Won Bin Im

A solid solution strategy helps increase the efficiency of Ce3+ oxyfluoride phosphors for solid-state white lighting. The use of a phosphor-capping architecture provides additional light extraction. The accompanying image displays electroluminescence spectra from a 434-nm InGaN LED phosphor that has been capped with the oxyfluoride phosphor.

A new, highly efficient green oxyfluoride phosphor family Sr2.975−xBaxCe0.025AlO4F (SBAF:Ce3+) has been developed as a component of solid state white light emitting diodes (LED). The phosphor emits with a maximum at 502 nm when excited by 405 nm excitation, with a quantum efficiency approaching 100%. When SBAF:Ce3+ (x = 1.0) is incorporated with encapsulant on an ultraviolet (405 nm) LED, greenish-white light with a color rendering index of 62 under a forward bias current of 20 mA is obtained. T

Cerium-doped lanthanum strontium aluminum oxide LaSr2AlO5:Ce3+ has recently been identified by us as a viable yellow phosphor that in conjunction with a blue-emitting diode can be used in solid-state white lighting sources. In this study, we present the energy level structure relevant to the luminescence process within LaSr2AlO5:Ce3+, based on crystal structure determination by powder X-ray diffraction and the peak deconvolution of excitation and emission spectra. We also establish the versatili

A yellow-emitting phosphor, La1−xCex3+Sr2AlO5, is reported that displays a peak in the excitation at 450nm and a peak in the emission at 556nm. When this phosphor is pumped by a blue InGaN light-emitting diode (λmax=450nm) we obtain white light with color rendering index (Ra) between 81 and 85 and color temperatures between 4200 and 5500K, suggesting that this material is competitive as a blue-pumped yellow phosphors.

Tactile pressure sensors as flexible bioelectronic devices have been regarded as the key component for recently emerging applications in electronic skins, health-monitoring devices, or human-machine interfaces. However, their narrow range of sensible pressure and their difficulty in forming high integrations represent major limitations for various potential applications. Herein, we report fully integrated, active-matrix arrays of pressure-sensitive MoS₂ transistors with mechanolumines

Scintillators are widely used for radiation detection in various fields, such as medical imaging, nondestructive testing, and crystallography. X-ray-generating systems typically emit large amounts of heat and require a high thermal stability of scintillators, particularly for nondestructive testing or radiation detection performed under harsh conditions. Therefore, highly stable scintillators must be developed for application in extreme environments. Herein, we developed new zero-dimensional lea

We have evaluated the thermal stability of BaAl2Si2O8:Eu2+ (BAS:Eu2+) phosphor using its polymorph property and hexagonal and monoclinic crystal structure, depending upon firing temperature for plasma display panel application. When BAS:Eu2+ samples having each characteristic crystal structure were baked at 500 °C in air for 30 min, the baked monoclinic BAS:Eu2+ showed the same photoluminescence (PL) intensity as the fresh one, whereas the baked hexagonal one lost its PL intensity significantly,

Solid solutions of two isotypic compounds from the end members LaSr2AlO5 and Sr3SiO5 are hosts for Ce3+ activator ions, allowing for careful tuning of the various parameters associated with efficient solid state (blue + yellow =) white lighting. By incorporating this phosphor with an encapsulant on InGaN light-emitting diodes (λmax = 430 nm), we obtain white light with a color rendering index (Ra) between 67 and 70 and color temperatures between 6550 and 7345 K, with relatively high efficacies,

In this study, we report on the development of a new garnet phosphor with enhanced optical properties and cost reduction. Samples were prepared using the solid-solution method, in which the chemical unit and substitutions with cation-size mismatch were combined. Solid solutions between two garnet structure compounds, green phosphor Lu3Al5O12:Ce3+ (LuAG:Ce3+) and orange phosphor Lu2CaMg2Si3O12:Ce3+ (Lu3–xCaxAl2–2xMg2xAl3–3xSi3xO12:Ce3+), constituted the complete solid-solution range x (x = 0–1).

A blue-color-emitting phosphor, (Sr(1-x),Ba(x))(3)MgSi(2)O(8):Eu(2+) (SB(x)MS:Eu(2+)), with various Ba contents, was synthesized, and its thermal stability was evaluated. Depending upon the Ba content, the dominant emission wavelength of the SB(x)MS:Eu(2+) phosphor could be tuned, and good photoluminescence (PL) properties were obtained under an excitation by a 147 nm source. The PL behavior showed that the thermal stability of SB(x)MS:Eu(2+) baked at 500 degrees C was dependent upon the Ba cont

Hydrochromic materials that change their luminescence color upon exposure to moisture have attracted considerable attention owing to their applications in sensing and information encryption. However, the existing materials lack high hydrochromic response and color tunability. This study reports the development of a new and bright 0D Cs₃ GdCl₆ metal halide as the host for hydrochromic photon upconversion in the form of polycrystals (PCs) and nanocrystals. Lanthanides co-dope