Optical analysis of Dy3+/Sm3+ co-doped NaY(MoO4)2 phosphors for warm white LED

Abstract

A series of NaY(MoO4)2: RE3+(RE=Dy3+, Sm3+) materials were synthesized by high temperature solid phase method and coated on UV chip to prepare white light LED devices. XRD and SEM scans showed that the material was small spherical particles, and the crystal form was consistent with the standard NaY(MoO4)2. The fluorescence spectrum analysis shows that under the excitation of 400 nm near-ultraviolet light, NaY(MoO4)2: Dy3+, Sm3+ materials show 482 nm blue light and 570 nm green-yellow light corresponding to the characteristic transitions of 4F9/2→6H15/2 and 4F9/2→6H13/2 of Dy3+, while yellow light at 600 nm and red light at 646 nm, on the other hand, correspond to characteristic transitions of 4G5/2→6H7/2 and 4G5/2→6H9/2 for Sm3+. Under the excitation of near ultraviolet light, the superposition of three colors can form a good white light emission. According to Dexter 's theory of energy transfer method, it is calculated that the mechanism of energy transfer is galvanic dipole-galvanic dipole interaction. The white light LED device can realize warm white light emission (3705 K) alone, and greatly reduce the cost under the premise of reducing the harm of blue light to the human eye. It suggests that this material is an excellent single substrate white phosphor material that can be applied to near-UV excited white LEDs.