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11 pages, 15647 KiB

Open AccessArticle

Tungsten–SiO₂–Based Planar Field Emission Microtriodes with Different Electrode Topologies

by Liga Avotina, Liga Bikse, Yuri Dekhtyar, Annija Elizabete Goldmane, Gunta Kizane, Aleksei Muhin, Marina Romanova, Krisjanis Smits, Hermanis Sorokins, Aleksandr Vilken and Aleksandrs Zaslavskis

Materials 2023, 16(17), 5781; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16175781 - 24 Aug 2023

Viewed by 752

Abstract

This study examines the electrical properties and layer quality of field emission microtriodes that have planar electrode geometry and are based on tungsten (W) and silicon dioxide (SiO₂). Two types of microtriodes were analyzed: one with a multi-tip cathode fabricated using [...] Read more.

This study examines the electrical properties and layer quality of field emission microtriodes that have planar electrode geometry and are based on tungsten (W) and silicon dioxide (SiO₂). Two types of microtriodes were analyzed: one with a multi-tip cathode fabricated using photolithography (PL) and the other with a single-tip cathode fabricated using a focused ion beam (FIB). Atomic force microscopy (AFM) analysis revealed surface roughness of the W layer in the order of several nanometers (Ra = 3.8 ± 0.5 nm). The work function values of the Si substrate, SiO₂ layer, and W layer were estimated using low-energy ultraviolet photoelectron emission (PE) spectroscopy and were 4.71 eV, 4.85 eV, and 4.67 eV, respectively. The homogeneity of the W layer and the absence of oxygen and silicon impurities were confirmed via X-ray photoelectron spectroscopy (XPS). The PL microtriode and the FIB microtriode exhibited turn-on voltages of 110 V and 50 V, respectively, both demonstrating a field emission current of 0.4 nA. The FIB microtriode showed significantly improved field emission efficiency compared to the PL microtriode, attributed to a higher local electric field near the cathode. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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10 pages, 2038 KiB

Open AccessArticle

Application of Bis-Adducts of Phenyl-C₆₁ Butyric Acid Methyl Ester in Promoting the Open-Circuit Voltage of Indoor Organic Photovoltaics

by Xueyan Hou, Xiaohan Duan, Mengnan Liang, Zixuan Wang and Dong Yan

Materials 2023, 16(7), 2613; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16072613 - 25 Mar 2023

Viewed by 1139

Abstract

Fullerene-based indoor OPVs, particularly phenyl-C₆₁ butyric acid methyl ester (PCBM), has been regarded as a prospective harvesting indoor light energy source to drive low-power consumption electronic devices such as sensors and IoTs. Due to the low tunability of its inherently spherical structure, [...] Read more.

Fullerene-based indoor OPVs, particularly phenyl-C₆₁ butyric acid methyl ester (PCBM), has been regarded as a prospective harvesting indoor light energy source to drive low-power consumption electronic devices such as sensors and IoTs. Due to the low tunability of its inherently spherical structure, the performance of the fullerene-based indoor OPVs seem to hit a bottleneck compared with the non-fullerene materials. Here, we explore the potential application of fullerene derivative bis-PCBM in indoor OPVs, which owns a higher the lowest unoccupied molecular orbital (LUMO) level than PCBM. The results show that when blended with PCDTBT, bis-PCBM devices yield a high V_OC of up to 1.05 V and 0.9 V under AM 1.5G illumination and 1000 lx indoor light, compared with the corresponding values of 0.93 V and 0.79 V for PCBM devices. Nevertheless, the disorders in bis-PCBM suppress the J_SC and FF and, therefore, result in a lower efficiency compared to PCBM devices. However, the efficiency and stability differences between the two kinds of cells were much reduced under indoor light conditions. After further optimization of the material composition and fabrication process, bis-PCBM could be an alternative to PCBM, offering great potential for indoor OPV with high performance. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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13 pages, 2957 KiB

Open AccessArticle

Simultaneous Measurement of Magnetic Field and Temperature Utilizing Magnetofluid-Coated SMF-UHCF-SMF Fiber Structure

by Ronghui Xu, Yipu Xue, Minmin Xue, Chengran Ke, Jingfu Ye, Ming Chen, Houquan Liu and Libo Yuan

Materials 2022, 15(22), 7966; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15227966 - 11 Nov 2022

Cited by 7 | Viewed by 1218

Abstract

We have proposed and experimentally demonstrated a dual-parameter optical fiber sensor for simultaneous measurement of magnetic field and temperature. The sensor is a magnetofluid-coated single-mode fiber (SMF)-U-shaped hollow-core fiber (UHCF)-single-mode fiber (SMF) (SMF-UHCF-SMF) fiber structure. Combined with the intermodal interference and the macro-bending [...] Read more.

