Search

The low-temperature optical properties of a SrTiO3 crystal doped with 0.7% wt. Nb and a pure SrTiO3 reference crystal were studied using spectroscopic ellipsometry. The optical constants and dielectric functions were obtained in the spectral range of 0.8–8.8 eV at temperatures from 10 to 300 K, and the optical conductivity was obtained in the spectral range of 0.03–1 eV at 300 K. Analysis of the optical conductivity spectra in the infrared spectral range confirmed the presence of free electrons and additional absorption hump between 0.1 and 0.4 eV (806 and 3226 cm−1) in doped SrTiO3 and optical phonons in both doped and undoped SrTiO3. The performed analysis of optical absorption spectra in the range 0.8–8.8 eV revealed frustration of the indirect bandgap and an increase in the direct bandgap energy by ∼0.03 eV in Nb-doped SrTiO3, compared to undoped SrTiO3 over the whole temperature range. The energies of the peaks' maxima of the dielectric function spectra did not significantly differ for doped and pure SrTiO3. For both Nb-doped and pure SrTiO3, temperature dependence of the direct bandgap energy and that of the index of refraction showed inflection between 100 and 150 K, which may be considered evidence of an antiferrodistortive phase transition from a cubic to a tetragonal structure. [ABSTRACT FROM AUTHOR]

In the presented work, the structure dependence as well as luminescence features of a wide range of hybrid crystals based on lead halides and a homologous series of alkyl diamines from 1,4-diaminobutane to 1,8-diaminooctane are investigated. The structure of several previously undescribed hybrid crystals has been established. The even–odd effect of alkanes and its influence on the structure of such hybrid crystals have been demonstrated for the first time. The luminescence properties of the crystals and their dependence on the type of anion as well as the length and oddity of the organic cation are described in detail. The obtained data expand our knowledge of the relationship between the structure of the organic cation, including its parity and structure, and the electronic and optical properties of the hybrid crystals. [ABSTRACT FROM AUTHOR]

Discovery of new materials with enhanced optical properties in the visible and UV‐C range can impact applications in lasers, nonlinear optics, and quantum optics. Here, the optical floating zone growth of a family of rare earth borates, RBa3(B3O6)3 (R = Nd, Sm, Tb, Dy, and Er), with promising linear and nonlinear optical (NLO) properties is reported. Although previously identified to be centrosymmetric, the X‐ray analysis combined with optical second harmonic generation (SHG) assigns the noncentrosymmetric P6¯$\overline{6}$ space group to these crystals. Characterization of linear optical properties reveals a direct bandgap of ≈5.61–5.72 eV and strong photoluminescence in both the visible and mid‐IR regions. Anisotropic linear and nonlinear optical characterization reveals both Type‐I and Type‐II SHG phase matchability, with the highest effective phase‐matched SHG coefficient of 1.2 pm V−1 at 800‐nm fundamental wavelength (for DyBa3(B3O6)3), comparable to β‐BaB2O4 (phase‐matched d22 ≈ 1.9 pm V−1). Laser‐induced surface damage threshold for these environmentally stable crystals is 650–900 GW cm−2, which is four to five times higher than that of β‐BaB2O4, thus providing an opportunity to pump with significantly higher power to generate about six to seven times stronger SHG light. Since the SHG arises from disorder on the Ba‐site, significantly larger SHG coefficients may be realized by “poling” the crystals to align the Ba displacements. These properties motivate further development of this crystal family for laser and wide bandgap NLO applications. [ABSTRACT FROM AUTHOR]

Three NaBa12(BO3)7F4 crystals were grown in the BaO–BaF2–B2O3–Na2O system from three different compositions of high-temperature solution. With the use of optical spectroscopy, energy-dispersive X-ray spectroscopy, and the Schering bridge method it was found that the crystals revealed sharp differences in their optical and dielectric properties. The relative permittivity of the crystals in direction perpendicular to the optical axis reached 319(5). The minimum deviation technique was used for refractive index measurements. [ABSTRACT FROM AUTHOR]

A strategic approach to develop efficient ultra‐broadband terahertz (THz) crystals involves the incorporation of different electron donating groups (EDGs) into cationic chromophores. In contrast to the widely utilized non‐cyclic 4‐(dimethylamino)phenyl (DA) EDG, cyclic 5‐membered 4‐(2‐(hydroxymethyl)pyrrolidine‐1‐yl)phenyl (PB) and cyclic 6‐membered 4‐(3‐(hydroxymethyl)piperidin‐1‐yl)phenyl (PN) EDGs exhibit an asymmetrical shape with a strongly interacting hydroxymethyl group at the chiral center. Notably, the PB EDG shows narrower intrinsic vibrational states with lower conformational flexibility and smaller ring flips compared to the PN EDG. In the crystalline state, introducing the PB EDG leads to the formation of a new class of nonlinear optical assembly, the so‐called stair‐type cation‐anion assembly. This assembly demonstrates optimal chromophore alignment with state‐of‐the‐art effective first hyperpolarizability (209 × 10−30 esu). Furthermore, the PB EDG‐based crystals exhibit significantly lower THz absorption compared to previously reported benchmark crystals. In THz wave generation experiments, PB EDG‐based crystals demonstrate state‐of‐the‐art efficiency and ultrabroad spectral bandwidth, featuring a cut‐off frequency of up to 16 THz. [ABSTRACT FROM AUTHOR]

As a new type of semiconductor material, halide perovskite materials has the advantages of low cost and excellent photoelectric conversion performance. Various photoelectric devices based on the halide perovskite materials have begun to be gradually applied. Polycrystalline thin films are still the main research direction, however, they have the disadvantages of disordered morphology and many impurities. In contrast, single crystals have the characteristics of no grain boundaries and low defects. Therefore, the research based on large-size single crystals gained widely concerned. In this paper, a set of internal and external reverse temperature control cycle filtration growth devices was designed. The CH3NH3PbBr3 single crystal with a diameter of more than 60 mm was prepared by the combination of inverse temperature crystallization and seed crystal. The phase, microstructure, and optical and electrical properties of the crystal samples were studied. The crystal belongs to the cubic system with space group of Pm3m. The ultraviolet-visible absorption spectrum shows that the absorption cut-off edge is about 576 nm and the fluorescence emission spectrum peak is 552 nm. The rocking curve shows that the half width at maximum of the crystal (100) plane is 91. 42". The wafer after cutting and polishing is sensitive to photo response, and the on-off ratio is 2. 4 x 104. [ABSTRACT FROM AUTHOR]

