Journals > > Topics > Materials
Materials|331 Article(s)
Terahertz Metamaterial Filter Based on Laser-Induced Graphene
Xu Zhang, Ruiqi Song, Guwei Zong, Shuangyue Wu, and Lei Wang
In this study, a terahertz metamaterial filter based on laser-induced graphene (LIG) is proposed. The electrical properties of the LIG under different laser parameters are investigated, and the transmission performance of the filter is measured using terahertz time-domain spectroscopy. The transmittance of the filter is 74.2% at 0.55 THz when the period of the filter unit is 500 μm. By changing the period of the filter, the center frequency can be increased to 0.65 THz. Furthermore, the characteristic of the filter amplitude is polarization-dependent. As the angle θ between the polarization direction of the incident terahertz waves and the x-axis increases, the transmittance of the filter decreases gradually. This simple and low-cost LIG method is expected to be used to prepare various terahertz metamaterial devices, which can be applied in many fields such as terahertz sensing, detection, and communication. In this study, a terahertz metamaterial filter based on laser-induced graphene (LIG) is proposed. The electrical properties of the LIG under different laser parameters are investigated, and the transmission performance of the filter is measured using terahertz time-domain spectroscopy. The transmittance of the filter is 74.2% at 0.55 THz when the period of the filter unit is 500 μm. By changing the period of the filter, the center frequency can be increased to 0.65 THz. Furthermore, the characteristic of the filter amplitude is polarization-dependent. As the angle θ between the polarization direction of the incident terahertz waves and the x-axis increases, the transmittance of the filter decreases gradually. This simple and low-cost LIG method is expected to be used to prepare various terahertz metamaterial devices, which can be applied in many fields such as terahertz sensing, detection, and communication.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2024
- Vol. 61, Issue 9, 0916003 (2024)
Microstructure and Properties of TiC/AlMgSc Composites by Selective Laser Melting
Weiyun Ding, Fugui Si, Changgeng Xia, Dezhi Sun, Yakun Xu, Yingcui Xu, Haojie Cheng, Mengzhi Wang, and Wei Ji
TiC nanoparticles reinforced AlMgSc composites are prepared based on selective laser melting (SLM) forming process, and the phase composition, microstructure and mechanical properties of TiC/AlMgSc composites are studied. The results show that TiC/AlMgSc composites with high density (99.73%) are obtained by using the optimized SLM forming process parameters. There is no reaction between TiC particles and AlMgSc matrix during SLM forming. TiC particles provide high-density effective nucleation points, which promote the transformation of the composite structure to equiaxed grains and grain refinement, and weaken the texture strength. After adding TiC particles, the tensile strength of the composites increased by 9.9% to 611 MPa, and the elongation decreased to 10.02%. The fracture mechanism of the composites is mainly ductile and brittle mixed fracture, and TiC clusters with a size of 3?8 μm remain on the fracture surface and adhere to the aluminum matrix. TiC nanoparticles reinforced AlMgSc composites are prepared based on selective laser melting (SLM) forming process, and the phase composition, microstructure and mechanical properties of TiC/AlMgSc composites are studied. The results show that TiC/AlMgSc composites with high density (99.73%) are obtained by using the optimized SLM forming process parameters. There is no reaction between TiC particles and AlMgSc matrix during SLM forming. TiC particles provide high-density effective nucleation points, which promote the transformation of the composite structure to equiaxed grains and grain refinement, and weaken the texture strength. After adding TiC particles, the tensile strength of the composites increased by 9.9% to 611 MPa, and the elongation decreased to 10.02%. The fracture mechanism of the composites is mainly ductile and brittle mixed fracture, and TiC clusters with a size of 3?8 μm remain on the fracture surface and adhere to the aluminum matrix.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2024
- Vol. 61, Issue 9, 0916002 (2024)
Influences of Hydrostatic Pressure on the Photoelectric Properties of Cubic Phase CsPbBr3 Materials Based on First Principles
Wei He, Xiangnong Wu, and Yiwen Zhang
In view of the incomplete coverage of the photoelectric properties of the cubic phase CsPbBr3 material under the same model, the influences of hydrostatic pressure on the structure and photoelectric properties of the material are studied in depth based on first principles. The results show that when the hydrostatic pressure increases from 0 to 7 GPa, the band gap of CsPbBr3 decreases from 1.80 eV to 0.74 eV, and the bond length of Cs—Br and Pb—Br decreases by 0.31 ? and 0.22 ?, respectively, which indicate that the coupling effect between atoms increases. The static permittivity, static refractive index and static reflectivity of CsPbBr3 increase by 10.3%, 5.0% and 12.0% under 7 GPa pressure, respectively. The transition degree and migration rate of electrons increase. When CsPbBr3 falls into the low-energy region, the pressure can reduce the edge energy of the imaginary part of the dielectric function, extinction