We have proposed and experimentally demonstrated a dual-parameter optical fiber sensor for simultaneous measurement of magnetic field and temperature. The sensor is a magnetofluid-coated single-mode fiber (SMF)-U-shaped hollow-core fiber (UHCF)-single-mode fiber (SMF) (SMF-UHCF-SMF) fiber structure. Combined with the intermodal interference and the macro-bending loss of the U-shaped fiber structure, the U-shaped fiber sensor with different bend diameters was investigated. In our experiments, the transmission spectra of the sensor varied with magnetic field strength and temperature around the sensing structure, respectively. The dip wavelengths of the interference spectra of the proposed sensor exhibit red shifts with magnetic field strength and temperature, and the maximum sensitivity of magnetic field strength and temperature were 1.0898 nm/mT and 0.324 nm/°C, respectively. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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10 pages, 3359 KiB

Open AccessArticle

Fiber-Optic Vector-Magnetic-Field Sensor Based on Gold-Clad Bent Multimode Fiber and Magnetic Fluid Materials

by Weinan Liu, Shengli Pu, Zijian Hao, Jia Wang, Yuanyuan Fan, Chencheng Zhang and Jingyue Wang

Materials 2022, 15(20), 7208; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207208 - 16 Oct 2022

Cited by 5 | Viewed by 1669

Abstract

A kind of bent multimode fiber (MMF) vector magnetic sensor based on surface plasmon resonance (SPR) was proposed. By plating gold film on the curved part of the bent multimode fiber, the surface plasmon mode (SPM) was excited via a whispering gallery mode [...] Read more.

A kind of bent multimode fiber (MMF) vector magnetic sensor based on surface plasmon resonance (SPR) was proposed. By plating gold film on the curved part of the bent multimode fiber, the surface plasmon mode (SPM) was excited via a whispering gallery mode (WGM). Fabricating the structure only required bending the fiber and plating it with gold, which perfectly ensured the integrity of the fiber and made it more robust compared with other structures. The sensor used magnetic fluid (MF) as the magnetically sensitive material. Through monitoring the shift of the surface plasmon resonance dip, the as-fabricated sensor not only had a high magnetic field intensity sensitivity of 9749 pm/mT but could also measure the direction of a magnetic field with a high sensitivity of 546.5 pm/°. The additional advantages of the proposed sensor lay in its easy fabrication and good integrity, which make it attractive in the field of vector-magnetic-field sensing. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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10 pages, 2263 KiB

Open AccessCommunication

Femtosecond Laser Modification of Silica Optical Waveguides for Potential Bragg Gratings Sensing

by Jian Chen, Ji-Jun Feng, Hai-Peng Liu, Wen-Bin Chen, Jia-Hao Guo, Yang Liao, Jie Shen, Xue-Feng Li, Hui-Liang Huang and Da-Wei Zhang

Materials 2022, 15(18), 6220; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15186220 - 07 Sep 2022

Cited by 3 | Viewed by 1358

Abstract

The optimum femtosecond laser direct writing of Bragg gratings on silica optical waveguides has been investigated. The silica waveguide has a 6.5 × 6.5 µm² cross-sectional profile with a 20-µm-thick silicon dioxide cladding layer. Compared with conventional grating inscribed on fiber platforms, [...] Read more.

