Abstract
To make further improvements in future WLED generation, bettering color uniformity is an important goal manufacturers desire to accomplish. One of the most common and effective methods to enhance the color homogeneity is the one focusing on improving scattering in phosphor layer which can be achieved by adding ZnO into the phosphor layer. Based on theoretical application of Mie-scattering, we compute and analyze the scattering characteristics of the diffusor particles. From the results, the ZnO particles are proven to have positive influences on the development of lighting quality. Additionally, the article analyzed and presented the effects of ZnO concentration which fluctuates from 2% to 22% on the color homogeneity. Thus, the color uniformity is influenced not only by the particle size but also by the concentration of the added ZnO. Hence, managing the color uniformity of WLEDs means controlling the size and concentration of ZnO. With the concentration of 10% ZnO, the lumen output of LEDs reaches the highest values. Meanwhile, when the concentration and size of ZnO are 14% and 500 nm respectively, ∆CCT is reduced to the lowest value. Based on the manufacturers' requirements, the most appropriate ZnO concentration and particle size can be determined. However, if requirements include both lumen and color uniformity, the right choice is 14% concentration with 500 nm particle size of ZnO. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.
Highlights
Light-emitting diodes (LEDs) have many benets for lighting solution because its component materials are strong and stable, cost-saving, and environment-friendly
Are fabricated from a compound of Indium Gallium Nitride (InGaN) with phosphor materials. This combination is capable of converting blue light to yellow light [3], for which these WLEDs are known as phosphor-converted white LEDs [4]
Many researchers put a lot of eorts into improving the light extraction of WLEDs [5]
Summary
Light-emitting diodes (LEDs) have many benets for lighting solution because its component materials are strong and stable, cost-saving, and environment-friendly. Beside the perk of being reusable, the particle number is one of the most vital factors inuencing lumen output and the color temperature of the lighting device [8] This state was explained and proved through experiments and model simulation, applying the Monte Carlo method, analyzing the diusion properties, the absorbing capacity, the converted light, the structural arrangement and the refractive index of materials in the conguration [9]. There is an obstacle that blocks the way of achieving the high color uniformity for white WLEDs, the yellow ring phenomenon This phenomenon occurs as the blue light which is strongest surrounding the center joins with phosphor molecule that has consistent strength in all positions [13].
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