2D Materials-Based Thin Films and Coatings

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Thin Films".

Deadline for manuscript submissions: 29 February 2024 | Viewed by 28376

Special Issue Editor

INFN-Laboratori Nazionali di Frascati, Via E. Fermi 54, I-00044 Frascati, Italy
Interests: graphene synthesis and characterization; graphene plasmonics; graphene coatings; pollutants removal; 2D materials experiments and modeling; DFT
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Since its initial isolation in 2004, graphene has attracted much attention, as a result of its outstanding properties and promising applications; however, the high diameter/thickness ratio, perfect water and oxygen blocking properties, ionic impermeability, and chemical stability of graphene-based materials are gradually emerging as properties that are being scrutinized and exploited. The nano-barrier effect observed in graphene greatly benefits the building of an internal labyrinth effect, to extend the infiltration path of corrosive media, which assists in producing novel protective coatings with interesting features, such as low loading of the inorganic component, lightweight, unique mechanical properties, corrosion resistance, and weather resistance. However, the application of graphene-based materials is restricted by their large-scale, stable, non-destructive dispersion, and their compatibility with resin interfaces; these properties limit their implementation, for instance, in the field of anticorrosive coatings.

To address the issues mentioned, a clear understanding of the state of the art of useful thin films and coatings, based on graphene or related two-dimensional (2D) materials, is necessary to devise countermeasures and solutions. With this in mind, the related 2D materials that are currently considered as promising thin films and coatings include the following: graphene oxide, molybdenum disulfide, boron nitride, mica, zirconium phosphate, layered hydrotalcite, the MXene family, carbon nitride, amongst others.  

This Special Issue is expected to serve as a forum for papers in the following concepts:

  • Recent developments in multi-functional graphene-based coatings;
  • Theoretical and experimental research, and new ideas in protective and preventive coating mechanisms using beyond-graphene materials;
  • Coatings or thin films produced by different processes as additive manufacturing processes, thermal spray, laser and plasma processing, CVD, plating, etc.;
  • Coatings with exposure to high temperatures, high stress, and other extreme environment applications;
  • Understanding the degradation mechanisms of coatings through friction, wear or other dynamic loading conditions, and corrosion;
  • Modeling and simulation to predict coating properties, performance, durability, and reliability.

Prof. Dr. Cristian Vacacela Gomez
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • graphene-based coatings
  • two-dimensional nanomaterials
  • anticorrosive coatings
  • performance and reliability modeling
  • multifunctional nanostructured materials

Published Papers (13 papers)

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Research

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15 pages, 10077 KiB  
Article
Fabrication of Polyurethane/Laponite/Graphene Transparent Coatings with High Surface Hardness
Coatings 2024, 14(1), 12; https://doi.org/10.3390/coatings14010012 - 21 Dec 2023
Viewed by 607
Abstract
A polyurethane/Laponite/graphene transparent coating with high surface hardness, obtained by dispersing the Laponite–graphene oxide (Lap-GO) in polyurethane for UV reduction, is reported. Lap-GO improves the hardness of the coating, where Laponite is intercalated between graphene layers through electrostatic action, preventing the re-accumulation or [...] Read more.
A polyurethane/Laponite/graphene transparent coating with high surface hardness, obtained by dispersing the Laponite–graphene oxide (Lap-GO) in polyurethane for UV reduction, is reported. Lap-GO improves the hardness of the coating, where Laponite is intercalated between graphene layers through electrostatic action, preventing the re-accumulation or aggregation of graphene and ensuring the transparency of the coating. The analysis of pencil hardness and light transmittance shows that when the Lap-GO content is 0.05 wt‰ and the UV reduction is 10 min, the hardness of the coated pencil increases to 5H, and the light transmittance remains above 85%. Furthermore, the polyurethane/Laponite/graphene transparent coating also has excellent cold liquid resistance and meets specific usage standards. The prepared polyurethane/Laponite/graphene transparent coatings are promising for broad application prospects in cover and protective coatings. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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13 pages, 3211 KiB  
Article
Reproducible Preparation of Thin Graphene Films Using a Green and Efficient Liquid-Phase Exfoliation Method for Applications in Photovoltaics
Coatings 2023, 13(9), 1628; https://doi.org/10.3390/coatings13091628 - 17 Sep 2023
Viewed by 787
Abstract
This paper presents an innovative, cost-effective, and environmentally sustainable approach to producing high-quality graphene nanosheets (G-NSs) on a large scale. Particularly, we have achieved a remarkable graphene material, expertly dissolved in ethanol at an impressive concentration of 0.7 mg/mL, using a cutting-edge electrophoretic [...] Read more.
This paper presents an innovative, cost-effective, and environmentally sustainable approach to producing high-quality graphene nanosheets (G-NSs) on a large scale. Particularly, we have achieved a remarkable graphene material, expertly dissolved in ethanol at an impressive concentration of 0.7 mg/mL, using a cutting-edge electrophoretic deposition method on an ITO/PET surface. This achievement holds great promise for a wide range of photovoltaic applications. The G-NSs were rigorously analyzed using advanced techniques, including FESEM, EDAX elemental mapping, X-ray diffraction (XRD), and Raman analysis. This comprehensive examination yielded a significant discovery: the thickness of the deposited films profoundly influences the material’s interaction with photons. This finding positions the synthesized graphene material as a game changer in the field of light detection sensors, with the potential to revolutionize the landscape of optoelectronics. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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12 pages, 3549 KiB  
Article
Photodetector-Based Material from a Highly Sensitive Free-Standing Graphene Oxide/Polypyrrole Nanocomposite
Coatings 2023, 13(7), 1198; https://doi.org/10.3390/coatings13071198 - 04 Jul 2023
Cited by 4 | Viewed by 774
Abstract
This paper describes the establishment of free-standing rolled graphene oxide (roll-GO) and polypyrrole (Ppy) using a modified Hummer method and oxidative polymerization. Then, a photodetector was created by removing a thin film of the free-standing rolled graphene oxide from a filter paper and [...] Read more.
This paper describes the establishment of free-standing rolled graphene oxide (roll-GO) and polypyrrole (Ppy) using a modified Hummer method and oxidative polymerization. Then, a photodetector was created by removing a thin film of the free-standing rolled graphene oxide from a filter paper and attaching it to a tape. The chemical structure of the roll-GO was confirmed using XRD and FTIR analysis, while SEM and TEM showed that it was rolled in nature. The material had a small bandgap of 2.4 eV and a high current density in light conditions. The photodetector responded well to monochromatic light, with Jph values changing from 0.027 to 0.019 mA/cm2 as the light wavelengths decreased from 340 to 730 nm. The photoresponsivity (R) and detectivity (D) values were high, at 340 nm (0.27 mA/W and 6.0 × 107 Jones, respectively) and at 730 nm (0.19 and 4.25 × 107 Jones, respectively). The addition of Ppy improved these parameters, with the Ppy/roll-GO/tape photoelectrode showing excellent R and D values of 0.33 mA/W and 7.34 × 107 Jones, respectively. Furthermore, the production of a photocurrent at V = 0 indicated that the Ppy/roll-GO layer could be used for solar cell applications. Overall, the results suggest that the prepared free-standing Ppy/roll-GO/tape photodetector has high potential for use in the optical region between 340 and 730 nm and may be suitable for industrial applications. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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12 pages, 10789 KiB  
Article
Synthesis of Polycrystalline Diamond Films in Microwave Plasma at Ultrahigh Concentrations of Methane
Coatings 2023, 13(4), 751; https://doi.org/10.3390/coatings13040751 - 08 Apr 2023
Cited by 4 | Viewed by 1544
Abstract
Polycrystalline diamond (PCD) films are usually grown by chemical vapor deposition (CVD) in hydrogen–methane mixtures. The synthesis conditions determine the structure and quality of the grown material. Here, we report the complex effect of the microwave plasma CVD conditions on the morphology, growth [...] Read more.
