Improved Long-Term Reliability of a Silica-Encapsulated Perovskite Quantum-Dot Light-Emitting Device with an Optically Pumped Remote Film Package.

In this study, inorganic perovskite (CsPbBr) quantum dots are wrapped in SiO to provide better performance against external erosion. Long-term storage (250 days) is demonstrated with very little changes in the illumination capability of these quantum dots. While in the continuous aging procedure, different package architectures can achieve very different lifetimes.

Multisite-Occupancy-Driven Intense Narrow-Band Blue Emission from SrSiOCl:Eu Phosphor with Excellent Stability and Color Performance.

The development of an efficient blue phosphor with remarkable thermal stability required for high-quality white-light-emitting diodes (WLEDs) remains an exigent task and mainly concerned BaMgAlO:Eu (BAM:Eu). Despite the outstanding performance of BAM:Eu, the reduction in luminescence efficiency under long-term operation results in numerous researches on new hosts having lattice rigidity with symmetrical coordination environment. Therefore, we have synthesized a competent blue-emitting Eu-activated SrSiOCl (SSC) phosphors.

Promising Er/Yb-Codoped GdBiWO Phosphor for Temperature Sensing by Upconversion Luminescence.

Yb/Er-codoped GdBiWO phosphors are prepared via the solid-state route for application in upconversion temperature sensors. The structural analyses indicate that all phosphors possess a single-phased orthorhombic structure. Upon the excitation of a laser wavelength of 980 nm, Yb/Er-codoped GdBiWO phosphors emanate green emission peaks, endorsed to the emission to the I state from the S and H states, respectively, and the weak emission (red) from the F state to the I state of Er ion.

Rapid synthesis of hybrid methylammonium lead iodide perovskite quantum dots and rich MnI substitution favouring Pb-free warm white LED applications.

We present a facile room temperature synthesis of CHNHPb Mn I perovskite quantum dots (PQDs) substituting manganese (Mn) at the lead (Pb) sites to minimize environmental pollution and make it commercially feasible. By varying the concentration of Mn from 0 to 60%, the PQDs exhibit strong color tunability from red to orange color suggesting successful energy transfer due to Mn inclusion. We observed a high external photoluminescence quantum yield (PLQY) of 98% for unsubstituted CHNHPbI and >50% for up to 15% Mn substituted PQDs.

Liquid Type Nontoxic Photoluminescent Nanomaterials for High Color Quality White-Light-Emitting Diode.

High-brightness white-light-emitting diodes (w-LEDs) with excellent color quality is demonstrated by using nontoxic nanomaterials. Previously, we have reported the high color quality w-LEDs with heavy-metal phosphor and quantum dots (QDs), which may cause environmental hazards. In the present work, liquid-type white LEDs composed of nontoxic materials, named as graphene and porous silicon quantum dots are fabricated with a high color rendering index (CRI) value gain up to 95.

LaSiS:Ce: luminescence and lighting applications of a novel green-emitting phosphor.

An efficient green-emitting La6Si4S17:Ce3+ phosphor was synthesized using a solid-state method. The phosphor exhibits a triclinic structure as the main phase. A broad green emission is observed upon excitation at 420 nm with a quantum efficiency of 83%.

Novel Eu-activated thiogallate phosphors for white LED applications: structural and spectroscopic analysis.

Novel Eu-activated BaGaSiS and BaGaSiS thiogallate phosphors were prepared by solid-state reaction route. The BaGaSiS:Eu phosphor generated a green emission upon excitation at 405 nm, whereas the BaGaSiS:Eu phosphor could be tuned from cyan to green range with increasing Eu concentration upon excitation at 365 nm. Additionally, the thermal luminescence properties of the thiogallate phosphors were investigated in the temperature range of 25 to 250 °C.

Fabrication of Flexible White Light-Emitting Diodes from Photoluminescent Polymer Materials with Excellent Color Quality.

This study developed flexible light-emitting diodes (LEDs) with warm white and neutral white light. A simple ultraviolet flip-chip sticking process was adopted for the pumping source and combined with polymer and quantum dot (QD) films technology to yield white light. The polymer-blended flexible LEDs exhibited higher luminous efficiency than the QD-blended flexible LEDs.

Synthesis and Luminescence Properties of Novel Ce(3+)- and Eu(2+)-Doped Lanthanum Bromothiosilicate La3Br(SiS4)2 Phosphors for White LEDs.

Novel Ce(3+)- and Eu(2+)-doped lanthanum bromothiosilicate La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)2:Ce(3+) phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)2:Eu(2+) phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors from 20 to 200 °C were investigated.

Resonant-enhanced full-color emission of quantum-dot-based micro LED display technology.

