A full-color emitting phosphor Ca9Ce(PO4)7:Mn2+, Tb3+: Efficient energy transfer, stable thermal stability and high quantum efficiency

Herein, we report a series of phosphate phosphors Ca9Ce(PO4)7:xTb3+/yMn2+, exhibiting much efficient energy transfer, stable thermal stability and high quantum efficiency. First of all, Ca9Ce(PO4)7 host is full of sensitizers (Ce3+) and the maximum energy transfer efficiency from Ce3+ to Mn2+ and Tb3+ reaches 91% and 72%, respectively. In Ca9Ce(PO4)7:xTb3+/yMn2+ system, white light can be obtained by mixing the tricolor composition at a suitable ratio. Energy transfer from Ce3+ to Mn2+/Tb3+ is confirmed via an electronic dipole-dipole (d-d) interaction. We found that the Mn2+ emission intensity of Ca9Ce(PO4)7: Mn2+ keeps unchanged during the rising temperature and the Tb emission lines of Ca9Ce(PO4)7:0.15Tb3+ are not affected by the increasing temperature. Meanwhile, quantum efficiency (QE > 60%) of Ca9Ce(PO4)7:xTb3+/yMn2+ presents a stable output until the temperature rises to 150 °C. We also report the luminescence quenching temperature (T > 300 °C) and the activation energy for thermal quenching (ΔE > 0.2 eV). To prove the potential application, a proof-of-concept white LEDs is fabricated by combining the single-component phosphor Ca9Ce(PO4)7:Mn2+, Tb3+ with a UV LED chip, which has a CIE chromaticity coordinate (0.347, 0.344), color temperature (4770 K), color rendering index (Ra = 80.4) and R9 = 92.3.