in variable-transmittance smart windows as well as in other optoelectronic devices. Here we report on electrochemical impedance spectroscopy applied to hydrous electrochromic tungsten oxide films in a wide range of applied potentials. [...] Read more.

Tungsten oxide is a widely used electrochromic material with important applications in variable-transmittance smart windows as well as in other optoelectronic devices. Here we report on electrochemical impedance spectroscopy applied to hydrous electrochromic tungsten oxide films in a wide range of applied potentials. The films were able to reversibly bleach and color upon electrochemical cycling. Interestingly, the bleaching potential was found to be significantly higher than in conventional non-hydrous tungsten oxide films. Impedance spectra at low potentials showed good agreement with anomalous diffusion models for ion transport in the films. At high potentials, where little ion intercalation takes place, it seems that parasitic side reactions influence the spectra. The potential dependence of the chemical capacitance, as well as the ion diffusion coefficient, were analyzed. The chemical capacitance is discussed in terms of the electron density of states in the films and evidence was found for a band tail extending below the conduction band edge. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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15 pages, 5303 KiB

Open AccessArticle

Tuning Magnetic and Transport Properties in Quasi-2D (Mn_1−xNi_x)₂P₂S₆ Single Crystals

by Yuliia Shemerliuk, Yonghui Zhou, Zhaorong Yang, Gang Cao, Anja U. B. Wolter, Bernd Büchner and Saicharan Aswartham

Electron. Mater. 2021, 2(3), 284-298; https://doi.org/10.3390/electronicmat2030020 - 08 Jul 2021

Cited by 20 | Viewed by 3918

Abstract

We report an optimized chemical vapor transport method to grow single crystals of (Mn_1−xNi_x)₂P₂S₆ where x = 0, 0.3, 0.5, 0.7, and 1. Single crystals up to 4 mm × 3 mm × 200 [...] Read more.

We report an optimized chemical vapor transport method to grow single crystals of (Mn_1−xNi_x)₂P₂S₆ where x = 0, 0.3, 0.5, 0.7, and 1. Single crystals up to 4 mm × 3 mm × 200 μm were obtained by this method. As-grown crystals are characterized by means of scanning electron microscopy and powder X-ray diffraction measurements. The structural characterization shows that all crystals crystallize in monoclinic symmetry with the space group C2/m (No. 12). We have further investigated the magnetic properties of this series of single crystals. The magnetic measurements of the all as-grown single crystals show long-range antiferromagnetic order along all principal crystallographic axes. Overall, the Néel temperature T_N is non-monotonous; with increasing Ni²⁺ doping, the temperature of the antiferromagnetic phase transition first decreases from 80 K for pristine Mn₂P₂S₆ (x = 0) up to x = 0.5 and then increases again to 155 K for pure Ni₂P₂S₆ (x = 1). The magnetic anisotropy switches from out-of-plane to in-plane as a function of composition in (Mn_1−xNi_x)₂P₂S₆ series. Transport studies under hydrostatic pressure on the parent compound Mn₂P₂S₆ evidence an insulator-metal transition at an applied critical pressure of ~22 GPa. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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10 pages, 1281 KiB

Open AccessArticle

Calculation of Band Offsets of Mg(OH)₂-Based Heterostructures

by Masaya Ichimura

Electron. Mater. 2021, 2(3), 274-283; https://doi.org/10.3390/electronicmat2030019 - 01 Jul 2021

Cited by 1 | Viewed by 3122

Abstract

The band alignment of Mg(OH)₂-based heterostructures is investigated based on first-principles calculation. (111)-MgO/(0001)-Mg(OH)₂ and (0001)-wurtzite ZnO/(0001)-Mg(OH)₂ heterostructures are considered. The O 2s level energy is obtained for each O atom in the heterostructure supercell, and the band edge energies [...] Read more.