Colloidal quantum dots which can emit red, green, and blue colors are incorporated with a micro-LED array to demonstrate a feasible choice for future display technology. The pitch of the micro-LED array is 40 μm, which is sufficient for high-resolution screen applications. The method that was used to spray the quantum dots in such tight space is called Aerosol Jet technology which uses atomizer and gas flow control to obtain uniform and controlled narrow spots.

Efficient hybrid white light-emitting diodes by organic-inorganic materials at different CCT from 3000K to 9000K.

The hybrid white light-emitting didoes (LED) with polyfluoren (PFO) polymer and quantum dot (QD) was investigated using dispensing method at the different correlated color temperature (CCT) for cool and warm color temperature. This result indicates that the hybrid white LED device has the higher luminous efficiency than the convention one, which could be attributed to the increased utilization rate of the UV light. Furthermore, the CIE 1931 coordinate of high quality white hybrid LED with different CCT range from 3000K to 9000K is demonstrated.

Novel reddish-orange-emitting BaLa2Si2S8:Eu(2+) thiosilicate phosphor for LED lighting.

A novel reddish-orange-emitting BaLa2Si2S8:Eu(2+) thiosilicate was prepared in a sealed fused silica ampule and its crystal structure was refined using Rietveld methods. The BaLa2Si2S8:Eu(2+) phosphor is excitable over a broad range from UV to blue (350-450 nm) and generated a reddish-orange broadband emission peaking at 645 nm with a quantum efficiency of ∼24%. The thermal luminescence quenching of BaLa2Si2S8:Eu(2+) was investigated over the range 25 to 150 °C.

New Ce3+-activated thiosilicate phosphor for LED lighting-synthesis, luminescence studies, and applications.

A new Ce(3+)-activated thiosilicate phosphor, BaLa2Si2S8:Ce(3+), was synthesized by using solid-state methods in a fused silica ampule and found to crystallize in the structure type of La2PbSi2S8. The crystal structure has been characterized by synchrotron X-ray diffraction and refined with Rietveld methods. This novel cyan-emitting phosphor can be excited over a broad range from UV to blue light (380-450 nm) and generates a broadband emission peaking at 471 nm with a quantum efficiency of 36%.

White light emitting diodes with enhanced CCT uniformity and luminous flux using ZrO2 nanoparticles.

To enhance the uniformity of correlated color temperature (CCT) and luminous flux, we integrated ZrO2 nanoparticles into white light-emitting diodes. This novel packaging scheme led to a more than 12% increase in luminous flux as compared to that in conventional dispensing structures. This was attributed to the scattering effect of ZrO2 nanoparticles, which enhanced the utilization of blue light.

Ligand-functionalization of BPEI-coated YVO4:Bi3+,Eu3+ nanophosphors for tumor-cell-targeted imaging applications.

In this study, surface-functionalized, branched polyethylenimine (BPEI)-modified YVO4:Bi(3+),Eu(3+) nanocrystals (NCs) were successfully synthesized by a simple, rapid, solvent-free hydrothermal method. The BPEI-coated YVO4:Bi(3+),Eu(3+) NCs with high crystallinity show broad-band excitation in the λ=250 to 400 nm near-ultraviolet (NUV) region and exhibit a sharp-line emission band centered at λ=619 nm under excitation at λ=350 nm. The surface amino groups contributed by the capping agent, BPEI, not only improve the dispersibility and water/buffer stability of the BPEI-coated YVO4:Bi(3+),Eu(3+) NCs, but also provide a capability for specifically targeted biomolecule conjugation.

Enhanced light harvesting with a reflective luminescent down-shifting layer for dye-sensitized solar cells.

For a dye-sensitized solar cell with a near-infrared squaraine (SQ1) sensitizer, the photovoltaic performance was enhanced remarkably with a reflective luminescent down-shifting (R-LDS) layer to increase the light-harvesting efficiency at the wavelength region 400-550 nm where the SQ1 dye has weak absorption. Relative enhancements greater than 200% in IPCE near 500 nm and 40-54% in JSC were achieved with red phosphor CaAlSiN3:Eu(2+) as the LDS material, attaining 5.0 and 4.

Eu(2+)-activated Sr8ZnSc(PO4)7: a novel near-ultraviolet converting yellow-emitting phosphor for white light-emitting diodes.

The crystal structure of Eu(2+)-activated Sr(8)ZnSc(PO(4))(7):Eu(2+) phosphor was refined and determined from XRD profiles by the Rietveld refinement method using a synchrotron light source. This phosphor crystallizes in the monoclinic structure with the I2/a space group. The SZSP:xEu(2+) phosphors showed a broad yellow emission band centered at 511 and 571 nm depending on the concentration of Eu(2+), and the composition-optimized concentration of Eu(2+) in the Sr(8)ZnSc(PO(4))(7):Eu(2+) phosphor was determined to be 2 mol %.