coefficient, absorption coefficient, conductivity and loss function from 0.94 eV to 0.69 eV, the conductivity increases by 17.7% and the extinction coefficient averagely increases by 11.5%. The pressure increases the loss function by 20.6% on average when CsPbBr3 falls into the high-energy region. In addition, the pressures in the UV-Vis and near-infrared regions can increase the absorption coefficients of CsPbBr3 to 1.1 and 4.7 times of the original value, respectively, and therefore can strengthen the absorption capacity of light. These properties can expand the application of the material. In view of the incomplete coverage of the photoelectric properties of the cubic phase CsPbBr3 material under the same model, the influences of hydrostatic pressure on the structure and photoelectric properties of the material are studied in depth based on first principles. The results show that when the hydrostatic pressure increases from 0 to 7 GPa, the band gap of CsPbBr3 decreases from 1.80 eV to 0.74 eV, and the bond length of Cs—Br and Pb—Br decreases by 0.31 ? and 0.22 ?, respectively, which indicate that the coupling effect between atoms increases. The static permittivity, static refractive index and static reflectivity of CsPbBr3 increase by 10.3%, 5.0% and 12.0% under 7 GPa pressure, respectively. The transition degree and migration rate of electrons increase. When CsPbBr3 falls into the low-energy region, the pressure can reduce the edge energy of the imaginary part of the dielectric function, extinction coefficient, absorption coefficient, conductivity and loss function from 0.94 eV to 0.69 eV, the conductivity increases by 17.7% and the extinction coefficient averagely increases by 11.5%. The pressure increases the loss function by 20.6% on average when CsPbBr3 falls into the high-energy region. In addition, the pressures in the UV-Vis and near-infrared regions can increase the absorption coefficients of CsPbBr3 to 1.1 and 4.7 times of the original value, respectively, and therefore can strengthen the absorption capacity of light. These properties can expand the application of the material.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2024
- Vol. 61, Issue 9, 0916001 (2024)
Regulation of SnO2 Electron Transport Layers for Perovskite Solar Cells
Yupeng Cui, Jue Gong, and Mingzhen Liu
Being an important part of planar heterojunction perovskite solar cells (PSCs), electron transport layer (ETL) plays important roles in enhancing the photovoltaic performance and stability of PSCs. Despite the two most commonly used ETL materials, titanium dioxide (TiO2) and tin oxide (SnO2) all being nanoparticles and fabricated through solution method, TiO2 suffers from low electron mobility, large device hysteresis, weak chemical stability and high-temperature processing. By comparison, SnO2 owns the advantages of excellent optoelectronic properties, greater stability because of its chemical inertness and low-temperature processability. We focus on the stability and interfacial charge extraction in PSCs based on SnO2 ETL. First, physical properties and advantages of SnO2 are reviewed. Then, starting from the preparation and film formation methods of SnO2 (e.g. chemical bath deposition, solution spin-coating, etc.), we further discuss the bulk and surface defects of SnO2. Finally, targeting the defect profiles of SnO2 ETL, we emphasize regulatory approaches to enhance the device stability and carrier extraction in PSCs based on interfacial passivation, bulk doping and double-ETL structures. This review article contributes to the further advancements of device performance and stability of PSCs, and provides insights for the practical application of this emerging photovoltaic technology. Being an important part of planar heterojunction perovskite solar cells (PSCs), electron transport layer (ETL) plays important roles in enhancing the photovoltaic performance and stability of PSCs. Despite the two most commonly used ETL materials, titanium dioxide (TiO2) and tin oxide (SnO2) all being nanoparticles and fabricated through solution method, TiO2 suffers from low electron mobility, large device hysteresis, weak chemical stability and high-temperature processing. By comparison, SnO2 owns the advantages of excellent optoelectronic properties, greater stability because of its chemical inertness and low-temperature processability. We focus on the stability and interfacial charge extraction in PSCs based on SnO2 ETL. First, physical properties and advantages of SnO2 are reviewed. Then, starting from the preparation and film formation methods of SnO2 (e.g. chemical bath deposition, solution spin-coating, etc.), we further discuss the bulk and surface defects of SnO2. Finally, targeting the defect profiles of SnO2 ETL, we emphasize regulatory approaches to enhance the device stability and carrier extraction in PSCs based on interfacial passivation, bulk doping and double-ETL structures. This review article contributes to the further advancements of device performance and stability of PSCs, and provides insights for the practical application of this emerging photovoltaic technology.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0516002 (2024)
Low-Dimensional Perovskite Templated Growth of MAPbI3 Perovskite Crystals and Photovoltaic Performance of Solar Cells
Yunyun Yang, Jingyi Wu, Yinyi Ma, Jue Gong, and Faming Li
