Excellent Optical Properties Research Articles

Unveiling the optical, electrical, and thermodynamic properties of γ-(Cs, Rb)PbBr3

The all-inorganic perovskite CsPbBr3 has garnered significant attention in the fields of optoelectronic devices owing to its favorable bandgap. However, CsPbBr3 undergoes polymorphic phase transitions, existing in three light-active phases: Pbnm (γ), P4/mbm (β), and Pm-3m (α). Although extensive investigations have been conducted on the α-phase, the room-temperature γ-phase has received limited investigation. The present work explores the thermodynamic properties and optoelectronic characteristics of the (Cs, Rb)PbBr3 perovskite system by means of a combinatorial density-functional-theory (DFT) and CALPHAD method. An increase in Rb doping of CsPbBr3 induces structural distortion of γ-phase, resulting in a widened bandgap from 2.12 eV to 2.28 eV. The bandgap increase will eventually lead to changes in optical properties, such as poor absorptivity and energy consumption under high Rb doping. Moderate doping enables (Cs, Rb)PbBr3 to retain the excellent optical properties and energy consumption of CsPbBr3. Especially when Rb doping is 0.25, the solid solution has the lowest reflection coefficient. The thermodynamic phase diagram shows that the solid solution (Cs, Rb)PbBr3 maintains excellent thermodynamic stability. In addition, the phase diagram quantifies the temperature range of the γ-phase, α-phase, and coexistence of two phases, which provides the theoretical guidance for the preparation of (Cs, Rb)PbBr3 solid solution films in the future.

Hg16O12(NO3)6F2(H2O): A Mercury-Rich Nitrate Oxyfluoride with Diverse Triple-Coordinated Mercury-Based Units That Exhibits an Unparalleled [(Hg16O12F2(H2O))6+]∞ Cationic Framework and a Large Birefringence.

Designing new compounds based on anion regulation has been widely favored due to the production of diverse crystal structures and excellent optical properties. Here, a new nitrate oxyfluoride, Hg16O12(NO3)6F2(H2O), has been obtained through a hydrothermal reaction. It crystallizes in the centric Ibca space group and shows a novel three-dimensional [(Hg16O12F2(H2O))6+]∞ cationic framework composed of interconnected HgO2F, HgO3, and HgO2(H2O) units, with isolated NO3- groups as balanced anions to build the whole structure. Notably, the HgO2F and HgO2(H2O) units are first presented here among mercury (Hg)-based compounds. Additionally, Hg16O12(NO3)6F2(H2O) exhibits a large birefringence of 0.17 at 546 nm. This work enriches the multiformity of Hg-based compounds and provides a route for developing promising birefringent materials.

Three new low-dimensional organic inorganic hybrid metal halides: Syntheses, structures and properties

It is well known that organic inorganic hybrid metal halides have been excellent materials in the field of luminescence. So far, organic-inorganic Pb(Ⅱ) halide hybrids materials have been extensively studied for their excellent optical properties. However, the toxicity of lead may generate additional pollution. It is important to develop new lead-free halide hybrids. In this work, three new organic inorganic hybrid metal halides, namely [(C4H10NO)Ag2I3] (1), [(C4H10NO)2CuI2.5]·0.5I·0.5H2O (2) and [(C4H9NO)2CdI2] (3) were synthesized under mild conditions. Compounds 1 and 2 display different one dimensional inorganic chains surrounded by organic amine cations, while compound 3 shows a zero dimensional structure. Their luminescent and optical properties were investigated in detail. The result suggests that these three compounds are potential optical materials.

One-photon three-dimensional printed fused silica glass with sub-micron features

The applications of silica-based glass have evolved alongside human civilization for thousands of years. High-precision manufacturing of three-dimensional (3D) fused silica glass objects is required in various industries, ranging from everyday life to cutting-edge fields. Advanced 3D printing technologies have emerged as a potent tool for fabricating arbitrary glass objects with ultimate freedom and precision. Stereolithography and femtosecond laser direct writing respectively achieved their resolutions of ~50 μm and ~100 nm. However, fabricating glass structures with centimeter dimensions and sub-micron features remains challenging. Presented here, our study effectively bridges the gap through engineering suitable materials and utilizing one-photon micro-stereolithography (OμSL)-based 3D printing, which flexibly creates transparent and high-performance fused silica glass components with complex, 3D sub-micron architectures. Comprehensive characterizations confirm that the final material is stoichiometrically pure silica with high quality, defect-free morphology, and excellent optical properties. Homogeneous volumetric shrinkage further facilitates the smallest voxel, reducing the size from 2.0 × 2.0 × 1.0 μm3 to 0.8 × 0.8 × 0.5 μm3. This approach can be used to produce fused silica glass components with various 3D geometries featuring sub-micron details and millimetric dimensions. This showcases promising prospects in diverse fields, including micro-optics, microfluidics, mechanical metamaterials, and engineered surfaces.

