Excellent Optical Properties Research Articles

Novel Advancements in the Field of Nanostructured Materials: Zero-, One-, Two- and Three-Dimensional Materials

Energy generation and preservation are significant difficulties that can be met using fuel cells, solar cells, and batteries. Micro- and nanomaterials with exciting chemical and physical characteristics offer a new avenue for addressing these issues. Nanostructured materials (NSMs) have attracted more attention due to their excellent electrical, optical, and thermal properties. In this paper, the innovative research on the synthesis, development, and classification of NSMs for various applications has been reviewed comprehensively. Furthermore, highlights the most recent research status on the structure and properties of NSMs and concludes the prospects and future difficulties in this area.

Controllable morphology, excellent stability and non-equivalent doping-induced optical properties of Mn4+-activated K2NaScF6 red phosphor for high-quality warm WLED

Currently, Mn4+ activated fluoride red phosphor has been widely studied to improve the optical performance of white light-emitting diode (WLED) in the field of high-efficiency lighting and wide color gamut backlight display. In this paper, a series of red-emitting K2NaScF6:Mn4+ phosphors are synthesized by a simple co-precipitation method with a non-equivalent substitution of Mn4+ for Sc3+ at room temperature. The crystal structure, morphology and elemental composition of K2NaScF6:Mn4+ phosphors prepared using different reaction conditions are systematically investigated. Interestingly, the K2NaScF6:Mn4+ phosphors exhibit narrowband red emission with low correlated color temperature (CCT), high color purity and short fluorescence lifetime. Compared to equivalent doping, the mechanism of short fluorescence lifetime caused by non-equivalent doping has also been systematically discussed. The optimal doping concentration is determined by setting a series of Mn4+ doping concentrations and the concentration quenching mechanism is analyzed. The crystal field strength (Dq), Racah parameters (B and C) and nephelauxetic ratio (β1) are calculated in detail to evaluate the crystal field environment of Mn4+ in K2NaScF6. The good water resistance of the as-prepared sample K2NaScF6:Mn4+ is verified by comparing with the commercially available phosphor K2SiF6:Mn4+. Moreover, the thermal stability is also analyzed by calculating the activation energy (Ea), chromaticity shift (ΔE) and chromaticity coordinate variation (CCV). Importantly, the as-packaged warm WLED (InGaN chip + YAG:Ce3+ + K2NaScF6:Mn4+) has excellent optical properties (CCT = 4082 K, color rendering index (CRI, Ra = 91.2) and luminous efficiency (LE) = 78.86 lm/W), and it exhibits good output stability at high drive currents. In summary, our work demonstrates that K2NaScF6:Mn4+ red phosphors possess a great potential application in warm WLED for the indoor lighting.

Preparation of CNT/diamond composite via MPCVD: The interface behavior

Carbon nanotubes (CNTs) and diamonds are allotropes of carbon, exhibiting excellent thermal, mechanical, optical, and electrical properties. Integrating CNTs with diamonds could advance the thermal management of high-heat-flux devices, light absorption, and novel semiconductor devices. This study reports the synthesis of vertical CNTs on a diamond substrate using microwave plasma chemical vapor deposition (MPCVD). Enhanced interfacial adhesion between the CNTs and diamond was confirmed by subjecting the CNT/diamond composite to ultrasonic vibrations and analyzing the morphology via scanning electron microscopy. The growth mechanism of CNTs on the diamond and the CNT/diamond interface bonding behavior were investigated using scanning transmission electron microscopy, electron energy loss spectroscopy, energy-dispersive X-ray spectroscopy, and optical emission spectroscopy. The results indicate that the carbon supplied from two different sources drove the growth of CNTs primarily through the root-growth mechanism and, to a lesser extent, through the tip-growth mechanism. The tip-growth mechanism may involve the formation of a covalent connection at the CNT/diamond interface. For the root-growth mechanism, two interfaces emerged in the CNT/diamond composite, namely Fe/diamond and CNT/Fe. Additionally, mixed cementite phases connected the CNTs to the diamond substrate. Elucidating the bonding mechanism between the CNTs and diamond can provide insights into the dynamics of the carbon atoms in the catalyst and offer a deeper understanding of the growth mechanism of CNTs on the diamond substrate.

