Design of binder-free phosphor paste for warm white LEDs

Cerium-doped yttrium aluminum garnet (YAG: Ce) is used to convert blue light which is emitted from InGaN-based LED chip for white light. In this study, the phosphor paste was prepared using monodispersed spherical YAG: Ce phosphor synthesized by co-precipitation based on one-pot synthesis. Also, orange-red emitting Sr₂Si₅N₈:Eu²⁺ (SSN: Eu) phosphor was added to confirm the change in optical characteristics. Alpha terpineol was used as a paste solvent because it enabled easy screen-printing. Phosphor paste films for optoelectronic devices were prepared by coating on a glass substrate using a doctor blade method. We compared the conversion efficacy, color rendering index (CRI), and correlated color temperature (CCT) of YAG: Ce which is added to various amounts of SSN: Eu. We measured scanning electron microscopy (SEM) images to confirm the difference of porosity between, depending on binder addition.