Entire Visible Region Research Articles

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO 2 Bioreduction

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO ₂ Bioreduction

A comprehensive linear and nonlinear study on a fluorescent stain

The optical properties, linear and nonlinear, for Leishman stain are studied in ethanol and chloroform over a wide spectral region. The stain consists of two components: Methylene blue (MB) and Eosin (E). The low intensity optical measurements, linear regime, show the absorption and emission characteristics of the E and the MB components in ethanol and only the MB component in chloroform. Under the influence of optical intensity less than 15[Formula: see text]MW/m2, the stain shows nonlinear absorption characteristics at excitation wavelengths 532[Formula: see text]nm and 650[Formula: see text]nm only. The nonlinear absorption coefficients of the solutions are in 1–12.4 [Formula: see text][Formula: see text] cm/W range in both solvents. Leishman stain solutions in ethanol and chloroform have a strong thermal nonlinearity with a negative index of refraction over the entire visible region. The value of the nonlinear refractive index ([Formula: see text]) of Leishman stain in both solvents increases as the wavelength of the excitation radiation increases. The value of [Formula: see text] of the solutions is in the range of about 2–46 [Formula: see text][Formula: see text][Formula: see text]cm2/W. As an example of the optoelectronic applications, the stain shows excellent properties of an energy spreading optical limiter.

Te4+/Bi3+ Co-Doped Double Perovskites with Tunable Dual-Emission for Contactless Light Sensor, Encrypted Information Transmission and White Light Emitting Diodes

• The energy transfer between Bi 3+ and Te 4+ is realized in Cs 2 ZrCl 6 perovskite. • Bi 3+ /Te 4+ co-doped perovskite can realize color hue evolution from blue to yellow. • High quality WLEDs can be fabricated by Cs 2 ZrCl 6 : Bi 3+ , Te 4+ and UV LED chip. • The phosphor can be exploited in visual light sensor and information transmission. Stable and high-efficiency inorganic lead-free double perovskites have aroused great attention for their application in photoluminescence field. However, most of the double perovskite materials with single dopant cannot realize multi-mode excitation, tunable or full-spectrum emission, which lead to the rare applications in contactless light sensor, encrypted information transmission and white light emitting diodes. Herein, inspired by a traditional methodology of co-doping rare-earth, ns 2 type ions (Bi 3+ and Te 4+ ) co-doped lead-free perovskite Cs 2 ZrCl 6 is proposed and developed. Comparing to the single dopant, Bi 3+ /Te 4+ co-doped perovskites can exhibit high sensitivity to the excitation wavelength and then emit greatly adjustable emission spectra from ∼457 to 577 nm, which corresponds to the color hue evolution from blue to yellow. Meanwhile, the high resonance energy transfer efficiency process from triplet STEs state of Bi 3+ to Te 4+ is also proved by employing the excitation/emission spectra and the transient fluorescence spectrum. Based on the efficient energy transfer process, high quality white light (CIE = (0.330, 0.347), CCT = 5608 K, Ra = 85.1), covering the entire visible region, can be obtained under ultraviolet light excitation. These features guarantee its potential application in contactless light sensor, encrypted information transmission and single-phase white light emitting diodes. The above results show that the methodology of co-doping ns 2 type ions in Cs 2 ZrCl 6 will open up new opportunities to the multifunctional application field.

Octagonal-siloxane based transparent and robust crack-healing surface for optical-scar recovery

Siloxane derivatives are a class of emerging hybrid materials that provide optical transparency and mechanically flexible characteristics owing to the low rotational barrier of the framework. To devise a robust and flexible self-healing platform, we designed an octagonal-siloxane derivative with four furan units and applied bifunctional maleimides as dienophiles to implement the reversible Diels–Alder (DA) reaction for crack healing. The feasibility of the DA reaction was confirmed by both the appearance of a cyclohexyl moiety in 1H-nuclear magnetic resonance spectra and heat transition behaviors during heating-cooling cycles in differential scanning calorimetry. The crack-healing efficiency of the designed octagonal-siloxane was sensitively affected by the heat-treatment temperature, and the crack recovery rate reached over 95% within 60 s upon heating at 100 °C. In addition, the crack recovery tendency was almost intact during repetitive heating-cooling cycles. The devised crack-healing film exhibited greater than 95% transparency in the entire visible region, and the effective modulus reached 7.8 GPa. In particular, when CdSe/ZnS quantum dots (QDs) were embedded into the octagonal-siloxane based film, it was confirmed that optical scars exhibiting luminescence defects were effectively recovered, and the emission characteristics of the QDs were not critically compromised even under solvent-exposed circumstances.