A new ice refractive index compilation is reported for a broad spectrum ranging from 0.0443 to 106 μm, focusing on the pronounced temperature‐dependence of ice optical properties in the far‐infrared (far‐IR) segment (15–100 μm). A sensitivity study assuming spherical particles shows that selecting ice refractive indices at 12 temperatures and 215 wavelengths in the far‐IR region gives sufficient accuracy in interpolated refractive indices for developing a new ice crystal optical property database. Furthermore, we demonstrate the differences between the bulk single‐scattering properties computed for hexagonal ice particles with this new compilation compared to a previous iteration at three far‐IR wavelengths where substantial differences are noticed between the two ice refractive index compilations. We suggest that our new ice refractive index data set will improve downstream light‐scattering applications for upcoming far‐IR satellite missions and allow robust modeling of outgoing longwave radiation under ice cloud conditions. Plain Language Summary: An imbalance between absorbed solar energy at ultraviolet (0.01–0.38 μm), visible (0.38–0.75 μm), and near‐infrared (IR) (0.75–2.5 μm) wavelengths and outgoing longwave radiation energy emitted from the Earth at mid‐IR (2.5–15 μm) and far‐IR (15–100 μm) wavelengths leads the surface temperature to change. Solar and mid‐IR energy is well‐observed by satellite sensors. However, it has been challenging to conduct spaceborne radiometric measurements in the far‐IR regime, which accounts for more than half of the OLR in cold areas such as polar regions. This study develops a new compilation of temperature‐dependent ice refractive index for application to the first far‐IR satellite missions extending beyond 25 microns, particularly toward a better understanding of ice clouds. It is shown that the improvements in the ice refractive index have a substantial impact on downstream light‐scattering computation in the far‐IR regime. Furthermore, the present study also explores adequate spectral and temperature resolutions for computing a new ice cloud optical property database to guarantee that the optical property values at other wavelengths and temperatures not included in the direct light‐scattering computations can be accurately obtained through interpolation. Key Points: A new compilation of ice refractive index covering the entire solar and terrestrial thermal spectrum is presentedThis study focuses on the far‐infrared spectrum, which is not well studied but accounts for most terrestrial emissions in cold regionsImplications of improved ice cloud modeling with temperature‐dependent ice refractive indices are discussed [ABSTRACT FROM AUTHOR]

Co/Mn co-substituted MgAl 2 O 4 pigments were spray pyrolysis, and their crystal structure and optical properties were characterized with changing the Co/Mn ratio and synthesis temperature. Regardless of the Co/Mn ratio, the resulting pigments showed spinel structured MgAl 2 O 4 phase without any impurity phase. The synthesized Mg 0.5 Co 0.5 Al 2 O 4 and Mg 0.5 Mn 0.5 Al 2 O 4 showed a dark blue and brown color due to the visible light absorption by the 4A 2 (F) → 4T 1 (P) transition of Co2+ and the d-d transition of Mn2+, respectively. The black colored pigment was achieved by simultaneous substituting Co2+ and Mn2+ in the Mg2+ tetrahedral site in MgAl 2 O 4. The optical band gap of the Mg 0.5 Co 0.5-x Mn x Al 2 O 4 pigment decreased linearly from 3.08 eV (x = 0) to 2.46 eV (x = 0.4) as the Mn2+ content increased. As a result, Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 uniformly absorbed the entire visible light and had a black color (L* = 28.10, C* = 1.68). In terms of obtaining high near-infrared reflectance and good blackness, the optimal calcination temperature of Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 was determined to be 900 °C. The optimized Mg 0.5 Co 0.1 Mn 0.4 Al 2 O 4 black pigment had a good LiDAR reflectance (38 % at 905 nm) and excellent chemical stability, and showed improved heat shielding performance compared to carbon black using in black vehicles. [ABSTRACT FROM AUTHOR]

The intramolecular coupling of dichloro‐substituted helically fused anthracenes using the Yamamoto coupling yielded cyclized products with sterically congested molecular structures. The X‐ray analysis and DFT calculations showed that the aromatic framework adopted a nonplanar structure with a twisted conformation about the newly formed single bond, which acts as a chiral axis. Interestingly, the X‐ray structure obtained through the Hirshfeld atom refinement revealed short interatomic distances between the inner hydrogen atoms (1.648–1.692 Å), much shorter than the sum of their van der Waals radii. Owing to these unusually short contacts, the 1H NMR spectrum exhibited a significant deshielding (12.5 ppm) and a large nuclear Overhauser effect (44 %). Additionally, the IR spectrum displayed a high‐frequency shift of the C−H stretching vibration. These observations, along with the noncovalent interaction plot indicative of a characteristic steric environment, strongly support the presence of steric hindrance. Moreover, dynamic NMR measurement of the mesityl‐substituted derivative yielded a barrier to helical inversion of 84 kJ mol−1. The optical properties and crystal packing of the cyclized products are also reported. [ABSTRACT FROM AUTHOR]

Lead‐free perovskites exhibit unique crystal structures and optical properties due to their low‐dimensional structure. However, the 0D structure of Cs2InCl5·H2O usually demonstrates poor optical properties at room temperature due to their extremely strong electron–phonon coupling interaction. In this study, a doping strategy is employed by introducing Pb2+ into Cs2InCl5·H2O, resulting in the achievement of an efficient broadband blue emission, with a photoluminescence quantum yield (PLQY) of 58%. The temperature‐dependent PL spectra reveal that the efficient emission is attributed to the weakening of the electron–phonon coupling strength in the lattice and the inhibition of the phonon‐assisted non‐radiative recombination process through Pb2+ doping. The validity of this deduction is further corroborated by the results of the Raman spectra. The results of the first‐principle calculation demonstrate that the broadband emission originates from multiple emission paths in In3+ and Pb2+ polyhedrons. In addition, Pb2+‐doped Cs2InCl5·H2O can realize the transformation from sky‐blue emission to deep‐blue emission by absorbing water in the air. Remarkably, this change is reversible during the heating–cooling cycles, demonstrating excellent optical stability with repeatable recyclability. [ABSTRACT FROM AUTHOR]