Highly luminescent CsPbBr3 perovskite nanocrystal films via the ligand-assisted reaction

Via the ligand-assisted reaction, highly luminescent CsPbBr3 perovskite nanocrystal (PNC) films were synthesized by a simple centrifugal casting process based on the supersaturated recrystallization method. The structure, the optical properties, the morphology, the stability and the potential application of the PNC films were investigated in detail. The results show that under the joint use of OA, DDAB and APTES, the obtained PNC films with 1.5 M DDAB show the strong PL emission with highest quantum yield of 77.5 %, the pure CsPbBr3 structure, the smooth surface and the enhanced stability under UV irradiation. Additionally, the white LED device based on the PNC films obtained here and a commercial red phosphor layer shows excellent optical and color properties and working stability, demonstrating the potential of the PNC films in this study in the field of light-emitting and display.

Bilayer Borophenes Exhibit Silicon‐Like Bandgap and Carrier Mobilities

AbstractBorophene, a boron analogue of graphene, is typically metallic, while all bulk boron phases are insulating. Here, we predict by first‐principles calculations that recently synthesized bilayer borophene, being suggested to be composed of two stacked v1/12 sheets, is a semiconductor with a bandgap of 1.13 eV, almost the same as that of silicon. It is shown that the stacking mode between two boron sheets as well as the density and pattern of the interlayer boron‐boron (B─B) bonds are the key factors for opening the bandgap in the otherwise metallic boron sheet. Moreover, the bilayer borophene exhibits electron mobility of 878.6 cm2 V−1 s−1 and a significantly higher optical absorption coefficient in the visible region than silicon. These excellent electronic and optical properties hosted in a two atom‐thick space, together with high thermal and mechanical stability, position the bilayer borophene as a promising nanomaterial for maintaining the miniaturization of electronics.

Structure evolution of the silica glass under the vibration field through molecular dynamics simulations

AbstractSilica glass has found wide applications, including space shuttle windows, optical fibers, and deep ultraviolet light lens elements, due to its excellent optical, electrical, and mechanical properties. However, understandings of its structure change under the vibration field are limited in literature. In this work, the structure of silica glass and its behavior under the vibration field have been investigated through molecular dynamics simulations. The short and medium‐range structures, including coordination number, Qn species distribution, pair distribution function, and bond angle distribution, were analyzed. It was found that the overall and local structures of silica glass showed periodic changes under the vibration field. The root‐mean‐square displacements as well as the kinetic energies of the atoms in the system were further analyzed. The results show that there is a periodic transformation of kinetic and potential energies. In addition, the kinetic energy decreases and is converted into the thermal energy during the vibration, which is confirmed by the increase of the system temperature. This can explain the thermoelastic loss mechanism in energy dissipation from literature. This work reveals the structure evolution and energy change of glass under the vibration field from atomistic level, which provides important understandings for related researches.

Enhanced acetone detection performance of mechanically-mixed WO3:ZnO composites

In recent years, the potential use of mixed metal oxide WO3:ZnO is widely sought in photocatalytic application due to its excellent electrical and optical properties, but is less explored for chemiresistive sensor. The heterojunction effect in WO3:ZnO is of particular interest to eradicate common issues suffered by the pristine metal oxide sensors, such as limited sensitivity, poor selectivity, and high operating temperature. In addition, the acetone detection study based on heterostructured WO3:ZnO is quite limited. Herein, we demonstrate that the mechanically-mixed WO3:ZnO sensor exhibits comparable reducing gas sensing performance as other doped WO3:ZnO and relative improvement compared with the undoped composites, without the need of catalyst. In this work, WO3:ZnO thin-film based chemiresistive sensors were fabricated through straightforward methods comprising mechanical mixing and drop casting of sensor materials onto gold interdigitated alumina substrates. Structural and morphological properties of the prepared WO3, ZnO, and WO3:ZnO composites were examined through the X-ray diffraction (XRD), Raman spectroscopy, photoluminescence spectroscopy (PL), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) analyses, respectively. Sensor performance parameters including operating temperature and response were determined. The sensing properties of WO3:ZnO composites with different weight compositions (1:1, 1:2, and 1:3) were evaluated against the pristine ZnO and WO3. The weight ratio of 1:2 was the optimal composition for the WO3:ZnO composite to achieve the highest sensor response of 53.8 % towards 300 ppm acetone at 200 ºC compared to the pristine ZnO with a response of 23.5 %. The WO3:ZnO (1:2) thin film displayed granular morphology with uniform particle dispersion and porosity, enhancing the gas diffusion. The WO3:ZnO (1:2) thin-film composite sensor exhibited improved sensing performance and good repeatability towards acetone compared with that of ZnO and WO3. The enhanced response to acetone was possibly contributed by the development of n-n heterojunctions, porous morphology, and surface defects in the WO3:ZnO composite. The underlying sensing mechanism of WO3:ZnO composite is also discussed extensively with the aid of energy band diagrams. This study presents a foundation for future development of cost-effective acetone sensors through mechanical mixing with great potential for practical and scalable implementation in various industries.