Preparation of high-performance water-soluble quantum dots for biorecognition through fluorescence resonance energy transfer.

An improved method for the synthesis of high-performance and water-soluble quantum dots (QDs) involving the encapsulation of mercaptosuccinic acid coated QDs (MSA-QDs) with poly(diallyldimethylammonium chloride) (PDDA) followed by their direct photoactivation with fluorescent radiation near 295 K to yield PDDA-coated QDs (PDDA-QDs) has been demonstrated. The quantum yield (QY) of the PDDA-QDs was significantly improved from 0.6 (QY of MSA-QDs) to 48%.

Host sensitization of Tb3+ ions in tribarium lanthanide borates Ba3Ln (BO3)3 (Ln = Lu and Gd).

The vacuum-ultraviolet (VUV) spectroscopic properties of undoped and Tb(3+)-doped borates Ba(3)Ln(BO(3))(3) (Ln = Lu and Gd) with different crystal structures were investigated by using synchrotron radiation. Ba(3)Lu(BO(3))(3) (BLB) crystallizes in a hexagonal structure, whereas Ba(3)Gd(BO(3))(3) (BGB) crystallizes in a trigonal structure. The maximum host absorption for BLB and BGB was found to locate at ~179 and ~195 nm, respectively.

A novel tunable green- to yellow-emitting β-YFS:Ce³+ phosphor for solid-state lighting.

A Ce(3+)-activated fluorosulfide phosphor (β-YFS:Ce(3+)) was synthesized by solid-state reaction in a sealed tube. The crystal structure has been refined from the XRD profiles and there are two different crystallographic rare earth sites, namely, Y(1) and Y(2), where the Ce(3+) ions occupied. The emission band with a maximum at 495 nm of β-Y(0.

Luminescence investigation on ultraviolet-emitting rare-earth-doped phosphors using synchrotron radiation.

Three series of new ultraviolet-emitting Ca(9)Y(PO(4))(7):Ln(3+) (Ln = Ce, Gd, Pr) phosphors were synthesized, and their luminescence was investigated. Under vacuum ultraviolet excitation Ca(9)Y(PO(4))(7):Ce(3+) phosphors emit UVA light with one broad emission centered at 346 nm, on account of the 5d(1) → 4f(1) transition of Ce(3+) ions; the optimal doping concentration of these phosphors is 0.2 mol.

Novel yellow-emitting Sr8MgLn(PO4)7:Eu2+ (Ln=Y, La) phosphors for applications in white LEDs with excellent color rendering index.

Eu(2+)-activated Sr(8)MgY(PO(4))(7) and Sr(8)MgLa(PO(4))(7) yellow-emitting phosphors were successfully synthesized by solid-state reactions for applications in excellent color rendering index white light-emitting diodes (LEDs). The excitation and reflectance spectra of these phosphors show broad band excitation and absorption in the 250-450 nm near-ultraviolet region, which is ascribed to the 4f(7) → 4f(6)5d(1) transitions of Eu(2+). Therefore, these phosphors meet the application requirements for near-UV LED chips.

Thermally stable green Ba(3)Y(PO(4))3:Ce(3+),Tb(3+) and red Ca(3)Y(AlO)(3)(BO(3))4:Eu(3+) phosphors for white-light fluorescent lamps.

A class of thermal stable of green-emitting phosphors Ba(3)Y(PO(4))(3):Ce(3+),Tb(3+) (BYP:Ce(3+),Tb(3+)) and red-emitting phosphors Ca(3)Y(AlO)(3)(BO(3))(4):Eu(3+) (CYAB:Eu(3+)) for white-light fluorescent lamps were synthesized by high temperature solid-state reaction. We observed a decay of only 3% at 150 °C for BYP:0.25Ce3+,0.

Intense violet-blue-emitting Ba(2)AlB(4)O(9)Cl:Eu(2+) phosphors for applications in fluorescent lamps and ultraviolet-light-emitting diodes.

We synthesized a violet-blue phosphor Ba(2)AlB(4)O(9)Cl:Eu(2+) with a solid-state reaction. The excitation and emission spectra of this phosphor showed that all were broadband due to 4f(7)-4f(6)d(1) transitions of Eu(2+). The phosphors with different Eu(2+) concentrations presented violet-blue luminescence for ultraviolet [(UV) 250-390nm] excitation.

Novel yellowish-orange Sr8Al12O24S2:Eu2+ phosphor for application in blue light-emitting diode based white LED.

A new yellowish-orange phosphor, Sr(8)Al(12)O(24)S(2):Eu(2+), was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability.