FWHM Research Articles

Selective site occupancy engineering enabling Mn5+ activated highly efficient near infrared-II emission in Ba3BPO7:Mn5+

The development of highly efficient near infrared (NIR) luminescence materials is crucial for advancing the next generation compact light sources. However, the realization of target material with emission in the NIR-II spectral region (1000–1700 nm) remains a major challenge. Herein, a NIR-II emission phosphor Ba3BPO7:Mn5+ peaking at 1176 nm with a full width of half maximum of 22 nm is demonstrated via a selective site occupancy engineering strategy. Upon 660 nm red-light excitation, high internal quantum efficiency of 50.6% and external quantum efficiency of 30.5% are obtained in this phosphor. Density functional theory calculations and structural analyses provide an understanding of stabilizing pentavalent manganese in Ba3BPO7:Mn5+. The highly efficient NIR-II emission is mainly ascribed to the relatively high distorted tetrahedral crystal field environment of Mn5+ in this system and the stable valence state. Combining this phosphor with 660 nm red-light chip, we fabricate a light emitting diode with NIR-II output power of 19.2 mW@300 mA, which shows promising applications in anti-counterfeiting, special information identification, etc. This work provides some important insights into the design of highly efficient Mn5+ based NIR-II emission and the emerging applications.

Highly‐Efficiency Far‐Red Emission in Cr3+ Activated Ca1.8Mg1.2Al2Ge3O12 toward Plant Precise Lighting

AbstractFar‐red (FR) region (beyond 700 nm) lighting sources possess special potential for plant lighting. However, it remains a challenge to obtain high‐performance Cr3+‐doped FR phosphors. This study developed a FR phosphor, Ca1.8Mg1.2Al2Ge3O12:Cr3+ (CMAGG: Cr3+), using the cation substitution strategy. Under 438 nm blue light excitation, the phosphors display FR emission centered at 720 nm with a full width at half maximum (FWHM) of 91 nm. Benefit from the favorable match with the FR phytochrome (Pfr), the phosphor is combined with InGaN blue light chips to create a FR phosphor‐converted light‐emitting diode (pc‐LED), which is used in Italian lettuce growth experiments and it results shown in a 15% increase in fresh weight and a 6.5% increase in dry weight. Notably, supplemental FR light modulated its growth morphology. The results of this study will be useful for further research on novel Cr3+‐doped FR phosphors to meet the precise spectral requirements for plant growth.

High Q-Factor, High Contrast, and Multi-Band Optical Sensor Based on Plasmonic Square Bracket Dimer Metasurface.

A high-performance resonant metasurface is rather promising for diverse application areas such as optical sensing and filtering. Herein, a metal-insulator-metal (MIM) optical sensor with merits of a high quality-factor (Q-factor), multiple operating bands, and high spectrum contrast is proposed using plasmonic square bracket dimer metasurface. Due to the complex square bracket itself, a dimer structure of two oppositely placed square brackets, and metasurface array configuration, multiple kinds of mode coupling can be devised in the inner and outer elements within the metasurface, enabling four sensing channels with the sensitivities higher than 200 nm/RIU for refractive index sensing. Among them, the special sensing channel based on the reflection-type surface lattice resonance (SLR) mechanism has a full width at half maximum (FWHM) of only 2 nm, a high peak-to-dip signal contrast of 0.82, a high Q-factor of 548, and it can also behave as a good sensing channel for the thickness measurement of the deposition layer. The multi-band sensor can work normally in a large refractive index or thickness range, and the number of resonant channels can be further increased by simply breaking the structural symmetry or changing the polarization angle of incident light. Equipped with unique advantages, the suggested plasmonic metasurface has great potential in sensing, monitoring, filtering, and other applications.

Triphenylamine Spirofunctionalized Light-Emitting Conjugated Polymer with an Ultradeep-Blue Narrowband Emission for Large-Area Printed Display.

