Optical Properties and Concentration Quenching Mechanism of Er3+ Heavy Doped Gd2(MoO4)3 Phosphor for Green Light-Emitting Diode

Upconversion materials capable of converting low-energy excitation photons into high-energy emission photons have attracted considerable interest in recent years. However, the low upconversion luminescence seriously hinders the application of upconversion phosphors. Heavy lanthanide doping without concentration quenching represents a direct and effective method to enhance the emission intensity. In this study, Er³⁺ heavy doped Gd₂(MoO₄)₃ phosphor with a monoclinic phase was prepared by a sol-gel process. Under excitation at 976 nm, Gd₂(MoO₄)₃:Er³⁺ phosphor emitted remarkably intense green emission, and Er³⁺ concentration up to 20 mol% did not cause concentration quenching. Here, we discuss the upconversion mechanism and concentration quenching. When the Er³⁺ concentration was in the range of 30-60 mol%, the concentration quenching was governed by the electric dipole-dipole interaction, and when the concentration was greater than 60 mol%, the concentration quenching was controlled by the exchange interactions. The result provides a schematic basis for identifying a phosphor host with heavy lanthanide doping.