Nontemplate Synthesis of CH3NH3PbBr3 Perovskite Nanoparticles

Visible and near-infrared luminescent properties of Pr3+ doped strontium molybdate thin films by a facile polymer-assisted deposition process

Luminescent properties of semiconductor nanocrystals

Covalent organic frameworks (COFs) have emerged as potential light‐emitting polymers for optoelectronic and optical devices, but their smart responsiveness to environmental stimuli has seldom been explored particularly for alkene‐linked conjugated COFs, which limits their application scope in “smart” systems. Herein, fluorine chemistry coupled with acrylonitrile linkage is introduced as a “one‐stone‐three‐bird” strategy to produce a smart COF with rapid pH‐responsive absorption and fluorescence, high fluorescence quantum yield (QY), and good crystallinity. In addition to increased crystallinity, the newly designed fluorinated acrylonitrile‐linked COF (TF‐COF) produces 20% enhancement in fluorescence QY and more rapid responsiveness of absorption and fluorescence under acid–base induction compared to the nonfluorinated counterpart. Impressively, the yielded QY reaches 33.6% in solid states and 41.0% in tetrahydrofuran dispersion, surpassing most existing COF materials. The synergy effect of fluorine chemistry induced charge redistribution and acrylonitrile linkage enabled reversible C═C bonds contributes to the rapid responsiveness, high fluorescence QY, and good crystallinity. The developed TF‐COF can be utilized as a responsive phosphor to endow image encryption with high coloration and good reversibility, and as an encryption data carrier via simple handwriting.

The construction of solid-state fluorescent materials with high quantum yield and good processability is of vital importance in the preparation of organic light-emitting devices. Herein, a series of tetraphenylethylene (TPE)-based multicomponent emissive metallacages are prepared by the coordination-driven self-assembly of tetra-(4-pyridylphenyl)ethylene, cis-Pt(PEt3 )2 (OTf)2 and tetracarboxylic ligands. These metallacages exhibit good emission both in solution and in the solid state because the coordination bonds and aggregation restrict the molecular motions of TPE synergistically, which suppresses the non-radiative decay of these metallacages. Impressively, one of the metallacages achieves very high fluorescence quantum yield (ΦF =88.46 %) in the solid state, which is further used as the coatings of a blue LED bulb to achieve white-light emission. The study not only provides a general method to the preparation of TPE-based metallacages but also explores their applications as solid-state fluorescent materials, which will promote the future design and applications of metallacages as useful emissive devices.

The construction of solid‐state fluorescent materials with high quantum yield and good processability is of vital importance in the preparation of organic light‐emitting devices. Herein, a series of tetraphenylethylene (TPE)‐based multicomponent emissive metallacages are prepared by the coordination‐driven self‐assembly of tetra‐(4‐pyridylphenyl)ethylene, cis‐Pt(PEt3)2(OTf)2 and tetracarboxylic ligands. These metallacages exhibit good emission both in solution and in the solid state because the coordination bonds and aggregation restrict the molecular motions of TPE synergistically, which suppresses the non‐radiative decay of these metallacages. Impressively, one of the metallacages achieves very high fluorescence quantum yield (ΦF=88.46 %) in the solid state, which is further used as the coatings of a blue LED bulb to achieve white‐light emission. The study not only provides a general method to the preparation of TPE‐based metallacages but also explores their applications as solid‐state fluorescent materials, which will promote the future design and applications of metallacages as useful emissive devices.

Stable Diarylamine-Substituted Tris(2,4,6-trichlorophenyl)methyl Radicals: One-Step Synthesis, Near-Infrared Emission, and Redox Chemistry

Pyrene-based red room-temperature phosphorescent guest-materials with high quantum yield and narrow emission peak.

Preparation of multicolor carbon dots with high fluorescence quantum yield and application in white LED

Europium(III) complexes have attracted tremendous interests from scientists for their excellent properties and their important potential applications in the fields of organic light emitting diodes, biological labeling, laser media. In this paper, two novel europium(III) complexes having 2-thenoyltrifluoroacetylacetone (tta) as the first ligand and the second ligands bearing benzimidazole groups were synthesized and characterized by FT-IR, UV–Vis, 1H-NMR, and elemental analysis. The photoluminescent properties of complexes in the solid state, in ethanol solution and embedded in poly(methyl methacrylate) (PMMA) were investigated. All europium(III) complexes exhibited strong luminescent intensity, high quantum yields (Φ) and long luminescent lifetimes. The intrinsic luminescent quantum yields (ΦLN) and the stimulated emission cross-section (σp) of complexes were obtained based on the emission spectra and luminescent lifetimes of 5D0 excited state for europium(III) ion. All europium(III) complexes exhibited relatively high intrinsic luminescent quantum yields. In view of σp values, which are the same order as the values of Nd-glass laser for practical use, these europium(III) complexes may find potential applications in the field of high-power laser media.

Preparation and characterization of silver nanoparticles homogenous thin films

Biologically derived fluorescent proteins are attractive candidates for lasing and sensing due to their excellent optical properties, including their high quantum yield, spectral tunability, and robustness against concentration quenching. Here, a time‐resolved study of the fluorescence dynamics of protein thin films is reported for the enhanced green fluorescent protein (EGFP), the red‐emitting tandem‐dimer protein tdTomato, and blends of EGFP and tdTomato. The exciton dynamics are characterized by using spectrally and time‐resolved measurements of fluorescence and a threefold reduction in lifetime is observed when going from solution to thin film, down to 1 and 0.6 ns for EGFP and tdTomato, respectively. This finding is attributed to a dipole–dipole nonradiative Förster resonant energy transfer (FRET) in solid state. The temporal characteristics of FRET in blended thin films are also studied and increased nonradiative transfer rates are found. Finally, efficient sensitization of a semiconductor surface with a protein thin film is reported. Such a configuration may have important implications for energy harvesting in hybrid organic–inorganic solar cells and other hybrid optoelectronic devices.