Manual intervention in the self‐assembly of soft matter to obtain a desired defect structure is a complex but significant project. Specifically, the flow and optical properties of liquid crystal (LC) materials have become the most important platform for studying topological structures in ordered physical systems. The regulation of liquid crystals (LCs) is largely limited to established means such as temperature, electric field, magnetic field, etc., however, a new effective strategy by mechanical stress is desirable but elusive. Here, using disclination controlled by stress, topologically continuous superstructure is generated to apply to touch display and wideband vector beam generator. This work demonstrates a new approach for direct controllable manipulation of disclination, unlocking the long‐sought full potential of topological defect, thus paving the way for optical and dynamic applications. [ABSTRACT FROM AUTHOR]

A new organic nonlinear optical single crystal, 1,4-diamino-2,5-dichlorobenzenium picrate (DADCBP) has been successfully grown by solvent slow evaporation method. DADCBP crystallizes in a triclinic structure with the centrosymmetric space setup, P-1. The molecular structure of the grown crystal has been determined by NMR spectral analysis. The existence of discrete functional branches of the crystal has been identified by FTIR spectral study. The optical property of the title crystal has been measured by UV-Vis-NIR spectral analysis. PL spectra reveal the emission bands of the grown crystal. The thermal stability of the harvested crystal has been examined by the TG/DTA study. The dielectric constant and loss have been taken to locate the arrangement of charges in the grown crystal. The quantum chemical studies have been performed to analyze the HOMO/LUMO, molecular geometry, and mulliken atomic charge by B3LYP at the 6-311++G (d,p) level of theory. H···H, O···H, C···H, C···C various intermolecular interactions of hydrogen bonds in the DADCBP molecule have been visualized by the Hirshfeld surface analysis. The nonlinear optical (NLO) characteristics like nonlinear absorption coefficient (β), nonlinear refractive index (n2) and susceptibility (χ(3)) have been examined using the Z-scan technique. [ABSTRACT FROM AUTHOR]

Herein, a chiral charge transfer crystal that exhibits reversible phase transition between chiral space groups has been fabricated. When the phase switches from left-handed to right-handed chiral space group, more pronounced orbital angular momentum effects will be generated, where magneto-responsive optics are the opposite for chiral enantiomers. Moreover, circularly polarized light could enhance the chiral orbit of the crystal with the same spiral orientation to let spin have a better ability to resist external magnetic field. Thus, the magnetic field dependence of transmission and photoluminescence of chiral crystals are strongly dependent on the polarized state of incident light. Furthermore, by studying the coupling among spin, orbit, and circular photon, we obtained that the chiral orbit plays a key role in the coupling between the spin and circular photon. It is expected that this work could promote further exploration of organic chiral magneto-optical crystals in potential applications of sensing. [ABSTRACT FROM AUTHOR]

The slow evaporation solution growth technique (SEST) was used to successfully grow inorganic single crystals of sodium sulphamate (NaS) in ambient conditions. The titled crystal's structural and optical characteristics were evaluated using a variety of spectroscopic techniques. Powder X-ray diffraction (PXRD) analysis and Fourier transform infrared (FT-IR) spectroscopy were used to examine the crystal structure characteristics. Using UV-Vis spectroscopy, the optical properties of the NaS crystal were carefully examined, and the optical bandgap was determined using Tauc's plot. The HR-XRD analysis examined crystalline perfection. Additionally, photoluminescence spectroscopy determined the emission spectra, and time-resolved photoluminescence measured the decay rate. The Z -scan technique was also used to examine the titled crystal's nonlinear optical (NLO) performance. [ABSTRACT FROM AUTHOR]

FTIR, FT-Raman and NMR are studied to explore the functional groups, the vibration modes and its coupling interactions for the grown single crystal piperazine-1,4-diium bis (4-aminobenzenesulfonate) (PABS). The cut-off wavelength at 303 nm of UV–Visible spectrum exhibits great transmittance over the entire visible spectrum. Photoluminescence spectral study revealed the electron excitation notably in blue emission range. The range of susceptibility and nonlinear refractive index was obtained from second and third harmonic generations of PABS crystals. At various temperatures, the thermal stability of the crystal and the crystal dielectric characteristics had been studied in relation to frequency. The hardness of the crystal was obtained by microhardness measurements. [ABSTRACT FROM AUTHOR]

This paper reports on the successful preparation of a series of ZnO–Ag2O nanocomposite crystals with varying elemental contents by a novel oil−water interface method. The structures, compositions, microscopic morphologies, and optical properties of these crystals were characterized using HRTEM, SEM, XRD, EDX, XPS, UV-Vis, and PL measurements. The obtained well-dispersed hetero-structure nanocomposite crystals, with a particle size mainly ranged from 50 to 100 nm and a high purity, displayed a good absorption ability in the visible region. Virtually, the nanocomposite crystals exhibited a significant red-shift 5–15 nm in the UV diffuse absorption edge towards the visible range, accompanied by a substantial reduction in fluorescence absorption intensity. Importantly, the photocatalytic degradation of these nanocomposites was tested against Congo red (CR) dye under visible light excitation. The results revealed that the degradation efficiencies of ZnO–Ag2O nanocomposite crystals against CR under visible light were 9.4 and 2.7 times as high as those of pure ZnO and Ag2O nanoparticles, respectively. Also, the antimicrobial function of ZnO–Ag2O nanocomposite crystals was tested against harmful bacteria. The study results indicated that the diameters of inhibition zone of the nanocomposite crystals were respectively 13.5 mm for Gram-negative Escherichia coli and 12.9 mm for Gram-positive Bacillus subtilis, significantly larger than that of pure ZnO due to the synergistic effects of ZnO and Ag2O nanoparticles. The high photocatalytic efficiency and strong antimicrobial activity of ZnO–Ag2O nanocomposite crystals suggest their great significance in degrading pollutants and killing harmful bacteria. [ABSTRACT FROM AUTHOR]

2‐(2‐methoxyphenyl)benzoxazole (MBO) displays similar photophysical properties to 2‐(2‐hydroxyphenyl)benzoxazole (HBO), but it lacks the large Stokes shifts necessary for fluorescence microscopy applications. In this paper, we report the 5‐substitution of MBO with aryl groups to produce 2‐(4‐methoxy‐[1,1'‐biphenyl]‐3‐yl)benzoxazoles (MBBOs) with large Stokes shifts. The synthesis of MBBOs 6–15 was accomplished in moderate to good yields by microwave‐assisted Sonogashira cross couplings. Crystal structures for compounds 6–9 and 15 are provided. MBBOs 6–10, 12, and 14 displayed considerably blue‐shifted absorption maxima and slight bathochromic shifts of their fluorescence maxima relative to the unsubstituted MBO. [ABSTRACT FROM AUTHOR]

