In this study, we realized a cylindrical tuber silicone layer for improving the light efficiency of chip-on-board light-emitting diodes (COB-LEDs) by fabricating patterned LED substrate with both silicone-wetting and silicone-repellency surfaces. To realize silicone-repellency surface, low surface energy modified nanosilica particles were prepared and deposited on the LED substrate to form porous hierarchical structure. Light efficiency enhancement for blue light COB-LEDs with pure cylindrical tuber silicone layer and white light COB-LEDs with phosphor–silicone composite layer was studied. The results show that for blue light COB-LEDs with pure cylindrical tuber silicone layer, the light efficiency increases with the contact angle and a highest light efficiency enhancement of 62.6% was achieved at 90 deg when compared to the flat silicone layer. For white light COB-LEDs at correlated color temperature (CCT) of ∼5500 K, the cylindrical tuber silicone layer enhances the light efficiency by 13.6% when compared to the conventional flat phosphor layer.

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