The band alignment of Mg(OH)₂-based heterostructures is investigated based on first-principles calculation. (111)-MgO/(0001)-Mg(OH)₂ and (0001)-wurtzite ZnO/(0001)-Mg(OH)₂ heterostructures are considered. The O 2s level energy is obtained for each O atom in the heterostructure supercell, and the band edge energies are evaluated following the procedure of the core-level spectroscopy. The calculation is based on the generalized gradient approximation with the on-site Coulomb interaction parameter U considered for Zn. For MgO/Mg(OH)₂, the band alignment is of type II, and the valence band edge of MgO is higher by 1.6 eV than that of Mg(OH)₂. For ZnO/Mg(OH)₂, the band alignment is of type I, and the valence band edge of ZnO is higher by 0.5 eV than that of Mg(OH)₂. Assuming the transitivity rule, it is expected that Mg(OH)₂ can be used for certain types of heterostructure solar cells and dye-sensitized solar cells to improve the performance. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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21 pages, 3678 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

In-Situ Characterisation of Charge Transport in Organic Light-Emitting Diode by Impedance Spectroscopy

by Pavel Chulkin

Electron. Mater. 2021, 2(2), 253-273; https://doi.org/10.3390/electronicmat2020018 - 08 Jun 2021

Cited by 2 | Viewed by 3520

Abstract

The article demonstrates an original, non-destructive technique that could be used to in situ monitor charge transport in organic light-emitting diodes. Impedance spectroscopy was successfully applied to determine an OLED’s charge carrier mobility and average charge density in the hole- and electron-transport layer [...] Read more.

The article demonstrates an original, non-destructive technique that could be used to in situ monitor charge transport in organic light-emitting diodes. Impedance spectroscopy was successfully applied to determine an OLED’s charge carrier mobility and average charge density in the hole- and electron-transport layer in a range of applied voltages. The fabricated devices were composed of two commercially available materials: NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine) and TPBi (2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) as hole- and electron-transport layers, respectively. By varying the thicknesses of the hole-transport layer (HTL) and the electron-transport layer (ETL), correlations between layer thickness and both charge carrier mobility and charge density were observed. A possibility of using the revealed dependencies to predict diode current–voltage characteristics in a wide range of applied voltage has been demonstrated. The technique based on a detailed analysis of charge carrier mobilities and densities is useful for choosing the appropriate transport layer thicknesses based on an investigation of a reference set of samples. An important feature of the work is its impact on the development of fundamental research methods that involve AC frequency response analysis by providing essential methodology on data processing. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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24 pages, 14412 KiB

Open AccessArticle

On the Role of LiF in Organic Optoelectronics

by Ayse Turak

Electron. Mater. 2021, 2(2), 198-221; https://doi.org/10.3390/electronicmat2020016 - 03 Jun 2021

Cited by 22 | Viewed by 5447

Abstract

Organic optoelectronic device behaviour is heavily dependent on interfacial effects due to the device architecture and thickness. Interfaces between the inorganic electrodes and the active organic layers play a defining role in the all of the electronic and stability processes that occur in [...] Read more.

Organic optoelectronic device behaviour is heavily dependent on interfacial effects due to the device architecture and thickness. Interfaces between the inorganic electrodes and the active organic layers play a defining role in the all of the electronic and stability processes that occur in organic light emitting diodes (OLEDs) and organic solar cells (OPVs). Amongst the many interlayers introduced at these interfaces to improve charge carrier movement and stability, LiF has proven to be the most successful and it is almost ubiquitous in all organic semiconductor devices. Implemented at both top and bottom contact interfaces, doped into the charge transporting layers, and used as encapsulants, LiF has played major roles in device performance and lifetime. This review highlights the use of LiF at both top and bottom contacts in organic optoelectronics, discusses the various mechanisms proposed for the utility of LiF at each interface, and explores its impact on device lifetimes. From examples relating to charge carrier flow, interfacial electronic level modification, and interfacial stability, a comprehensive picture of the role of LiF in organic devices can be formed. This review begins with a brief overview of the role of the interface in OLEDs and OPVs, and the general properties of LiF. Then, it discusses the implementation of LiF at the top contact electrode interface, followed by the bottom substrate contact electrode, examining both performance and degradation effects in both cases. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 2103 KiB

Open AccessArticle

Imaging the Morphological Structure of Silk Fibroin Constructs through Fluorescence Energy Transfer and Confocal Microscopy

by Alessio Bucciarelli, Alberto Quaranta and Devid Maniglio

Electron. Mater. 2021, 2(2), 186-197; https://doi.org/10.3390/electronicmat2020015 - 03 Jun 2021

Cited by 3 | Viewed by 2835

Abstract

Silk fibroin is a well-known biopolymer that is used in several applications in which interactions with biological tissue are required. Fibroin is extremely versatile and can be shaped to form several constructs that are useful in tissue engineering applications. Confocal imaging is usually [...] Read more.

