Designing tunable luminescence in Ce3+/Eu2+-codoped Ca8Zn(SiO4)4Cl2 phosphors for white light-emitting diode and optical anti-counterfeiting applications

Abstract

Developing highly-efficient phosphors with tunable emissions is important since they can realize multiple applications in one compound. Herein, Ce3+/Eu2+-codoped Ca8Zn(SiO4)4Cl2 phosphors with multicolor emissions are developed to meet this requirement. The phase composition, microstructure, luminescence properties and thermal stability of the synthesized phosphors are investigated. Excited by 360 nm, Ce3+-doped Ca8Zn(SiO4)4Cl2 phosphors can emit dazzling blue light, where its intensity is impacted by Ce3+ content and the involved concentration quenching mechanism is contributed by electric dipole-dipole interaction. Moreover, with Eu2+ codoping, tunable luminescence (i.e., from blue to cyan and finally to green), which is caused by the energy transfer from Ce3+ to Eu2+, is realized in the resultant compounds excited at 360 nm. Through theoretical analysis based on emission spectrum and decay time, it is found that the energy transfer between Ce3+ and Eu2+ in the selected host lattices is efficient and its corresponding mechanism is decided by electric dipole-dipole interaction. Furthermore, the synthesized phosphors not only have splendid thermal stability but also show appropriate internal and extra quantum efficiencies of 37.6% and 15.6%, respectively. Using the designed phosphors as a cyan emitting component, a warm white light-emitting diode (i.e., white-LED) was packaged, where its correlated color temperature and color rendering index values are 4964 K and 92.4, respectively, when the driven current is 100 mA. Additionally, the feasibility of the obtained samples for optical anti-counterfeiting application is also explored. These achievements suggest that Ce3+/Eu2+-codoped Ca8Zn(SiO4)4Cl2 phosphors are promising candidates for both white-LED and optical anti-counterfeiting applications.