The optimum femtosecond laser direct writing of Bragg gratings on silica optical waveguides has been investigated. The silica waveguide has a 6.5 × 6.5 µm² cross-sectional profile with a 20-µm-thick silicon dioxide cladding layer. Compared with conventional grating inscribed on fiber platforms, the silica planar waveguide circuit can realize a stable performance as well as a high-efficiency coupling with the fiber. A thin waveguide cladding layer also facilitates laser focusing with an improved spherical aberration. Different from the circular fiber core matching with the Gaussian beam profile, a 1030-nm, 400-fs, and 190-nJ laser is optimized to focus on the top surface of the square silica waveguide, and the 3rd-order Bragg gratings are inscribed successfully. A 1.5-mm long uniform Bragg gratings structure with a reflectivity of 90% at a 1548.36-nm wavelength can be obtained. Cascaded Bragg gratings with different periods are also inscribed in the planar waveguide. Different reflection wavelengths can be realized, which shows great potential for wavelength multiplexing-related applications such as optical communications or sensing. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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16 pages, 7315 KiB

Open AccessArticle

BTO-Coupled CIGS Solar Cells with High Performances

by Congmeng Li, Haitian Luo, Hongwei Gu and Hui Li

Materials 2022, 15(17), 5883; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15175883 - 25 Aug 2022

Cited by 4 | Viewed by 1975

Abstract

In order to improve the power conversion efficiency (PCE) of Cu(In,Ga)Se₂ (CIGS) solar cells, a BaTiO₃ (BTO) layer was inserted into the Cu(In,Ga)Se₂. The performances of the BTO-coupled CIGS solar cells with structures of Mo/CIGS/CdS/i-ZnO/AZO, Mo/BTO/CIGS/CdS/i-ZnO/AZO, Mo/CIGS/BTO/CdS/i-ZnO/AZO, Mo/CIGS/CdS/BTO/i-ZnO/AZO, Mo/CIGS/BTO/i-ZnO/AZO, [...] Read more.

In order to improve the power conversion efficiency (PCE) of Cu(In,Ga)Se₂ (CIGS) solar cells, a BaTiO₃ (BTO) layer was inserted into the Cu(In,Ga)Se₂. The performances of the BTO-coupled CIGS solar cells with structures of Mo/CIGS/CdS/i-ZnO/AZO, Mo/BTO/CIGS/CdS/i-ZnO/AZO, Mo/CIGS/BTO/CdS/i-ZnO/AZO, Mo/CIGS/CdS/BTO/i-ZnO/AZO, Mo/CIGS/BTO/i-ZnO/AZO, Mo/CIGS/CdS/BTO/AZO, and Mo/ CIGS/CdS(5 nm)/BTO(5 nm)/i-ZnO/AZO were systematically studied via the SCAPS-1D software. It was found that the power conversion efficiency (PCE) of a BTO-coupled CIGS solar cell with a device configuration of Mo/CIGS/CdS/BTO/AZO was 24.53%, and its open-circuit voltage was 931.70 mV. The working mechanism for the BTO-coupled CIGS solar cells with different device structures was proposed. Our results provide a novel strategy for improving the PCE of solar cells by combining a ferroelectric material into the p-n junction materials. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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11 pages, 3784 KiB

Open AccessArticle

Electrospun PA66/Graphene Fiber Films and Application on Flexible Triboelectric Nanogenerators

by Qiupeng Wu, Zhiheng Yu, Fengli Huang and Jinmei Gu

Materials 2022, 15(15), 5191; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155191 - 26 Jul 2022

Cited by 1 | Viewed by 1373

Abstract

Triboelectric nanogenerators (TENGs) are considered to be the most promising energy supply equipment for wearable devices, due to their excellent portability and good mechanical properties. Nevertheless, low power generation efficiency, high fabrication difficulty, and poor wearability hinder their application in the wearable field. [...] Read more.

Triboelectric nanogenerators (TENGs) are considered to be the most promising energy supply equipment for wearable devices, due to their excellent portability and good mechanical properties. Nevertheless, low power generation efficiency, high fabrication difficulty, and poor wearability hinder their application in the wearable field. In this work, PA66/graphene fiber films with 0, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% graphene and PVDF films were prepared by electrospinning. Meanwhile, TENGs were prepared with PA66/graphene fiber films, PVDF films and plain weave conductive cloth, which were used as the positive friction layer, negative friction layer and the flexible substrate, respectively. The results demonstrated that TENGs prepared by PA66/graphene fiber films with 2 wt% grapheme showed the best performance, and that the maximum open circuit voltage and short circuit current of TENGs could reach 180 V and 7.8 μA, respectively, and that the power density was 2.67 W/m² when the external load was 113 MΩ. This is why the PA66/graphene film produced a more subtle secondary network with the addition of graphene, used as a charge capture site to increase its surface charge. Additionally, all the layered structures of TENGs were composed of breathable electrospun films and plain conductive cloth, with water vapor transmittance (WVT) of 9.6 Kgm⁻²d⁻¹, reflecting excellent wearing comfort. The study showed that TENGs, based on all electrospinning, have great potential in the field of wearable energy supply devices. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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9 pages, 3110 KiB