Silk fibroin is a well-known biopolymer that is used in several applications in which interactions with biological tissue are required. Fibroin is extremely versatile and can be shaped to form several constructs that are useful in tissue engineering applications. Confocal imaging is usually performed to test cell behavior on a construct, and, in this context, the fibroin intrinsic fluorescence is regarded as a problem. In addition, the intrinsic fluorescence is not intense enough to provide useful morphological images. In fact, to study the construct’s morphology, other techniques are used (i.e., SEM and Micro-CT). In this work, we propose a method based on fluorescence energy transfer (FRET) to suppress the fibroin intrinsic fluorescence and move it to a higher wavelength that is accessible to confocal microscopy for direct imaging. This was done by creating two FRET couples by dispersing two fluorophores (2,5-diphenyloxazole (PPO) and Lumogen F Violet 570 (LV)) into the fibroin matrix and optimizing their percentages to suppress the fibroin intrinsic fluorescence. With the optimized composition, we produced an electrospun mat, and the dimensions of the fibers were accurately determined by confocal microscopy. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 2769 KiB

Open AccessFeature PaperArticle

Portable Photovoltaic-Self-Powered Flexible Electrochromic Windows for Adaptive Envelopes

by Antonio Cánovas-Saura, Ramón Ruiz, Rodolfo López-Vicente, José Abad, Antonio Urbina and Javier Padilla

Electron. Mater. 2021, 2(2), 174-185; https://doi.org/10.3390/electronicmat2020014 - 02 Jun 2021

Viewed by 2824

Abstract

Variable transmission applications for light control or energy saving based on electrochromic materials have been successfully applied in the past in the building, sports, or automotive fields, although lower costs and ease of fabrication, installation, and maintenance are still needed for deeper market [...] Read more.

Variable transmission applications for light control or energy saving based on electrochromic materials have been successfully applied in the past in the building, sports, or automotive fields, although lower costs and ease of fabrication, installation, and maintenance are still needed for deeper market integration. In this study, all-printed large area (900 cm² active area) flexible electrochromic devices were fabricated, and an autoregulating self-power supply was implemented through the use of organic solar cells. A new perspective was applied for automotive light transmission function, where portability and mechanical flexibility added new features for successful market implementation. Special emphasis was placed in applying solution-based scalable deposition techniques and commercially available materials (PEDOT-PSS as an electrochromic material; vanadium oxide, V₂O₅, as a transparent ion-storage counter electrode; and organic solar modules as the power supply). A straightforward electronic control method was designed and successfully implemented allowing for easy user control. We describe a step-by-step route following the design, materials optimization, electronic control simulation, in-solution fabrication, and scaling-up of fully functional self-powered portable electrochromic devices. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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20 pages, 34459 KiB

Open AccessEditor’s ChoiceArticle

Porous Polymer Gel Electrolytes Influence Lithium Transference Number and Cycling in Lithium-Ion Batteries

by Buket Boz, Hunter O. Ford, Alberto Salvadori and Jennifer L. Schaefer

Electron. Mater. 2021, 2(2), 154-173; https://doi.org/10.3390/electronicmat2020013 - 27 May 2021

Cited by 7 | Viewed by 4512

Abstract

To improve the energy density of lithium-ion batteries, the development of advanced electrolytes with enhanced transport properties is highly important. Here, we show that by confining the conventional electrolyte (1 M LiPF₆ in EC-DEC) in a microporous polymer network, the cation transference [...] Read more.

To improve the energy density of lithium-ion batteries, the development of advanced electrolytes with enhanced transport properties is highly important. Here, we show that by confining the conventional electrolyte (1 M LiPF₆ in EC-DEC) in a microporous polymer network, the cation transference number increases to 0.79 while maintaining an ionic conductivity on the order of

10^{- 3}

S cm⁻¹. By comparison, a non-porous, condensed polymer electrolyte of the same chemistry has a lower transference number and conductivity, of 0.65 and 7.6 × 10⁻⁴ S cm⁻¹, respectively. Within Li-metal/LiFePO₄ cells, the improved transport properties of the porous polymer electrolyte enable substantial performance enhancements compared to a commercial separator in terms of rate capability, capacity retention, active material utilization, and efficiency. These results highlight the importance of polymer electrolyte structure–performance property relationships and help guide the future engineering of better materials. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 3516 KiB

Open AccessEditor’s ChoiceArticle

Pyrimidine-Based Push–Pull Systems with a New Anchoring Amide Group for Dye-Sensitized Solar Cells

by Egor V. Verbitskiy, Alexander S. Steparuk, Ekaterina F. Zhilina, Viktor V. Emets, Vitaly A. Grinberg, Ekaterina V. Krivogina, Sergey A. Kozyukhin, Ekaterina V. Belova, Petr I. Lazarenko, Gennady L. Rusinov, Alexey R. Tameev, Jean Michel Nunzi and Valery N. Charushin

Electron. Mater. 2021, 2(2), 142-153; https://doi.org/10.3390/electronicmat2020012 - 26 May 2021

Cited by 12 | Viewed by 2899

Abstract

New donor–π–acceptor pyrimidine-based dyes comprising an amide moiety as an anchoring group have been designed. The dyes were synthesized by sequential procedures based on the microwave-assisted Suzuki cross-coupling and bromination reactions. The influence of the dye structure and length of π-linker on the [...] Read more.

New donor–π–acceptor pyrimidine-based dyes comprising an amide moiety as an anchoring group have been designed. The dyes were synthesized by sequential procedures based on the microwave-assisted Suzuki cross-coupling and bromination reactions. The influence of the dye structure and length of π-linker on the photophysical and electrochemical properties and on the photovoltaic effectiveness of dye-sensitized solar cells was investigated. An increase in efficiency with a decrease in the length of π-linker was revealed. The D1 dye with only one 2,5-thienylene-linker provided the highest power conversion efficiency among the fabricated dye sensitized solar cells. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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17 pages, 477 KiB

Open AccessArticle

A Model for Bias Potential Effects on the Effective Langmuir Adsorption–Desorption Processes

by Luiz Roberto Evangelista, Giovanni Barbero and Anca Luiza Alexe-Ionescu

Electron. Mater. 2021, 2(2), 125-141; https://doi.org/10.3390/electronicmat2020011 - 17 May 2021

Cited by 1 | Viewed by 1908

Abstract

We discuss the foundations of a model based on an extension of the Langmuir approximation for the adsorption–desorption phenomena, in which the phenomenological coefficients depend on the bias potential, in addition to their dependence on the adsorption energy. The theoretical analysis focuses on [...] Read more.

We discuss the foundations of a model based on an extension of the Langmuir approximation for the adsorption–desorption phenomena, in which the phenomenological coefficients depend on the bias potential, in addition to their dependence on the adsorption energy. The theoretical analysis focuses on the effect of these effective coefficients on the electrical response of an electrolytic cell to an external electric field, as predicted by the Poisson–Nernst–Planck model. Kinetic balance equations govern the current densities on the electrodes when the adsorption phenomenon occurs in the presence of an electric bias. The influence of the phenomenological parameters entering the model, as well as of the symmetry of the cell on the cyclic voltammetry, is investigated. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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11 pages, 2114 KiB

Open AccessEditor’s ChoiceArticle

Towards Sustainable Crossbar Artificial Synapses with Zinc-Tin Oxide

by Carlos Silva, Jorge Martins, Jonas Deuermeier, Maria Elias Pereira, Ana Rovisco, Pedro Barquinha, João Goes, Rodrigo Martins, Elvira Fortunato and Asal Kiazadeh

Electron. Mater. 2021, 2(2), 105-115; https://doi.org/10.3390/electronicmat2020009 - 16 Apr 2021

Cited by 6 | Viewed by 3371

Abstract

In this article, characterization of fully patterned zinc-tin oxide (ZTO)-based memristive devices with feature sizes as small as 25 µm² is presented. The devices are patterned via lift-off with a platinum bottom contact and a gold-titanium top contact. An on/off ratio of [...] Read more.

