Simple prismatic patterning approach for nearly room-temperature processed planar remote phosphor layers for enhanced white luminescence efficiency

Abstract

Efforts have been made to enhance light-extraction by controlling phosphor structure for higher efficiency white light-emitting diodes (LEDs). Here, we introduce a technical method for improving luminous efficacy by applying prismatic patterns for a planar remote yellow phosphor structure. The remote phosphor structure is based on a UV-cured prismatic pattern/polyethylene terephthalate (PET)/glass substrate/silicate phosphor layer. The phosphor layer was formed via another UV-curing process of the screen-printed polymer/ phosphor-mixture. As a result, the prismatic layer of the apex angle 90° of each pitch enhanced the luminous efficacy of the remote phosphor-LED by 29% compared with the reference sample when a smaller pitch size was used. As anticipated, it is assumed that the escape probability of the emitted lights from a blue LED chip through the phosphor structure increases by reducing the possibilities of total internal reflection at the top surfaces of the structure.