White Light-Emitting Diodes With Visible Uniform Spectral Power Distribution Packaged With Phosphor-in-Silicone/Phosphor-in-Glass Stacked Structure

Liyu Huang,Chunliang Lin,Zhenjin Wang

doi:10.1109/jeds.2021.3059339

Liyu Huang, Chunliang Lin + Show 1 more

Open Access

https://doi.org/10.1109/jeds.2021.3059339

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Abstract

White light-emitting diodes (WLEDs) with a visible uniform spectral power distribution (SPD) were fabricated by integrating a blue LED chip and a phosphor-in-silicone (PiS)/phosphor-in-glass (PiG) stacked package. After adjusting the doping concentrations of phosphors (cyan, green and red) in the silicone encapsulant, the PiS was dispensed in the cavity of lead frame already bonded with a blue LED chip. Then the top surface of the PiS was covered with a PiG sheet. WLEDs with the PiS/PiG stacked package achieve a warm correlated color temperature (CCT) 4200K and a high color rendering index (CRI; Ra = 90.9, R9 = 73.0, and R15 = 85.9) at 350 mA. The full-spectrum index (FSI) of WLEDs with the PiS/PiG stacked packages is 4.24 in the wavelength range of 380 nm to 730 nm, respectively. Warm WLEDs with a visible uniform SPD and a high light quality can be fabricated through the PiS/PiG stacked package.

Highlights

White light-emitting diodes (WLEDs) have the advantages of small volume, high efficiency, long lifetime, and environmentally friendly, and WLEDs are the main light source for lighting, display backlight, and signage, etc., [1], [2]
Traditional WLEDs fabricated by combining only a blue light-emitting diode (LED) chip with a yttrium aluminum garnet (YAG) phosphor-in-silicone (PiS) are not easy to meet the requirements of illumination for correlated color temperature (CCT) and color rendering index (CRI) [3]–[7]
Fig. 3 shows the normalized spectral power distribution (SPD) for WLEDs with the silicone/PiG, G-PiS/PiG, GC-PiS/PiG and GCR-PiS/PiG stacked packages operating at 350 mA and room temperature

Summary

Introduction

White light-emitting diodes (WLEDs) have the advantages of small volume, high efficiency, long lifetime, and environmentally friendly, and WLEDs are the main light source for lighting, display backlight, and signage, etc., [1], [2]. For a long time, irradiating natural light sources such as sunlight with continuous and relatively uniform spectral power distribution (SPD) has been considered beneficial to physical and mental health. In order to achieve a visible uniform SPD of WLEDs, violet or ultraviolet (UV) LEDs were used as the light source to excite multiple phosphors [11], [12]. If using a blue LED to excite multiple phosphors, there is an opportunity to balance light output quality with luminous efficacy. Because the spectral width of the general blue LED is relatively narrow, it is not easy to achieve a visible uniform SPD even when using a blue LED to excite multiple phosphors unless there are suitable phosphor materials and mixing ratio

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Conclusion