Zero-Dimensional Hybrid Antimony Chloride with Near-Unity Broad-Band Orange-Red Emission toward Solid-State Lighting.

Zero-dimensional (0D) hybrid metal halides are attractive owing to their distinctive structure as well as photoluminescence (PL) characteristics. To discover 0D hybrid metal halides with high photoluminescence quantum yield and good stability is of great significance for white light-emitting diodes (LEDs). Herein, a novel hybrid antimony chloride (CTP)2SbCl5 is synthesized, which shows a bright broad-band orange-red emission peaking at 620 nm under the low energy excitation (365 nm), achieving an excellent photoluminescence quantum yield of 96.8%. In addition, (CTP)2SbCl5 shows an additional emission peaking at 470 nm when excited at high energy (323 nm). PL spectra and density functional theory results demonstrate that the observed dual-band emission originates from the singlet and triplet self-trapped excitons confined in isolated [SbCl5]2- square pyramids. Moreover, (CTP)2SbCl5 presents relatively superior air stability, and the PL intensity still maintains 78% of the initial PL intensity when exposed to the air for above 2 weeks. Benefiting from high-efficiency PL emission and good stability of (CTP)2SbCl5, a stable warm white LED device with a 92.3% color rendering index was prepared by coating blue phosphor BaMgAl10O17:Eu2+, green (Sr,Ba)2SiO4:Eu2+, and orange-red (CTP)2SbCl5 on a 365 nm LED chip. This work provides an efficient luminescent material and also demonstrates the potential application of 0D hybrid antimony chloride in solid-state lighting.

High-Efficiency Narrow-Band Green-Emitting Manganese(II) Halide for Multifunctional Applications.

Zero-dimensional (0D) Mn2+-based metal halides used as luminescent materials and scintillators have become a research hotspot in the field of photoelectric materials and devices due to their unique composition, structure, and fluorescence properties. It is of great value to explore new Mn2+-based metal halides to achieve multifunctional applications. Herein, the novel 0D Mn2+-based metal halide single crystal (BPTP)2MnBr4 is synthesized by a simple solvent-antisolvent recrystallization method. Under excitation at 468 nm, the (BPTP)2MnBr4 single crystal shows a pronounced narrow-band green luminescence centered at 515 nm derived from the d-d transition of the Mn2+ ion. This emission has a relatively narrow full width at half maximum of 43 nm and a high photoluminescence quantum yield (PLQY) of 82%. In addition, (BPTP)2MnBr4 exhibits good thermal stability at 393 K with a retention of 79% of the initial photoluminescence intensity at 298 K. Benefiting from its strong blue light excitation, high PLQY, and good thermal stability, we manufacture an ideal white light-emitting diode (LED) device using a 460 nm blue LED chip, green-emitting (BPTP)2MnBr4, and commercial K2SiF6:Mn4+ red phosphor. Under 20 mA drive current, the LED shows a high luminous efficiency of 112 lm/W and a wide color gamut of 110.8%, according to the National Television System Committee standard. In addition, (BPTP)2MnBr4 crystals show a strong X-ray absorption. Based on the commercial Lu3Al5O12:Ce3+ scintillator, the calculated light yield of (BPTP)2MnBr4 reaches up to about 136,000 photons/MeV and the detection limit reaches 0.282 µGyair s-1. Additionally, a melt quenching approach is used to construct a (BPTP)2MnBr4 clear glass scintillation screen, realizing a spatial resolution of 10.1 lp/mm. The proper performances of (BPTP)2MnBr4 as phosphor-converted LED materials and the X-ray scintillator with the addition of eco-friendly, low-cost solution processability make 0D Mn2+-based metal halides potential luminescent materials for multifunctional applications.

A broadband yellow-green emitting mixed orthoborate-pyroborate phosphor, Ba2Sc2B4O11:Ce3+, for white light emitting diodes.

The development of yellow-green phosphors for high quality white light emitting diodes (WLEDs) is critical. Herein, we successfully synthesized a mixed orthoborate-pyroborate phosphor, Ba2Sc2B4O11:Ce3+, using a high-temperature solid-state method, which exhibits bright yellow-green emission with a peak located at 540 nm and a full width at half maximum (FWHM) of 130 nm under 410 nm light excitation. In addition, the crystal structure, morphology, and thermal quenching properties of Ba2Sc2B4O11:Ce3+ were investigated in detail. The quantum yield of the optimal sample was found to be 53.3%. The concentration quenching occurred through the energy transition between the nearest-neighbor Ce3+ ions. A WLED with a low correlated color temperature (CCT = 3906 K) and a high color rendering index (Ra = 89) was prepared by coating the mixture of the phosphor Ba2Sc2B4O11:Ce3+, the commercial blue phosphor BaMgAl10O17:Eu2+ and the red phosphor CaAlSiN3:Eu2+ on a 395 nm n-UV LED chip. The results show that the yellow-green phosphor Ba2Sc2B4O11:Ce3+ could be an excellent candidate for WLEDs.