In this article, characterization of fully patterned zinc-tin oxide (ZTO)-based memristive devices with feature sizes as small as 25 µm² is presented. The devices are patterned via lift-off with a platinum bottom contact and a gold-titanium top contact. An on/off ratio of more than two orders of magnitude is obtained without the need for electroforming processes. Set operation is a current controlled process, whereas the reset is voltage dependent. The temperature dependency of the electrical characteristics reveals a bulk-dominated conduction mechanism for high resistance states. However, the charge transport at low resistance state is consistent with Schottky emission. Synaptic properties such as potentiation and depression cycles, with progressive increases and decreases in the conductance value under 50 successive pulses, are shown. This validates the potential use of ZTO memristive devices for a sustainable and energy-efficient brain-inspired deep neural network computation. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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23 pages, 5024 KiB

Open AccessArticle

Trapping of Electrons around Nanoscale Metallic Wires Embedded in a Semiconductor Medium

by Chi Cuong Huynh, Roger Evrard and Ngoc Duy Nguyen

Electron. Mater. 2021, 2(2), 82-104; https://doi.org/10.3390/electronicmat2020008 - 14 Apr 2021

Viewed by 2198

Abstract

We predict that conduction electrons in a semiconductor film containing a centered square array of metal nanowires normal to its plane are bound in quantum states around the central wires, if a positive bias voltage is applied between the wires at the square [...] Read more.

We predict that conduction electrons in a semiconductor film containing a centered square array of metal nanowires normal to its plane are bound in quantum states around the central wires, if a positive bias voltage is applied between the wires at the square vertices and the latter. We obtain and discuss the eigenenergies and eigenfunctions of two models with different dimensions. The results show that the eigenstates can be grouped into different shells. The energy differences between the shells is typically a few tens of meV, which corresponds to frequencies of emitted or absorbed photons in a range of

3 THz

to

20 THz

approximately. These energy differences strongly depend on the bias voltage. We calculate the linear response of individual electrons on the ground level of our models to large-wavelength electromagnetic waves whose electric field is in the plane of the semiconductor film. The computed oscillator strengths are dominated by the transitions to the states in each shell whose wave function has a single radial node line normal to the wave electric field. We include the effect of the image charge induced on the central metal wires and show that it modifies the oscillator strengths so that their sum deviates from the value given by the Thomas-Reiche-Kuhn rule. We report the linear response, or polarizability, versus photon energy, of the studied models and their absorption spectra. The latter show well-defined peaks as expected from the study of the oscillator strengths. We show that the position of these absorption peaks is strongly dependent on the bias voltage so that the frequency of photon absorption or emission in the systems described here is easily tunable. This makes them good candidates for the development of novel infrared devices. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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12 pages, 1497 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Solution-Processed Organic and ZnO Field-Effect Transistors in Complementary Circuits

by John Barron, Alec Pickett, James Glaser and Suchismita Guha

Electron. Mater. 2021, 2(2), 60-71; https://doi.org/10.3390/electronicmat2020006 - 30 Mar 2021

Cited by 4 | Viewed by 2986

Abstract

The use of high κ dielectrics lowers the operating voltage in organic field-effect transistors (FETs). Polymer ferroelectrics open the path not just for high κ values but allow processing of the dielectric films via electrical poling. Poled ferroelectric dielectrics in p-type organic FETs [...] Read more.

The use of high κ dielectrics lowers the operating voltage in organic field-effect transistors (FETs). Polymer ferroelectrics open the path not just for high κ values but allow processing of the dielectric films via electrical poling. Poled ferroelectric dielectrics in p-type organic FETs was seen to improve carrier mobility and reduce leakage current when compared to unpoled devices using the same dielectric. For n-type FETs, solution-processed ZnO films provide a viable low-cost option. UV–ozone-treated ZnO films was seen to improve the FET performance due to the filling of oxygen vacancies. P-type FETs were fabricated using the ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) as the dielectric along with a donor–acceptor polymer based on diketopyrrolopyrrole (DPP-DTT) as the semiconductor layer. The DPP-DTT FETs yield carrier mobilities upwards of 0.4 cm²/Vs and high on/off ratios when the PVDF-TrFE layer is electrically poled. For n-type FETs, UV–ozone-treated sol–gel ZnO films on SiO₂ yield carrier mobilities of 10⁻² cm²/Vs. DPP-DTT-based p- and ZnO-based n-type FETs were used in a complementary voltage inverter circuit, showing promising characteristic gain. A basic inverter model was used to simulate the inverter characteristics, using parameters from the individual FET characteristics. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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11 pages, 1652 KiB