Phenylethylammonium bromide-assisted solution-phase ligand exchange in CsPbBr3 quantum dot solar cells

CsPbBr3 quantum dots (QDs) have excellent optical properties and good phase stability, but the long-chain ligands on their surfaces affect the charge transfer between QDs. Here, we propose a simple ligand exchange strategy: solution-phase ligand exchange. By adding an acetone solution of phenylethylammonium bromide to the purification process of CsPbBr3 QDs, the long-chain ligands were effectively replaced and the electric coupling between QDs was improved. As a result, the power conversion efficiency of the solar cell was increased from 1.95% to 2.83%. Meanwhile, the stability of the devices was significantly improved in the unencapsulated case.

Smart design of highly luminescent octupolar mesogenic tetra styryl-alkynyl bipyrimidine-based chromophores presenting non-linear optical properties

The research investigations reported in this paper focuses on the influence of rational design on the photophysical properties of new all-organic multifunctional chromophores. Nonlinear optical (NLO) behavior, optical properties and mesogenicity of several new π-conjugated octupolar chromophores, presenting alkoxy styryl-alkynyl donor groups carrying aliphatic achiral and chiral chains in the 3,4/3,5/2,4 position, connected to electron-accepting 2,2-bipyrimidine cores are investigated by various techniques (light-transmission measurements, polarized-light optical microscopy, differential scanning calorimetry measurements, two-photon excited fluorescence and Hyper Rayleigh Scattering). The mesogenic properties were investigated depending on the position of the alkoxy chain and the 3,4 derivatives were found to exhibit liquid-crystal properties with the formation columnar phases over large temperature ranges which were confirmed by small-angle X-ray scattering analysis. All the molecules exhibit exceptional high fluorescence quantum yields values around 80 % and excellent nonlinear optical properties.

Label-Free Electrochemical Dopamine Biosensor Based on Electrospun Nanofibers of Polyaniline/Carbon Nanotube Composites.

The development of conducting polymer incorporated with carbon materials-based electrochemical biosensors has been intensively studied due to their excellent electrical, optical, thermal, physical and chemical properties. In this work, a label-free electrochemical dopamine (DA) biosensor based on polyaniline (PANI) and its aminated derivative, i.e., poly(3-aminobenzylamine) (PABA), composited with functionalized multi-walled carbon nanotubes (f-CNTs), was developed to utilize a conducting polymer as a transducing material. The electrospun nanofibers of the composites were fabricated on the surface of fluorine-doped tin oxide (FTO)-coated glass substrate under the optimized condition. The PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which confirmed the existence of f-CNTs in the composites. The electroactivity of the electrospun nanofibers was investigated in phosphate buffer saline solution using cyclic voltammetry (CV) before being employed for label-free electrochemical detection of DA using differential pulse voltammetry (DPV). The sensing performances including sensitivity, selectivity, stability, repeatability and reproducibility of the fabricated electrospun nanofiber films were also electrochemically evaluated. The electrochemical DA biosensor based on PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers exhibited a sensitivity of 6.88 µA·cm-2·µM-1 and 7.27 µA·cm-2·µM-1 in the linear range of 50-500 nM (R2 = 0.98) with a limit of detection (LOD) of 0.0974 µM and 0.1554 µM, respectively. The obtained DA biosensor showed great stability, repeatability and reproducibility with precious selectivity under the common interferences, i.e., glucose, ascorbic acid and uric acid. Moreover, the developed electrochemical DA biosensor also showed the good reliability under detection of DA in artificial urine.

