Optical Materials最新文献

The work presents the results of comprehensive studies of the optical and transport properties, phase transition heats, the X-Ray diffraction and Raman spectra of Ge₂Sb₂Se₄Te₁, Sb₂Se₃ and Bi₂Se₃ samples obtained by vacuum thermal deposition. We demonstrate a high contrast in the refractive index and extinction coefficient in the spectral range in wavelengths of 500–1800 nm and transmissivity and reflectivity spectra in the range in wavelengths of 500–3000 nm. The investigated materials show low optical losses and high figure of merit in much of the IR-spectrum. Changes in structural properties are analyzed by XRD and Raman methods. Features of phase transformations are described by thermogravimetry and differential scanning calorimetry.

Carbon dots (CDs) are normally feature with zero-dimensional structure, excellent solubility, good biosafety, and exceptional photoelectronic properties, thus, awakening the homogeneous-like photocatalytic potency of CDs in peroxymonosulfate (PMS) activation can afford new idea for water body remediation. Herein, we presented a facile nitrogen and sulfur co-doping strategy for the development of high-performance CDs-based photocatalysts. Through the deep investigation on the structure-activity relationship, we proposed that the incorporated pyridinic N within CDs structure could serve as efficient Lewis basic sites for PMS confinement. Importantly, the co-existence of oxidized sulfur groups and specific nitrogen speciation (pyridine N and pyrrolic N) induced unique “push-pull” effect on the photogenerated carriers within the surface state of S,N co-doped CDs. The unique synergy sites and surface hydrophilic nature conferred the CDs exceptional photocatalytic effectiveness, presenting a remarkable PMS consumption ratio of 7.62 per gram of the CDs photocatalyst within just 20 min. Profited from the improved kinetics of interfacial reactions, the CDs-photocatalyzed oxidation system that consisted largely of sulfate radicals can completely degrade rhodamine B within 12.5 min, and hold great potential in long-term operation without needing to regenerate CDs catalyst.

The future commercial advancement of lead-halide perovskites (LHPs) faces obstacles due to the existence of harmful lead and the inadequate stability associated with these materials. To tackle this challenge, we have prepared a Cs₃Sb₂I₉ perovskite single-crystalline thin film (Cs₃Sb₂I₉ device) using a technique based on the restricted evaporation of solvents in space, aiming for effective photodetection. The photodetector in the current study shows a responsivity (R) of around 111 mA/W and a detectivity (D∗) of approximately 3.7 × 10¹² Jones. While these performance metrics are comparable to other photodetectors, there is a need for additional optimization to match the capabilities of commercial silicon and germanium-based counterparts. The examination of ultrafast transient absorption provides insights into the essential photophysics inherent in Cs₃Sb₂I₉. The synergy between the deformation potential and the Fröhlich effect plays a crucial role in shaping electronic dynamics. This synergy leads to the self-trapping of charge carriers, resulting in the creation of localized polarons within the Cs₃Sb₂I₉ lattice within just some picoseconds. The restriction of carrier mobility within Cs₃Sb₂I₉ arises from the self-capturing and confinement of small polarons (SPs). Furthermore, it was noted that SPs in a localized state could undergo absorption into an elevated state (photon energy ⁓ 1.60 eV). This process effectively facilitates the charge carriers' mobilization to a more dispersed eigenstate. Our research provides essential comprehension into the light-induced processes of lead-free halide perovskites (LFHPs), offering valuable insights for their prospective use in optoelectronics as promising future semiconducting agents.

Free-standing graphene oxide (FSGO)-based films with angular and polarization insensitivities are demonstrated for broadband absorption applications. The modified Hummers’ method was used to prepare the GO powder. An easily scalable process (evaporation-induced self-assembly) was used to synthesize the FSGO films. The FSGO broadband absorbers with omni-direction and polarization-independent nature was achieved by varying the GO concentrations. The FSGO films were prepared at different GO concentrations to achieve different thicknesses (2–15 μm). The FSGO film with the highest GO concentration (∼10 mg/ml) exhibited high absorptance (α = 0.91) in the broadband region (i.e., 250–2500 nm). The transition from narrow band absorber to a broadband absorber is achieved by varying the GO concentration. The optimized FSGO film (8 mg/ml) shows α of 0.91 with angular and polarization-insensitivity in the visible region. At concentrations <8 mg/ml, the FSGO films are translucent and do not exhibit broadband absorption behavior. Spectroscopic ellipsometry measurements indicate the low refractive index nature of the FSGO films (n = 1.7–1.2 at 400–800 nm). The low refractive index combined with the unique surface morphology of the FSGO films resulted in broadband absorption. Optical simulations were performed to validate the absorption mechanism of the FSGO films.