Open AccessArticle

Structural Changes Induced by Heating in Sputtered NiO and Cr₂O₃ Thin Films as p-Type Transparent Conductive Electrodes

by Cecilia Guillén and José Herrero

Electron. Mater. 2021, 2(2), 49-59; https://doi.org/10.3390/electronicmat2020005 - 29 Mar 2021

Cited by 7 | Viewed by 2600

Abstract

NiO and Cr₂O₃ are transition metal oxides with a partially filled d electron band that supports p-type conduction. Both are transparent to the visible light due to optical absorption beginning at wavelengths below 0.4 μm and the creation of holes [...] Read more.

NiO and Cr₂O₃ are transition metal oxides with a partially filled d electron band that supports p-type conduction. Both are transparent to the visible light due to optical absorption beginning at wavelengths below 0.4 μm and the creation of holes by metal vacancy defects. The defect and strain effects on the electronic characteristics of these materials need to be established. For this purpose, NiO and Cr₂O₃ thin films were deposited on unheated glass substrates by reactive DC sputtering from metallic targets. Their structural, morphological, optical and electrical properties were analyzed comparatively in the as-grown conditions (25 °C) and after heating in air at 300 °C or 500 °C. The cubic NiO structure was identified with some tensile strain in the as-grown conditions and compressive strain after heating. Otherwise, the chromium oxide layers were amorphous as grown at 25 °C and crystallized into hexagonal Cr₂O₃ at 300 °C or above also with compressive strain after heating. Both materials achieved the highest visible transmittance (72%) and analogous electrical conductivity (~10⁻⁴ S/cm) by annealing at 500 °C. The as-grown NiO films showed a higher conductivity (2.5 × 10⁻² S/cm) but lower transmittance (34%), which were related to more defects causing tensile strain in these samples. Full article

(This article belongs to the Special Issue Feature Papers of Electronic Materials)

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10 pages, 12620 KiB

Open AccessArticle

Preparation of Li₃PS₄–Li₃PO₄ Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

by Nguyen H. H. Phuc, Takaki Maeda, Tokoharu Yamamoto, Hiroyuki Muto and Atsunori Matsuda

Electron. Mater. 2021, 2(1), 39-48; https://doi.org/10.3390/electronicmat2010004 - 12 Mar 2021

Cited by 7 | Viewed by 3845

Abstract

A solid solution of a 100Li₃PS₄·xLi₃PO₄ solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the [...] Read more.

A solid solution of a 100Li₃PS₄·xLi₃PO₄ solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li₂S, P₂S₅ and Li₃PO₄ was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li₃PO₄ were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li₃PO₄ remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS₃³⁻ unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0. Full article

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16 pages, 3278 KiB

Open AccessFeature PaperArticle

Ta₂O₅/SiO₂ Multicomponent Dielectrics for Amorphous Oxide TFTs

by Jorge Martins, Asal Kiazadeh, Joana V. Pinto, Ana Rovisco, Tiago Gonçalves, Jonas Deuermeier, Eduardo Alves, Rodrigo Martins, Elvira Fortunato and Pedro Barquinha

Electron. Mater. 2021, 2(1), 1-16; https://doi.org/10.3390/electronicmat2010001 - 29 Dec 2020

Cited by 9 | Viewed by 4320

Abstract

Co-sputtering of SiO₂ and high-κ Ta₂O₅ was used to make multicomponent gate dielectric stacks for In-Ga-Zn-O thin-film transistors (IGZO TFTs) under an overall low thermal budget (T = 150 °C). Characterization of the multicomponent layers and of the TFTs [...] Read more.