Atomically Dispersed Cu Catalyst for Efficient Chemoselective Hydrogenation Reaction.

The Cu-based nanocatalysts have shown a high selectivity toward selective hydrogenation reaction, but the underlying catalytic mechanism is still murky. Herein, we report a new gram-scale strategy for realizing the single atom Cu site incorporated into the melem ring of graphitic carbon nitride (Cu1/CN) for understanding the catalytic mechanism of a hydrogenation reaction. The as-synthesized Cu1/CN exhibits unprecedented selectivity (100%), high activity (TOF = 2.9 × 103 h-1), and outstanding stability for selective hydrogenation of 4-nitrostyrene. We reveal that the presence of hydroxymethyl from trimethylolmelamine is beneficial to atomically disperse Cu atoms in the CN. X-ray absorption fine structure tests reveal that the Cu atom of Cu1/CN is dominated by the quaternary coordination way (Cu-N4) in the melem ring of CN. Density functional theory calculations confirm that the high reactivity and selectivity originate from the anchored Cu sites creating the optimal chemical environment for the highly efficient hydrogenation reaction.

New phenomena of photo-luminescence and persistent luminescence of a Eu2+,Tb3+ codoped Ca6BaP4O17 phosphor under high hydrostatic pressure.

In this study, we present a photo-luminescence (PL) and persistent luminescence (PersL) investigation of Ca6BaP4O17:Eu2+,Tb3+ (CBPO:Eu,Tb) at high hydrostatic pressure in the range of 0-11.04 GPa. More importantly, there is a significant increase of PL intensity and extension of PersL duration time at a pressure point of ∼0.15 GPa.

A K3ScSi2O7:Eu2+ based phosphor with broad-band NIR emission and robust thermal stability for NIR pc-LEDs.

In this work, an Eu2+-doped K3ScSi2O7 (KSSO) NIR phosphor with broad-band NIR emission and robust thermal stability was designed and synthesized successfully. The crystal structure, luminescent properties, the mechanism of abnormal NIR emission, thermal stability and application to NIR pc-LEDs were investigated in detail.

Applicability Evaluation of Bright Green-Emitting Carbon Dots in the Solid State for White Light-Emitting Diodes.

Self-quenching-resistant and bright green-emitting carbon dots (CDs) in the solid state were synthesized via a facile hydrothermal method. Their structure, optical properties together with their thermal and photostabilities, as well as their applicability in white LEDs were investigated. The obtained CDs have nearly spherical shape with a size around 4-5 nm. The resulting powder CDs show excitation-independent emission behavior, and can be excited over a broad range from 300-450 nm. Under optimal excitation at 400 nm, the resultant powder CDs yield bright and broad green emission around 505 nm with full width at half maximum (FWHM) of about 110 nm and under 360 nm excitation with lifetime of 15.8 ns. A potential application of the green-emitting CDs was evaluated by constructing a white light-emitting diode lamp. The fabricated white LED lamp emitted bright, warm white light with excellent color rendering properties (a color rendering index of 86.9 and a correlated color temperature of 3863 K).

High Quantum Yield Green-Emitting Carbon Dots for Fe(ІІІ) Detection, Biocompatible Fluorescent Ink and Cellular Imaging.

In the present work, we reported the luminescence of a green-emitting carbon dots (CDs) synthesized via solid state reaction method using diammonium hydrogen citrate and urea as a starting materials. The obtained green-emitting CDs shows strong absorption in the 350-450 nm region and gives intense green emission (λmax = 537 nm) with quantum yield as high as 46.4% under 420 nm excitation. The obtained green-emitting CDs also demonstrates high photo-stability, which is evidenced by the fact that its emission intensity almost has no change under irradiation by a 365 nm UV lamp for 2 hours. Moreover, the obtained green-emitting CDs shows high sensitivity and selectivity for the detection of Fe3+, and their emission intensity response towards Fe3+ ions is highly linear (R2 = 0.995) over the concentration range from 25 to 300 µM, which could provide an effective platform for detection of Fe3+. Mostly important, we further demonstrate that such photoluminescent green-emitting CDs exhibits low toxicity and are biocompatible for use with in cellular imaging. Combining with low cytotoxicity, good water solubility and excellent luminescence properties, green-emitting CDs could be used as a biocompatible fluorescent ink in future applications.