Polycrystalline diamond (PCD) films are usually grown by chemical vapor deposition (CVD) in hydrogen–methane mixtures. The synthesis conditions determine the structure and quality of the grown material. Here, we report the complex effect of the microwave plasma CVD conditions on the morphology, growth rate and phase composition of the resulting PCD films. Specifically, we focus on the factors of (i) increased methane concentrations (νc) that are varied over a wide range of 4%–100% (i.e., pure methane gas) and (ii) substrate temperatures (Ts) varied between 700–1050 °C. Using scanning electron microscopy, X-ray diffraction and Raman spectroscopy, we show that diamond growth is possible even at ultrahigh methane concentrations, including νc = 100%, which requires relatively low synthesis temperatures of Ts < 800 °C. In general, lower substrate temperatures tend to facilitate the formation of higher-quality PCD films; however, this comes at the cost of lower growth rates. The growth rate of PCD coatings has a non-linear trend: for samples grown at Ts = 800 °C, the growth rate increases from 0.6 µm/h at νc = 4% to 3.4 µm/h at νc = 20% and then falls to 0.6 µm/h at νc = 100%. This research is a step toward control over the nature of the CVD-grown PCD material, which is essential for the precise and flexible production of diamond for various applications. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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10 pages, 2764 KiB  
Article
Combined HF+MW CVD Approach for the Growth of Polycrystalline Diamond Films with Reduced Bow
Coatings 2023, 13(2), 380; https://doi.org/10.3390/coatings13020380 - 07 Feb 2023
Cited by 1 | Viewed by 1515
Abstract
A combination of two methods of chemical vapor deposition (CVD) of diamond films, microwave plasma–assisted (MW CVD) and hot filament (HF CVD), was used for the growth of 100 µm-thick polycrystalline diamond (PCD) layers on Si substrates. The bow of HF CVD and [...] Read more.
A combination of two methods of chemical vapor deposition (CVD) of diamond films, microwave plasma–assisted (MW CVD) and hot filament (HF CVD), was used for the growth of 100 µm-thick polycrystalline diamond (PCD) layers on Si substrates. The bow of HF CVD and MW CVD films showed opposite convex\concave trends; thus, the combined material allowed reducing the overall bow by a factor of 2–3. Using MW CVD for the growth of the initial 25 µm-thick PCD layer allowed achieving much higher thermal conductivity of the combined 110 µm-thick film at 210 W/m·K in comparison to 130 W/m·K for the 93 µm-thick pure HF CVD film. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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9 pages, 2911 KiB  
Article
Features of the Oxidation of Multilayer (TiAlCrSiY)N/(TiAlCr)N Nanolaminated PVD Coating during Temperature Annealing
Coatings 2023, 13(2), 287; https://doi.org/10.3390/coatings13020287 - 27 Jan 2023
Cited by 1 | Viewed by 1013
Abstract
A nano-multilayer Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N PVD coating was deposited on Kennametal carbide K 313 inserts. These coatings are widely used to protect cutting tools under severe exploitation conditions. Under [...] Read more.
A nano-multilayer Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N PVD coating was deposited on Kennametal carbide K 313 inserts. These coatings are widely used to protect cutting tools under severe exploitation conditions. Under equilibrium conditions, it was found that the Al2O3 oxide possessed better adhesive properties than the TiO2. The addition of chromium further enhanced the oxidation resistance of the coatings. Silicon significantly increased the oxidation resistance of this type of coating. The properties of the diffusion process in this coating have not been sufficiently investigated, despite the considerable number of articles published on this topic. For the purpose of this study, a multilayer ion-plasma (TiAlCrSiY)N/(TiAlCr)N coating was oxidized under equilibrium conditions; its chemical inhomogeneity was studied by time-of-flight mass spectroscopy using a TOF SIMS5-100 instrument. The data was collected from an area of 100 × 100 µ. A D-300 profilometer (KLA-Tencor Corp., Milpitas, California 95035, USA) was used to determine the rate of ion etching. It was found that oxidation commenced at the surface nanolayer of a TiAlCrN nitride, forming loose films of Cr2O3, TiO2, and Al2O3 oxides. This passivating film had a thickness of around 140 nm. For the first time, the interlayer diffusion coefficients of Si and Y were determined in multilayer coatings based on Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N, under open air annealing at 700 °C. The physical nature of the differences in the diffusion of these elements is discussed. The diffusion rate in the near-surface volumes was lower than in the deep layers of the multilayer coating, most likely due to the formation of passivating oxide films on the surface. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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19 pages, 5042 KiB  
Communication
THz Surface Plasmons in Wide and Freestanding Graphene Nanoribbon Arrays
Coatings 2023, 13(1), 28; https://doi.org/10.3390/coatings13010028 - 23 Dec 2022
Cited by 2 | Viewed by 1168
Abstract
Graphene is a thin-film carbon material that has immense potential as a key ingredient in new nanoelectronic and nanophotonic devices due to its unique characteristics. In particular, plasmons in graphene appear as a practical tool for the manipulation of light with potential applications [...] Read more.
