Method for the analysis of saturation effects of cathodoluminescence in phosphors; applied to Zn2SiO4:Mn and Y3Al5O12:Tb

Inverse bottleneck in Eu2+–Mn2+ energy transfer

“…Thermal effects are found to be negligible by analyzing the Mn 2+ emission green shift and intensity versus temperature; the 150 1C efficiency of HALO is 490% of the room temperature value. Given the literature on the saturation of Mn 2+ phosphors whose main cause is the slow Mn 2+ emission (t$11.3 ms in HALO) [12][13][14][15][16][17], it is reasonable to assign the Mn 2+ quenching of HALO in these pcLEDs to saturation. However, standard models cannot explain the Eu 2+ quenching due to the fast radiative decay time of Eu 2+ (t$580 ns for Ca 5 (PO 4 ) 3 Cl:Eu 2+ ), and experiments with Eu 2+ phosphors in similar pcLEDs show virtually no quenching with variations in the LED excitation duty cycle.…”

“…6); a single exponential fit to the Mn 2+ decay profile in HALO-coated pcLEDs has t ¼ 9.6 ms versus spectrometer measurements of 11.3 ms. The faster decay is indication that energy transfer to the Mn 2+ -excited state also occurs between excited Mn 2+ ions [13,17,20].…”

“…8). Taking this similarity into account, we take the route of using rate equations to analyze both Eu 2+ and Mn 2+ emission quenching with the addition of ground state depletion [12,16,17] due to the long Mn 2+ lifetime and relatively high violet LED fluxes (89 s À1 ), and k rate constant for ET between excited Mn 2+ ions [13,17,20]. There are two main assumptions that we have in using these rate equations.…”

Phosphor quenching in LED packages: measurements, mechanisms, and paths forward

“…Since the 150 o C efficiency of HALO is >90% of the room temperature value, thermal effects are neglected in this analysis. Given this and the literature on the saturation of Mn 2+ phosphors arising from the slow Mn 2+ emission (τ~11.3 ms in HALO) [8][9][10], it is reasonable to assign the Mn 2+ quenching of HALO in these pcLEDs to saturation. These additional paths for Mn 2+ emission quenching can be analyzed using standard mechanisms for phosphor saturation: ground state depletion and ET between excited activator ions [8][9][10].…”

Investigation of host-to-activator energy transfer and surface losses in SrY2O4:Eu3+ under VUV excitation

“…It has been shown that if the excitation density is below saturation, and in the absence of surface losses, the transfer efficiency can be modeled using first-order competition kinetics between trapping at the activator and trapping at bulk killers [1,[11][12][13],…”