Emerging printed large-area polymer light-emitting diodes (PLEDs) are essential for manufacturing flat-panel displays and solid lighting devices. However, it is challenging to obtain large-area and stable ultradeep-blue PLEDs because of the lack of light-emitting conjugated polymers (LCPs) with robust deep-blue emissions, excellent morphological stabilities, and high charging abilities. Here, a novel unsymmetrically substituted polydiarylfluorene (POPSAF) is obtained with stable narrowband emission for large-area printed displays via triphenylamine (TPA) spirofunctionalization of LCPs. POPSAF films show narrowband and stable ultradeep-blue emission with a full width at half maximum (FWHM) of 36nm, associated with their intrachain excitonic behavior without obvious polaron formation. Compared to controlled poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenylfluoren-2,7-diyl] (PODPF), excellent charge transport is observed in the POPSAF films because of the intrinsic hole transport ability of the TPA units. Large-area PLEDs are fabricated via blade-coating with an emission area of 9 cm2, which exhibit uniform ultradeep-blue emission with an FWHM of 36nm and corresponding Commission internationale de l'éclairage (CIE) coordinates of (0.155, 0.072). These findings are attributed to the synergistic effects of robust emission, stable morphology, and printing capacity. Finally, preliminary printed passive matrix (PM) PLED displays with 20 × 20 pixels monochromes are fabricated, confirmed the effectiveness of spirofunctionalization in optoelectronics.

A challenge and solution for automatic thin slice thickness measurements on images of the Catphan phantom

Purpose. The use of the Hough transform for angle detection is quite accurate for relatively wide slice thickness. However, the Hough transform fails to accurately detect the angle for thin slice thickness. This study proposes a method for automatically measuring the thickness of thin slices on images of a Catphan phantom. Methods. In the proposed method, the angle of the phantom’s orientation was determined based on the relative coordinates of the four hole objects in the phantom. After the angles of the wires were determined, the profiles of pixel values across the wire objects were constructed. Finally, their full widths at half maximum (FWHMs) were determined and multiplied by tan 23° to obtain the slice thicknesses of the images. The results of the proposed method were compared to a previous method, which used the Hough transform to obtain the phantom’s orientation. We used slice thicknesses ranging from 0.8 mm to 5.0 mm, and phantom angles from 0° to 10°. Results. Our proposed method detected the angle of the phantom accurately for thin slices, whereas a previous method did not accurately detect the angle. The results of the slice thickness using this current method were slightly higher (within 7.9%) compared to the previous method. However, the results of the two methods did not differ significantly (p-value > 0.05). Using different angles, the current method detected all the angles more accurately. Again, the slice thicknesses were not significantly different from the previous method (p-value > 0.05). Conclusion. The proposed method for measuring the thickness of thin slices in an image of a Catphan phantom, based on the relative coordinates of the four hole objects in the phantom, outperformed a previous method based on the Hough transform.

Evolution of kerogen structure during the carbonization stage

Currently, certain unconventional gas is mainly extracted from high-maturity shale reservoirs, but limited attention has been given to the evolution of kerogen structure subsequent to the overmature, gas generative stage, corresponding to metagenesis and is termed the carbonization stage. In this study, we performed heating treatment on overmature kerogen samples to obtain samples in the carbonization stage and then conducted Raman, thermogravimetric-mass spectrometric analysis (TG-MS), X ray diffraction (XRD), and high resolution transmission electron microscope (HRTEM) experiments on these samples to investigate the changes in kerogen structure. Low pressure N2 and CO2 adsorption experiments also were performed to investigate the changes in pore structure. The results show that as the heat treatment temperature is raised to 1000 °C, the ID/IG ratio (D band intensity to G band intensity) experiences an increase, reaching 1.12. Additionally, the full width at half maximum (FWHM) of 002 peak consistently remains above 3.8°. This suggests that these samples were matured to an early meta-anthracite (meta-kerogen) stage, which is significantly distant from the graphite stage. During this particular stage, the most obvious changes in molecular structure are the enlargement of aromatic clusters and the decrease in hydrogen atoms, and thus, H2 rather than methane is produced, as revealed by the results of TC-MS experiment. Following an initial increase, the pore volume and surface area of kerogen samples decrease gradually, reaching their maximum values at 700 °C. Kerogen subjected to a heating temperature of 1000 °C exhibits a greater pore volume in comparison to the initial overmature kerogen. Thus, this observation provides evidence that shale kerogen in carbonization stage, which is typically lying at significant depths, holds promise as a viable reservoir for shale gas extraction.

