Blue–white–orange color-tunable luminescence of Ce3+/Mn2+-codoped NaCaBO3via energy transfer: potential single-phase white-light-emitting phosphors

Abstract

Ce³⁺/Mn²⁺-codoped NaCaBO₃ single-phase color-tunable phosphors were synthesized by solid-state reaction, and their photoluminescence properties were investigated in detail. Under UV excitation, two main emission bands peaking at 400 and 610 nm were realized in the NaCa_0.89BO₃: 0.01Ce³⁺, 0.10Mn²⁺ phosphor on the basis of the energy transfer from Ce³⁺ to Mn²⁺ with an efficiency of over 83%. The energy transfer was validated and demonstrated to be a resonant type via a dipole–dipole mechanism, and the critical distance R_C values calculated by the quenching concentration method and the spectral overlap method were 22.85 and 19.41 Å, respectively. On examining the Mn²⁺-concentration-dependent photoluminescence properties, it was observed that the emission color could be tuned from blue (0.162, 0.031) to white-light (0.335, 0.259) and eventually to orange (0.489, 0.246) through energy transfer by changing the Ce³⁺/Mn²⁺ ratio. Combining a 370 nm UV chip and a single-phase white-emitting NaCa_0.96BO₃: 0.01Ce³⁺, 0.03Mn²⁺ phosphor produced a white light-emitting diode with CIE chromaticity coordinates of (0.326, 0.274) and an excellent color rendering index of 90.7 at a correlated color temperature of 4046 K. These results indicate that the NaCaBO₃: Ce³⁺, Mn²⁺ phosphors have potential applications as single-phase white-light-emitting phosphor-converted materials for UV-pumped light-emitting diodes.