Potential single phased full colour white light Sr_2−xCeO₄∶xSm³⁺ phosphor for UV light emitting diodes

Abstract

A potential single phased white Sr₂CeO₄∶Sm³⁺ phosphor was fabricated by a hydrothermal calcine method. The luminescence intensity of Sr₂CeO₄ host and redistribution depended on the doped Sm³⁺ concentration. It is also found that the photoluminescence spectrum exhibits a redshift when the Sm³⁺ concentration is increased from 0 to 2 mol-%. The phosphor can emit full colour white light with the Sm³⁺ concentration increasing from 0·5 to 1·0 mol-%. The energy transfer model is interpreted as the possible mechanisms of energy transfer from Sr₂CeO₄ host to Sm³⁺ in Sr₂CeO₄∶Sm³⁺ system. The fabrication and packaging of a white phosphor-converted light emitting diode (LED) by adopting a white Sr₂CeO₄∶Sm³⁺ phosphor with an ultraviolet (UV) LED chip with the wavelength of 350 nm is also successfully demonstrated. A white light with colour coordinates (0·3315, 0·3109) and luminescence efficiency of 56 lm W⁻¹ could be obtained from the fabricated LEDs when keeping the Sr_2−xCeO₄∶xSm³⁺ phosphor doped with the content of Sm³⁺ at 1·0 mol-%, which shows that the phosphor is a promising single phase phosphor for UV LED.

Keywords:

• Photoluminescence
• Sr₂CeO₄ phosphor
• Energy transfer
• Light emitting diode

This work was financially supported by the National Natural Science Foundation of China (grant no. 51072234). The first author would also like to thank the China Scholarship Council for financial support (No. 201206370063).