Open AccessArticle

Effects of Three-Dimensional Circular Truncated Cone Microstructures on the Performance of Flexible Pressure Sensors

by Weikan Jin, Zhiheng Yu, Guohong Hu, Hui Zhang, Fengli Huang and Jinmei Gu

Materials 2022, 15(13), 4708; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15134708 - 05 Jul 2022

Cited by 5 | Viewed by 1500

Abstract

Three-dimensional microstructures play a key role in the fabrication of flexible electronic products. However, the development of flexible electronics is limited in further applications due to low positioning accuracy, the complex process, and low production efficiency. In this study, a novel method for [...] Read more.

Three-dimensional microstructures play a key role in the fabrication of flexible electronic products. However, the development of flexible electronics is limited in further applications due to low positioning accuracy, the complex process, and low production efficiency. In this study, a novel method for fabricating three-dimensional circular truncated cone microstructures via low-frequency ultrasonic resonance printing is proposed. Simultaneously, to simplify the manufacturing process of flexible sensors, the microstructure and printed interdigital electrodes were fabricated into an integrated structure, and a flexible pressure sensor with microstructures was fabricated. Additionally, the effects of flexible pressure sensors with and without microstructures on performance were studied. The results show that the overall performance of the designed sensor with microstructures could be effectively improved by 69%. Moreover, the sensitivity of the flexible pressure sensor with microstructures was 0.042 kPa⁻¹ in the working range of pressure from 2.5 to 10 kPa, and the sensitivity was as low as 0.013 kPa⁻¹ within the pressure range of 10 to 30 kPa. Meanwhile, the sensor showed a fast response time, which was 112 ms. The stability remained good after the 100 cycles of testing. The performance was better than that of the flexible sensor fabricated by the traditional inverted mold method. This lays a foundation for the development of flexible electronic technology in the future. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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Review

Jump to: Research

36 pages, 8306 KiB

Open AccessEditor’s ChoiceReview

Gallium Oxide for Gas Sensor Applications: A Comprehensive Review

by Jun Zhu, Zhihao Xu, Sihua Ha, Dongke Li, Kexiong Zhang, Hai Zhang and Jijun Feng

Materials 2022, 15(20), 7339; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207339 - 20 Oct 2022

Cited by 19 | Viewed by 3751

Abstract

Ga₂O₃ has emerged as a promising ultrawide bandgap semiconductor for numerous device applications owing to its excellent material properties. In this paper, we present a comprehensive review on major advances achieved over the past thirty years in the field of [...] Read more.

Ga₂O₃ has emerged as a promising ultrawide bandgap semiconductor for numerous device applications owing to its excellent material properties. In this paper, we present a comprehensive review on major advances achieved over the past thirty years in the field of Ga₂O₃-based gas sensors. We begin with a brief introduction of the polymorphs and basic electric properties of Ga₂O₃. Next, we provide an overview of the typical preparation methods for the fabrication of Ga₂O₃-sensing material developed so far. Then, we will concentrate our discussion on the state-of-the-art Ga₂O₃-based gas sensor devices and put an emphasis on seven sophisticated strategies to improve their gas-sensing performance in terms of material engineering and device optimization. Finally, we give some concluding remarks and put forward some suggestions, including (i) construction of hybrid structures with two-dimensional materials and organic polymers, (ii) combination with density functional theoretical calculations and machine learning, and (iii) development of optical sensors using the characteristic optical spectra for the future development of novel Ga₂O₃-based gas sensors. Full article

(This article belongs to the Special Issue Development of Novel Functional Materials for the Manufacture of Electronic and Optoelectronic Devices)

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