In this work, a variety of Sm³⁺ ions doped gallium silicate glasses have been made using the conventional melt quenching procedure, and characterized by X-ray diffraction, absorption spectrum, fluorescence spectrum, fluorescence decay curves, respectively. The density of the glass increases with the increase of the concentration of Sm³⁺ ions, and XRD shows that the samples are all amorphous glasses. Absorption spectra were used to determine the J-O intensity parameters (Ω_λ, λ = 2, 4, 6), as well as the radiation transition probability(A), fluorescence branching ratio(β_r), and radiation lifetime(τ_r) of Sm³⁺ ions at the ⁴G_5/2 energy level. Under 403 nm excitation, the emission spectra show obvious emission peaks at 602 nm and 649 nm, corresponding to ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 transitions respectively. The B3 glass sample has the largest emission cross section(σ_em) at the ⁴G_5/2 → ⁶H_7/2 transition, with σ_em = 11.40 × 10⁻²² cm². The color coordinates, color purity and color temperature values of all samples were calculated. The color purity of all samples varied in the range of 96.20%–99.14 %, with the relevant samples separating in the orange-red light region. The experimental results indicate that the glass samples have a potential application prospect in the field of orange-red LEDs.

Structural color is expected to replace traditional chemical color due to its advantages of brilliant colors, environmental friendliness and fading resistance. At present, the research of structural color mainly focuses on color saturation and color fastness. Structural colors with specific functions are urgently needed to expand their applications. In this study, poly (methyl methacrylate/tert-butyl acrylate/[3-(methyl acrylamide) propyl] trimethyl ammonium chloride) (P (MMA/t-BA/MAPTMA)) microspheres containing antibacterial quaternary ammonium salt monomer were synthesized by soap-free emulsion polymerization method. The structural color was prepared on the black polyester fabric by atomization deposition, and then sprayed polydimethylsiloxane (PDMS) to prepare structural color fabrics with antibacterial and superhydrophobic properties. By changing the molar ratio of the monomer, five kinds of P (MMA/t-BA/MAPTMA) microspheres with different particle sizes can be obtained, so as to obtain different structural colors of blue, purple, green, cyan and red on the polyester fabric. The inhibition rates of structural color fabric against E. coli and S. aureus are over 99 % showing excellent antibacterial properties. The water contact angles of structural color fabric after PDMS treatment can reach greater than 150° showing excellent superhydrophobicity. And the superhydrophobic structural color fabric had self-cleaning function. This study provides a new approach and strategy for the development of functional structural color textiles.

Few reports on absorbers achieve both high transmittance of visible light and strong absorption of mid-infrared light. Here a multilayered absorber with high visible light transmittance and strong broadband absorption in the mid-infrared band is proposed. The absorber is four-layer films of ITO/SiO₂/ITO/SiO₂ successively deposited on single-sided conductive glass by electron beam evaporation technology. The experiment shows that the integral transmittance in the 400–800 nm range is 82.8 %, and the integral absorption in the 3–5 μm band is 88.2 %.

This study explains the intricate interplay between functional groups and the single crystal structure of the compound 1-(furan-2-yl)-3-(2,4,6-trimethoxyphenyl)prop-2-en-1-one (FT2MP) using Density Functional Theory (DFT) calculations. Notably, geometry optimization at B3LYP using 6-311G+(2d,p) closely aligned with experimental distances from X-ray diffraction (XRD) upon comparison. A Q-switched, frequency-doubled pulsed Nd. YAG laser (532 nm, 7 ns pulses), a 25 cm focal length lens, and a 0.001 mol/L FT2MP solution in Dimethylformamide was used to measure third-order nonlinear optical (NLO) parameters and subsequently the origin of second/third harmonic generation efficiency is discussed. The third-order nonlinear parameters of FT2MP were found to be Δɸ = 0.95, n₂ = −9.605 × 10⁻⁹ cm²/W, β = 2.74 × 10⁻⁶ cm/W, and χ⁽³⁾ = 5.58 × 10⁻⁷ esu. Information about the electronic structure and reactivity of the molecule is provided via the addition of Global Chemical Reactivity Descriptors (GCRD), molecular electrostatic potential (MEP) and Frontier Molecular Orbitals (FMOs) for electronic structure and reactivity insights. Hirshfeld surface analysis was used to study intermolecular interactions. This investigation indicates the potential of FT2MP for third harmonic generation, providing a comprehensive understanding of its molecular structure, reactivity, and intermolecular interactions.

NaI is the most commonly used host lattice for scintillators, which makes it interesting to further improve its scintillation properties. Many alternative activators have been tried instead of the conventionally used Tl${}^{\text{+}}$. In this work, Sm${}^{\text{2+}}$ is used as an near-infrared emitting activator for NaI to study whether it is suitable for readout with silicon based photodetectors. NaI single crystals (co-)doped with 0-0.2% Tl${}^{\text{+}}$ and 0.2%–2% Sm${}^{\text{2+}}$ were grown by the vertical Bridgman technique. The emission of the samples was studied under optical and X-ray excitation. It is shown by photoluminescence decay studies that Tl${}^{\text{+}}$ works as a sensitiser for Sm${}^{\text{2+}}$. The samples indicate the formation of multiple (at least 5) different Sm${}^{\text{2+}}$ emission sites. Annealing the samples changes their emission intensity and scintillation properties. NaI:Sm${}^{\text{2+}}$ shows great similarities with its Eu${}^{\text{2+}}$-doped counterpart. Finally, it is demonstrated that NaI:Sm${}^{\text{2+}}$ can be read out with silicon photomultipliers and an energy resolution of 11% has been attained.