Investigation of the thermal quenching of two emission centers in SrMnLi(PO):Eu using time-resolved technique.

The thermal stability of the phosphors in phosphor-converted light-emitting diodes (LEDs) plays an important role in the practical application of lighting. Herein, the Mn-based red-emitting phosphors of pure and Eu-doped SrMnLi(PO) (SMPO) samples were prepared using the high temperature solid-state reaction method. The crystal field environment around the Mn ions was analyzed by combining the results of photoluminescence excitation spectroscopy and Tanabe-Sugano diagrams. By comparing the results of X-ray photoelectron spectroscopy, two additional bands centered at about 129.8 eV and 130.7 eV were found in the Eu-doped sample, which corresponded to the chemical states of P 2p and P 2p. Two different sets of emission spectra were observed for SrMnLi(PO):5%Eu (SMPO:Eu) on employing the time-resolved technique. The emission peaks centered at 615 nm and 661 nm were attributed to Mn and Eu ions, respectively. The thermal quenching behaviors of Eu and Mn were investigated in the temperature range of 300-620 K and the thermal quenching mechanisms are given in this work. Systematic research on the luminescent properties of Eu and Mn ions in the SMPO:Eu phosphor contributes to the understanding of the thermal stability and aids in the development of Mn-based red-emitting phosphors.