Blue Emission Properties Research Articles

Crystal Growth and Ferroelectric Properties of Thiourea Picrate Single Crystal

Ferroelectric hysteresis (P-E) loop study strongly confirmed that Thiourea Picrate (TUP) crystal is a new lead free, prolific ferroelectric material and good switching behavior of the polarization. Curie phase transition at 70OC was observed in the dielectric analysis and AC conductivity study followed the power law with frequency depended. The elemental composition and surface morphology of the TUP crystal were investigated by EDX and SEM analysis. The thermal behavior of the TUP crystal was analyzed using TG/DTA, and found that the melting point of the prepared crystal was 155 ℃. The photoluminescence study shows TUP has a Blue Emission Property.

Augmenting the effect of solvents on optical nonlinearity by spectroscopic, DFT, solvatochromism and z-scan studies of push-pull chalcone: (2E)-1-(4-ethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one

In this article, the structural and nonlinear optical behaviour of a chalcone derivative, (2E)-1-(4-ethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one have been studied. FT-IR, FT-Raman, and NMR spectroscopy were analyzed to validate the molecular structure. To predict the nonlinear optical characteristics of the chalcone, the DFT approach was used and the experimental results were corroborated by the computations. The bathochromic shift is obtained in linear absorbance spectra and is validated using TD-DFT. Also, the broad emission in the blue region demonstrates the blue light emission property of the sample. Using the finite-field method, the dipole moments, polarizability, first-order and second-order hyperpolarizability parameters have been computed. Ground and excited state dipole moments were quantified by solvatochromism. The third-order nonlinear optical characteristics of chalcone in polar and non-polar solvent media were examined using the open/closed-aperture z-scan technique. The chalcone displayed considerable two-photon absorption with a positive nonlinear absorption coefficient and a positive index of refraction due to the self-focussing effect. Furthermore, the optical limiting study manifests that the investigated chalcone might well be favourable for NLO applications.

Modulation of components toward blue light emission and scintillation properties of Eu2+ activated Sr1-xLaxMgxAl12-xO19 crystal

The development of Eu2+-activated oxide materials with high efficiency, fast decay and narrow bandwidth emission in the visible region is still challenging for the field of luminescence and scintillation applications. Generally, Eu2+ in oxide hosts can emit intense and broad 5d-4f emission in the visible region, but efficient emitting with stable bivalence of Eu is rare in inorganic oxide system. In this work, a series of ASL:Eu2+ (Sr1-xLaxMgxAl12-xO19) powder samples with various La, Mg doping ratios were designed and synthesized to modulate the UV or X-ray excited luminescence properties, including redshift, quantum yield, and decaying lifetime. Moreover, an ASL:Eu2+ crystal with the optimal ratio x = 1/3 was grown, its scintillation performance was compared with standard Bi4Ge3O12 crystal sample and evaluated in detail. These results indicate that the ASL:Eu2+ crystal is potential scintillator as a kind of X-ray detection and provide a reference for the further development of high-performance Eu-activated oxide scintillation materials.

Blue emitting exciplex for yellow and white organic light-emitting diodes

White organic light-emitting diodes (WOLEDs) have several desirable features, but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures. Herein, we investigate a standard blue emitting hole transporting material (HTM) N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and its exciplex emission upon combining with a suitable electron transporting material (ETM), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ). Blue and yellow OLEDs with simple device structures are developed by using a blend layer, NPB:TAZ, as a blue emitter as well as a host for yellow phosphorescent dopant iridium (III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate (PO-01). Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units. The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer (CGL). Judicious choice of the spacer prevents exciton diffusion from the blue emitter unit, yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation. This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission. The overall white light emission properties are enhanced, achieving CIE coordinates (0.36, 0.39) and color temperature (4643 K) similar to daylight. Employing intermolecular exciplex emission in OLEDs simplifies the device architecture via its dual functionality as a host and as an emitter.Graphical abstract

Crystal Structure, Quantum Chemical, Hirshfeld Surface and Molecular Docking of Organic Molecular Salt: 2‐Amino‐5‐Chloropyridinium‐2,4‐Dihydroxybenzoate