Electrical, optical and mechanical properties of monolayer MoTe2 for applications in wearable optoelectronic devices

Transition metal dichalcogenides (TMDs) have excellent optical and mechanical properties and have potential application value in wearable optoelectronic response devices. MoTe2, a representative material of TMDs, is studied by first-principles calculation in this paper. The results show that the MoTe2 monolayer has a direct band gap of 1.110eV, which has a strong light absorption capacity and can produce a high concentration of photogenerated charge carriers after light absorption. The material is soft and exhibits the unique mechanical properties of layered materials. The effects of biaxial strain and defects on the properties of the materials were analyzed. The results show that the biaxial compression strain can enhance the light absorption curve of the material, enhance the light absorption of the photogenerated carrier, and expand the range of its energy distribution. The tensile strain decreases the value of the photon absorption curve and decreases the range of energy distribution of photogenerated carriers. The Mo vacancy defect increases the absorption curve value in the low energy region and broadens the optical response range of the material. The two types of vacancy defects both induce a ‘discrete’ distribution of photogenerated carriers. The Mo vacancy significantly affects the elastic modulus and anisotropy properties of the material, resulting in the material changing from ductile to brittle. When Mo vacancy is added, the spatial distribution of the elastic modulus of the material also changes greatly. Therefore, MoTe2 has potential application in flexible optoelectronic devices, and its performance can be controlled by strains and defects.

Effects of the deflection angle of the indenter on the material removal and damage evolution of fused silica during scratching

Fused silica is widely used as key optical components and window materials due to its excellent optical and thermal properties. However, surface and subsurface damages occur in fused silica during the machining and usage process. This study aims to investigate the influence of the deflection angle of Vickers indenter on the damage evolution and removal mechanism of fused silica during scratching. Scratch tests with a linearly increasing axial load were conducted under four typical deflection angles (0°, 15°, 30°, and 45°). The resultant surface morphologies of scratch grooves were analyzed. It was seen that as the axial load increased, the scratch groove transformed from ductile deformation to brittle breaking. The asymmetric placement of the indenter led to asymmetric crack expansion. As the deflection angle increased, it became increasingly difficult to form a stable groove on the material surface. Among the four deflection angles, the groove at 0° was symmetrical, with long and good quality ductile area. For the deflection angle of 30°, the widest range of chips was observed; for 45°, the contact area of the indenter with the material was minimized, and specifically, there was a situation where the bottom of the groove was higher than the reference plane. Furthermore, statistical analysis of the loads during the scratching process was carried out. As the axial load increased, the lateral load increased approximately linearly at first and then fluctuated dramatically. Furthermore, under relatively small axial loads, the coefficient of friction (COF) is lower when the deflection angle is small; while, under relatively high axial loads, the COF is larger when the deflection angle is small. This transition could be related to the change in material removal mode from completely ductile removal to the brittle dominated removal.

Functional carbon dots-hydrogel complex for selective antibacterial and detection applications

The carbon dots (CDs) with excellent optical properties and their hydrogel complex are of great significance in biomedicine, healthcare and biochemical detection fields. This paper reports the preparation of green-emitting CDs (MA-CDs) through one-step hydrothermal route with citric acid as reducing agent, L-malic acid as carbon source and N-(2-hydroxyethyl)ethylenediamine as nitrogen source. To expand its application in biology, MA-CDs were coupled with vancomycin to obtain multifunctional CDs (VMA-CDs). The prepared VMA-CDs exhibit selective antibacterial behavior to Gram-positive bacteria, and it could be used as a fluorescent probe to selectively label Staphylococcus aureus (S. aureus). Moreover, thanks to the excellent optical properties of VMA-CDs, it has been used as a fluorescent sensor to detect Au3+ with detection range of 6.50 nM–21.93 μM and detection limit 3.98 nM. By introducing the fluorescence of CDs as the reference signal, and VMA-CDs as a response signal, the hydrogel (V-SP) was prepared and realized the detection of Au3+ in microfluidics with assistance of a smartphone to collect and analyze data.

