Light Output Efficiency of Surface-Mount Lamp Beads Based on New Solid–Liquid UV Encapsulation

Abstract

To address the problem of low efficiency of AIGaN-based UV LED chips, this study developed a type of solid-liquid packaged UV LED chip and analyzed its light output efficiency under different parameters. The light output efficiency of UV LED chips with and without solid-liquid encapsulation were analyzed using different reflective materials inside the chips. It was found that Au, Ag, and total-absorption reflective materials could not improve the light-output efficiency of UV LED liquid packaging. In addition, Al reflective materials and total reflection photonic crystals can improve the light output efficiency of UV LED liquid packaging, with the highest efficiency increase reaching over 74%. The light output efficiencies of liquid packaging with quartz cover sheets of different thicknesses were analyzed; the results revealed that the thinner the quartz cover sheet, the higher the efficiency; Under the same conditions, the efficiency improvement of UV LED surface-mount beads is not significant with different thicknesses of quartz cover sheets; Under the same thickness of quartz cover, Al reflective material and total reflection photonic crystal can improve the light output efficiency of UV LED liquid packaging.

Table 2 Simulated optical parameters of different materials

Table 3 Simulated optical parameters of LEDs of different sizes

The structures of the UV chip and patch-lamp bead used in this simulation are shown in Figure 1-3. The UV LED chip includes a sapphire substrate, an N-type AlGaN material, a quantum well, and a P-type AlGaN material; its front-top view is shown in Figure 1, and its cross-sectional view is shown in Figure 2. As shown in Figure 3, the UV patch-lamp bead includes packaging materials, UV LED chips, filling materials, such as air or water, and a quartz cover from bottom to top; the angle between the inner and bottom surfaces is 85°.

Figure 2 (a) Silicon dioxide glass structure for external microprocessor arrays (b) Internal microprocessor arrays

Table 5 The light efficiency of the different SiO2 thickness

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