AbstractAn organic molecular salt, 2‐amino‐5‐chloropyridinium‐2,4‐dihydroxybenzoate (ACP‐DHB) is synthesized by the slurry method followed by crystallization from methanol. The formation of molecular salt is initially confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectral data. Single crystal X‐ray diffraction (XRD) analysis shows that the crystal belongs to the monoclinic crystal system with space group, P21/n. Further, the supramolecular assembly involved the extensive network of N+−H···O− and N−H···O hydrogen bonds as well as C‐Cl···O halogen bond. Using UV‐Visible spectral data, the optical band gap is calculated and found to be 4.21 eV. Photoluminescence studies indicate the crystal has blue light emission properties. TG/DTA analysis shows that ACP‐DHB is thermally stable up to 162 °C. The quantum chemical calculations and natural bond analysis (NBO) are performed at B3LYP/6‐311G++ (d,p) basis set using Gaussian 09 software. The relative contributions of various intermolecular connections are discussed using Hirshfeld surface analysis and fingerprint plot illustration. The antibacterial and antifungal activity exhibits better inhibitory capacity against pathogens. Molecular docking revealed that ACP‐DHB efficiently binds with the 1UAG and 5KEE targets and has strong binding ability to the proteins. ADMET factors and Lipinski's rule of five are used to predict drug likeness property.

Asymmetrical liquid crystals synthesis for effective sensing: Fluorescence investigations

Currently, a new set of asymmetrical dimeric molecules with a Schiff-base at one end and a chalcone alkali substitution by di-ether are made and their liquid crystal and fluorescence properties are investigated. The proposed chemical structure was confirmed by routine analytical methods using FT-IR and NMR spectroscopy. Additionally, polarized optical microscopy (POM); was used to assess the pointed compounds' liquid crystalline characteristics, while differential scanning calorimetry (DSC); was employed to confirm the compounds' transitions. The results report the length of the alkali chain at one end of the molecule is critical to the creation of the mesophase type. Compounds with medium-length chains exhibit nematic mesophases with moderate transition temperatures. The fluorescence of compounds was analyzed, with blue-emitting results indicating the presence of blue-light-emitting features. The 10a had higher ɛ; as well as red-shifted λmax; and Fmax; compared to the others and has blue light emission properties. Eventually; the expanding range of possible uses to include OLED material and fluorescent probes for sensing applications.

Room temperature tri-alkynyl benzene based discotic nematic mesophase enabling high-efficiency deep blue OLEDs

In the hunt to develop room-temperature nematic discotic materials, we engineered a molecular structure that employs a tri-alkynyl benzene core incompatible with π-π stacking, providing flexibility to the system. Micro-segregation was prohibited due to the direct attachment of the flexible alkoxy chain to the central benzene ring, leading to a discotic nematic phase. The nematic phase was found stable down to room temperature and, on further cooling, transformed into a glassy state. Detailed analysis of differential scanning calorimetry plots, polarized optical microscopic textures, and temperature-dependent X-ray diffraction patterns confirmed the glassy nematic phase at low temperatures. The tri-alkynyl benzene moiety imparts high solid and solution-state blue emission properties to mesogens 1a and 1b. On stimulating the compounds electrically as a solid-state emitter in organic light-emitting diodes, they showed emission in the deep blue (CIEy < 0.08) region at 100 cd m−2 luminance and pure blue (CIEy < 0.11) region at maximum luminance using CBP host. Amongst all the configurations used, the device based on 0.5 wt% 1a displayed the best performance with a maximum external quantum efficiency of 4.1% with a turn-on voltage of 3.5 V and CIExy coordinates of (0.16,0.07).

Development of PEGylated Cu nanoclusters: A nontoxic, multifunctional colloidal system for bioimaging and peroxide sensing

This study introduces the development of blue-emitting colloidal Cu NCs through a novel and easy PEGylation method using different functional groups, including -SH and -COOH. The surface functionalization controls the size, cellular toxicity, and emission properties of Cu NCs. The combination of PEG, thiol, and carboxylic groups protects the particle surface from aggregation and oxidation. Among the samples, CAGP (Surface modified Cu NCs with -SH-COOH-PEG combination) emerges as an amazing candidate with the lowest toxicity and enhanced blue emission properties. The bright blue fluorescence emission from Hela cells after treatment with CAGP demonstrated this property. It also has excellent peroxide sensing potential, with a detection limit of 1.4 μM. Because of their excellent bioimaging and peroxide sensing properties, these Cu NCs could be a promising candidate for cellular oxidative stress sensing applications with high clinical relevance.