A Giant Stokes Shift in Wide‐Band Red Phosphor [Ca0.33(Sr1‐xBax)0.67]7(SiO3)6Cl2: Eu2+

AbstractThis paper investigates a wide‐band emitting red phosphor, an advancement that solves shortcomings including the re‐absorption of the yellow phosphor in the blue light area and a lack of red spectrum components which result in low color rendering and an uneven white light tone. An examination through femtosecond, Raman, and low‐temperature spectroscopy demonstrates why this phosphor has large Stokes shift (SS = 7.5×103 cm−1) and wide half‐peak width with a full‐width at half maximum (FWHM) of more than 170 nm. In these samples, it is importantly observed that larger lattice causes smaller electron–phonon coupling of Eu2+ activator, and meanwhile leads to less temperature dependency of emission peak width. The obtained sample, after cation replacement in (Ca1‐xSrx)7(SiO3)6Cl2: Eu2+ (CSSC: Eu2+), exhibits an emission spectrum covers the range from 450 to 800 nm while its excitation range is below 450 nm, in which not reabsorb the blue light. This matches well with blue phosphors that can also be excited by near‐ultraviolet chips. The fabricated white light‐emitting diode (w‐LED) device has an ideal color rendering index and correlated color temperature (Ra = 90.5, CCT = 3894 K), making it an excellent candidate material for white LED illumination.

Quantitative Understanding of Ionic Channel Network Variation in Nafion with Hydration Using Current Sensing Atomic Force Microscopy.

Proton exchange membranes are an essential component of proton-exchange membrane fuel cells (PEMFC). Their performance is directly related to the development of ionic channel networks through hydration. Current sensing atomic force microscopy (CSAFM) can map the local conductance and morphology of a sample surface with sub-nano resolution simultaneously by applying a bias voltage between the conducting tip and sample holder. In this study, the ionic channel network variation of Nafion by hydration has been quantitatively characterized based on the basic principles of electrodynamics and CSAFM. A nano-sized PEMFC has been created using a Pt-coated tip of CSAFM and one side Pt-coated Nafion, and studied under different relative humidity (RH) conditions. The results have been systematically analyzed. First, the morphology of PEMFC under each RH has been studied using line profile and surface roughness. Second, the CSAFM image has been analyzed statistically through the peak value and full-width half-maximum of the histograms. Third, the number of protons moving through the ionic channel network (NPMI) has been derived and used to understand ionic channel network variation by hydration. This study develops a quantitative method to comprehend variations in the ionic channel network by calculating the movement of protons into the ionic channel network based on CSAFM images. To verify the method, a comparison is made between the NPMI and the changes in proton conductivity under different RH conditions and it reveals a good agreement. This developed method can offer a quantitative approach for characterizing the morphological structure of PEM. Also, it can provide a quantitative tool for interpretating CSAFM images.

High-Efficiency Blue-Emitting Mn-Ligand passivated CsPbBr3 nanoplatelets

Perovskite nanoplatelets (NPLs), as a promising material to achieve pure blue emission, have attracted significant attention in high gamut displays. However, the high surface-to-volume ratio and the loosely connected ligands of NPLs make them susceptible to degradation from light, air and heat. As a result, NPLs often exhibit low photoluminescence (PL) intensity and instability. Here, an Mn-ligand passivation strategy is proposed, in which Mn-doped DMAPbBr3 is used as a precursor. During the perovskite transformation, Mn2+ ions migrate from the lattice of DMAPbBr3 to the surface of CsPbBr3 NPLs, which have strong binding forces with ligands. The final products Mn-CsPbBr3 (M−CPB) NPLs are then acquired by the ligand-induced ripening growth process, which not only exhibit pure blue emission with narrow full width at half maximum (FWHM), but also possess near-unity PL quantum yields (QYs). Besides, M−CPB NPLs show excellent stability due to the strong Mn-ligand passivation layer. Based on the new growth mechanism discovery, the reaction time can be shortened to several minutes by heating. The innovative growth model proposed in this work will provide a paradigm for designing and optimizing future synthesis schemes.