Photonic crystal structural color is a novel method in the field of colored coating on the surface of wood products. However, the subjective brightness of photonic crystal structural colored wood products under different color temperature light sources has not been studied. In this study, poly(styrene-methyl methacrylate-acrylic acid) latex microspheres with different diameters were used to construct photonic crystal coatings on wood surface. The subjective brightness psychological quantity under different color temperature light sources was obtained. Combined with the optical properties of the coatings, the correlation between the physical optical properties of the photonic crystal coating, the color temperature of the light source and the subjective brightness of the coating was obtained. The photonic crystal coating in the near red visible light wavelength range had higher subjective brightness under low color temperature light source, and coating in the near purple visible light wavelength range had higher subjective brightness under high color temperature light source. The subjective brightness of the photonic crystal coating was very closely related to the light source color temperature and closely related to the reflectivity of the coating. This study expands the research on the optical properties of photonic crystal structure colored wood products. [ABSTRACT FROM AUTHOR]

This study investigates three mounting methods—clamping, soldering, and a hybrid clamping–soldering approach—for cryogenically cooled thin diamond crystals crucial to stable operation of X-ray Free Electron Laser (XFEL) systems. While clamping methods exhibit temperature resilience and flexibility, meticulous design is required to prevent stress-induced warping and reduce thermal contact area. Soldering methods offer reliable mechanical and thermal bonding but encounter challenges due to the coefficient of thermal expansion mismatch at cryogenic temperatures. The hybrid method, integrating clamping and soldering with strain relief cuts, effectively mitigates overall distortion caused by mounting and XFEL thermal loads. These findings offer a novel mounting solution for high-performance x-ray optics in XFEL research and applications, ensuring stability and optimal functionality in cryogenic conditions. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP) doped with 4-N,N-dimethylamino-4-N-methyl-stilbazolium tosylate (DAST) composites with various concentrations of DAST dye is prepared using the casting method. The crystal structure and optical properties of the pure and P(VDF-HFP)/DAST composites with various contents of DAST dye are investigated using various techniques such as UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and polarized optical microscopy (POM). The analysis of XRD data and FTIR spectra revealed that the β-fraction has been improved in the composite samples with increasing the content of DAST dye. Analysis of UV spectra displayed that the optical band gap of P(VDF-HFP) pure copolymer is 5.41 eV and has been reduced to be 3.75 eV for P(VDF-HFP)/10 wt% DAST that will be suitable for efficient systems of energy conversion and multijunction-based layer solar cells. Also, it is found that the nonlinear and linear optical parameters of the composite samples are DAST dye-dependent. Thermally stimulated depolarization current (TSDC) technique has been applied to investigate the dipolar and space charge relaxations of the composites. Moreover, it is observed that the pyroelectricity and piezoelectricity are enhanced with increasing the content of DAST dye. The highest content of the DAST dye showed maximum values of the pyroelectric and the piezoelectric coefficients of ~ 4 × 10–5 C/m2 K and ~ 34 pC/N at stress of 6.27 × 105 Pa, respectively. Our results of the polymer/dye composites give an opportunity of a promising material for flexible piezoelectricity devices used in many potential applications and energy harvesting systems. [ABSTRACT FROM AUTHOR]

Intentionally adding select ions such as Al3+ could be helpful in controlling the crystal habit of KDP crystal for high yield of optics. The study of how Al3+ ions affect crystal quality can provide a basis for selecting an appropriate doping level without negatively affecting the optical properties of crystals. Here, the influence of Al3+ ions on the crystal structure and properties of KDP crystals have been investigated by using first-principles calculations. Theoretical calculations show that Al3+ ions mainly replace K sites in KDP crystals and could complex with intrinsic VH− point defects to form AlK2+ + 2VH− cluster defects. The linear absorption spectra indicate that the presence of Al3+ ions has minimal impact on the linear absorption of KDP crystals, aligning well with the experimental findings. And Al3+ ions could cause a slight shortening of the band gap of KDP crystals. However, these ions could bring significant deformations of O-H bonds. As the concentration of Al3+ ions increase, more O-H bonds linking to PO4 groups are distorted in KDP crystals. As a result, the structural instability could be fast enhanced with increasing the defect concentration. Therefore, high concentrations of Al3+ ions could cause the instability of the crystal structure, which finally affects the laser-induced damage resistance of the KDP crystals. This manuscript contributes to a more comprehensive understanding of the physical mechanisms by which different impurity ions affect the optical properties of KDP crystals. [ABSTRACT FROM AUTHOR]

The results of the studies performed at the Shubnikov Institute of Crystallography and devoted to the development of UV optical filters based on complex nickel and cobalt compounds are reviewed. The structural dependence of the optical properties of these crystals and their thermal stability is discussed. The fundamental features of mixed crystals grown from solution and developed approaches to the design of optical filters based on structurally perfect mixed K2(Co,Ni)(SO4)2⋅6H2O crystals are described. The possibility of designing UV-А optical filters by partial substitution of the ligand environment of transition metal ions is demonstrated. [ABSTRACT FROM AUTHOR]

This study utilizes spectral analysis techniques and various computational methods to examine the impact of hydrogen bonding on the optical characteristics of supramolecular liquid crystals within the UV-visible spectrum. This investigation involves the computational method of spectral denoising for quantitative analysis of UV-visible spectra, and then spectral analysis is carried out for the measurement of the optical properties of supramolecular liquid crystals. Other computational methods, like the texture absorbance method, are also employed for colorimetric studies of compounds. The investigation will focus on supramolecular systems:p,n-alkoxy benzoic acid: Do-decyl hydroxybenzoate (nOBA:12HB), where n = 7, 8, and 9. The supramolecular system is formed via hydrogen bond development between the OH acceptor of the non-liquid crystalline substance Do-decyl hydroxyl benzoate (12HB) and the COOH donor of the liquid crystal p-n alkoxy benzoic acid. Here, optical properties: such as absorption coefficient, optical energy band gap, Urbach energy, and refractive index of supramolecular liquid crystals are measured for the denoised spectral data. The influence of hydrogen bonding and alkoxy chain length on the optical properties of liquid crystals has been deliberated upon. Further, the attempt at computation studies on the spectral data will yield important insights for subsequent investigations into UV-visible spectral data measurements. [ABSTRACT FROM AUTHOR]