Broadband High-Precision Faraday Rotation Spectroscopy with Uniaxial Single Crystal CeF3 Modulator

We present a low-noise (<10 µrad/Hz) broadband Faraday Rotation Spectroscopy method which is feasible for near-ultraviolet through near-infrared wavelengths. We demonstrate this in the context of a high-precision spectroscopy experiment using a heated Pb vapor cell and two different lasers, one in the UV (368 nm) and a second in the IR (1279 nm). A key element of the experimental technique is the use of a uniaxial single crystal CeF3 Faraday modulator with excellent transmission and optical rotation properties across the aforementioned wavelength range. Polarimeter performance is assessed as a function of crystal orientation and alignment, AC modulation amplitude, laser power, and laser wavelength. Crystal-induced distortion of the (6p2)3P0→(6p2)3P1 (1279 nm) and (6p2)3P1→(6p7s)3P0 (368 nm) spectral lines due to misalignment-induced birefringence is discussed and modeled using the Jones calculus.

Theoretical and experimental investigation on material removal mechanism in dual-rotation polishing of fused silica glass

Fused silica glass is utilized extensively in various optical components owing to its excellent optical properties, but its high hardness and brittleness make it difficult to process with high surface accuracy and low subsurface damage. To solve this problem, a series of experiments is carried out to explore the mechanism of material removal during dual-rotation polishing of fused quartz glass. A predictive model is proposed to predict the material removal rate and the microtopography of polished surface. This model considers fundamental physics of the dual-rotation polishing process, for instance, the surface micro-topography and the pressure distribution of the polishing pad, the brittle–ductile material removal mechanism, the planetary motion during the polishing, and the influence of chemical reactions. The reliability and accuracy of the model are quantitatively evaluated through practical experiments. It is turned out that the simulated results reasonably agree with the experimental data. In addition, simulation experiments show that a Gaussian removal function with a strong central peak can be obtained when the eccentricity is 0.9 and the rotating speed ratio is between −10 and −1. This indicates that the theoretical model can be successfully applied to the prediction and optimization of polishing processes.

Composition analysis of Magnolia flower and their use for highly bright carbon dots

Colloidal carbon dots (C-dots) have excellent optical properties and they have been widely used for various types of applications. Compared to the C-dots prepared using chemicals, the Biomass-derived C-dots have attracted a great of attention because of their environmental friendliness and biocompatibility. However, currently obtained C-dots using biomass have low quantum yield. In this work, we demonstrated an efficient precursor of Magnolia flower for synthesizing high-quantum yield C-dots via hydrothermal approach. High performance liquid chromatography and Bradford assay were used to analyze the compositions of the Magnolia flower, which determine the quality of the C-dots. The typical emission bands of the as-prepared C-dots cover from 400 to 550 nm at different excitation wavelengths. The C-dots synthesized using violet Magnolia flower have the QY as high as 11.9%, which is higher than that of 10.4% (white Magnolia flower), because the violet color gives the higher content of the N. The as-obtained C-dots have excitation-dependent color and high quantum yield, showing a great potential for the use of the anti-counterfeiting system.

Preparation and properties of PC/PCTG blends with excellent optical properties and solvent resistance

AbstractBlends of polycarbonate (PC) and poly(1,4‐cyclohexylene dimethylene terephthalate glycol) (PCTG) were synthesized using a twin‐screw extruder. Four distinct PC/PCTG blends were produced with PCTG constituting 10%, 20%, 30%, and 40% of the total weight. Comprehensive evaluations were performed to investigate their thermal properties, solvent resistance, light transmittance, mechanical characteristics, and melt flow index. Differential scanning calorimetry and thermogravimetric analysis demonstrated a single glass transition temperature in the PC/PCTG blends, indicating high compatibility. The incorporation of PCTG was observed to affect the blends' thermal stability. The data revealed a progressive increase in solvent resistance, light transmittance, and melt flow index with increasing PCTG content. The light transmittance of the blend reached 87.5%, and the melt flow index was recorded at 124.2 g (10 min)−1. Mechanical tests showed that the tensile and bending strengths were relatively stable with the addition of PCTG, but there was a noticeable reduction in notched impact strength as the proportion of PCTG increased. © 2024 Society of Industrial Chemistry.