Co-sputtering of SiO₂ and high-κ Ta₂O₅ was used to make multicomponent gate dielectric stacks for In-Ga-Zn-O thin-film transistors (IGZO TFTs) under an overall low thermal budget (T = 150 °C). Characterization of the multicomponent layers and of the TFTs working characteristics (employing them) was performed in terms of static performance, reliability, and stability to understand the role of the incorporation of the high-κ material in the gate dielectric stack. It is shown that inherent disadvantages of the high-κ material, such as poorer interface properties and poor gate insulation, can be counterbalanced by inclusion of SiO₂ both mixed with Ta₂O₅ and as thin interfacial layers. A stack comprising a (Ta₂O₅)_x(SiO₂)_{100 − x} film with x = 69 and a thin SiO₂ film at the interface with IGZO resulted in the best performing TFTs, with field-effect mobility (µ_FE) ≈ 16 cm²·V⁻¹·s⁻¹, subthreshold slope (SS) ≈ 0.15 V/dec and on/off ratio exceeding 10⁷. Anomalous V_th shifts were observed during positive gate bias stress (PGBS), followed by very slow recoveries (time constant exceeding 8 × 10⁵ s), and analysis of the stress and recovery processes for the different gate dielectric stacks showed that the relevant mechanism is not dominated by the interfaces but seems to be related to the migration of charged species in the dielectric. The incorporation of additional SiO₂ layers into the gate dielectric stack is shown to effectively counterbalance this anomalous shift. This multilayered gate dielectric stack approach is in line with both the large area and the flexible electronics needs, yielding reliable devices with performance suitable for successful integration on new electronic applications. Full article

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14 pages, 1343 KiB

Open AccessFeature PaperArticle

Extending the Color Retention of an Electrochromic Device by Immobilizing Color Switching and Ion-Storage Complementary Layers

by Monika Wałęsa-Chorab and William G. Skene

Electron. Mater. 2020, 1(1), 40-53; https://doi.org/10.3390/electronicmat1010005 - 14 Dec 2020

Cited by 3 | Viewed by 2889

Abstract

The thermal polymerization of a bis(triphenylamine)-bis(styrene) monomer on ITO coated glass gave an electroactive film that underwent two stepwise oxidations. The perceived color change of the film upon stepwise oxidation was colorless-to-yellow followed by yellow-to-blue. The anodic cyclic voltammogram of the monomer was [...] Read more.

The thermal polymerization of a bis(triphenylamine)-bis(styrene) monomer on ITO coated glass gave an electroactive film that underwent two stepwise oxidations. The perceived color change of the film upon stepwise oxidation was colorless-to-yellow followed by yellow-to-blue. The anodic cyclic voltammogram of the monomer was consistent over multiple cycles. The immobilized film could be reversibly switched between its colorless and blue states with applied potential in both a half- and full-electrochromic functioning device. The devices could also reversibly switch their colors upwards of 6 h. The retention of the electrochemically induced blue color was contingent on the device architecture. Upwards of 80% of the color was maintained 30 min after the potential was turned off with the double-layer electrochromic device structure. This device was prepared from two electroactive layers: a bis(triphenylamine) and viologen-based polymers that were immobilized on the electrodes. In contrast, 50% of the color of the active electrochromic device that was prepared from a single electroactive layer bleached 7 min once the potential was no longer applied. Full article

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12 pages, 3462 KiB

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Coating 1-Octanethiol-Coated Copper Nano-Ink on a Paper Substrate via Multi-Pulse Flash Light Sintering for Application in Disposable Devices

by Yeonho Son, Dongho Shin, Minkyu Kang and Caroline Sunyong Lee

Electron. Mater. 2020, 1(1), 28-39; https://doi.org/10.3390/electronicmat1010004 - 23 Sep 2020

Cited by 1 | Viewed by 2941

Abstract

Inkjet-printed patterns were formed on a paper substrate using anti-oxidant copper nano-ink for application to disposable electronic devices. To prevent substrate damage, the pattern was flash light sintered under ambient conditions using the multi-pulse technique. Pure copper nanoparticles were coated with 1-octanethiol for [...] Read more.

