Research

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13 pages, 2389 KiB

Open AccessArticle

Effect of Argon on the Properties of Copper Nitride Fabricated by Magnetron Sputtering for the Next Generation of Solar Absorbers

by C. A. Figueira, G. Del Rosario, D. Pugliese, M. I. Rodríguez-Tapiador and S. Fernández

Materials 2022, 15(24), 8973; https://doi.org/10.3390/ma15248973 - 15 Dec 2022

Cited by 6 | Viewed by 1302

Abstract

Copper nitride, a metastable semiconductor material with high stability at room temperature, is attracting considerable attention as a potential next-generation earth-abundant thin-film solar absorber. Moreover, its non-toxicity makes it an interesting eco-friendly material. In this work, copper nitride films were fabricated using reactive [...] Read more.

Copper nitride, a metastable semiconductor material with high stability at room temperature, is attracting considerable attention as a potential next-generation earth-abundant thin-film solar absorber. Moreover, its non-toxicity makes it an interesting eco-friendly material. In this work, copper nitride films were fabricated using reactive radio frequency (RF) magnetron sputtering at room temperature, 50 W of RF power, and partial nitrogen pressures of 0.8 and 1.0 on glass and silicon substrates. The role of argon in both the microstructure and the optoelectronic properties of the films was investigated with the aim of achieving a low-cost absorber material with suitable properties to replace the conventional silicon in solar cells. The results showed a change in the preferential orientation from (100) to (111) planes when argon was introduced in the sputtering process. Additionally, no structural changes were observed in the films deposited in a pure nitrogen environment. Fourier transform infrared (FTIR) spectroscopy measurements confirmed the presence of Cu–N bonds, regardless of the gas environment used, and XPS indicated that the material was mainly N-rich. Finally, optical properties such as band gap energy and refractive index were assessed to establish the capability of this material as a solar absorber. The direct and indirect band gap energies were evaluated and found to be in the range of 1.70–1.90 eV and 1.05–1.65 eV, respectively, highlighting a slight blue shift when the films were deposited in the mixed gaseous environment as the total pressure increased. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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10 pages, 3275 KiB

Open AccessArticle

Comparison of the Material Quality of Al_xIn_1−xN (x—0–0.50) Films Deposited on Si(100) and Si(111) at Low Temperature by Reactive RF Sputtering

by Michael Sun, Rodrigo Blasco, Julian Nwodo, María de la Mata, Sergio I. Molina, Akhil Ajay, Eva Monroy, Sirona Valdueza-Felip and Fernando B. Naranjo

Materials 2022, 15(20), 7373; https://doi.org/10.3390/ma15207373 - 21 Oct 2022

Cited by 1 | Viewed by 1073

Abstract

Al_xIn_1−xN ternary semiconductors have attracted much interest for application in photovoltaic devices. Here, we compare the material quality of Al_xIn_1−xN layers deposited on Si with different crystallographic orientations, (100) and (111), via radio-frequency (RF) sputtering. [...] Read more.

Al_xIn_1−xN ternary semiconductors have attracted much interest for application in photovoltaic devices. Here, we compare the material quality of Al_xIn_1−xN layers deposited on Si with different crystallographic orientations, (100) and (111), via radio-frequency (RF) sputtering. To modulate their Al content, the Al RF power was varied from 0 to 225 W, whereas the In RF power and deposition temperature were fixed at 30 W and 300 °C, respectively. X-ray diffraction measurements reveal a c-axis-oriented wurtzite structure with no phase separation regardless of the Al content (x = 0–0.50), which increases with the Al power supply. The surface morphology of the Al_xIn_1−xN layers improves with increasing Al content (the root-mean-square roughness decreases from ≈12 to 2.5 nm), and it is similar for samples grown on both Si substrates. The amorphous layer (~2.5 nm thick) found at the interface with the substrates explains the weak influence of their orientation on the properties of the Al_xIn_1−xN films. Simultaneously grown Al_xIn_1−xN-on-sapphire samples point to a residual n-type carrier concentration in the 10²⁰–10²¹ cm⁻³ range. The optical band gap energy of these layers evolves from 1.75 to 2.56 eV with the increase in the Al. PL measurements of Al_xIn_1−xN show a blue shift in the peak emission when adding the Al, as expected. We also observe an increase in the FWHM of the main peak and a decrease in the integrated emission with the Al content in room-temperature PL measurements. In general, the material quality of the Al_xIn_1-xN films on Si is similar for both crystallographic orientations. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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17 pages, 3333 KiB