Improvements in Between-Vendor MRI Harmonization of Renal T2 Mapping using Stimulated Echo Compensation.

T2 mapping is valuable to evaluate pathophysiology in kidney disease. However, variations in T2 relaxation time measurements across MR scanners and vendors may occur requiring additional correction. To harmonize renal T2 measurements between MR vendor platforms, and use an extended-phase-graph-based fitting method ("StimFit") to correct stimulated echoes and reduce between-vendor variations. Prospective. 8 healthy "travelling" volunteers (37.5% female, 32 ± 6 years) imaged on four MRI systems across three vendors at four sites, 10 healthy volunteers (50% female, 32 ± 8 years) scanned multiple times on a given MR scanner for repeatability evaluation. ISMRM/NIST system phantom scanned for evaluation of T2 accuracy. 3T, multiecho spin-echo sequence. T2 images fit using conventional monoexponential fitting and "StimFit." Mean absolute percentage error (MAPE) of phantom measurements with reference T2 values. Average cortex and medulla T2 values compared between MR vendors, with masks obtained from T2-weighted images and T1 maps. Full-width-at-half-maximum (FWHM) T2 distributions to evaluate local homogeneity of measurements. Coefficient of variation (CV), linear mixed-effects model, analysis of variance, student's t-tests, Bland-Altman plots, P-value <0.05 considered statistically significant. In the ISMRM/NIST phantom, "StimFit" reduced the MAPE from 4.9%, 9.1%, 24.4%, and 18.1% for the four sites (three vendors) to 3.3%, 3.0%, 6.6%, and 4.1%, respectively. In vivo, there was a significant difference in kidney T2 measurements between vendors using a monoexponential fit, but not with "StimFit" (P = 0.86 and 0.92, cortex and medulla, respectively). The intervendor CVs of T2 measures were reduced from 8.0% to 2.6% (cortex) and 7.1% to 2.8% (medulla) with StimFit, resulting in no significant differences for the CVs of intravendor repeat acquisitions (P = 0.13 and 0.05). "StimFit" significantly reduced the FWHM of T2 distributions in the cortex and whole kidney. Stimulated-echo correction reduces renal T2 variation across MR vendor platforms. 2 TECHNICAL EFFICACY: Stage 1.

Fluorescence lifetime of pyrene butyric acid as a versatile sensing tool for monitoring self-assembled systems and microenvironment

Sensing applicability of the fluorescence lifetime of pyrene butyric acid (PBA) to understand the aggregation behaviour and microheterogeneity of different charged self-assembled surfactants i.e., anionic (sodium dodecyl sulfate, ∼ 8.5 mM), cationic (Cetyltrimethylammonium bromide, ∼ 0.95 mM), and non-ionic (Triton X100, ∼ 0.27 mM) in aqueous solution is explored in this study. Time domain fluorescence decay of PBA is introduced for the first time as a sensitive tool for characterizing the molecular microenvironment and for predicting the aggregation behaviour of surfactants, including the monitoring low to higher-order aggregates. A non-extensive distribution analysis on the fluorescence decay profiles yields the fluorescence lifetime and Full Width at Half Maxima (FWHM), with the latter serving as an indicator of the heterogeneity of the molecular microenvironment of the 'fluoroprobe'.The analytical strength of the fluorescence lifetime of PBA as a sensing tool has been validated using biosurfactants sodium cholate (NaC) and sodium deoxycholate (NaDC) with high fidelity. Careful analysis of the non-extensive distribution of the lifetime of PBA displays a substantial sensitivity towards microheterogeneity in its immediate vicinity and hence monitors the higher-order aggregation behaviour of bile salts in aqueous medium.