Graphene is a thin-film carbon material that has immense potential as a key ingredient in new nanoelectronic and nanophotonic devices due to its unique characteristics. In particular, plasmons in graphene appear as a practical tool for the manipulation of light with potential applications from cancer treatment to solar cells. A motivating tunability of graphene properties has been observed in graphene nanoribbons (GNRs) due to their geometrically controllable bandgaps that, in turn, influence the plasmonic properties. The formidable effort made over recent years in developing GNR-based technologies is, however, weakened by a lack of predictive approaches that draw upon available semi-analytical electromagnetic models. An example of such a framework is used here, focusing on experimentally realized GNRs from 155 to 480 nm wide and organized as two-dimensional (2D) GNR arrays. The results show that the plasmon frequency behavior is highly affected by the experimental setup or geometrical factors. In particular, the bandgap of the analyzed systems is of the order of a few meV with a density of states opening around zero energy (Fermi level) in contrast to what is observed in graphene. From the plasmonic part, it is observed in all 2D GNR arrays that the frequency–momentum trend follows a q-like plasmon dispersion whose plasmon frequency can be increased substantially by increasing the ribbon width or charge density concentration. Forbidden plasmon regions are observed for high values of plasmon excitation angle or electron relaxation rate. From a sensing point of view, the important finding is the fact that 2D GNR arrays of 155 nm wide with high values of electron relaxation rate have plasmon responses similar to those observed for αthrombin in water. Our predictions are projected to be of fast support for detecting plasmons in more complex designs of ribbon nanodevices with potential applications in molecular sensing of aqueous molecules. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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17 pages, 3254 KiB  
Article
Deep Learning-Based Layer Identification of 2D Nanomaterials
Coatings 2022, 12(10), 1551; https://doi.org/10.3390/coatings12101551 - 14 Oct 2022
Cited by 1 | Viewed by 1482
Abstract
Two-dimensional (2D) nanomaterials exhibit unique properties due to their low dimensionality, which has led to great potential for applications in biopharmaceuticals, aerospace, energy storage, mobile communications and other fields. Today, 2D nanomaterials are often prepared and exfoliated by a combination of mechanical and [...] Read more.
Two-dimensional (2D) nanomaterials exhibit unique properties due to their low dimensionality, which has led to great potential for applications in biopharmaceuticals, aerospace, energy storage, mobile communications and other fields. Today, 2D nanomaterials are often prepared and exfoliated by a combination of mechanical and manual methods, which makes the production of 2D nanomaterials inefficient and prevents standardized and industrialized manufacturing. Recent breakthroughs in semantic segmentation techniques based on deep learning have enabled the accurate identification and segmentation of atomic layers of 2D nanomaterials using optical microscopy. In this study, we analyzed in detail sixteen semantic segmentation models that perform well on public datasets and apply them to the layer identification and segmentation of graphene and molybdenum disulfide. Furthermore, we improved the U2-Net model to obtain the best overall performance, namely 2DU2-Net. The accuracy of the 2DU2-Net model was 99.03%, the kappa coefficient was 95.72%, the dice coefficient was 96.97%, and the average cross–merge ratio was 94.18%. Meanwhile, it also had good performance in terms of computation, number of parameters, inference speed and generalization ability. The results show that deep learning-based semantic segmentation methods can greatly improve efficiency and replace most manual operations, and different types of semantic segmentation methods can be adapted to different properties of 2D nanomaterials, thus promoting the research and application of 2D nanomaterials. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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12 pages, 6385 KiB  
Article
Characteristics of Thin High Entropy Alloy Films Grown by Pulsed Laser Deposition
Coatings 2022, 12(8), 1211; https://doi.org/10.3390/coatings12081211 - 18 Aug 2022
Viewed by 1642
Abstract
Starting from solid-solutions (SS) of AlCoCrFeNix high-entropy alloys (HEAs) that have been produced with high purity constituent elements by vacuum arc remelting (VAR) method varying the nickel molar ratio x from 0.2 to 2.0, we investigated the synthesis of protective thin films [...] Read more.
Starting from solid-solutions (SS) of AlCoCrFeNix high-entropy alloys (HEAs) that have been produced with high purity constituent elements by vacuum arc remelting (VAR) method varying the nickel molar ratio x from 0.2 to 2.0, we investigated the synthesis of protective thin films of HEAs and high-entropy nitrides (HENs) with the aid of the pulsed laser deposition (PLD) system. The structure of all ten available bulk targets have been examined by means of X-Ray Diffraction (XRD), as well as their elemental composition by means of energy dispersion X-ray spectroscopy (EDS). Three targets with nickel molar composition x = 0.4, 1.2 and 2.0 corresponding to BCC, mixed BCC and FCC, and finally FCC structures were used for thin film depositions using a KrF excimer laser. The depositions were performed in residual low vacuum (10−7 mbar) and under N2 (10−4 mbar) at room temperature (RT~25 °C) on Si and glass substrates. The deposited films’ structure was investigated using grazing incidence XRD, their surface morphology, thickness and elemental composition by scanning electron microscopy (SEM), EDS and X-ray photoelectron spectroscopy (XPS), respectively. A homemade four-point probe (4PP) set-up was applied to determine layers electrical resistance. Besides, a Nanoindentation (NI) was employed to test films’ mechanical properties. XRD results showed that all deposited films, regardless of the initial structure of targets, were a mixture of FCC and BCC structures. Additionally, the quantitative and qualitative EDS and XPS results showed that the elemental composition of films was rather close to that of the targets. The depositions under an N2 atmosphere resulted in the inclusion of several percentage nitrogen atoms in a metallic nitride type compound into films, which may explain their higher electrical resistivity. The Young’s modulus, nanohardness and friction coefficient values showed that the deposited films present good mechanical properties and could be used as protective coatings to prevent damage in harsh environments. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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14 pages, 2648 KiB  