Nonmetal-containing organic molecules typically do not emit blue phosphorescence efficiently due to weak intersystem crossing and the challenge of protecting high-energy triplet states from nonradiative decay. We show that use of triplet-promoting bromine atoms and careful control of molecular packing can lead to well-defined, efficient room-temperature phosphorescence (RTP) from organic crystals. We report on the distinct optical properties of a polymorphic bromine-containing organic molecule, 1,4-bis-(bromomethyl)-2,5-bis-(octyloxy)-benzene (Br8) in solid-state (micro)-crystal and thin-film forms. The two polymorphs, named Br8-H and Br8-J, exhibit different molecular packing arrangements in single crystals and thin films and, consequently, different photophysical behaviors. The Br8-J polymorph is characterized by a head-to-tail molecular arrangement in a triclinic crystal, while the Br8-H polymorph adopts a face-to-face arrangement (monoclinic crystal). Br8-J has a higher quantum yield (38% for the microcrystal form and 8% for the thin film), lower energy, and narrower emission, compared to Br8-H (quantum yield of just 2% for the microcrystal and 0.2% in the thin film). The higher quantum yields in the microcrystal forms indicate the key role of intermolecular interactions in reducing nonradiative recombination in these polymorphs. The presence of both prompt and delayed blue emission (in the range 420-470 nm) and large Stokes shifts from both polymorphs indicates the involvement of triplet excited states and the occurrence of RTP with lifetimes of ∼325 μs. With an emission wavelength of 470 nm and a quantum yield of 38%, the Br8-J polymorph demonstrates how specific head-to-tail packing can unlock highly efficient solid-state phosphorescence compared to its face-to-face counterpart. The optimal intermolecular halide bonding in the J-type packing arrangement combined with the heavy atom effect is key to unlocking efficient blue emission from Br8 crystals. Our findings uncover rich photophysics in halogenated organic molecules in the solid state and the importance of molecular packing in their emission characteristics.

The high luminescent near infrared (NIR)--emitting CdTe nanocrystals (NCs) with 3-mercaptopropionic acid (MPA) as the stabilized molecules had been sucessfully fabricated by a facile and simple water-reflux method. By virtue of the characterizations for the as-prepared MPA-capped CdTe NCs, such as UV-Vis absorption, steady-state photoluminescence (PL), time-resolved PL spectra and PL image, the optical properties, diameters and morphologies of the CdTe NCs were investigated detailedly. With the increase of reflux time, the PL peak wavelength of NCs gradually shifted from red light to NIR spectra range within 7 h, and the PL quantum yield (QY) was increased firstly and then decreased slightly. It was worth noted that the NCs still showed a relative high PL QY of 47% as well as a narrow full width at half maximum (FWHM) of PL spectra even when the NCs emitted at the NIR wavelength of 754 nm. In addition, the average PL lifetime also exhibited an obvious increase as the growth of CdTe NCs due to the formation of thin CdS shell on the surface of CdTe. The PL stabilities for these NIR-emitting NCs (754 nm) in phosphate-buffered saline (PBS) buffer solution with various concentrations ranged from 0.005 to 0.1 M were also checked accordingly, and the results indicated that the as-prepared NIR-emitting CdTe NCs had a satisfied PL stability, implying a potential application in the biological field. Hopefully, all the superiority of these NIR-emitting CdTe NCs, such as high PL QY and PL lifetime, narrow FWHM of PL spectra, high PL stability in PBS solution, would make them to be a good candidate for biological applications in future.

Two kinds of cadmium sulfate (CdS) thin films have been grown at 600 °C onto Si(111) and quartz substrates using femtosecond pulsed laser deposition (PLD). The influence of substrates on the structural and optical properties of the CdS thin films grown by femtosecond pulsed laser deposition have been studied. The CdS thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), photoluminescence (PL) and Raman spectroscopy. Although CdS thin films deposited both on Si(111) and quartz substrates were polycrystalline and hexagonal as shown by the XRD , SEM and AFM results, the crystalline quality and optical properties were found to be different. The size of the grains for the CdS thin film grown on Si(111) substrate were observed to be larger than that of the CdS thin film grown on quartz substrate, and there is more microcrystalline perpendicularity of c-axis for the film deposited on the quartz substrate than that for the films deposited on the Si substrate. In addition, in the PL spectra, the excitonic peak is more intense and resolved for CdS film deposited on quartz than that for the CdS film deposited on Si(111) substrate. The LO and TO Raman peaks in the CdS films grown on Si(111) substrate and quartz substrate are different, which is due to higher stress and bigger grain size in the CdS film grown on Si(111) substrate, than that of the CdS film grown on the amorphous quartz substrate. All this suggests that the substrates have a significant effect on the structural and optical properties of thin CdS films.

Engineering mixed polyanion red-emitting Rb2Bi(PO4)(WO4):Eu3+ phosphors with negligible thermal quenching and high quantum yield