Inkjet-printed patterns were formed on a paper substrate using anti-oxidant copper nano-ink for application to disposable electronic devices. To prevent substrate damage, the pattern was flash light sintered under ambient conditions using the multi-pulse technique. Pure copper nanoparticles were coated with 1-octanethiol for oxidation resistance using the dry-coating method. Mixing these with 1-octanol solvent at a concentration of 30 wt% produced the copper nano-ink. Photo paper was used as the substrate. The contact angle between the photo paper and copper nano-ink was 37.2° and the optimal energy density for the multi-pulse flash light sintering technique was 15.6 J/cm². Using this energy density, the optimal conditions were an on-time of 2 ms (duty cycle of 80%) for three pulses. The resistivity of the resulting pattern was 2.8 × 10⁻⁷ Ω∙m. After bending 500 times to a radius of curvature of 30 mm, the relative resistance (ΔR/R₀) of the multi-pulse flash light-sintered pattern hardly changed compared to that of the unbent pattern, while the single-pulse-sintered pattern showed dramatic increase by 8-fold compared to the unbent pattern. Therefore, the multi-pulse light sintering technique is a promising approach to produce an inkjet-printed pattern that can be applied to disposable electronic devices. Full article

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17 pages, 3454 KiB

Open AccessFeature PaperReview

Passive Intermodulation at Contacts of Rough Conductors

by Amir Dayan, Yi Huang and Alex Schuchinsky

Electron. Mater. 2022, 3(1), 65-81; https://doi.org/10.3390/electronicmat3010007 - 03 Feb 2022

Cited by 11 | Viewed by 3381

Abstract

Passive intermodulation (PIM) is a niggling phenomenon that debilitates the performance of modern communications and navigation systems. PIM products interfere with information signals and cause their nonlinear distortion. The sources and basic mechanisms of PIM have been studied in the literature but PIM [...] Read more.

Passive intermodulation (PIM) is a niggling phenomenon that debilitates the performance of modern communications and navigation systems. PIM products interfere with information signals and cause their nonlinear distortion. The sources and basic mechanisms of PIM have been studied in the literature but PIM remains a serious problem of signal integrity. In this paper, the main sources and mechanisms of PIM generation by joints of good conductors are discussed. It is shown that the passive electrical, thermal and mechanical nonlinearities are intrinsically linked despite their distinctively different time scales. The roughness of the contact surfaces plays an important role in PIM generation by conductor joints. A review of the PIM phenomenology at the contacts of the good conductors suggests that novel multiphysics models are necessary for the analysis and reliable prediction of PIM products generated by several concurrent nonlinearities of a diverse physical nature. Full article

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31 pages, 9047 KiB

Open AccessReview

Oligothiophene-Naphthalimide Hybrids Connected through Rigid and Conjugated Linkers in Organic Electronics: An Overview

by Matías J. Alonso-Navarro, Elena Gala, M. Mar Ramos, Rocío Ponce Ortiz and José L. Segura

Electron. Mater. 2021, 2(2), 222-252; https://doi.org/10.3390/electronicmat2020017 - 05 Jun 2021

Cited by 4 | Viewed by 3233

Abstract

In this article, we summarize the synthetic approaches developed in our research groups during the last decade to efficiently tune the optical, electrochemical and morphological characteristics of oligothiophene–naphthalimide assemblies. Different variables were tuned in these organic semiconductors, such as the planarity and the [...] Read more.

In this article, we summarize the synthetic approaches developed in our research groups during the last decade to efficiently tune the optical, electrochemical and morphological characteristics of oligothiophene–naphthalimide assemblies. Different variables were tuned in these organic semiconductors, such as the planarity and the length of their π-conjugated backbones, the topology and energy levels of the frontier molecular orbitals (HOMO and LUMO) and their molecular dipole moments. The tuning of these properties can be connected with the microstructure properties observed by atomic force microscopy (AFM) and X-ray diffraction (XRD) in thin films as well as with the performances in organic field-effect transistors (OFETs). The possibility of incorporating these donor-acceptor assemblies into macromolecular structures is also addressed, and some innovative applications for these macromolecular systems, such as the degradation of organic pollutants in aqueous media, are also presented. Full article

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