Communication
Adsorption Kinetics of Hg(II) on Eco-Friendly Prepared Oxidized Graphenes
Coatings 2022, 12(8), 1154; https://doi.org/10.3390/coatings12081154 - 10 Aug 2022
Cited by 1 | Viewed by 1363
Abstract
Extra-functionalized oxidized graphenes are widely preferred for the removal of different pollutants, however, removal with pristine oxidized graphenes, i.e., graphene oxide (GO) and reduced graphene oxide (rGO) is vaguely explored. Herein, we report a comparative adsorption kinetics study of the removal of mercury(II) [...] Read more.
Extra-functionalized oxidized graphenes are widely preferred for the removal of different pollutants, however, removal with pristine oxidized graphenes, i.e., graphene oxide (GO) and reduced graphene oxide (rGO) is vaguely explored. Herein, we report a comparative adsorption kinetics study of the removal of mercury(II) (Hg(II)) from water using eco-friendly prepared GO and rGO. This work consists of the synthesis protocol and the corresponding morphological and spectroscopical characterization of the obtained pristine adsorbents as well as the adsorption mechanism in terms of initial concentration, removal percentage, pseudo-first and pseudo-second-order models, intraparticle diffusion study, and pH analysis. In particular, scanning electron microscope (SEM) and transmission electron microscope (TEM) images evidence the presence of thin sheets with some defects on the GO structure, these defects substantially disappear in rGO, after reduction. Raman spectrum of rGO shows a less intense D* peak which is attributed to the diamond-like carbon phase. Most importantly, the equilibrium adsorption time in GO is 10 min with a removal percentage of ~28% while in rGO it is 20 min with a removal percentage of ~75%. The adsorption process of Hg(II) either in GO or rGO is more in line with the pseudo-second-order model, suggesting that the adsorption kinetics could be controlled by chemisorption. Our results evidence the interesting adsorbing properties of pristine oxidized graphenes and are expected to be useful for the proposal and study of non-extra functionalized graphene-based materials for water treatment. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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10 pages, 5418 KiB  
Article
Three-Dimensional Construction Method for Two-Dimensional Film Pattern Design in Sustainable Rhinoceros Skin Coating Technology
Coatings 2022, 12(8), 1132; https://doi.org/10.3390/coatings12081132 - 05 Aug 2022
Viewed by 1397
Abstract
In order to effectively save material- and time-related costs in sustainable rhinoceros skin lacquering technology, a three-dimensional construction method is developed based on optical microscope tomography and computer image recognition technology. By analyzing the influence of the underlying twisting method, the number of [...] Read more.
In order to effectively save material- and time-related costs in sustainable rhinoceros skin lacquering technology, a three-dimensional construction method is developed based on optical microscope tomography and computer image recognition technology. By analyzing the influence of the underlying twisting method, the number of lacquer layers and the grinding process, the pattern presentation process of rhinoceros skin lacquer is shown in three-dimensional space, and the relationship between pattern style and process flow is further revealed. Computer-aided technology can design and simulate the presentation of the pattern in virtual space, providing a priori guidance for the production of rhinoceros skin lacquerware and new ideas for the innovation of process methods. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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11 pages, 3571 KiB  
Article
Fundamental Properties of Transition-Metals-Adsorbed Germanene: A DFT Study
Coatings 2022, 12(7), 948; https://doi.org/10.3390/coatings12070948 - 04 Jul 2022
Cited by 2 | Viewed by 1311
Abstract
The transition metal (TM)-absorbed germanene systems enriched by strong chemical bonding are investigated using first-principles calculations. Dedicated calculations include the geometry, preferable adsorption sites, atom-dominated band structure, spin–density distributions, spatial charge distribution, and the projected density of states (DOS). The strong multi-orbital chemical [...] Read more.
The transition metal (TM)-absorbed germanene systems enriched by strong chemical bonding are investigated using first-principles calculations. Dedicated calculations include the geometry, preferable adsorption sites, atom-dominated band structure, spin–density distributions, spatial charge distribution, and the projected density of states (DOS). The strong multi-orbital chemical bonds between TMs and Ge atoms can create seriously buckled structures and a non-uniform chemical environment, which are responsible for the unusual electronic properties. Of the three chosen systems, the Fe–Ge and Co–Ge ones possess magnetic properties, while the Ni–Ge system exhibits non-magnetic behavior. The orbital-hybridization-induced characteristics are revealed in van Hove singularities of the DOS. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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Review

