Effect of Particle Size on the Optical Properties of Yellow Silicate Phosphor in Light‐Emitting Diodes

Abstract

Understanding the effect of particle size on the optical properties of phosphor is important to increase packaging efficiency in white light-emitting diodes (LEDs). We have investigated the effect of particle size (10-20 lm, 20-25 lm, 25-32 lm) on the optical properties of a yellow silicate phosphor adopted in white LEDs. X-ray diffraction results show negligible modification in crystallinity as the particle size of the yellow silicate phosphor varies, whereas the photoluminescence excitation intensity and quantum yield are enhanced as the particle size increased. LED packages fabricated using phosphors with different mean particle sizes, and their optical properties were analyzed. The radiant flux improved with increasing particle size, whereas the luminous flux increased with decreasing particle size. The effect of immersion on the optical properties of the LED light source has been also measured, and the details are discussed.

Optical efficiency characterization of LED phosphors using a double integrating sphere system

“…The reliability of the laser based DIS system was proven by the agreement found on the measured QY value of the YAG:Ce phosphor and the value given by supplier A. Our values are also in fair agreement with phosphor QY values found in literature [14][15][16]. The differences between the QY values measured in this work Figure 2 Emission spectra of phosphors at 450 nm excitation wavelength.…”

Micronization of red-emitting K2SiF6:Mn4+ phosphor by pulsed laser irradiation in liquid

“…The decreased PL efficiency is due to the increased nonradiative recombination channels through the formation of internal and/or surface defects. A W-LED packaging with the present micronized red-emitting phosphor is expected to show more angularly uniform emission than the conventional one [28,29]. Moreover, the present micronization technique utilizing laser fragmentation in liquid can be applied to other Mn-or rare-earth-doped hexafluoride phosphors.…”

“…The control of particle size is a key issue for the application of these phosphors to W-LEDs. This is because the various emission characteristics of W-LEDs, such as angular uniformity and light extraction efficiency, are strongly dependent on their phosphor particle sizes [25][26][27][28][29].…”

Effects of the optical absorption of a LED chip on the LED package

“…e l s e v i e r . c o m / l o c a t e / s s e down slightly to a chip before curing [17]. Using a convection oven, curing was performed at 70°C for 1 h then at 150°C for 2 h. The chips with and without encapsulation were subjected to optical property tests at 3.6 V and 120 mA using a spectrometer (Instrument Systems, CAS-140CT) which has an integrating sphere to collect overall emitting light from a package.…”