Due to low costs and exceptional photoelectric properties, perovskite solar cell materials have attracted great attention. During the fabrication of perovskite light-absorbing layers, dual-source vapor-deposited perovskite thin films suffer from long-standing issues of unknown growth mechanism and inferior crystallization quality, which negatively impacts the optical absorbance and charge carrier lifetimes of perovskite thin films, impeding the performance development of vapor-deposited perovskite solar cell devices. By utilizing bulky organic cations with different radii, this work designs quasi two-dimensional perovskite materials, and apply them as buffering templates at the perovskite/hole transport layer interfaces, thus manipulating the crystal growth process of vapor-deposited perovskite grains. The modified crystallization patterns result in vertically grown perovskite grains with columnar shapes, which notably enhances light-absorbing properties and carrier lifetimes of perovskite layers, boosting the power conversion efficiency from 16.21% to 19.55% on perovskite solar cells. The abovementioned results have provided valuable references to the vapor-deposited perovskite films and photovoltaic devices with outstanding optoelectronic performance. Due to low costs and exceptional photoelectric properties, perovskite solar cell materials have attracted great attention. During the fabrication of perovskite light-absorbing layers, dual-source vapor-deposited perovskite thin films suffer from long-standing issues of unknown growth mechanism and inferior crystallization quality, which negatively impacts the optical absorbance and charge carrier lifetimes of perovskite thin films, impeding the performance development of vapor-deposited perovskite solar cell devices. By utilizing bulky organic cations with different radii, this work designs quasi two-dimensional perovskite materials, and apply them as buffering templates at the perovskite/hole transport layer interfaces, thus manipulating the crystal growth process of vapor-deposited perovskite grains. The modified crystallization patterns result in vertically grown perovskite grains with columnar shapes, which notably enhances light-absorbing properties and carrier lifetimes of perovskite layers, boosting the power conversion efficiency from 16.21% to 19.55% on perovskite solar cells. The abovementioned results have provided valuable references to the vapor-deposited perovskite films and photovoltaic devices with outstanding optoelectronic performance.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0516001 (2024)
Research Progress on Excitonic Upconversion Photoluminescence in Two-Dimensional Materials (Invited)
Haiyi Liu, and Pengfei Qi
Upconversion photoluminescence, an anti-Stokes process in which the emitted photon energy exceeds the excitation photon energy, can effectively achieve energy renormalization and conversion, with great application prospects in fields such as biological imaging, solar cells, photocatalysis, and optical refrigeration. As a strategically important new material in the post-Moore era, two-dimensional materials are crucial in realizing efficient room-temperature excitonic upconversion because of their large dipole moments, narrow linewidths, low disorder, and high exciton binding energies, which have recently attracted extensive research interest. This study first introduces the luminescence mechanisms used to achieve photon upconversion, including phonon-assisted upconversion, two-photon absorption, and Auger recombination. Then, research on upconversion based on two-dimensional material systems, such as hexagonal boron nitride, monolayer transition metal dichalcogenides, and two-dimensional perovskites, is summarized. Modulation and enhancement approaches for upconversion in two-dimensional materials that target low upconversion efficiency are also discussed. Finally, application prospects of excitonic upconversion effects in two-dimensional material systems are envisioned. Upconversion photoluminescence, an anti-Stokes process in which the emitted photon energy exceeds the excitation photon energy, can effectively achieve energy renormalization and conversion, with great application prospects in fields such as biological imaging, solar cells, photocatalysis, and optical refrigeration. As a strategically important new material in the post-Moore era, two-dimensional materials are crucial in realizing efficient room-temperature excitonic upconversion because of their large dipole moments, narrow linewidths, low disorder, and high exciton binding energies, which have recently attracted extensive research interest. This study first introduces the luminescence mechanisms used to achieve photon upconversion, including phonon-assisted upconversion, two-photon absorption, and Auger recombination. Then, research on upconversion based on two-dimensional material systems, such as hexagonal boron nitride, monolayer transition metal dichalcogenides, and two-dimensional perovskites, is summarized. Modulation and enhancement approaches for upconversion in two-dimensional materials that target low upconversion efficiency are also discussed. Finally, application prospects of excitonic upconversion effects in two-dimensional material systems are envisioned.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0316007 (2024)
Phosphate-Bismuthate Glass and Fiber with Heavy Doping of Silver Nanoparticles (Invited)