This article presents an automated setup for studying the nonlinear optical properties of crystals by single-beam Z-scan with the pulse duration of 5.3 ns. The scheme has been successfully applied to study the nonlinear refractive index of a polycrystalline ZnSe window. The experimental setup and data analysis are described in detail. The measured value of the nonlinear refractive index n2 was (1.01 ± 0.09) × 10–11 esu. The developed experimental setup can be used to study the nonlinear optical characteristics of new nonlinear crystals. [ABSTRACT FROM AUTHOR]

Introducing post-transition metal cations is an excellent strategy for enhancing optical properties. This paper focuses on four isomers, namely the X2PO4I (X = Pb, Sn, Ba, and Sr) series. For the first time, the paper's attention is paid to the changes in electronic structure, as well as refractive indices and birefringence, with and without the inclusion of spin–orbit effects in this series. The first-principles results show that spin–orbit effects of the 5p and 6p states found in these compounds lead to splitting of the bands, narrowing of the band gap, enhancement of the lone-pair stereochemistry, and enhancement of the refractive indices and birefringence. Moreover, a comparison of the lone-pair electron phosphates, X2PO4I (X = Pb and Sn), and the isomeric alkaline earth metal phosphates, X2PO4I (X = Ba and Sr), reveals that changes in the band structure have a greater effect on the enhancement of the birefringence than the slight enhancement of the lone-pair stereochemical activity. This study has important implications for a deeper understanding of the optical properties of crystals and the design of novel optical materials. [ABSTRACT FROM AUTHOR]

Zn 1-x Co x AlFeO 4 (0 ≤ x ≤ 0.5) pigments with excellent 905 nm NIR reflectance were synthesized by spray pyrolysis, and the crystal structure and optical properties with changing the change of Co content were investigated. Regardless of the Co2+ content, the crystal structure of (Zn,Co)AlFeO 4 produced is in good agreement with that of ZnAlFeO 4 in the cubic crystal structure. The lattice constant of (Zn,Co)AlFeO 4 gradually decreases and the microstrain increases as the Co2+ content increases, which is attributed to effective substitution of Zn2+ by Co2+. The powder color of (Zn,Co)AlFeO 4 was found to be changeable depending on the Co2+ content. ZnAlFeO 4 has yellow characteristics, but (Zn,Co)AlFeO 4 gradually changes to a dark achromatic color as the Co2+ content increases. This is because (Zn,Co)AlFeO 4 effectively absorbs light between 550 nm and 700 nm due to the 4A 2 (4F) → 4T 1 (4F) transition of Co2+ substituted at tetrahedral sites. The band gap of (Zn,Co)AlFeO 4 decreases linearly from 2.43 eV to 1.91 eV with increasing Co2+ content. The minimum Co2+ content to maintain high NIR reflectance while having black characteristics was determined to be 30 % (x = 0.3). Zn 0.7 Co 0.3 AlFeO 4 black pigment (L* = 25.69, a* = 1.19, b* = 2.41) prepared by spray pyrolysis showed excellent chemical stability, and the reflectance at 905 nm was 32.2 %, which is about 2.7 times larger than that of commercial inorganic black pigment (11.9 %). Therefore, Zn 0.7 Co 0.3 AlFeO 4 is a good black pigment to improve the LiDAR detection performance in automotive vehicle applications. [ABSTRACT FROM AUTHOR]

The reduction of soluble U(VI) to insoluble and less toxic U(IV) by photocatalysis is an effective method to control uranium contamination. The graphitic carbon nitride nanosheet (CNN)/UiO-66 composites (CNNU) were prepared by thermal polymerization and solvothermal methods for the removal of U(VI). The morphology, crystal structure and optical properties of composites were analyzed by SEM, XRD, BET, UV-DRS, PL and EIS. The results showed the introduction of UiO-66 increased the specific surface of CNN from 9.07 m2/g to 46.24 m2/g, and effectively suppressed the recombination of photogenerated electrons and holes and improved the photocatalytic activity. The U(VI) removal capacity by adsorption and photocatalysis of CNNU was reached 779.47 mg/g, which significantly higher than that of adsorption (478.38 mg/g). The adsorption process was found to conform to the pseudo-second-order kinetic model and the Langmuir isothermal model. Meanwhile, U(VI) adsorbed on the CNNU was reduced to U(IV) via e− and ·O2− generated in the photocatalytic process. Therefore, this outstanding performance of CNNU in U(VI) removal is attributed to the synergistic effect of adsorption and photocatalytic reduction. [ABSTRACT FROM AUTHOR]

The slow evaporation solution growth technique is used to grow single crystals of 2-phenylbenzimidazole (2PBMZ). The crystal belongs to the monoclinic system with space group C2/c, which is revealed through the single crystal XRD. The cutoff wavelength and optical band gap energy of the 2PBMZ crystal were observed at 568 nm and 1.96 ev respectively. The Vickers (Hv) hardness number, yield strength and stiffness constant are calculated, which is found to increase with the applied load. The Z-scan technique with He–Ne laser (632.8 nm) has been used to study the third-order nonlinear optical property of 2PBMZ crystal. [ABSTRACT FROM AUTHOR]

Using first principles calculations based on the density functional theory and the structural, electronic, and optical properties of the substitution of K elements by Li+, Na+, Mg2+, and Ca2+ in KH2PO4 (KDP) crystals are investigated in depth. This study provides insight into the structural properties of crystals, with particular emphasis on internal chemical bonding effects. It further discusses the impact of H and O defects on the bandgap and optical properties of KDP crystals. Detailed analysis of structural characteristics and comprehensive examination of the effects of chemical bonds contribute to a deeper understanding of the effects of defects on the lattice and electronic structure, revealing potential alterations and their underlying mechanisms. Our investigation focuses on the regulatory role of different defects on the bandgap and optical properties. These comprehensive analyses provide a more thorough understanding of the impact of defects on the properties of KDP crystals, establishing an essential research foundation for further exploration of nonlinear optics crystal potential applications. [ABSTRACT FROM AUTHOR]

