How to induce highly efficient long-lasting phosphorescence in a lamp with a commercial phosphor: a facile method and fundamental mechanisms

Abstract

We successfully tailor the properties of a well-known commercial lamp used Zn2SiO4:Mn 2+ phosphor as a novel, highly efficient, long-lasting green phosphor with the co-doping method. The long-lasting phosphorescence (LLP) of the optimal Zn2SiO4:Mn 2+ ,Yb 3+ sample can be recorded for approximately 30 h (0.32 mcd/m 2 ) and is visible for even more than 60 h in dark by using dark-adapted vision. This exciting result is sufficiently encouraging for the initiation of a more thorough investigation. Several classical methods of investigation including decay curves, thermoluminescence, fading experiments, multi-peak fitting based on general-order kinetics, and first-principle calculations are used in this study to examine the LLP properties, the effects of such co-dopants and the nature of traps in detail. The important retrapping and tunneling effects, combined with a kinetics investigation, are discussed. A modified law concerning the influences of co-dopants on the traps around the Mn 2+ (3d5, d→d type) centers and the LLP properties are summarized. Finally, the LLP mechanism of the Zn2SiO4:Mn 2+ ,Yb 3+ phosphor is proposed.

Structure, long persistent luminescent properties and mechanism of a novel efficient red emitting Ca2Ga2GeO7:Pr3+ phosphor

“…The actual situation may be that the retrapping can be ignored in the early stage (t < 300 s) resulting in the well-fitting with the exponential curve, then the retrapping becomes dominate which contributes the LPL decay time in the later stage (t > 300 s), leading to the deviation of the curves, no more sticks to the first-order kinetics mode. Actually, the existing formulas are always in accordance with the experimental decay data in the initial fast decay stage [26][27]. This result is due to that every charge carrier managing to thermally escape from a trap can immediately move to Pr 3+ levels for efficient recombination through the conduction band, and will not be captured by another trap.…”

Surface crystallized Mn‐doped glass‐ceramics for tunable luminescence

“…All glass and GC samples present a broad red emission band from 500 to 780 nm centering at 610 nm, which can be assigned to spin-forbidden 4 T 1g (G)→ 6 A 1g (S) transition of Mn 2+ (d 5 ) located in the octahedral coordination site of the glass host. [39][40][41] We note that the Mn 2+ ions are located in the tetrahedral site in the precipitated crystals, but obviously, the related emission is not dominating here. 23,42,43 All the GC samples-heat treated at 790°C for 1 h maintain the red emission with a slight redshift accompanied by increasing the Mn 2+ concentration (inset in Figure 4B).…”

“…The emission spectra were measured at an excitation wavelength of 275 nm. All glass and GC samples present a broad red emission band from 500 to 780 nm centering at 610 nm, which can be assigned to spin‐forbidden 4 T 1g (G)→ 6 A 1g (S) transition of Mn 2+ (d 5 ) located in the octahedral coordination site of the glass host . We note that the Mn 2+ ions are located in the tetrahedral site in the precipitated crystals, but obviously, the related emission is not dominating here .…”

Crystallization‐induced valence state change of Mn2+ → Mn4+ in LiNaGe4O9 glass‐ceramics

“…As shown in Figure 7A,B, under excitation wavelength (λ = 410 nm), the emission spectra of the sample G-0.5 display a broad band from 500 to 780 nm centering at 613 nm, which can be attributed to spin-forbidden 4 T 1g (G) → 6 A 1g (S) transition of Mn 2+ (d 5 ) located in the octahedral coordination site of the glass host. 12,[34][35][36] In the excitation spectra (monitored at λ = 613 nm), the spectrum shows a strong and broad band located at 265 nm corresponding to Mn-O charge transfer (CT) transition, and three other bands located at 347 nm, 361 nm, and 408 nm, attributed to transitions 6 A 1g (s) → 4 E( 4 D), 6 A 1g (s) → 4 T 2g (D), and 6 A 1g (s) → ( 4 E 1g (G), 4 E 1g (G)), respectively. This result is in good agreement with the absorption spectra ( Figure 4B).…”