Effect of silver incorporation on the photocatalytic degradation of Reactive Red 120 using ZnS nanoparticles under UV and solar light irradiation

In this work, the Ag modified ZnS nanoparticles were synthesized via the hydrothermal method, and used for photocatalytic degradation of organic dyes. Various analytical techniques were utilized to characterize the prepared ZnS and Ag incorporated ZnS nanoparticles. The vibrational and structural properties of the prepared nanoparticles were analyzed by FT-IR and XRD, which confirm the modification of Ag in the ZnS. The broadening of the hydroxyl group after incorporation of Ag in ZnS was observed in the FT-IR spectra. The additional (111), (200), and (220) planes in XRD of Ag–ZnS belong to the silver. The increased absorbance in the entire visible region facilitates the ZnS/Ag photocatalytic performance under direct sunlight. ZnS/Ag nanoparticles showed excellent photocatalytic activity toward degradation of RR 120, DB 15, and AB 1. The ZnS/Ag catalyst efficiently degrades the RR 120 under sunlight with higher pseudo-first order kinetic k = 0.0179 min−1 than the other dyes. The reusability study exhibited ZnS/Ag has highly stable and degraded more than 80% of RR 120 under sunlight irradiation after 4th cycle.

Aliphatic mixed ligands Sn(II) complexes as photon absorbers in quantum dots sensitized solar cell

Dye-sensitized solar cells have attracted a lot of research interest due to the quest for an alternative energy supply given that it is cost-effective and its materials are easily available. However, the need to improve the conversion efficiency of these solar cell devices has necessitated the search for new materials that will lead to more energy conversion. One of such material of interest is tin (II) sulfide (SnS). In present study, we report results from the synthesis of hexadecylamine (HDA)-capped SnS and uncapped SnS photosensitizer using a molecular precursor. The efficiency of the photon absorbers, their morphological, structural and electrochemical properties were examined using different techniques. Both photosensitizers displayed X-ray diffraction (XRD) peaks within the range 26.03°–66.05°, which corresponds to orthorhombic structure. Field Emission Scanning Electron Microscope (FE-SEM) and High-Resolution Transmission Electron Microscope (HRTEM) further revealed that HDA-capped SnS has a better morphology and size distribution. UV–Vis analysis shows that the HDA-capped SnS exhibits strong absorption in the entire visible region which is attributed to perfect orientation. The HDA-capped photosensitizer superiority was linked to well reduced electron recombination and electron lifetime. The addition of HDA capping agent improved the J-V performance with a new conversion efficiency of 8.20%. Results obtained from present work proselytize the concept of using capping agent as an approach for improving the quality of photon absorbers.

Terbium doped zinc ortho titanate nanocomposite for optical application – A complementary theoretical calculations

Zinc ortho titanate nanomaterial was synthesized hydrothermally under surfactant free conditions. The crystalline nature of the synthesized nano composite has been affirmed by PXRD analysis. FTIR analysis reports the existence of Ti-O and Zn-O metal organic bonds at 495 and 558 cm-1 respectively. UV cut off wavelength was found to be 232 nm which is evident that the narrow transparent window was in the entire visible region. The structural morphology and elemental analyses have been confirmed by SEM and EDX respectively and as well characterized by photoluminescence, scanning electron microscopy and thermal analysis. The SEM image is further analyzed and compared with laser speckle image processing. Thermal analysis evidenced the stability of the nano composite up to 990 °C which suitable to thermal devices. To reinforce the experimental findings, theoretical calculations were carried out using DFT functional B3LYP/cc-pvtz level of basis set through Gaussian 09 program.

On direct synthesis of high quality APbX3 (A = Cs+, MA+ and FA+; X = Cl−, Br− and I−) nanocrystals following a generic approach

A generic method of obtaining APbX3 (A = Cs+, MA+ and FA+; X = Cl−, Br− and I−) perovskite NCs, emitting throughout the entire visible region (395–760 nm), has been developed employing 1,3-dihalo-5,5-dimethylhydantoin (DXDMH) as a halide precursor.

Photoluminescence coupled to electric and magnetic surface lattice resonance in periodic arrays of zirconia nanoparticles

Zirconia is transparent from near-ultraviolet through the entire visible region, and here we utilize the periodic arrays of zirconia nanoparticle to excite electric and magnetic SLRs in the visible.