Optimum filter-based analysis for the characterization of a high-resolution magnetic microcalorimeter

Ultrasensitive cryogenic calorimeters have become a favored technology with widespread application where eV-scale energy resolutions are needed. In this article, we characterize the performance of an x-ray magnetic microcalorimeter (MMC) using a Fe55 source. Employing an optimum filter-based amplitude estimation and energy reconstruction, we demonstrate that a full-width half-maximum (FWHM) resolution of ΔEFWHM=(1.25±0.17(stat)−0.07+0.05(syst)) eV can be achieved, leading to an unprecedented energy resolving power E/ΔEFWHM∼4700 among existing energy-dispersive detectors for soft and tender x-rays. We also derive the best possible resolution and discuss limiting factors affecting the measurement. The analysis pipeline for the MMC data developed in this paper is furthermore an important step for the realization of the proposed superfluid helium-based experiment DELight, which will search for direct interaction of dark matter particles with masses below 100 MeV/c2. Published by the American Physical Society 2024

Passively mode-locked fiber lasers with broadband FeOOH saturable absorber

In this contribution, we synthesized iron oxide hydroxide (FeOOH) nanomaterials and successfully demonstrated the application of FeOOH-based saturable absorbers in ultrafast photonics at 1 μm and 1.5 μm. Various characterizations were conducted to analyze the morphological and structural features of FeOOH nanomaterials. Subsequently, a tapered fiber coated with FeOOH was integrated into the resonator as a saturable absorber, exhibiting the significant saturable absorption effect with modulation depths of 1.26 % at 1 μm and 2.61 % at 1.5 μm, respectively. In an Yb-doped fiber laser, stable noise-like mode-locking pulses were achieved with a pulse duration of 519 fs at the operating wavelength of 1037.2 nm with a full-width at half-maximum (FWHM) spectral bandwidth of 4.7 nm, yielding a maximum single pulse energy of 1.23 nJ with a high signal-to-noise ratio (SNR) of 47.8 dB. Meanwhile, the conventional soliton pulses were produced in the passively mode-locked Er-doped fiber laser, featuring a pulse duration of 1.02 ps, and an SNR of 42.5 dB at a peak wavelength of 1559.25 nm with a FWHM bandwidth of 2.8 nm. This work demonstrates the considerable nonlinear optical properties of FeOOH nanomaterials in the near-infrared range, proposing a promising saturable absorber for ultrafast photonics applications.

Tetradentate Pt(II) Complexes with Bulky Carbazole Moieties for High-Efficiency and Narrow-Emitting Blue Organic Light-Emitting Devices.

Blue tetradentate Pt(II) complexes, Pt-tBuCz and Pt-dipCz, are synthesized by introducing carbazoles with bulky substituents for improving the rigidity and inhibiting intermolecular interactions of phosphorescent emitter. tert-Butyl and 2,6-diisopropylphenyl groups are substituted as the blocking groups at 3 position of the carbazole in Pt-tBuCz and Pt-dipCz, respectively. These new phosphorescent emitters exhibit a narrow full width at half maximum (FWHM) and a high horizontal emitting dipole orientation ratio. Pt-dipCz demonstrates a small FWHM of 24nm, a high emitting dipole orientation ratio of 81%, and a high photoluminescence quantum yield value of 94%. As a result, the Pt-tBuCz and Pt-dipCz devices exhibited external quantum efficiencies (EQEs) of 23.7% and 25.0% with small FWHMs of 25 and 22nm, respectively. For the Pt-dipCz device, the small FWHM and high EQE of >20% are maintained even at a doping concentration of 20 wt%. Furthermore, phosphor-sensitized organic light-emitting diodes fabricated using Pt-dipCz as a sensitizer achieved a high EQE of 31.4% with an FWHM of 18nm. This result indicates that the 2,6-diisopropylphenyl group is a effective blocking group for Pt(II) complexes to develop highly efficient, color stable, doping concentration resistant, and efficiently sensitizing blue phosphors.