Thin film technology has gained significant attention in the industry due to its superior properties in comparison to bulk materials. Specifically, iron nitride-based thin films are a fascinating area of research in semiconductor technologies. The crystal structure and optical properties of these films are highly dependent on the growth method, deposition technique, gas flow, pressure, and several other factors. In this work, we prepared polycrystalline thin films of iron nitride on silicon (100) substrates by using the active screen low temperature plasma-assisted method. These films are deposited under the varying atmosphere of nitrogen and hydrogen in four proportions: 80% N2 + 15% H2; 60% N2 + 35% H2; 40% N2 + 55% H2; and 20% N2 + 75% H2, along with 5% argon to investigate its influence on the structural, morphological, and optical properties. The structural properties are determined by x-ray diffraction and revealed a mixture of ζ-Fe2N, ε-Fe3N, and γ′-Fe4N phases. Surface morphology is analyzed by scanning electron microscopy, which confirms the formation of a thin layer on the substrate. In addition, UV–Vis spectrophotometry is used to assess the optical response and bandgap energy of the samples. The result of UV–Vis optical diffuse reflectance spectra shows a decrease in the bandgap from 3.17 to 3.06 eV of substrate. For the S4 sample, we obtained a pure Fe4N phase, showing a significant decrease in the energy bandgap. [ABSTRACT FROM AUTHOR]

Helical morphologies are widely observed in nature, however, it is very challenging to prepare artificial helical polymers. Especially, precisely understanding the structure information of artificial metal‐free helical covalent inorganic polymers via single‐crystal X‐ray diffraction (SCXRD) analysis is rarely explored. Here, we successfully prepare a novel metal‐free helical covalent inorganic polymer ({[Te(C6H5)2] [PO3(OH)]}n, named CityU‐10) by introducing angular anions (HOPO32−) into traditional tellurium‐oxygen chains. The dynamic reversibility of the reaction is realized through the introduction of organic tellurium precursor and the slow hydrolysis of polyphosphoric acid. High‐quality and large‐size single crystals of CityU‐10 have been successfully characterized via SCXRD, where the same‐handed helical inorganic polymer chains form a pseudo‐two‐dimensional layer via multiple hydrogen‐bonding interactions. The left‐handed layers and right‐handed layers alternatively stack together through weak hydrogen bonds to form a three‐dimensional supramolecular structure. The single crystals of CityU‐10 are found to display promising optical properties with a large birefringence. Our results would offer new guidelines for designing and preparing new crystalline covalent polymers through tellurium‐based chemistry. [ABSTRACT FROM AUTHOR]

This work studies the technological preparation conditions, morphology, structural characteristics and elemental composition, and optical and photoluminescent properties of GaSe single crystals and Eu-doped β–Ga2O3 nanoformations on ε–GaSe:Eu single crystal substrate, obtained by heat treatment at 750–900 °C, with a duration from 30 min to 12 h, in water vapor-enriched atmosphere, of GaSe plates doped with 0.02–3.00 at. % Eu. The defects on the (0001) surface of GaSe:Eu plates serve as nucleation centers of β–Ga2O3:Eu crystallites. For 0.02 at. % Eu doping, the fundamental absorption edge of GaSe:Eu crystals at room temperature is formed by n = 1 direct excitons, while at 3.00 at. % doping, Eu completely shields the electron–hole bonds. The band gap of nanostructured β–Ga2O3:Eu layer, determined from diffuse reflectance spectra, depends on the dopant concentration and ranges from 4.64 eV to 4.87 eV, for 3.00 and 0.05 at. % doping, respectively. At 0.02 at. % doping level, the PL spectrum of ε–GaSe:Eu single crystals consists of the n = 1 exciton band, together with the impurity band with a maximum intensity at 800 nm. Fabry–Perrot cavities with a width of 9.3 μm are formed in these single crystals, which determine the interference structure of the impurity PL band. At 1.00–3.00 at. % Eu concentrations, the PL spectra of GaSe:Eu single crystals and β–Ga2O3:Eu nanowire/nanolamellae layers are determined by electronic transitions of Eu2+ and Eu3+ ions. [ABSTRACT FROM AUTHOR]

In this paper, we have performed a study on the optical properties of single crystals ZnGa2S4 by method of density functional theory (DFT) and ellipsometry measurements. The calculated results for the real ε r and imaginary ε i parts of the dielectric function are compared with the measured experimental spectroscopic ellipsometry (SE) spectra in the 0.7–6.5 eV spectral region. Absorption coefficient-photon energy dependency revealed the existence of direct bandgap transitions with energy 3.5 eV. This result is very close to bandgap obtained from our theoretical calculation. [ABSTRACT FROM AUTHOR]

In this paper, we have performed a study on the optical properties of single crystals ZnGa2S4 by method of density functional theory (DFT) and ellipsometry measurements. The calculated results for the real ε r and imaginary ε i parts of the dielectric function are compared with the measured experimental spectroscopic ellipsometry (SE) spectra in the 0.7–6.5 eV spectral region. Absorption coefficient-photon energy dependency revealed the existence of direct bandgap transitions with energy 3.5 eV. This result is very close to bandgap obtained from our theoretical calculation. [ABSTRACT FROM AUTHOR]

The method of cooling aqueous solution and the Sankaranarayanan–Ramasamy technique were used for the preparation of urea doped KDP single crystals with additive concentrations of 0.1, 0.5, and 1 mol%. The single crystals were grown unidirectionally from seeds that were inclined to type I phase-matching angle, the requirement for maximal second harmonic generation (SHG) efficiency. The analysis employed to study the chemical composition, crystal structure, bonding vibrations, and optical properties of the crystal samples was energy-dispersive X-ray spectroscopy, X-ray diffraction patterns, Raman spectroscopy, ultraviolet-visible spectroscopy, and SHG measurement respectively. The differences in chemical composition, crystal structure, optical transmittance, and SHG efficiency of the parts on each urea doped KDP single crystal rod were explained by the variation in the growth sector boundary. This work aims to improve the second-order nonlinear optical coefficient of KDP crystals and suggests which part of the urea doped KDP crystal rod grown by the SR technique is most acceptable for frequency-doubling applications. [ABSTRACT FROM AUTHOR]