Open AccessArticle

Numerical Study on Hydrodynamic Characteristics and Electrochemical Performance of Alkaline Water Electrolyzer by Micro-Nano Surface Electrode

by Ye Xia, Mengyu Gao, Jincheng Yu, Yang Si, Laijun Chen and Shengwei Mei

Materials 2022, 15(14), 4927; https://doi.org/10.3390/ma15144927 - 15 Jul 2022

Cited by 1 | Viewed by 1758

Abstract

This study constructed a two-dimensional alkaline water electrolyzer model based on the two-phase flow Euler–Euler model. In the model, the micro-nano surface electrodes with different structure types and graphic parameters (distance, height, and width) were used and compared with the vertical flat electrode [...] Read more.

This study constructed a two-dimensional alkaline water electrolyzer model based on the two-phase flow Euler–Euler model. In the model, the micro-nano surface electrodes with different structure types and graphic parameters (distance, height, and width) were used and compared with the vertical flat electrode to evaluate their influence on electrolysis performance. The simulation results show that the performance of the micro-nano surface electrode is much better than that of the vertical flat electrode. The total length of micro-nano structural units relates to the contact area between the electrode and the electrolyte and affects the cell voltage, overpotential, and void fraction. When rectangular structural units with a distance, height, and width of 0.5 µm, 0.5 µm, and 1 µm are used, the total length of the corresponding micro-nano surface electrode is three times that of the vertical flat electrode, and the cathode overpotential decreases by 65.31% and the void fraction increases by 54.53% when it replaces the vertical flat electrode. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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14 pages, 4571 KiB

Open AccessArticle

Photoelectric Properties of Planar and Mesoporous Structured Perovskite Solar Cells

by Steponas Ašmontas, Aurimas Čerškus, Jonas Gradauskas, Asta Grigucevičienė, Remigijus Juškėnas, Konstantinas Leinartas, Andžej Lučun, Kazimieras Petrauskas, Algirdas Selskis, Laurynas Staišiūnas, Algirdas Sužiedėlis, Aldis Šilėnas and Edmundas Širmulis

Materials 2022, 15(12), 4300; https://doi.org/10.3390/ma15124300 - 17 Jun 2022

Cited by 7 | Viewed by 1907

Abstract

The high efficiency of perovskite solar cells strongly depends on the quality of perovskite films and carrier extraction layers. Here, we present the results of an investigation of the photoelectric properties of solar cells based on perovskite films grown on compact and mesoporous [...] Read more.

The high efficiency of perovskite solar cells strongly depends on the quality of perovskite films and carrier extraction layers. Here, we present the results of an investigation of the photoelectric properties of solar cells based on perovskite films grown on compact and mesoporous titanium dioxide layers. Kinetics of charge carrier transport and their extraction in triple-cation perovskite solar cells were studied by using transient photovoltage and time-resolved photoluminescence decay measurements. X-ray diffraction analysis revealed that the crystallinity of the perovskite films grown on mesoporous titanium dioxide is better compared to the films grown on compact TiO₂. Mesoporous structured perovskite solar cells are found to have higher power conversion efficiency mainly due to enlarged perovskite/mesoporous -TiO₂ interfacial area and better crystallinity of their perovskite films. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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12 pages, 2506 KiB

Open AccessArticle

Oxygen-Plasma-Induced Hetero-Interface NiFe₂O₄/NiMoO₄ Catalyst for Enhanced Electrochemical Oxygen Evolution

by Nuo Xu, Wei Peng, Lei Lv, Peng Xu, Chenxu Wang, Jiantao Li, Wen Luo and Liang Zhou

Materials 2022, 15(10), 3688; https://doi.org/10.3390/ma15103688 - 20 May 2022

Cited by 10 | Viewed by 1769

Abstract

The electrolysis of water to produce hydrogen is an effective method for solving the rapid consumption of fossil fuel resources and the problem of global warming. The key to its success is to design an oxygen evolution reaction (OER) electrocatalyst with efficient conversion [...] Read more.