From Sub-Solar to Super-Solar Chemical Abundances along the Quasar Main Sequence

The 4D (four-dimensional) eigenvector 1 (E1) sequence has proven to be a highly effective tool for organizing observational and physical properties of type-1 active galactic nuclei (AGNs). In this paper, we present multiple measurements of metallicity for the broad line region gas, from new and previously-published data. We demonstrate a consistent trend along the optical plane of the E1 (also known as the quasar main sequence), defined by the line width of Balmer hydrogen Hβ profile and by a parameter measuring the prominence of singly-ionized iron emission. The trend involves an increase from sub-solar metallicity in correspondence with extreme Population B (weak Feii emission, large Hβ FWHM (full width at half maximum)) to metallicity several tens the solar value in correspondence with extreme Population A (strongest Feii optical emission, narrower Hβ profiles). The data establish the metallicity as a correlate of the 4DE1/main sequence. If the considerably high metallicity (Z≳10Z⊙, solar metallicity) gas is expelled from the sphere of influence of the central black hole, as indicated by the widespread evidence of nuclear outflows and disk wind in the case of sources radiating at a high Eddington ratio, then it is possible that the outflows from quasars played a role in chemically enriching the host galaxy.

An Investigation of Residual Stresses after the Turning of High-Tempered Bearing Steel

This study is focused on analysing residual stresses (RSs) after turning high-tempered bearing steel through the use of the X-ray diffraction (XRD) technique. Phase transformations expressed in terms of the near-surface white layer (WL) and the corresponding microhardness profiles are correlated with the RSs as well as the depth of the RS profiles. Normal and shear components of RS and FWHM (full width at half maximum) of the diffraction peaks are analysed as a function of cutting insert flank wear as well as the cutting speed. It was found that the influence of tool wear prevails over cutting speed, RSs tend to shift into the compressive region with increasing tool flank wear, and the valuable shear components of RSs can be found in the near-surface region when the cutting inserts of lower flank wear are employed. The increasing flank wear also increases the depth in which the compressive RSs can be found. Furthermore, surface RSs are affected by the phase transformation process (formation of re-hardened WL) as well as the superimposing mechanical and thermal load.

Optical, electrical and thermal investigations on brucinium di-hydrogen citrate tri-hydrate single crystal: An optimistic tool for microelectronics, OPO and OLED applications

Highly capable nonlinear optical brucinium di-hydrogen citrate tri-hydrate (BDHCTH) single crystal under organic material category has been grown-up successfully by slow evaporation method. Optical, electrical, and thermal investigations were made on title crystal to discover the suitability of fabrication of an optical as well as electrical device for the first time. Crystal structure analysis confirms that, the BDHCTH crystal belongs to triclinic crystal system with non-centro symmetric space group P1. The SLDT value of BDHCTH crystal was found to be 4.22 GW/cm2. Second harmonic generation efficiency of the BDHCTH compound is 1.08 times superior to the reference sample KDP. An attribution of single and sharp peak with lesser full width half maximum value confirms the presence of very fewer defects in the grown crystal. An electric response of the title compound shows the normal dielectric behavior. The piezoelectric charge co-efficient (d33) was found to be 4.5 p C/N. Photo luminescence study confirms that the synthesized sample possess violet, blue and red emission behaviors. Presences of various functional groups in the title sample were identified by FT-IR study. Thermal stability of the compound BDHCTH was found to be 135 °C. Kinetic parameters such as activation energy, Arrhenius factor, standard entropy of activation, standard enthalpy of activation, standard Gibb's energy of activation (ΔG*) and induction time of the grown sample were found to be 161.6396 k J mol−1, 7.4854 s−1, -230.8278 J K mol−1, 154.854 k J mol−1, 249.0314 k J mol−1 and 52 days respectively. At the end of an optical, electrical and thermal analysis, we concluded that the grown crystal is an optimistic tool for microelectronics, OPO and OLED applications due to existence of good SHG value, lesser defect and red emission behavior.

