“…Obviously, the absorption at 220 nm is assigned to the host lattice absorption and the last two bands are attributed to the energy level transitions. To further discuss the energy levels, the energy gap was calculated according to the Kubelka-Munk function:The band gap of Ca 3 Si 2 O 4 N 2 host was calculated to be approximately 4.689 eV based on above equation 37 .Figure 7DRS of Ca 3 Si 2 O 4 N 2 host and Ca 2.97 Si 3− x O 3+ x N 4−2 x : 0.03Eu 2+ phosphors ( x = 0, 0.5, 1 and 1.5). The inset shows the absorption spectrum of Ca 2.97 Si 3 O 3 N 4 : 0.03Eu 2+ host calculated using the Kubelka-Munk equation.
…”
Discovery of novel phosphors is one of the main issues for improving the color rendering index (CRI) and correlated color temperature (CCT) of white light-emitting diodes (w-LEDs). This study mainly presents a systematic research on the synthesis, crystal structure variation and photoluminescence tuning of novel (oxy)nitride solid solution Ca3Si3−xO3+xN4−2x: Eu2+ phosphors. XRD refinements show that lattice distortion occurs when x value diverges the optimum one (x = 1). The lattice distortion causes a widening of emission spectrum and an increase of Stokes shift (ΔSS), which leads to a bigger thermal quenching. With decrease of x value, the emission spectrum shows an obvious red-shift from 505.2 to 540.8 nm, which is attributed to the crystal field splitting. The enhanced crystal field splitting also broadens the excitation spectrum, making it possible to serve as the phosphor for near ultraviolet (n-UV) LEDs. A 3-phosphor-conversion w-LED lamp was fabricated with the as-prepared phosphor, which exhibits high CRI (Ra = 85.29) and suitable CCT (4903.35 K). All these results indicate that the Ca3Si3−xO3+xN4−2x: Eu2+ phosphor can serve as the green phosphor for n-UV w-LEDs, with a tunable spectrum by controlling the crystal structure and morphology.
“…Obviously, the absorption at 220 nm is assigned to the host lattice absorption and the last two bands are attributed to the energy level transitions. To further discuss the energy levels, the energy gap was calculated according to the Kubelka-Munk function:The band gap of Ca 3 Si 2 O 4 N 2 host was calculated to be approximately 4.689 eV based on above equation 37 .Figure 7DRS of Ca 3 Si 2 O 4 N 2 host and Ca 2.97 Si 3− x O 3+ x N 4−2 x : 0.03Eu 2+ phosphors ( x = 0, 0.5, 1 and 1.5). The inset shows the absorption spectrum of Ca 2.97 Si 3 O 3 N 4 : 0.03Eu 2+ host calculated using the Kubelka-Munk equation.
…”
Discovery of novel phosphors is one of the main issues for improving the color rendering index (CRI) and correlated color temperature (CCT) of white light-emitting diodes (w-LEDs). This study mainly presents a systematic research on the synthesis, crystal structure variation and photoluminescence tuning of novel (oxy)nitride solid solution Ca3Si3−xO3+xN4−2x: Eu2+ phosphors. XRD refinements show that lattice distortion occurs when x value diverges the optimum one (x = 1). The lattice distortion causes a widening of emission spectrum and an increase of Stokes shift (ΔSS), which leads to a bigger thermal quenching. With decrease of x value, the emission spectrum shows an obvious red-shift from 505.2 to 540.8 nm, which is attributed to the crystal field splitting. The enhanced crystal field splitting also broadens the excitation spectrum, making it possible to serve as the phosphor for near ultraviolet (n-UV) LEDs. A 3-phosphor-conversion w-LED lamp was fabricated with the as-prepared phosphor, which exhibits high CRI (Ra = 85.29) and suitable CCT (4903.35 K). All these results indicate that the Ca3Si3−xO3+xN4−2x: Eu2+ phosphor can serve as the green phosphor for n-UV w-LEDs, with a tunable spectrum by controlling the crystal structure and morphology.
“…To achieve sufficient conversion efficiency, the grain size is expected to be smaller than 1/10 of a sub-pixel, i.e. a few 100 nm [32]. Hence, an advanced synthesis method guaranteeing size-controllability and conversion efficiency is required for the materials.…”
In this paper, some of the technological bottlenecks of the microlight-emitting diode (μLED) for a micro-display were reviewed. Although there remain other issues, the μLED technology has a potential for some micro-display applications which especially demand high brightness and reliability such as augmented reality (AR) display, automotive head-up display (HUD), and so on. The efficiency of μLED needs to be improved, and an integration technology for active matrix driving and technologies for full-color realization as well as defective pixel control must be developed. An optimum specification of a μLED display was proposed to maximize reality in micro-display products.
“…Defining the optical properties of the MCW-LEDs model and its PSL is of essential importance [11][12][13]. Varying the silica concentration would alter the ACU and IU optical performance due to enhanced scattering in the proposed PSL.…”
Section: Optical and Simulation Modelmentioning
confidence: 99%
“…For that reason, white light quality is also improved over time [10][11][12][13]. This paper uses silica particles SiO2 in the PSL of MCW-LEDs to improve color uniformity and illumination.…”
Abstract:We analyze the influence of silica particle (SiO2) concentrations on color and illuminance uniformity of multichip white LEDs (MCW-LEDs) with a correlated color temperature (CCT) near 7700 K. It is suggested that the novel phosphor silicone layer (PSL), which added silica particles, can improve CCT and illumination uniformity. Using the commercial simulation program LightTools, based on Monte Carlo method, the novel PSL demonstrated a reduction of the CCT deviation (DCCT) to 1719 K from 2211 K, while the illuminance uniformity increased from 0.328 to 0.353. The simulation results could be totally convinced by Mie theory. This results point towards an approach for manufacturing high-quality MCW-LEDs.
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