Jump to: Research

24 pages, 2463 KiB  
Review
Perovskite Solar Cells: A Review of the Recent Advances
Coatings 2022, 12(8), 1089; https://doi.org/10.3390/coatings12081089 - 31 Jul 2022
Cited by 41 | Viewed by 11622
Abstract
Perovskite solar cells (PSC) have been identified as a game-changer in the world of photovoltaics. This is owing to their rapid development in performance efficiency, increasing from 3.5% to 25.8% in a decade. Further advantages of PSCs include low fabrication costs and high [...] Read more.
Perovskite solar cells (PSC) have been identified as a game-changer in the world of photovoltaics. This is owing to their rapid development in performance efficiency, increasing from 3.5% to 25.8% in a decade. Further advantages of PSCs include low fabrication costs and high tunability compared to conventional silicon-based solar cells. This paper reviews existing literature to discuss the structural and fundamental features of PSCs that have resulted in significant performance gains. Key electronic and optical properties include high electron mobility (800 cm2/Vs), long diffusion wavelength (>1 μm), and high absorption coefficient (105 cm−1). Synthesis methods of PSCs are considered, with solution-based manufacturing being the most cost-effective and common industrial method. Furthermore, this review identifies the issues impeding PSCs from large-scale commercialisation and the actions needed to resolve them. The main issue is stability as PSCs are particularly vulnerable to moisture, caused by the inherently weak bonds in the perovskite structure. Scalability of manufacturing is also a big issue as the spin-coating technique used for most laboratory-scale tests is not appropriate for large-scale production. This highlights the need for a transition to manufacturing techniques that are compatible with roll-to-roll processing to achieve high throughput. Finally, this review discusses future innovations, with the development of more environmentally friendly lead-free PSCs and high-efficiency multi-junction cells. Overall, this review provides a critical evaluation of the advances, opportunities and challenges of PSCs. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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