3-D Microlens Phosphor With Curvatures Manufactured by Imprinting for Chip-on-Board Light-Emitting Diodes

TLDR: In this article, a 3D microlens-phosphor structure was proposed for high power light-emitting diodes (LEDs) assembled in 3-D micro-lens.

Abstract: High-power light-emitting diodes (LEDs) assembled in 3-D microlens-phosphor structures are investigated. For the proposed design, the phosphor–air interface with arrayed high-valued curvatures replaces the conventional flat counterpart, enabling abundant randomized lights to exit. Monte Carlo algorithm ray tracing and finite-element method were utilized in this paper to analyze the light propagation and thermal migration, simulatively indicating that the redirecting regulation and heat dispassion way of the proposed architecture are considerably different. Experimentally, in comparison with the conventional flat chip-on-board (COB) LEDs, the proposed single-layered structure is capable of improving the luminous efficacy of radiation by 38.1%. For multilayered structures, within which the light transmits first through red phosphor layer and then yellow phosphor layer molded with microlens, a 7% increase in quantum efficiency and an 8.7 increase in color rendering index have been achieved. The proposed structure can guide LED manufacturing communities to significantly improve the optical performance and designs of COB packaging.