NondemandingIn SituEncapsulation Route to Ultrastable Perovskite Nanocrystals for White Light-Emitting Diodes

Although tremendous advancement regarding the highly stable metal halide perovskite nanocrystals (PNCs) has been achieved, previous studies were primarily focused on green light-emitting PNCs (i.e., bromine-based PNCs). The stability of chlorine-based PNCs with a violet or blue emission property was still lagging behind that of their bromine-based counterparts. Herein, a nondemanding and versatile strategy for in situ encapsulating all-inorganic chlorine-based PNCs with multifold exceptionally high stabilities was presented. Well-ordered mesoporous silica enabled the confined growth of PNCs in its pores followed by the porosity sealing by tetramethyl orthosilicate hydrolysis, thereby rendering full encapsulation of chlorine-based PNCs in dense silica that originated from high-temperature calcination. This judiciously designed structure imparted enclosed violet/blue emitting PNCs impart with outstanding long-term stability (>1.5 year) with high photoluminescence quantum yield (i.e., 30.4%) in pure water as the result of complete isolation of PNCs from detrimental stimuli, eventually leading to the application in the white light-emitting diode device.

Synthesis and characterization of new chalcone compounds, and investigation of their DFT, optical and electrochemical properties

This paper considers chalcone compounds photochemical behavior for their potential as dye-sensitized solar cell compounds. 21 chalcone compounds have been synthesized using Claisen-Schmidt condensation. The theoretical calculations (DFT), chemical structure, photoluminescence, optical properties and electrochemical properties were identified by some technical methods. The band gaps and the quantum chemical parameters of compounds have been investgated through density functional theory. The result theoretical calculations showed band gaps for this compounds range between at (4.04–4.07 eV) and compared with the optical energy gaps (Egopt) defined from UV–Vis spectroscopy. The Photoluminescence study revealed that these compounds have blue light emission properties. The oxidation energy and energy of HOMO were calculated using cyclic voltammetry.

Dual-mode strategy for 2,6-dipicolinic acid detection based on the fluorescence property and peroxidase-like activity inhibition of Fe-MIL-88NH2

This work designed a fluorometric/colorimetric dual-mode sensor for detecting 2,6-dipicolinic acid (DPA) based on the blue emission property and peroxidase-like activity of Fe-MIL-88NH2. The fluorescence of Fe-MIL-88NH2 was obviously turned off by Cu2+, but DPA was able to bring it back because it has a strong chelate bond with Cu2+. Fe-MIL-88NH2 also displayed high peroxidase-like activity, which accelerated the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to the blue oxidation product (oxTMB) when H2O2 was present. When DPA was added, it efficiently inhibited the peroxidase-like activity of Fe-MIL-88NH2, causing less oxTMB and less absorbance at 652 nm. The fluorescence recovery of Fe-MIL-88NH2 and the change in absorbance at 652 nm were used as analytical signals for dual-mode detection of DPA. The linear responses in the range of 10–60 μM and 60–160 μM were achieved for the fluorometric mode, and the limit of detection (LOD) was 1.46 μM. The respective values of linear range and LOD for the colorimetric mode were 5–25 μM and 3.00 μM, respectively. In summary, the dual-mode testing strategy successfully detected DPA in aqueous environmental samples, suggesting great potential in disease prevention and environmental analysis.

Microstructure and properties of mono-crystalline germanium enhanced by high-current pulsed electron beam

High current pulsed electron beam (HCPEB) technology was applied to irradiate the surface of mono-crystalline Ge wafers (Ge (100) and Ge (111)) with different orientations, and the microstructure and properties of the irradiated surface were analyzed in detail. The results show that after HCPEB irradiation, numerous molten pits and local microcracks were produced on the surface of mono-crystalline Ge, and the pit density decreased with the increase of irradiation pulses. TEM observations indicated that after irradiation, the defects are mainly vacancy group defects and dislocation rings, and Ge nanocrystals with uniform size distribution are produced. HCPEB irradiation also formed self-assembled nanostructures on the surface of Ge. Cross section TEM indicated that the 250 nm deep defect channels were under the quantum dots, which confirms the formation mechanism of self-assembled nanostructures. The photoluminescence results indicated that the irradiated mono-crystalline Ge still has blue emission properties, and the luminescence mechanism is the quantum confinement effect of Ge nanocrystals embedded in slightly oxidized or nitrided amorphous structures.

Developing silk sericin-based and carbon dots reinforced bio-nanocomposite films and potential application to litchi fruit

Designing cost-effective and sustainable edible packaging films featuring multifunctional activities (antimicrobial, antioxidant, UV shielding) is of great interest in the field of food science and engineering. Herein, the films containing various components of silk sericin (SS), chitosan (CS) as well as carbon dots (CDs) were developed and their physicochemical, structural and bioactive properties were also investigated. Compared with the SS-made film alone, the bio-nanocomposite films (made up of SS, CS, as well as CDs) showed the enhanced flexibility, antimicrobial and antioxidant properties. Moreover, a good compatibility was present among these components, which were well dispersed in the film matrix network. Importantly, due to the existence of CDs, the bio-nanocomposite films indicated a blue fluorescent emission property, which could be used as an anti-counterfeit label. Lastly, the fruit-litchi was selected to verify the fresh-keeping effect of the bio-nanocomposite film, which is effective to reduce the loss of nutritional components, such as water, soluble solids, ascorbic acid, etc. The study can shed light on the use of SS as matrix and CDs as functional ingredient for facile and environmentally friendly preparation of the edible food packaging film as well as for its utilization in food preservation to treat fruits effectively.

Synthesis and Blue Emission Properties of Co-Doped CdS Semiconductor Nanoparticles

Background: Cadmium sulfide (CdS) based semiconductors are of great interest for different high-end applications because they pose a direct bandgap (2.42 eV). CdS are used as the main constituent material in many applications, namely solar cells, electroluminescent, and quantum dot light-emitting diodes. Transition metal-doped CdS revealed considerable influence in the bandgap, photoluminescence properties and peak energy upon increasing the metal content. Objective: In this work, we study the single-phase cubic structure of CdS. Photoluminescence spectra revealed a strong blue emission peak located at about 445 nm. Methods: We investigate the Co-doping CdS semiconductor nanoparticles prepared via the chemical co-precipitation method using thiophenol as template, 300 °C/2h in vacuum optimum temperature and period of annealing to yield nanosized particles. Morphology and structural studies of the particles were using XRD, and TEM, respectively. Results: XRD and TEM studies for the calcined samples revealed a cubic structure. The crystalline size was in the range of 10-17 nm. Thermogravimetric analysis (TGA) was employed to stabilize the temperature of annealing for the samples. The blue shift in the spectra and the band gap value of Codoped CdS nanoparticles were estimated using UV-vis absorption spectra. Photoluminescence spectra revealed a strong blue emission peak around 445 nm indicating the presence of surface states within the bandgap region, which is a characteristic feature of nanoparticles. Conclusion: XRD analysis indicated zinc blend structure and the intensity decreased with increasing Co content. TEM images show that the particles are spherical in shape with average sizes around 13 nm. Luminescence of the synthesized nanoparticles exhibited blue emission between 400 – 500 nm with the peak located at about 445 nm. The emission intensity increased with the increase in Co concentration.

Carbon dots enhanced gelatin/chitosan bio-nanocomposite packaging film for perishable foods

Carbon dots (CDs) with intriguing fluorescent property, good biocompatibility, high stability, easy interaction with substrates, are burgeoning carbon nanoparticles with large potential in various applications. Incorporating CDs into the polymer matrix is becoming a popular strategy to endow the complex with new functions. Herein, the green-synthesized CDs was integrated into the mixture of gelatin (derived from waste fish scale) and chitosan, and a multifunctional bio-nanocomposite (defined as Gelatin/Chitosan/CDs) film was developed, which showed the excellent antibacterial, antioxidant, pH-sensitivity, UV shielding, and blue-emission properties. The effects of different concentrations of CDs on the physical, mechanical, structural, and functional activity of bio-nanocomposite film were tested. Compared with the Gelatin/Chitosan film, the Gelatin/Chitosan/CDs film with an optimum addition of 20% CDs showed the enhanced antibacterial, antioxidant as well as UV shielding activities. More importantly, it was used as an effective packaging material for fish meat preservation, reducing the loss of nutritional quality consumption, extending the shelf life of food. Besides, the bio-nanocomposite films also possessed the anti-counterfeiting and pH-responsive properties due to the strong fluorescent emission of CDs, and had the great potential in developing the intelligent packaging materials. Our work shed new light on the new application of CDs and the synthesis of bio-nanocomposite film in food industry.

A new cucurbit[10]uril-based AIE fluorescent supramolecular polymer for cellular imaging

The synthesis of the AIE fluorescent supramolecular polymer TPE-B@Q[10] is reported. This system exhibits excellent blue emission properties, good biocompatibility and was successfully employed for cytoplasmic imaging of cells.

