Enhanced luminescence and tunable color in [Eu2+, Si4+]/Mn2+ doped K2BaCa(PO4)2 based on charge compensation and energy transfer

Abstract

Recently, using the Eu²⁺ → Mn²⁺ energy transfer strategy to explore new single-phase phosphors suitable for the near-ultraviolet (n-UV) region has become one of the major strategies in solid-state lighting applications. Therefore, a novel color-tunable K₂BaCa(PO₄)₂ (KBCPO):[Eu²⁺,Si⁴⁺],Mn²⁺ phosphor was developed because of the preeminent thermal stability of luminescence of Eu²⁺-activated KBCPO. In this study, we first designed a [Eu²⁺, Si⁴⁺] → [K⁺, P⁵⁺] charge compensation strategy to optimize the luminescence properties of Eu²⁺ in the KBCPO matrix. In terms of the obtained KBCPO:[Eu²⁺,Si⁴⁺] phosphor, this charge compensation method on the one hand strengthens the emission of Eu²⁺, and on the other hand, it dramatically improves the thermal stability of luminescence. In particular, the emission intensity of the KBCPO:0.03[Eu²⁺,Si⁴⁺] sample at 548 K can reach 103% relative to that at the initial temperature of 298 K. Based on this charge compensation strategy, we finally obtained a new dual emission KBCPO:[Eu²⁺,Si⁴⁺],Mn²⁺ phosphor. The analysis of the luminescence properties indicates that the emission enhancement of Mn²⁺ in KBCPO:[Eu²⁺,Si⁴⁺],Mn²⁺ stems from the energy transfer of Eu²⁺ → Mn²⁺ with the mechanism of the electric dipole–dipole interaction when excited at 365 nm. In addition, KBCPO:[Eu²⁺,Si⁴⁺],Mn²⁺ also has excellent thermal stability and the emission color could be easily tuned from cyan to orange only by adjusting the Eu²⁺ doping level. These results confirm that the KBCPO:[Eu²⁺,Si⁴⁺],Mn²⁺ phosphor is a viable candidate for n-UV white light emitting diodes.