V-MXenes for Energy Storage/Conversion Applications.

MXenes, a two-dimensional (2D) material, exhibit excellent optical, electrical, chemical, mechanical, and electrochemical properties. Titanium-based MXene (Ti-MXene) has been extensively studied and serves as the foundation for 2D MXenes. However, other transition metals possess the potential to offer excellent properties in various applications. This comprehensive review aims to provide an overview of the properties, challenges, key findings, and applications of less-explored vanadium-based MXenes (V-MXenes) and their composites. The current trends in V-MXene and their composites for energy storage and conversion applications have been thoroughly summarized. Overall, this review offers valuable insights, identifies potential opportunities, and provides key suggestions for future advancements in the MXenes and energy storage/conversion applications.

A Lu3Sc2Ga3O12: Eu3+ red-emitting phosphor with excellent optical properties and thermal stability was obtained by partially replacing Lu3+ with Gd3+ / Y3+

A novel red phosphor Lu3(1-x)Sc2Ga3O12: xEu3+(0 ≤ x ≤ 0.3) was successfully prepared by high temperature solid state method. The Lu2.4Sc2Ga3O12: 0.2Eu3+ phosphor shows strong high internal quantum efficiency and thermal stability with values of 64.79 % and 87.0 %, respectively. Based on Lu2.4Sc2Ga3O12: 0.2Eu3+ phosphor, the partial replacement of Lu3+ ions in the host by Gd3+ / Y3+ ions changes the local crystal field environment of Eu3+ ions, resulting in wonderful changes in the luminous center, and the luminous intensity at 593 nm is increased by 3.66 and 3.54 times, respectively. The decay time of Eu3+ ions is analyzed from the perspective of dynamics, and the reasons for the enhancement of luminescence after partial replacement of Lu3+ ions are discussed in detail from two aspects of phosphor structure and crystal field effect around Eu3+ ions. In addition, with the substitution of Gd3+ / Y3+ ions, the thermal stability of the sample is 90.3 %/89.4 % with excellent low thermal quenching. The thermal quenching mechanism is described by combining Debye temperature and activation energy. The sample also has a high internal quantum efficiency IQE=79.03 % / 78.24 %. Finally, under the excitation of 365 nm chip, the phosphors of Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Gd3+ and Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Y3+ synthesized R-LED device has extremely high color rendering index, Ra is 78.23/77.15 and color temperature is 1640.38 K/1642.97 K. The experimental results show that the Lu2.34Sc2Ga3O12: 0.2Eu3+, 0.02Gd3+ / Y3+ phosphors prepared has a wide application prospect in w-LED devices.

Preparation and Characterization of Cellulose Nanocrystal‐Doped Cellulose Triacetate Optical Films by Sol‐Gel Process

AbstractA bio‐based nanocomposite optical film was obtained through a simple sol‐gel process and solution casting. The dispersion effect of cellulose nanocrystals (CNCs) gel and the optical properties, mechanical performance and thermal stability of CNC‐doped cellulose triacetate (TAC) films (TAC−X) were systematically evaluated. The results show that CNCs can be well dispersed in hydrophobic organic solvents and TAC matrices through the sol‐gel process. TAC−X film has excellent optical properties, its light transmittance is above 92 %, its haze value and birefringence are low, ranging from 0.21±0.01 % to 0.38±0.02 %, and (1.64±0.26)×10−6 to (2.49±0.50)×10−6 respectively. When doped with 2 wt % CNCs, the tensile strength and Young's modulus of the TAC‐2 film were 33.0 % and 30.1 % higher than those of the pure TAC film, separately. At the same time, the TAC−X film also maintains good thermal stability, with its glass transition temperature and maximum decomposition temperature falling between 215–216 °C and 366–368 °C respectively. The simple sol‐gel process provides a convenient and efficient way to use CNCs doping to enhance the physical and mechanical properties of TAC optical films.