The electrolysis of water to produce hydrogen is an effective method for solving the rapid consumption of fossil fuel resources and the problem of global warming. The key to its success is to design an oxygen evolution reaction (OER) electrocatalyst with efficient conversion and reliable stability. Interface engineering is one of the most effective approaches for adjusting local electronic configurations. Adding other metal elements is also an effective way to enrich active sites and improve catalytic activity. Herein, high-valence iron in a heterogeneous interface of NiFe₂O₄/NiMoO₄ composite was obtained through oxygen plasma to achieve excellent electrocatalytic activity and stability. In particular, 270 mV of overpotential is required to reach a current density of 50 mA cm⁻², and the overpotential required to reach 500 mA cm⁻² is only 309 mV. The electron transfer effect for high-valence iron was determined by X-ray photoelectron spectroscopy (XPS). The fast and irreversible reconstruction and the true active species in the catalytic process were identified by in situ Raman, ex situ XPS, and ex situ transmission electron microscopy (TEM) measurements. This work provides a feasible design guideline to modify electronic structures, promote a metal to an active oxidation state, and thus develop an electrocatalyst with enhanced OER performance. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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11 pages, 3462 KiB

Open AccessArticle

Material Optimization Engineering toward xLiFePO₄·yLi₃V₂(PO₄)₃ Composites in Application-Oriented Li-Ion Batteries

by Yuqiang Pi, Gangwei Luo, Peiyao Wang, Wangwang Xu, Jiage Yu, Xian Zhang, Zhengbing Fu, Xiong Yang, Li Wang, Yu Ding and Feng Wang

Materials 2022, 15(10), 3668; https://doi.org/10.3390/ma15103668 - 20 May 2022

Cited by 2 | Viewed by 1375

Abstract

The development of LiFePO₄ (LFP) in high-power energy storage devices is hampered by its slow Li-ion diffusion kinetics. Constructing the composite electrode materials with vanadium substitution is a scientific endeavor to boost LFP’s power capacity. Herein, a series of xLiFePO₄·yLi [...] Read more.

The development of LiFePO₄ (LFP) in high-power energy storage devices is hampered by its slow Li-ion diffusion kinetics. Constructing the composite electrode materials with vanadium substitution is a scientific endeavor to boost LFP’s power capacity. Herein, a series of xLiFePO₄·yLi₃V₂(PO₄)₃ (xLFP·yLVP) composites were fabricated using a simple spray-drying approach. We propose that 5LFP·LVP is the optimal choice for Li-ion battery promotion, owning to its excellent Li-ion storage capacity (material energy density of 413.6 W·h·kg⁻¹), strong machining capability (compacted density of 1.82 g·cm⁻³) and lower raw material cost consumption. Furthermore, the 5LFP·LVP||LTO Li-ion pouch cell also presents prominent energy storage capability. After 300 cycles of a constant current test at 400 mA, 75% of the initial capacity (379.1 mA·h) is achieved, with around 100% of Coulombic efficiency. A capacity retention of 60.3% is displayed for the 300th cycle when discharging at 1200 mA, with the capacity fading by 0.15% per cycle. This prototype provides a valid and scientific attempt to accelerate the development of xLFP·yLVP composites in application-oriented Li-ion batteries. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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9 pages, 3076 KiB

Open AccessArticle

Photo-Charging of Li(Ni_0.65Co_0.15Mn_0.20)O₂ Lithium-Ion Battery Using Silicon Solar Cells

by Seungbum Heo, Baeksang Yoon, Hyunsoo Lim, Hyung-Kee Seo, Cheul-Ro Lee and Inseok Seo

Materials 2022, 15(8), 2913; https://doi.org/10.3390/ma15082913 - 15 Apr 2022

Cited by 1 | Viewed by 1713

Abstract

This study reports an integrated device in which a lithium-ion battery (LIB) and Si solar cells are interconnected. The LIB is fabricated using the Li(Ni_0.65Co_0.15Mn_0.20)O₂ (NCM622) cathode and the Li₄Ti₅O₁₂ (LTO) [...] Read more.

This study reports an integrated device in which a lithium-ion battery (LIB) and Si solar cells are interconnected. The LIB is fabricated using the Li(Ni_0.65Co_0.15Mn_0.20)O₂ (NCM622) cathode and the Li₄Ti₅O₁₂ (LTO) anode. The surface and shape morphologies of the NCM and LTO powders were investigated by field emission scanning electron microscopy (FE-SEM). In addition, the structural properties were thoroughly examined by X-ray diffraction (XRD). Further, their electrochemical characterization was carried out on a potentiostat. The specific discharge capacity of the NCM cathode (half-cell) was 188.09 mAh/g at 0.1 C current density. In further experiments, the NCM-LTO full-cell has also shown an excellent specific capacity of 160 mAh/g at a high current density of 1 C. Additionally, the capacity retention was outstanding, with 99.63% at 1 C after 50 cycles. Moreover, to meet the charging voltage requirements of the NCM-LTO full-cell, six Si solar cells were connected in series. The open-circuit voltage (V_OC) and the short-circuit photocurrent density (J_SC) for the Si solar cells were 3.37 V and 5.42 mA/cm². The calculated fill factor (FF) and efficiency for the Si solar cells were 0.796 and 14.54%, respectively. Lastly, the integrated device has delivered a very high-power conversion-storage efficiency of 7.95%. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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16 pages, 9310 KiB