Materials today: Proceedings χ (3) measurement and second harmonic generation of organic–inorganic hybrid compounds headed for optoelectronic applications-L cysteine hydrogen orthoborate

Novel semi organic non-linear single crystal of L-cysteine hydrogen orthoborate was grown from aqueous solution by the slow evaporation technique at room temperature. The grown crystal was characterized by single crystal x-ray diffraction. The chemical composition of the crystal was identified by the energy dispersive x-ray analysis. The fourier transform infrared spectra were recorded to identify the functional groups presented in the sample. The transparency range of the material was analyzed by the UV–Vis-NIR measurements. The absorption studies showed that the UV cut-off wavelength to be at 224 nm. The transmission studies indicated a rapid and intensive transition at the cutoff wavelength. Crystals showed transparency in the entire visible region with 5.5 eV optical band gap and also showed an excellent second order nonlinear optical properties and third order susceptibilities. Z Scan measurements revealed the saturation absorption of the grown crystal. Such parameters as nonlinear refractive index, absorption coefficient and nonlinear optical susceptibility were determined. The thermal behavior of the grown crystal was analyzed by TG/DSC analysis, showed a major weight loss around 246 °C and that corresponds to the melting point of the sample that showed good thermal stability of the grown crystal. The laser damage threshold value for L-Cysteine hydrogen orthoborate was found to be 139 mJ/cm−2.

Influence of V2O5 and B2O3 addition on the sintering behaviour and physical properties of ZnO ceramics

The effect of V2O5 and B2O3 additions on sintering behaviour and physical properties of ZnO ceramics was investigated. XRD studies revealed ZnO as main phase with a hexagonal wurtzite-type structure. The V2O5 addition is the reason for an increase in grain size and some grains of oblong shape morphology in the ZnO ceramics. The dual addition of V2O5-B2O3 improved the liquid-assisted sintering of ZnO ceramics and resulted in further increase in grain size with more uniform grain growth. The reduction of sintering temperature to 900?C for ZnO ceramics was observed with the dual addition of V2O5 and B2O3. The room temperature PL spectra of the Z (ZnO), ZV (ZnO with 0.5mol% V2O5) and ZVB (ZnO with 0.5mol% V2O5 and 0.5mol% B2O3) ceramics revealed broad visible emission band because of impurities and defects in ZnO ceramics caused by oxygen vacancies due to vanadium and boron additions, as well as zinc interstitials. This emission band between 450-750 nm includes the entire visible region from blue to red.

Synthesis, optical, dielectric and thermal property studies of lead mandelate crystals

Lead Mandelate crystals which belong to the class of Metal Organic Frameworks were grown by gel encapsulation technique using chemical reaction method. Powder XRD studies were conducted. The crystalline nature of the grown sample is evident from the XRD data. The grown crystals were characterized by FTIR, Raman and UV–Visible spectroscopy. The FTIR and Raman spectrum confirmed the presence of the various functional groups in the sample. From the UV–Vis studies, it is observed that the sample shows very less absorbance in the entire visible region, which makes it a potential candidate for nonlinear application. The lower cut off wavelength was calculated to be 254 nm. The estimated value of optical bandgap of the grown crystal is 4.42 eV. Thermogravimetric analysis (TGA) was done to study the thermal stability of the grown crystal. The TGA curve establishes that Lead Mandelate crystals have thermal stability upto a temperature of 210 °C. The dielectric studies of the grown crystals conducted at room temperature shows a normal dielectric behavior. The variation of dielectric constant and dielectric loss of the sample with frequency of applied field is studied. Both dielectric constant and dielectric loss is found to decrease with increase in frequency of applied field. The dielectric constant varies in the range between 21.41 and 10.53 for an applied frequency range 0.01Hz–10MHz. The conductivity of the grown crystal is observed to increase with frequency.

Powerful Direct C-H Amidation Polymerization Affords Single-Fluorophore-Based White-Light-Emitting Polysulfonamides by Fine-Tuning Hydrogen Bonds.

The development of white-light-emitting polymers has been actively pursued because of the importance of such polymers in various applications, such as lighting sources and displays. To generate white-light, numerous research efforts have focused on synthesizing multifluorophore-based random copolymers to effectively cover the entire visible region. However, due to their intrinsic synthetic and structural features, this strategy has limitations in securing color reproducibility and stability. Herein, we report the development of single-fluorophore-based white-light-emitting homopolymers with excellent color reproducibility. A powerful direct C-H amidation polymerization (DCAP) strategy enabled the synthesis of defect-free polysulfonamides that emit white-light via excited-state intramolecular proton-transfer (ESIPT). To gain structural insights for designing such polymers, we conducted detailed model studies by varying the electronic nature of substituents that allow facile tuning of the emission colors. Further analysis revealed precise control of the thermodynamics of the ESIPT process by fine-tuning the strength of the intramolecular hydrogen bond. By applying this design principle to polymerization, we successfully produced a series of well-defined polysulfonamides with single-fluorophore emitting white-light. The resulting polymers emitted consistent fluorescence, regardless of their molecular weights or phases (i.e., solution, powder, or thin film), guaranteeing excellent color reproducibility. With these advantages in hand, we also demonstrated practical use of our DCAP system by fabricating a white-light-emitting coated LED.