Recent Excellent Optoelectronic Applications Based on Two-Dimensional WS2 Nanomaterials: A Review.

Tungsten disulfide (WS2) is a promising material with excellent electrical, magnetic, optical, and mechanical properties. It is regarded as a key candidate for the development of optoelectronic devices due to its high carrier mobility, high absorption coefficient, large exciton binding energy, polarized light emission, high surface-to-volume ratio, and tunable band gap. These properties contribute to its excellent photoluminescence and high anisotropy. These characteristics render WS2 an advantageous material for applications in light-emitting devices, memristors, and numerous other devices. This article primarily reviews the most recent advancements in the field of optoelectronic devices based on two-dimensional (2D) nano-WS2. A variety of advanced devices have been considered, including light-emitting diodes (LEDs), sensors, field-effect transistors (FETs), photodetectors, field emission devices, and non-volatile memory. This review provides a guide for improving the application of 2D WS2 through improved methods, such as introducing defects and doping processes. Moreover, it is of great significance for the development of transition-metal oxides in optoelectronic applications.

Strong light-trapping probes with high antibody activity for sensitive detecting FB1 by “turn-on” lateral flow immunoassay

Due to the insufficient chromaticity, traditional Au nanoparticles (AuNPs) are usually unsatisfactory in the lateral flow immunoassay (LFIA) for tracing targets. Polypyrrole nanoparticles (PPyNPs), known for their excellent optical properties, have a limited chemical surface, which is unsuitable for use in LFIA. PPyNPs@metal-phenolic materials (PMNPs) were designed to break the restriction, which were then applied in fluorescence quenching LFIA to detect fumonisin B1 (FB1). PMNPs, as an efficient fluorescence quencher, with strong absorption in the ultraviolet–visible region, had the molar extinction coefficient of 2.47 × 1011 M−1 cm−1 and 1.86 × 1011 M−1 cm−1 at 335 nm and 620 nm. Meanwhile, the quenching constant of PMNPs was 2.30 × 10−10, 23.6-fold higher than that of AuNPs. After the surface modification with the Au-TA structure, PMNPs exhibited higher hydrophilicity than PPyNPs, making them more favorable to antibody binding. Compared with AuNPs-mAb and PPyNPs-mAb, the PMNPs-mAb had a higher affinity constant and lower equilibrium dissociation constant. The visual limit of detection (vLOD) and LOD of the “turn-on” LFIA based on PMNPs were 25 ng mL−1 and 1.58 ng mL−1, which were 20-fold and 4.82-fold lower than that of AuNPs-LFIA, respectively. Furthermore, the method demonstrated satisfactory recoveries in detecting FB1 in food samples, confirmed by LC-MS.

Photogenerated carrier-accelerated 3D mesh-NH2 functionalized Zr-metal organic framework/MgAl-type hydrotalcite composites attacking diclofenac

Developing efficient photocatalysts for high-concentration pharmaceutically active compounds (PhACs) removal in aquatic environments holds immense promise. Metal-organic frameworks (MOF) and layered double hydroxides (LDH), with their metal ions and electron transfer properties, emerge as promising candidates for advanced degradation. The three-dimensional UiO-66-NH2/MgAl-LDH3 (UNL3) composites used in this work exhibited excellent thermal stability and reduced crystallinity. Under optimized conditions, the UNL3/DCF system achieved nearly 100 % DCF degradation in 1 min. Notably, this outstanding photocatalytic activity persisted, maintaining a 90 % DCF removal rate across a pH range of 2–12, even after five cycles. The total organic carbon concentration rapidly halved within 3 min of the initial reaction. Leveraging UNL3′s benign chemical stability (with ion leaching below 0.4 mg/L) and excellent optical properties, photogenerated charges enhanced charge separation and transport, generating ample reactive species (h+) under visible light. This study introduces a novel strategy for designing robust, stable, and environmentally friendly UiO-66-NH2-based photocatalysts for chlorinated PhAC pollutants removal.