Electronic and optical properties of pyrochlore Re2Ti2O7 (Re = Sm and Eu) from first-principles

Rare-earth titanate oxides are believed to be prospective functional materials for photocatalytic and photoluminescent applications because of their excellent optical properties and thermal stability of their physical properties. However, the relationships between optical properties and photoelectron trapping mechanisms are unclear. Herein, the structure, electronic, and optical properties of pyrochlore-structure Re2Ti2O7 (Re = Sm and Eu) were investigated using the first-principles approach with the Hubbard parameter U (GGA + U). The calculated bandgap is 2.5 eV for Sm2Ti2O7 and 2.4 eV for Eu2Ti2O7, which is in good agreement with the experimental observation. The results indicate that the strongly localized f states at the top of valence band are charge-trapping sites for photoexcitation of Re2Ti2O7, where electrons can absorb photon energy and transfer from the valence band to the conduction band, resulting in the photocatalytic and/or fluorescent effects in the visible and early UV regions. The important optical parameters, dielectric function ε(ω), refractive index n(ω), extinction coefficient k(ω), reflectivity R(ω), absorption coefficient I(ω), optical conductivity σ(ω), and electron energy-loss L(ω) were studied in detail, indicating that these optical parameters of Sm2Ti2O7 and Eu2Ti2O7 are insensitive to the ultra-violet (UV) radiation, but both Sm2Ti2O7 and Eu2Ti2O7 exhibit excellent optical properties in the visible and early UV regions. This work provides a clear understanding on the photoelectron trapping mechanism of pyrochlore-structure Re2Ti2O7, which will help to improve the photocatalytic and photoluminescent performance of Re2Ti2O7 and broaden their applications.

Polymerization strategy for cellulose nanocrystals-based photonic crystal films with water resisting property

Cellulose nanocrystals (CNCs) can form a liquid crystal film with a chiral nematic structure by evaporative-induced self-assembly (EISA). It has attracted much attention as a new class of photonic liquid crystal material because of its intrinsic, unique structural characteristics, and excellent optical properties. However, the CNCs-based photonic crystal films are generally prepared via the physical crosslinking strategy, which present water sensitivity. Here, we developed CNCs-g-PAM photonic crystal film by combining free radical polymerization and EISA. FT-IR, SEM, POM, XRD, TG-DTG, and UV–Vis techniques were employed to characterize the physicochemical properties and microstructure of the as-prepared films. The CNCs-g-PAM films showed a better thermo-stability than CNCs-based film. Also, the mechanical properties were significantly improved, viz., the elongation at break was 9.4 %, and tensile strength reached 18.5 Mpa, which was a much better enhancement than CNCs-based film. More importantly, the CNCs-g-PAM films can resist water dissolution for more than 24 h, which was impossible for the CNCs-based film. The present study provided a promising strategy to prepare CNCs-based photonic crystal film with high flexibility, water resistance, and optical properties for applications such as decoration, light management, and anti-counterfeiting.

Two-Photon Polymerization of Nanocomposites for Additive Manufacturing of Transparent Magnesium Aluminate Spinel Ceramics.

Transparent polycrystalline magnesium aluminate (MAS) spinel ceramics are of great interest for industry and academia due to their excellent optical and mechanical properties. However, shaping of MAS is notoriously challenging especially on the microscale requiring hazardous etching methods. Therefore, a photochemically curable nanocomposite is demonstrated that can be structured using high-resolution two-photon lithography. The printed nanocomposites are converted intro transparent MAS by subsequent debinding, sintering, and hot isostatic pressing. The resulting transparent spinel ceramics exhibit a surface roughness Sq of only 10nm and can be shaped with minimum feature sizes of down to 13µm. This technology will be important for the production of microstructured ceramics used for optics, photonics, or photocatalysis.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Direct-Write Printed Slippery Surface for Assembling a High-Quality Graphene Structure and Its Application in Flexible Electric Actuators.

Graphene is a two-dimensional honeycomb-like nanomaterial generated by carbon atoms in sp2 hybridized orbitals to form a hexagonal lattice structure with excellent electrical, optical, and mechanical properties. The solution process method has been widely used to realize large-area patterned graphene structures for high-performance devices. In the method, graphene usually needs to be dispersed in solution, and the π-π bonding gravitational interactions between graphene sheets would lead to uncontrollable structures in solution and difficulty in obtaining high performance. In this work, a patterned graphene oxide (GO) structure with controllable thickness and layer spacing was realized by a direct-write printed slippery surface, which was used as a slippery limited template. After reducing GO into reduced graphene oxide (rGO), a flexible electric pattern with a conductivity of up to 6.425 × 103 S/m was realized. Furthermore, the patterned rGO structure was transferred on polydimethylsiloxane (PDMS), which could generate less than a 5% change in resistance after 10,000 consecutive bends, and an anisotropic expansion based on rGO and PDMS materials under electro-thermal coupling. The patterned rGO structures could meet the performance requirements of highly sensitive and complex deformation applications as flexible electric actuators. This study provides great research significance and application value for patterning high-quality graphene structures and realizing high-performance flexible electronic devices.