Pyrene-Based Deep-Blue Fluorophores with Narrow-Band Emission.

High-efficiency narrow-band luminescent materials have attracted intense interest, resulting in their great colorimetric purity. This has led to a variety of high-tech applications in high-definition displays, spectral analysis, and biomedicine. In this study, a rigid pyrene core was employed as the molecular backbone, and four narrow-band pyrene-based blue emitters were synthesized using various synthetic methods (such as Lewis-acid catalyzed cyclization domino reactions, Pd-catalyzed coupling reactions like Suzuki-Miyaura and Sonogashira). Due to the steric effect of the hydroxy group at the 2-position, the target compounds exhibit deep blue emission (<429 nm, CIEy < 0.08) with full width at half-maximum (FWHM) less than 33 nm both in solution and when solidified. The experimental and theoretical results indicated that the substituents at the 1- and 3-positions afford a large dihedral angle with the pyrene core, and the molecular motion is almost fixed by multiple intra- and intermolecular hydrogen bonding interactions in the crystallized state, leading to a suppression of the vibrational relaxation of the molecular structure. Moreover, we observed that the suppression of the vibrational relaxation in the molecular structures and the construction of rigid conjugated structures can help develop narrow-band organic light-emitting materials.

Electromechanically reconfigurable plasmonic nanoslits for efficient nano-opto-electro-mechanical tuning

Plasmonic metamaterials with strong localized surface plasmon resonances (LSPRs) have been improved by incorporating a nano-opto-electro-mechanical system (NOEMS) for tunable optical and electrical responses. However, conventional NOEMS devices suffer from the inefficient free-space coupling due to the limited design of reconfigurable antennas and the low optical tunability due to electrostatic pull-in of moving parts. In this paper, we propose efficient mid-infrared plasmonic nanoslits with variable nanometer-sized gaps giving rise to broad optical tunability. Our finite element method (FEM) analysis shows that by applying a voltage bias to asymmetric nanoslits supported on dielectric pillars, the gap width can be increased by more than 60 nm from an initial 1 nm. The large change in gap width results in a significant spectral shift in reflectance, while maintaining strong free-space coupling and a constant full width at half maximum (FWHM). We also analyze the effect of geometrical parameters on the nanometer-sized gap width and optical responses. Our nanoslits with simple geometry resulting in efficient optical coupling show promise for improving active metasurfaces and electromechanically tunable plasmonic devices.

Batch preparation process of composite materials of quantum dot glass and polystyrene used in backlight displays

All-inorganic CsPbX3 quantum dots (X = Cl, Br, or I) are regarded as a new generation of efficient luminescent materials for displays and solid-state lighting due to their excellent optoelectronic properties. However, the poor stability of CsPbX3 quantum dots severely hampers their commercial applications. Currently, the in-situ growth of CsPbX3 quantum dots in amorphous glass has emerged as a crucial approach to significantly enhance their stability. This study successfully synthesized large-scale CsPbBr3@glass materials using a one-step self-crystallization method involving melting, quenching, and heat treatment. CsPbBr3@glass was blended with polystyrene (PS) through melt blending and extrusion, resulting in the fabrication of a CsPbBr3@glass@PS film. By controlling the content of quantum dot glass in polystyrene and adjusting the film's thickness, a green light film with color coordinates (0.1629, 0.7759) and a Full Width Half Maximum (FWHM) of 19.78 nm was achieved. The film produced through this process demonstrated exceptional stability, retaining 90% of its luminous intensity after 1000 h of rigorous aging experiments. Furthermore, when combined with potassium fluorosilicate composite polystyrene film and a blue light chip, a 7-inch LCD display with a color gamut of 135.8% of NTSC 1953 and 92.8% of Rec. 2020 was successfully assembled. This research holds significant reference value for the commercial application of quantum dot glass.