Low loss ridge waveguides on the hybrid single crystalline silicon and lithium niobate thin films

The hybridization of silicon (Si) thin film and lithium niobate (LN) thin film with remarkable properties, including the excellent optical properties of LN, excellent electrical properties and mature processing advantages of Si, can provide an important material platform for integrated photonic applications. In this work, a 4-inch single crystalline Si thin film wafer was prepared using wafer bonding, grinding and polishing techniques on LN thin film substrate. The films were characterized by using high-resolution transmission electron microscopy (HRTEM). The interplanar spacings and strain of Si film were calculated by analysis of high-resolution X-ray diffraction (HRXRD). Si ridge straight waveguides were fabricated on the hybrid thin films, and the transmission loss was 1.2 dB/cm. The near-field mode distribution of the waveguide was investigated by combining FDTD (Finite-Difference Time-Domain) simulation and end coupling measurement.

Surface Plasmon Resonance Sensor Based on Fe2O3/Au for Alcohol Concentration Detection.

Hematite (α-Fe2O3) is widely used in sensor sensitization due to its excellent optical properties. In this study, we present a sensitivity-enhanced surface plasmon resonance alcohol sensor based on Fe2O3/Au. We describe the fabrication process of the sensor and characterize its structure. We conduct performance testing on sensors coated multiple times and use solutions with the same gradient of refractive indices as the sensing medium. Within the refractive index range of 1.3335-1.3635, the sensor that was coated twice achieved the highest sensitivity, reaching 2933.2 nm/RIU. This represents a 30.26% enhancement in sensitivity compared to a sensor with a pure gold monolayer film structure. Additionally, we demonstrated the application of this sensor in alcohol concentration detection by testing the alcohol content of common beverages, showing excellent agreement with theoretical values and highlighting the sensor's potential in food testing.

Quantum-Confined Perovskite Nanocrystals Enabled by Negative Catalyst Strategy for Efficient Light-Emitting Diodes.

The perovskite nanocrystals (PeNCs) are emerging as a promising emitter for light-emitting diodes (LEDs) due to their excellent optical and electrical properties. However, the ultrafast growth of PeNCs often results in large sizes exceeding the Bohr diameter, leading to low exciton binding energy and susceptibility to nonradiative recombination, while small-sized PeNCs exhibit a large specific surface area, contributing to an increased defect density. Herein, Zn2+ ions as a negative catalyst to realize quantum-confined FAPbBr3 PeNCs with high photoluminescence quantum yields (PL QY) over 90%. Zn2+ ions exhibit robust coordination with Br- ions is introduced, effectively retarding the participation of Br- ions in the perovskite crystallization process and thus facilitating PeNCs size control. Notably, Zn2+ ions neither incorporate into the perovskite lattice nor are absorbed on the surface of PeNCs. And the reduced growth rate also promotes sufficient octahedral coordination of PeNC that reduces defect density. The LEDs based on these optimized PeNCs exhibits an external quantum efficiency (EQE) of 21.7%, significantly surpassing that of the pristine PeNCs (15.2%). Furthermore, the device lifetime is also extended by twofold. This research presents a novel approach to achieving high-performance optoelectronic devices.

Gradual Increase in Birefringence of Antimony Oxalates through Precise Tuning of the Sb3+/[C2O4]2- Ratio.

Birefringent crystals play a crucial role in modulating and controlling the polarization of light in the optical communication and laser industries. Recently, adopting appropriate strategies to enhance the birefringence of crystals has become a prominent area of research focus. Herein, four UV antimony oxalate birefringent crystals, namely, K5Sb2(C2O4)5.5·3H2O, BaSb(C2O4)2.5·3H2O, Na4Sb2O(C2O4)4·6H2O, and Na3Sb(C2O4)2F2·2H2O, have been successfully synthesized. These compounds feature a similar zero-dimensional (0D) cluster structure and share the same functional groups, including π-conjugated [C2O4]2- groups and Sb3+-based distorted polyhedra with stereochemically active lone pairs (SCALPs). Interestingly, we achieved a stepwise increase in birefringence by precisely controlling the Sb3+/[C2O4]2- ratio, ultimately resulting in the compound Na3Sb(C2O4)2F2·2H2O exhibiting a large birefringence (0.21@546 nm). Additionally, we confirmed that the synergistic effects between the π-conjugated [C2O4]2- groups and the distorted polyhedra based on Sb3+ are responsible for the excellent optical properties observed in the reported compounds.