Luminescence enhancement of spherical Sr3La(PO4)3:Eu3+ red nanophosphor with core–shell configuration and added sensitizer for low-voltage field-emission lamp

摘要： Spherical red Sr3La(PO4)3:Bi3+,Eu3+ (SLPO:Bi3+,Eu3+) nanophosphors were synthesized by coprecipitation and thermal annealing for a low-voltage field-emission lamp (FEL). The luminescence intensity of the phosphor was improved using a coreeshell configuration with SiO2 as the core with a diameter of 360 nm and 5e15-nm-thick phosphor as the shell. A 4.4-fold enhancement in the external quantum efficiency (EQE) was obtained. A bright red cathodoluminescence was observed from a 0.25-cm2 FEL at 400 V. The excitation energy efficiently cascade-transferred through the Bi3+ sensitizer to the Eu3+ activator. A coreeshell SLPO:Bi3+,Eu3+ nanophosphor with a maximum EQE of 25.4% and high color purity of 99.7% was obtained when 5-mol% Bi3+ was doped. The energy transfer mechanism and model of the phosphor are proposed.