Double tungstates (DT) and double molybdates (DM) have significant importance because of their optoelectronic applications. Regarding the importance of DT and DM, we investigated experimentally structural and optical properties of (Na0.5Bi0.5)(Mo1−xWx)O4 (x = 0.25) crystal that belongs to the NaBi-DT and DM crystals group. Czochralski method was used to grow the single crystals. The structure of the crystal was identified using X-ray diffraction (XRD) measurements. Two sharp peaks associated with tetragonal crystal structure appeared in the pattern. Vibrational modes of the studied crystal were obtained from the Raman experiments. By the help of the Fourier transform infrared spectrophotometer (FTIR) measurements, infrared transmittance spectrum of the studied compound was recorded. Band gap energy wase found around 3.04 eV using two methods, Tauc and derivative analysis, based on transmission spectrum. Based on the analysis of absorption coefficient, Urbach energy was obtained as 0.22 eV. The revealed structural and optical properties of the crystal indicated that the material may be a candidate for optoelectronic devices in which NaBi(MoO4)2 and NaBi(WO4)2 materials are utilized. [ABSTRACT FROM AUTHOR]

With dramatically improved brightness and repetition rate, the thermal load for crystal optics in x-ray free-electron laser applications has also significantly increased. To mitigate the thermal load, one effective method is cryogenic cooling. However, the emerging nondiffusive heat transfer phenomenon at cryogenic temperature may cause design failure if overlooked. To evaluate the optical performance of thin crystal optics under thermal load at cryogenic temperature, an integrated numerical tool is presented and applied to characterize the thermal load on thin crystals with nondiffusive phenomena accounted. Significant thermally induced distortion of the rocking curve is observed from numerical simulation, leading to potential seed power reduction in hard x-ray self-seeding application. Cryogenic cooling is confirmed necessary by simulation to handle the thermal load at high repetition rate operation. [ABSTRACT FROM AUTHOR]

Heteroepitaxial growth of GaN will inevitably generate a large number of defects; serious residual stress will be caused by the mismatch of the lattice and thermal expansion coefficient between the substrate and the GaN material, and eventually the crystal may be broken. We designed a double selective etching method, which can flexibly control the etching rate and degree of GaN substrates. And a hydrothermal etching buffer substrate (hydrothermal MOCVD GaN/Al2O3, HMGA) composed of a porous buffer layer with a weak connection between seed layer and a sapphire substrate was obtained. The 4-inch GaN crystal with excellent optical properties and a thickness of approximately 3 mm was successfully grown on the HMGA substrate. The crystal quality and optical quality of the as-obtained GaN crystal were greatly improved and the residual stress was reduced. At the same time, a metal–semiconductor–metal (MSM) structure ultraviolet (UV) photodetector was made using the as-obtained GaN crystal which showed good photoresponse in the UV band. These prove that the double selective etching technology has broad application prospects in heteroepitaxial growth of semiconductor materials. [ABSTRACT FROM AUTHOR]

The role of the material structure in the energy transfer between Ag and Tb3+/Yb3+ ions is studied in silica-soda-zirconia sol-gel glasses and glass-ceramics. The preparation of Tb3+ and Yb3+ doped silica-soda-zirconia layers was carried out by sol-gel and dip-coating, followed by thermal annealing. The precipitation of zirconia nanocrystals was obtained by controlling the annealing temperature: from a full amorphous glass at 700 °C into a glass-ceramic at 1000 °C. A different crystalline structure of zirconia nanocrystals, tetragonal or cubic, was controlled by the rare-earth doping and investigated in relation to the Tb3+/Yb3+ optical properties. Moreover, Ag codoping was introduced by ion-exchange, obtaining a significant photoluminescence enhancement, both in the intensity and in the broadness of the excitation band, covering the whole UV region and part of the violet-blue region. Ag-sensitized Tb3+/Yb3+ doped silica-soda-zirconia glass-ceramics were attested to be potential candidates for energy-related applications, such as spectral conversion layers for solar cells, lasers and light-emitting devices (LEDs) in the visible and NIR spectral regions. [ABSTRACT FROM AUTHOR]

The growth system has been upgraded, technological growth parameters have been optimized, and a high-quality crystal has been grown from the LiNb0.95Ta0.05O3 charge. Spectral dependences of the transmittance of a sample cut from this crystal have been measured before and after the transition to the single-domain state in the range of 300–700 nm with allowance for anisotropy and dichroism. Spectral dependences of the absorption coefficient α(λ) and degree of dichroism Δ(λ) have been obtained. The dependences α(λ) contain an absorption band at λ ~ 480 nm, regardless of the light propagation direction. When light propagates perpendicular to the optical axis, absorption bands at λ ~ 560, 608, 620, and 656 nm can additionally be observed. The transition to the single-domain state leads to sample bleaching. The dependences Δ(λ) for the X and Y cuts are characterized by identical extrema, whose positions correspond to the absorption bands in the dependences α(λ); additional extrema manifest themselves at λ ~ 400 and 445 nm. When light propagates along the optical axis, the dependences Δ(λ) are nonzero; they are characterized by much smaller values (in comparison with the directions perpendicular to the optical axis) and have extrema at λ ~ 440, 560, 600, 620, and 640 nm. [ABSTRACT FROM AUTHOR]

The growth system has been upgraded, technological growth parameters have been optimized, and a high-quality crystal has been grown from the LiNb0.95Ta0.05O3 charge. Spectral dependences of the transmittance of a sample cut from this crystal have been measured before and after the transition to the single-domain state in the range of 300–700 nm with allowance for anisotropy and dichroism. Spectral dependences of the absorption coefficient α(λ) and degree of dichroism Δ(λ) have been obtained. The dependences α(λ) contain an absorption band at λ ~ 480 nm, regardless of the light propagation direction. When light propagates perpendicular to the optical axis, absorption bands at λ ~ 560, 608, 620, and 656 nm can additionally be observed. The transition to the single-domain state leads to sample bleaching. The dependences Δ(λ) for the X and Y cuts are characterized by identical extrema, whose positions correspond to the absorption bands in the dependences α(λ); additional extrema manifest themselves at λ ~ 400 and 445 nm. When light propagates along the optical axis, the dependences Δ(λ) are nonzero; they are characterized by much smaller values (in comparison with the directions perpendicular to the optical axis) and have extrema at λ ~ 440, 560, 600, 620, and 640 nm. [ABSTRACT FROM AUTHOR]