The Emerging Star of Carbon Luminescent Materials: Exploring the Mysteries of the Nanolight of Carbon Dots for Optoelectronic Applications.

Carbon dots (CDs), a class of carbon-based nanomaterials with dimensions less than 10nm, have attracted significant interest since their discovery. They possess numerous excellent properties, such as tunability of photoluminescence, environmental friendliness, low cost, and multifunctional applications. Recently, a large number of reviews have emerged that provide overviews of their synthesis, properties, applications, and their composite functionalization. The application of CDs in the field of optoelectronics has also seen unprecedented development due to their excellent optical properties, but reviews of them in this field are relatively rare. With the idea of deepening and broadening the understanding of the applications of CDs in the field of optoelectronics, this review for the first time provides a detailed summary of their applications in the field of luminescent solar concentrators (LSCs), light-emitting diodes (LEDs), solar cells, and photodetectors. In addition, the definition, categories, and synthesis methods of CDs are briefly introduced. It is hoped that this review can bring scholars more and deeper understanding in the field of optoelectronic applications of CDs to further promote the practical applications of CDs.

Germanene: demonstration of the conversion from mode-locked to Q-switched mode-locked in Er-doped fiber laser

Some two-dimensional layered mono-elemental materials have been reported as saturable absorbers (SAs) for the generation of various soliton phenomena, and many excellent results have been achieved. In our experiment, we made thin films of germanene-polyvinyl alcohol (Ge-PVA) and applied them as SA in Er-doped fiber lasers, investigated Ge’s characteristics, and demonstrated the conversion from mode-locked to Q-switched mode-locked (QML). The conventional mode-locked operation with a repetition rate of 9.63 MHz and a central wavelength of 1559.7 nm was stably triggered when the pump power exceeded the threshold of 40 mW. QML pulse with a central wavelength of 1530.26 nm and the maximum pulse energy of 86 nJ can be obtained by changing the pump power and polarization state of the light in the cavity. This work reveals the excellent optical properties of Ge SA in ultrafast fiber lasers and provide a new approach for the generation of QML pulses.

Tailoring Bandgap and Photocatalytic Performance of Designed Zinc Oxide Platelets by Cobalt Doping

AbstractPlatelet‐shaped zinc oxide (ZnO) particles exhibit certain advantages compared to conventional micron and nano forms. Their superior surface coverage and excellent optical properties make these particles very attractive as UV filters in cosmetics and personal care applications. Although ZnO is non‐toxic, it exhibits photocatalytic activity (PCA), which increases when the size of particles approaches the nanoscale. High PCA of mineral/inorganic filters is not desired in cosmetics and personal care applications. Therefore, it is essential to develop strategies to reduce PCA of such materials under UV exposure. Accordingly, the research objective of this study is to develop an understanding of the effects of Co‐doping on the optoelectronic and crystal structure of platelet shaped ZnO particles with Zn1‐xMxO stoichiometry (x=0‐4 wt % cobalt). XRD‐based Rietveld refinement and WD‐XRF reveal that Co was successfully doped into the ZnO lattice. SEM and particle size analyses confirmed that the shape and size of the designed ZnO platelets did not change significantly after doping. ~85 % reduction in PCA has was achieved by 3 wt % Co doping which was attributed to reduced OH and O2 free radical concentration. These results clearly show that Co‐doping can be used to effectively tailor the bandgap and optical properties of the designed ZnO particles.

Nature-inspired polymer photocatalysts for green NADH regeneration and nitroarene transformation

Photocatalysis has emerged as a promising approach for generating solar chemical and organic transformations under the solar light spectrum, employing polymer photocatalysts. In this study, our aim is to achieve the regeneration of NADH and fixation of nitroarene compounds, which hold significant importance in various fields such as pharmaceuticals, biology, and chemistry. The development of an in-situ nature-inspired artificial photosynthetic pathway represents a challenging task, as it involves harnessing solar energy for efficient solar chemical production and organic transformation. In this work, we have successfully synthesized a novel artificial photosynthetic polymer, named TFc photocatalyst, through the Friedel-Crafts alkylation reaction between triptycene (T) and a ferrocene motif (Fc). The TFC photocatalyst is a promising material with excellent optical properties, an appropriate band gap, and the ability to facilitate the regeneration of NADH and the fixation of nitroarene compounds through photocatalysis. These characteristics are necessary for several applications, including organic synthesis and environmental remediation. Our research provides a significant step forward in establishing a reliable pathway for the regeneration and fixation of solar chemicals and organic compounds under the solar light spectrum.