Facile fabrication and luminescence characteristics of Ce:YAG phosphor glass thick films coated on a glass substrate for white LEDs

Abstract

A pivotal step in providing a better fluorescent material that has high luminous efficacy and excellent thermal stability is to utilize inexpensive phosphors for white light-emitting diodes (W-LEDs). Herein, we demonstrate a feasible tape-casting technique for creating phosphor thick films that consist of Ce: YAG phosphor embedded in relatively low melting point glass frits on an ultrathin glass substrate with controllable film thickness. The glass matrix has ideal densification and interfaces with the glass substrate at a relatively low temperature of 580°C. Subsequently, the structure and optical properties of the phosphor layer are investigated. In addition, the effect of the phosphor concentration, thick film thickness and location (top or bottom) of the phosphor layer on the photoluminescence properties and chromaticity are also discussed with respect to use in W-LEDs. Significantly, this promising structure has excellent thermal stability and the potential to overcome current limitations of phosphors in high-power W-LEDs. Finally, a high-performance W-LED based on the planar phosphor glass exhibits a luminous efficiency of 108.45lmW−1, a correlated color temperature of 5408K and a color rendering index of 76.