Colorless-to-colorful switching of electrochromic MXene by reversible ion insertion

Electrochromic (EC) materials that change color with voltage have been widely studied for use in dynamic windows. However, colorless-to-colorful switching with high contrast ratio is generically unattainable, especially for colorless-to-black electrochromic materials with an ultrahigh contrast ratio over the entire visible region. In this work, we developed Nb1.33C MXene-based dynamic windows with colorless-to-black switching of up to 75% reversible change in transmittance from 300 to 1,500 nm. By exploring the electrochromic effects of different electrolytes through in situ optical changes and electrochemical quartz crystal microbalance (EQCM), it is found that electrochromic behavior is greatly influenced by the extent of reversible Li+ insertion/deinsertion between the two-dimensional Nb1.33C MXene nanosheets. In addition, a colorless-to-black EC device based on Nb1.33C with an overall integrated contrast ratio over 80% was successfully constructed by a solution-processable spin coating method. This work enables a simple route to fabricate MXene-based high-performance electrochromic smart windows, which is important for further expanding the application of MXenes to optoelectronic and photonic applications.

Growth, structural, thermal and dielectric studies of a-glycine single crystals grown under the influence of potassium iodide for nonlinear optical applications

Glycine has the simplest structure among all amino acids. Many attempts have been made to grow different derivative crystals of glycine. However, the title compound was not investigated thoroughly to understand the usability of the crystal for its device application. In the present investigation, using slow evaporation solution growth technique, single crystals of glycine have been grown in the presence of potassium iodide. Detailed investigations were made on structural and thermal properties of the grown crystals. Structural analysis was carried out by X-ray diffraction method, Fourier Transform Infrared, FT-Raman and Nuclear Magnetic Resonance spectral methods to conform the grown crystals. Thermal stability of the grown crystals was studied by Thermogravimetric (TG) and Differential Thermal analysis (DTA) and it was found that the crystal is stable up to 113°C. UV-Vis spectral analysis has been carried out and the crystal has not any significant absorbance in the entire visible region. Dielectric studies for the grown samples have also been studied. Nonlinear optical property has been confirmed by Kurtz powder technique and found that the grown crystal has nearly fifty percentage of SHG efficiency as that of standard KDP sample. The observed properties have confirmed that the grown crystal is suitable for nonlinear optical applications. Copyright © 2017 VBRI Press.

Broadband titanium nitride disordered metasurface absorbers

We experimentally demonstrate titanium nitride (TiN) broadband metasurface perfect absorbers by conformally coating plasmonic TiN films onto disordered anodic aluminum oxide (AAO) nanotemplates. The disordered metasurface absorbers exhibit polarization-insensitive and weak angle-dependent perfect absorption over the entire visible and near-infrared spectral regions (300 < λ < 2500 nm). We show from experimental results and numerical simulations that the light scattering induced by the strong disorder of the AAO nanopores and the strong absorption of the TiN deposited on their sidewall are of critical importance for achieving broadband perfect absorption. The TiN disordered metasurface perfect absorbers are superior to many other types of broadband perfect absorbers previously reported and are more suitable for practical applications especially in harsh environments. The device concept for broadband perfect absorption based on plasmonic metal-nitride film coated disordered dielectric media could potentially be extended to significantly enhance the efficiency of solar energy harvesting and the performance of hot-carrier based optoelectronics.

Indeno[1,2,3,4-pqra]Perylene: A Medium-Sized Aromatic Hydrocarbon Exhibiting Full-Range Visible-Light Absorption.