Open AccessArticle

Transport Mechanisms and Dielectric Features of Mg-Doped ZnO Nanocrystals for Device Applications

by Chayma Abed, Amira Ben Gouider Trabelsi, Fatemah. H. Alkallas, Susana Fernandez and Habib Elhouichet

Materials 2022, 15(6), 2265; https://doi.org/10.3390/ma15062265 - 18 Mar 2022

Cited by 17 | Viewed by 1874

Abstract

Magnesium-doped zinc oxide “ZnO:Mg” nanocrystals (NCs) were fabricated using a sol gel method. The Mg concentration impact on the structural, morphological, electrical, and dielectric characteristics of ZnO:Mg NCs were inspected. X-ray diffraction (XRD) patterns display the hexagonal wurtzite structure without any additional phase. [...] Read more.

Magnesium-doped zinc oxide “ZnO:Mg” nanocrystals (NCs) were fabricated using a sol gel method. The Mg concentration impact on the structural, morphological, electrical, and dielectric characteristics of ZnO:Mg NCs were inspected. X-ray diffraction (XRD) patterns display the hexagonal wurtzite structure without any additional phase. TEM images revealed the nanometric size of the particles with a spherical-like shape. The electrical conductivity of the ZnO NCs, thermally activated, was found to be dependent on the Mg content. The impedance spectra were represented via a corresponding circuit formed by a resistor and constant phase element (CPE). A non-Debye type relaxation was located through the analyses of the complex impedance. The conductivity diminished with the incorporation of the Mg element. The AC conductivity is reduced by raising the temperature. Its plot obeys the Arrhenius law demonstrating a single activation energy during the conduction process. The complex impedance highlighted the existence of a Debye-type dielectric dispersion. The various ZnO:Mg samples demonstrate high values of dielectric constant with small dielectric losses for both medium and high-frequency regions. Interestingly, the Mg doping with 3% content exhibits colossal dielectric constant (more than 2 × 10⁴) over wide temperature and frequency ranges, with Debye-like relaxation. The study of the electrical modulus versus the frequency and at different temperatures confirms the non-Debye relaxation. The obtained results reveal the importance of the ZnO:Mg NCs for device applications. This encourages their application in energy storage. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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Review

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34 pages, 6915 KiB

Open AccessReview

Energy Conversion Strategies for Wind Energy System: Electrical, Mechanical and Material Aspects

by Anudipta Chaudhuri, Rajkanya Datta, Muthuselvan Praveen Kumar, João Paulo Davim and Sumit Pramanik

Materials 2022, 15(3), 1232; https://doi.org/10.3390/ma15031232 - 07 Feb 2022

Cited by 28 | Viewed by 4908

Abstract

Currently, about 22% of global electricity is being supplemented by different renewable sources. Wind energy is one of the most abundant forms of renewable energy available in the atmospheric environment due to different air-currents spread over the troposphere and stratosphere. The demand of [...] Read more.

Currently, about 22% of global electricity is being supplemented by different renewable sources. Wind energy is one of the most abundant forms of renewable energy available in the atmospheric environment due to different air-currents spread over the troposphere and stratosphere. The demand of modern wind energy conversion system (WECS) has increased to achieve a suitable alternate renewable energy source. In this paper, after a brief introduction, the classification of WECS is reviewed with attractive illustrations. The various mechanical materials and electrical components of WECS are discussed. The flow of power in WECS and its control strategies are also been described. The wind energy conversion is carried out with a suitable controlling mechanism for power grid integration. A maximum power-point tracking controller is an effective controlling method to extract the maximum possible power from the turbines. The present trends in WECS and the scope for improvement and future prospects are discussed. The materials used for both the blade and generator have been found to be key elements of wind turbines. Recycling of the polymer matrix composite materials are found to be a great threat to wind power plants, as well as to their supply chain industries. Full article

(This article belongs to the Special Issue Emerging Materials for Energy Applications)

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