Synthesis, characterization and DFT study of new anthracene-based semiconducting polyethers for OLED application

New soluble semiconducting anthracene-based polyethers (An-BPS and An-TDP) were synthetized via the Williamson polycondensation of 9,10-dichloromethylanthracene with 4,4′-thiodiphenol (TDP) and bisphenol S (BPS), respectively. The polymers were investigated by density functional theory (DFT): the structural and optoelectronic properties, frontier molecular orbitals (HOMO/LUMO), as well as the infrared, absorption and fluorescence spectra were discussed. The polyethers structures were confirmed by NMR and FTIR spectroscopies, revealing good agreements between experimental and theoretical results. Quasi-identical absorption and blue emission properties were obtained for both polymers in dilute solutions, with a higher fluorescence efficiency for An-BPS. The cyclic voltammetry analysis of these electrochemically active materials showed a higher electron affinity for An-BPS and a lower ionization potential for An-TDP. The DFT calculations showed that the HOMO/LUMO frontier energy distributions are confined on the anthracene moiety in An-BPS. However in An-TDP, the LUMO distribution is localized on anthracene group, while the HOMO is on the TDP unit. The electric behavior of organic light-emitting diodes (OLEDs) based on these macromolecular structures has been investigated via numerical simulation using Silvaco TECAD software. Good electrical properties are estimated, with a low turn on voltages of 3.1 V and 2.9 V for An-TDP and An-BPS, respectively. However, An-BPS showed improved current conductivity, which makes it a good candidate for OLEDs.

Unsymmetrical Coumarin based dimeric liquid crystals: Synthesis, Characterization, Mesomorphic investigation, Photoluminescence and Thermal conductivity

ABSTRACT In this paper a synthesis, liquid crystal behaviours, photoluminescence and thermal conductivity have been described for new sets of unsymmetrical dimeric molecules with coumarin unit at one end connected to chalcones alky substitution by diether. Chemical proposed structure was confirmed by routine analytical methods using FT-IR, 1D NMR and 2D NMR spectroscopy and CHN elemental analysistechniques. The compounds were investigated for liquid crystalline properties using differential scanning calorimetry and polarising optical microscopy with heating assembly. Most of the compounds are showing nematic mesophases with moderate transition ranges. Photoluminescence of compounds was examined and the results indicated that the emission in the blue region reveals that material has blue light emission properties. Moreover, thermal conductivity of the prepared compounds was measured, result indicated that slight change in the structure increased the thermal conductivity.

N-Doped Carbon Dots Derived from Melamine and Triethanolamine for Selective Sensing of Fe3+ Ions

This work reports nitrogen-doped carbon dots (NCDs) as a selective sensing probe to detect Fe3+ in water samples. NCD probes were synthesized via solvothermal method using nitrogen-rich melamine and triethanolamine as precursors. Properties of the resulting NCDs were studied using different characterization techniques, through which N-doping was confirmed. The quantum yield of obtained NCDs was measured to be 21%. When excited at 370 nm, the excellent blue emission property makes this probe adoptable for selectively sensing Fe3+ in practical water samples. The limit of detection (LOD) was identified as 216 nM with a good linear range between the concentrations of 0.2-2 μM. The obtained LOD is far less than the World Health Organization (WHO) permissible limits of Fe3+ in water. Interference studies reveal that the presence of other competing ions did not alter the sensing of Fe3+, even at the presence of 10 equivalents which indicates the high selectivity of NCDs towards Fe3+. The reversibility studies showed that adding a cheap and readily available EDTA ligand to the NCD results in fluorescence regeneration, leading to exceptional reusability for the detection of Fe3+. So, the synthesized NCDs can be used as a suitable probe for the selective determination of Fe3+ in real water samples.

Optical and strong blue emission properties of alumina abrasive grains mediated grinding induced SiO2 glass surfaces for navigation grade sensors

We report, fused silica samples have been processed with various grit sizes (3, 5, 12 and 25 μm) of Aluminium oxide (Al2O3) abrasives. Aluminium oxide has a significant effect on the vibrational and optical properties of the silica glass. The prepared samples were characterized through UV–Vis spectroscopy, Photoluminescence spectroscopy and Raman spectroscopic technique to understand the effect of aluminium oxide powders with different grit size on the silica glass. The transmittance spectra of all the fused silica samples excellent transmission at far infrared and visible region up to approximately 2750 nm. The steady-state photoluminescence (PL) measurement of all the samples was performed under excitation wavelength of 300 nm at room temperature which shows the maximum emission peak at 430 nm. The typical Raman spectra for all the samples were recorded at 532 nm excitation at room temperature to study the Alumina abrasive induced vibrational properties.