We report the synthesis and properties of indeno[1,2,3,4-pqra]perylene, which was prepared by the fusion of one anthracene unit with one naphthalene unit via three carbon-carbon bonds. The synthetic route through two-fold C-H arylation enabled not only the synthesis of unsubstituted indenoperylene, but also rapid access to its arylated derivatives on the gram scale. Indenoperylene is a medium-sized aromatic hydrocarbon with the composition C24 H12 that is isomeric to coronene. Nevertheless, its absorption covers the entire visible region owing to its small HOMO-LUMO gap. Furthermore, indenoperylene exhibits high stability despite the absence of peripheral substituents. We propose that the unique electronic structure of indenoperylene originates from the coexistence of an electron-withdrawing subunit (benzoaceanthrylene) and an electron-donating subunit (perylene). The electronic properties of indenoperylene were modulated via post-functionalization through regioselective bromination. The current research demonstrates that indenoperylene is a promising candidate as a main skeleton for near-infrared-responsive and redox-active materials.

Experimental, computational analysis of new organic NLO crystal: Piperazinium nicotinic acid and its efficiency in optoelectronic applications

Abstract Slow evaporation solution growth method was adapted for the effective growth of single crystals of piperazinium nicotinic acid (PNA) in distilled water. Single crystal X-ray diffraction analysis was used to investigate the cell parameters of crystalline PNA and the grown crystal belongs to triclinic crystal family with the space group Pī. 3-D molecular hirshfeld surface analysis was supported to visualize the various inter contacts present within the crystal and their percentage contribution to the total hirshfeld surface area was quantified using the 2D finger print plot process. DFT approach was carried out to conduct the theoretical investigation and HOMO-LUMO energy band difference was calculated. B3LYP level of theory with 6-31++G (d,p) basis set was employed to compute the Molecular optimized geometry, FT-IR, FT-Raman and HOMO-LUMO energy distance. FT-IR and FT-Raman spectral studies have accompanied for looking into the modes of vibration of various functional groups in the PNA crystal. UV–visible NIR transmittance studies have revealed that the grown crystal has high transmittance in the entire visible region. Single beam Z-scan technique was explored to determine the third-order nonlinear optical nature and susceptibility of the grown PNA crystal. The results of computational and experimental values suggest suitability and potentiality of PNA crystal for NLO and optical limiting applications.

Dielectric properties and second harmonic generation of glycine doped bisthiourea cobalt and nickel malonates as new semiorganic non-linear optical materials

A new class of materials viz. glycine doped bisthiourea cobalt malonate (BTCoM-Gly) and glycine doped bisthiourea nickel malonate (BTNi-Gly) have been synthesized by simple solvent free mechanochemical method. The chemical composition was evaluated by chemical and elemental analysis. Incorporation of glycine in compound was confirmed by EDAX and FTIR techniques. FTIR studies also ascertained the coordination of metal ion to thiourea through sulphur atom. SEM images showed that both the compounds have linear array type morphology. Thermal stability of material has been investigated by TG and DTA showing BTNiM-Gly is more stable (74.85 °C). Transmittance spectra reveals that lower cut-off wavelength of BTCoM-Gly is 296 nm and that of BTNiM-Gly, 298 nm, indicating to have a good optical transmission in entire visible region, which is desired characteristic for non-linear optical (NLO) materials. The dielectric measurements of the compounds were accomplished with varying frequencies at ambient temperature. Dielectric constant and dielectric loss values of both compounds were decreased with the increase in frequency which ultimately enhanced the second harmonic generation (SHG) efficiency. The SHG conversion efficiency was measured by modified Kurtz-Perry powder technique and found to be 0.751 nm and 0.610 nm times higher than standard KDP for BTCoM-Gly and BTNiM-Gly respectively. The higher SHG conversion efficiency of the compounds illustrates non-linear optical nature of materials and their suitability for NLO applications.

Toward Organic Light Emitting Diode Satisfying Simultaneously Highly Enhanced Light Extraction and Lowly Ambient Light Reflection

AbstractIt is verified that an organic light‐emitting display (OLED) device combined with an advanced optical film characterized by the optical combination of a pyramid‐shaped structure coupled with light absorber simultaneously satisfies highly enhanced light extraction and lowly ambient light reflection as one of the long‐awaited needs of OLED. Thus, it does not require a polarizer that reduces optical efficiency in the OLED device. The results of the optical calculation for the OLED device combined with the proposed film indicate that its optical efficiency has been remarkably improved in the entire visible light region, compared to the polarizer‐based OLED device. Then, its external light reflection is ≈10%, which shows it is lower than when a polarizer and optical films are used to reduce the reflection of ambient light. The experimental data of the OLED device coupled with a film for enhancing optical efficiency (FEOE) confirms the intriguing results of the simulation and thus corroborates the fact that FEOE improves the optical efficiency of OLED devices. The highly efficient FEOE‐based OLED will be of significant interest in materials science and display devices.