Fuguang Chen, Bofan Jiang, Zhi Chen, Siyuan Ma, Yupeng Huang, Hang Zhang, and Zhijun Ma
Glass with heavy doping of noble metal nanoparticles is expected to exhibit high optical nonlinearity. In this study, the effects of glass composition, structure, and heat treatment on the formation of silver nanoparticles (Ag NPs) in phosphate-bismuthate (PB) glass are investigated. By optimizing the chemical composition and preparation parameters, strong localized surface plasmon resonance is achieved in the PB glass with a silver mass fraction of more than 13%, which is 20 and 6 times higher than that in bismuthate and phosphate glasses reported previously, respectively. The high solubility of the phosphate component and the self-reduction effect of the bismuthate component jointly contributed to the stability and high content of Ag NPs in the PB glass. Z-scan measurements show that such heavy doping PB glass has a reverse saturable absorption coefficient of -14×10-12 m·W-1 and a saturable absorption coefficient of 4.94×10-12 m·W-1 at 800 nm. Furthermore, the heavy doping PB glass exhibits excellent thermal stability, making it promising for the fabrication of nonlinear optical fibers. In addition, with a heavily silver-doped PB glass rod as the core and a commercial silicate glass tube as the cladding, a composite glass fiber with high Ag-NP doping is successfully fabricated using a "molten-core" fiber drawing method. Glass with heavy doping of noble metal nanoparticles is expected to exhibit high optical nonlinearity. In this study, the effects of glass composition, structure, and heat treatment on the formation of silver nanoparticles (Ag NPs) in phosphate-bismuthate (PB) glass are investigated. By optimizing the chemical composition and preparation parameters, strong localized surface plasmon resonance is achieved in the PB glass with a silver mass fraction of more than 13%, which is 20 and 6 times higher than that in bismuthate and phosphate glasses reported previously, respectively. The high solubility of the phosphate component and the self-reduction effect of the bismuthate component jointly contributed to the stability and high content of Ag NPs in the PB glass. Z-scan measurements show that such heavy doping PB glass has a reverse saturable absorption coefficient of -14×10-12 m·W-1 and a saturable absorption coefficient of 4.94×10-12 m·W-1 at 800 nm. Furthermore, the heavy doping PB glass exhibits excellent thermal stability, making it promising for the fabrication of nonlinear optical fibers. In addition, with a heavily silver-doped PB glass rod as the core and a commercial silicate glass tube as the cladding, a composite glass fiber with high Ag-NP doping is successfully fabricated using a "molten-core" fiber drawing method.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0316006 (2024)
Research Progress in Lead-Free Metal Halide Scintillator Materials and Imaging Devices (Invited)
Junzhe Lin, Dan Guo, and Tianrui Zhai
High-energy radiation detection and imaging technology has important applications in high-energy physics research, medical imaging, industrial detection, and other fields. Lead-free metal halides have many advantages, such as low toxicity, good stability, high light yield, and large stokes shift; they exhibit excellent potential in indirect X-ray detection. The latest research progress of lead-free metal halide scintillators and imaging devices is reviewed herein. First, the material composition and luminescence mechanism are introduced. The key parameters of scintillator performance are listed. The synthesis methods of single crystal, powder, and nanocrystal are summarized. Some recent novel ideas about improving the resolution of imaging devices are also described. We focus on the new-type scintillator imaging devices, including composite film, ceramic, glass, and structured scintillators. Finally, we have summarized the challenges and potential problems of scintillator imaging detectors and provided some suggestions. High-energy radiation detection and imaging technology has important applications in high-energy physics research, medical imaging, industrial detection, and other fields. Lead-free metal halides have many advantages, such as low toxicity, good stability, high light yield, and large stokes shift; they exhibit excellent potential in indirect X-ray detection. The latest research progress of lead-free metal halide scintillators and imaging devices is reviewed herein. First, the material composition and luminescence mechanism are introduced. The key parameters of scintillator performance are listed. The synthesis methods of single crystal, powder, and nanocrystal are summarized. Some recent novel ideas about improving the resolution of imaging devices are also described. We focus on the new-type scintillator imaging devices, including composite film, ceramic, glass, and structured scintillators. Finally, we have summarized the challenges and potential problems of scintillator imaging detectors and provided some suggestions.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0316005 (2024)
Li3Na3Ga2F12∶Cr3+ Fluoride Wideband Near-Infrared Fluorescence Material Synthesized by Green Method (Invited)
Yang Li, Xiang Yu, Ximei An, Qiaoling Tan, Hongjia Liu, Zhenzhang Li, and Shaoan Zhang
