Improving light output by micro-TiO₂ scatters in pc-WLED encapsulants

Abstract

Phosphor-converted white light emitting diodes (pc-WLEDs) are used worldwide for an extensive amount of applications. The device is a complex combination of various components that introduce various technical issues: materials, electrical, chemical, thermal, and so on. All of these combined to obtain a targeted optical characteristic. While most of the pc-WLEDs are sufficient for basic illumination performance, there are still many issues to improve the pc-WLED performance. In this work, we deal with the incorporation of micron size particles of titanium oxide (TiO2) in silicone encapsulant that contains yttrium aluminum garnet (YAG) phosphor in remote phosphor pc-WLED. Based on the light output and the scattering spatial distribution measurements of the phosphor plates, we have found that several essential performance indices, like the color uniformity, the efficiency, and the amount of phosphor for the pc-WLEDs, can be adjusted by tuning the amount of TiO2 particles and thus be optimized. With a comprehensive model using a Monte-Carlo ray tracing process combined with the Mie scattering theory, two TiO2 loading conditions are revealed. The first one is the sparse condition that the TiO2 particles act as the scattering particles such as to increase the output flux to improve the efficiency of YAG. The second one is the dense condition that the TiO2 particles act more as barrier particles such so to decrease the output flux.

Three new AIE-cored luminescent Cd-based MOFs with high quantum yields and selective detection of ions in aqueous media

“…[1][2][3][4][5][6][7] Due to the dominant role of phosphors in the final performance of pc-WLEDs, exploring high-performance phosphors has become a challenging and targeted research topic. [8][9][10] Luminescent metal-organic frameworks (LMOFs) are a new type of ideal fluorescent powder potential material for pc-WLEDs. [11][12][13] In the past few decades, MOFs have attracted widespread research interest in many application fields due to their highly designable porous structure, large specific surface area, and modifiable chemical functions, including gas storage and separation, [14][15][16][17] catalysis, [18][19][20] light-emitting diodes, 21,22 fluorescence sensors, [23][24][25] nonlinear optics, 26,27 laser, 28,29 biomedical field, 30,31 and medical imaging.…”

Angle‐dependent light scattering in tissue phantoms for the case of thin bone layers with predominant forward scattering

“…These phantoms consist of a filler matrix and a proportion of homogeneous, spherical, polymer scatterers. For our simulative approach, we combine a wave optical method, to calculate the Mie-scattering [21,22] behavior on a single polymer sphere, with the ray optical approach of the Monte-Carlo simulation [23,24]. In this way, we calculate the angle distribution of one scatterer which we utilize as the phase function for scattering events in the Monte-Carlo simulation.…”

Angle-dependent light scattering in tissue phantoms for the case of thin bone layers with predominant forward scattering

“…These phantoms consist of a filler matrix and a proportion of homogeneous, spherical, polymer scatterers. For our simulative approach we combine a wave optical method, to calculate the Mie-scattering [21,22] behaviour on a single polymer sphere, with the ray optical approach of the Monte-Carlo simulation [23,24]. In this way, we calculate the angle distribution of one scatterer which we utilize as the phase function for scattering events in the Monte-Carlo simulation.…”