Two series of chiral liquid crystal compounds were synthesised from benzoic acid containing cholesterol with different carbon-chain lengths and bisphenol monoester containing camphoric acid with different carbon-chain lengths, named BCP-C and DCP-C. The structure of the monomers is characterised by IR, 1H NMR and 13C NMR, which indicate that the synthesised molecule conforms to the molecular design. The textures of monomers were characterised by POM, and their selective reflection was studied. It was found that the synthesised liquid crystal compounds exhibited good liquid crystal and optical properties. The phase transition behaviour was characterised using DSC, and the results were consistent with those observed by POM. TGA showed that they had good thermal stability. [ABSTRACT FROM AUTHOR]

This study introduces the synthesis of graphite-carbon nitrite (g-C3N4) using thermal treatment of urea. The prepared powder is treated to generate nanoparticles. The structure and grain size of the g-C3N4 have been obtained via X-ray diffraction (XRD) technique and transmission electron microscope. The graphite-carbon nitride on Polyvinyl Chloride (PVC/g-C3N4) nanocomposite films were produced by mixing different concentrations (0, 3, 5, 7, 10 and 20 wt%) of nanoparticles with Polyvinyl Chloride (PVC) solutions. The structure and elemental composition of the prepared nanocomposites films PVC/g-C3N4 were studied by using XRD, scanning electron microscope (SEM), (EDX), infrared spectroscopy (IR) and electron spin resonance (ESR). Also, spectral distribution of the optical absorbance for the PVC/g-C3N4 nanocomposites films was studied in the wavelength range from 190 to 1100 nm. Thermal stability of the investigated nanocomposites films was investigated by thermal gravimetric analysis technique (TGA). The effect of various concentrations of the g-C3N4 and different doses of gamma-rays on the polymeric matrix and electrical properties of PVC film also has been investigated. The g-C3N4 additives on PVC influenced the crystal structure and optical properties of the nanocomposites films. The nanocomposite film with 10% g-C3N4 achieved higher values of the refractive index and optical conductivity compared with the other films. With different doses of gamma-ray irradiation, the crystal structure and optical properties of PVC/g-C3N4 nanocomposite films were changed in accordance to the cross-linking process within the PVC polymeric chains where a structural rearrangement can be occurred as a result of gamma irradiation. The elemental composition and morphological study of PVC/g-C3N4 nanocomposite films have been checked by the scanning electron microscopy which indicated the homogeneous dispersion of g-C3N4 nanoparticles within PVC network. Finally, electrical properties of PVC/g-C3N4 nanocomposite films with different ratios and distinct gamma doses also have been studied. [ABSTRACT FROM AUTHOR]

The organic aromatic acid 4-Chloroanilinium Bromide (CAB) and 4-Chloroanilinium Thiocyanate (CAT) crystals were grown using solution method in ethanol solvent at room temperature. The crystalline structural parameters of the grown CAB and CAT crystals were determined using single XRD study. The Gaussian 09 programme was applied to determine the molecular geometrical structure and second-order hyperpolarisability value. The linear optical property of the grown crystals was confirmed with the determined energy band gap value from Gaussian 09 programme as well as experimental UV-visible spectrum analysis. The calculated value of second-order hyperpolarisability from Gaussian 09 programme for nonlinear optical property is proved that the grown crystals are suitable candidates for optoelectronic device applications. The biological activity of the grown crystals was proved with antibacterial and antifungal studies and are promising candidates for the development of antibiotic drugs against tested bacterial strains and hence it is suitable for pharmaceutical applications. [ABSTRACT FROM AUTHOR]

In order to meet the demand for low-absorption sapphire crystal materials in important national defense projects in China, a self-produced crystal growth apparatus is developed in this study and the successful growth of low-absorption sapphire crystal can be achieved. The as-obtained crystal exhibits excellent transparency in the ultraviolet, visible, and near to midinfrared wavelength ranges. The transmittance is above 83% as the wavelength in the range of 250 nm to 400 nm, while the transmittance is above 85% as the wavelength in the range of 400 nm to 4 200 nm. On the basis of the characterization tests conducted on different regions of the crystal, the average dislocation density of crystal can be determined as 253. 19 cm-2. The rocking curve shows symmetrical and sharp peaks with a full width at half maximum of 14". In addition, it is worth noting that the light absorption coefficient of crystal is (23.3 -30.4) x 10-6 cm-1 at the wavelength of 1 064 nm, indicating that the impurity elements inside the crystal can be effectively controlled. Accordingly, the outstanding optical properties crystal can be applied in high-energy laser systems, space camera lenses and other relevant fields. [ABSTRACT FROM AUTHOR]

The advent of next-generation synchrotron radiation sources and X-ray freeelectron lasers calls for high-quality Bragg-diffraction crystal optics to preserve the X-ray beam coherence and wavefront. This requirement brings new challenges in characterizing crystals in Bragg diffraction in terms of Bragg-plane height errors and wavefront phase distortions. Here, a quantitative methodology to characterize crystal optics using a state-of-the-art at-wavelength wavefront sensing technique and statistical analysis is proposed. The method was tested at the 1-BM-B optics testing beamline at the Advanced Photon Source for measuring silicon and diamond crystals in a self-referencing single-crystal mode and an absolute double-crystal mode. The phase error sensitivity of the technique is demonstrated to be at the λ/100 level required by most applications, such as the characterization of diamond crystals for cavity-based X-ray freeelectron lasers. [ABSTRACT FROM AUTHOR]

In this study, the fabrication of a large bulk crystal based on the hybrid structure of CH3NH3PbBr3 (MAPBr) and PbS quantum dots (QDs) with excellent crystal lattice match using an in situ epitaxial crystallization technique is presented. The hybrid bulk crystal is successfully constructed by uniformly dispersing PbS QDs within the MAPBr matrix. The crystalline growth method is also changed to achieve the desired hybrid structure. The light emission range is modulated and the light emission lifetime is prolonged by constructing a MAPBr‐PbS hybrid structure. Additionally, the hybrid bulk crystal exhibited an up‐conversion effect, which does not appear in MAPBr single crystal. These findings highlight the promising potential of the MAPBr‐PbS QDs hybrid bulk crystal in the fields of optics and photoelectronic, such as all solid‐state lasers, bio‐imaging, optical data storage, and photovoltaic applications. This in situ hybrid crystallization technique also provides a universal pathway for the preparation of other bulk crystals based on perovskite‐QDs hybrid structures. [ABSTRACT FROM AUTHOR]