Sr3Y(BO3)3:Bi3+ phosphor with excellent thermal stability and color tunability for near-ultraviolet white-light LEDs

Abstract

In this study, a blue fluorescent material Sr₃Y(BO₃)₃:Bi³⁺ was synthesized by the high temperature solid-state reaction method. The corresponding structural characteristics, concentration and temperature dependent luminescence characteristics of Sr₃Y(BO₃)₃:Bi³⁺ and the LED device performances were systematically studied. At different excitation wavelengths in the range of 340–375 nm, the photoluminescence (PL) region can be adjusted from green (CIE: (0.2524, 0.4063); Peak: 511 nm) to blue (CIE: (0.1936, 0.1236); Peak: 415 nm). The best excitation peaked at ∼370 nm, which well matches with the emission of a commercial near-ultraviolet (NUV) light-emitting diode (LED) chip. The thermal quenching experiment was performed, and the activation energy was calculated as 0.23 eV. At high temperature, the Sr_2.55Y(BO₃)₃:0.45Bi³⁺ phosphor presented good thermal stability (79.99% of RT emission intensity at 420 K). LED devices (chip: 370 nm) using the Sr_2.55Y(BO₃)₃:0.45Bi³⁺ phosphor as a fluorescent material showed excellent electroluminescence performance. Under a driving current of 20 mA, the devices showed CIE coordinates of (0.3842, 0.3980), a correlated color temperature (CCT) of 4053 K and a high color rendering index (R_a) of 91.6. This work demonstrates that Sr₃Y(BO₃)₃:Bi³⁺ is a promising NUV excited blue fluorescent material which shows advantage in white light-emitting diodes for solid-state lighting.