The near-infrared light source possesses strong penetration, non-destructive testing capabilities, and a high signal-to-noise ratio for biological tissues. It finds extensive applications in component detection, security monitoring, biomedicine, national defense, and the military industry. However, the lack of highly efficient and portable near-infrared light sources has become a key obstacle to the development of intelligent detection technology. In comparison with traditional near-infrared light sources, phosphor-converted near-infrared LED light sources (NIR pc-LEDs) offer advantages such as portability and high efficiency. This study focuses on synthesizing Li3Na3Ga2F12∶Cr3+ broadband phosphors through a simple and environmentally friendly hydrothermal synthesis method. By controlling factors like holding temperature and holding time, an optimal synthesis scheme for fluorescent materials is determined. The influence of fluoride particle size, morphology evolution, and Cr3+ doping concentration on the luminescence properties of Li3Na3Ga2F12∶Cr3+ is also investigated. The synthesized Li3Na3Ga2F12∶Cr3+ material exhibits broadband emission ranging from 630 nm to 980 nm with a full width at half maximum (FWHM) of 110 nm and a peak value at 766 nm. Its internal quantum efficiency reaches an impressive 74%. Through successful packaging with commercial blue LED, a NIR wideband LED source is achieved. The output power of NIR light at 50 mA driving current is 10.32 mW, and the photoelectric conversion efficiency reaches 5.1%. Finally, the feasibility of using the NIR broadband LED light source in imaging fields such as medical and food detection is verified by NIR imaging of veins under chicken breast and night vision imaging demonstrations. The near-infrared light source possesses strong penetration, non-destructive testing capabilities, and a high signal-to-noise ratio for biological tissues. It finds extensive applications in component detection, security monitoring, biomedicine, national defense, and the military industry. However, the lack of highly efficient and portable near-infrared light sources has become a key obstacle to the development of intelligent detection technology. In comparison with traditional near-infrared light sources, phosphor-converted near-infrared LED light sources (NIR pc-LEDs) offer advantages such as portability and high efficiency. This study focuses on synthesizing Li3Na3Ga2F12∶Cr3+ broadband phosphors through a simple and environmentally friendly hydrothermal synthesis method. By controlling factors like holding temperature and holding time, an optimal synthesis scheme for fluorescent materials is determined. The influence of fluoride particle size, morphology evolution, and Cr3+ doping concentration on the luminescence properties of Li3Na3Ga2F12∶Cr3+ is also investigated. The synthesized Li3Na3Ga2F12∶Cr3+ material exhibits broadband emission ranging from 630 nm to 980 nm with a full width at half maximum (FWHM) of 110 nm and a peak value at 766 nm. Its internal quantum efficiency reaches an impressive 74%. Through successful packaging with commercial blue LED, a NIR wideband LED source is achieved. The output power of NIR light at 50 mA driving current is 10.32 mW, and the photoelectric conversion efficiency reaches 5.1%. Finally, the feasibility of using the NIR broadband LED light source in imaging fields such as medical and food detection is verified by NIR imaging of veins under chicken breast and night vision imaging demonstrations.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0316004 (2024)
Terahertz Sensing with Exceptional Points in Metasurfaces (Invited)
Yuancheng Fan, Zhenning Yang, Ziyi Xu, Hong Zhang, Kangyao Sun, Zhehao Ye, Fuli Zhang, and Jing Lou
Exceptional points are singularities in non-Hermitian systems, generated when two or more eigenvalues and their corresponding eigenvectors merge simultaneously. Metasurfaces are two-dimensional artificial electromagnetic materials constructed at subwavelength scales, which provide a versatile platform for studying this non-Hermitian phenomenon by introducing dissipation and amplification within their unit cells. This paper provides an overview of the latest research progress in exceptional points sensing. It begins by introducing the basic theory of non-Hermitian systems and exceptional points, then focuses on the research achievements in exceptional points sensing on metasurfaces in terahertz band. Lastest, we summarize the disadvantages of exceptional points sensing, and its future development trends are also discussed. Exceptional points are singularities in non-Hermitian systems, generated when two or more eigenvalues and their corresponding eigenvectors merge simultaneously. Metasurfaces are two-dimensional artificial electromagnetic materials constructed at subwavelength scales, which provide a versatile platform for studying this non-Hermitian phenomenon by introducing dissipation and amplification within their unit cells. This paper provides an overview of the latest research progress in exceptional points sensing. It begins by introducing the basic theory of non-Hermitian systems and exceptional points, then focuses on the research achievements in exceptional points sensing on metasurfaces in terahertz band. Lastest, we summarize the disadvantages of exceptional points sensing, and its future development trends are also discussed.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0316003 (2024)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20