Tunable long lasting phosphorescence due to the selective energy transfer from defects to luminescent centres via tunnelling in Mn2+ and Tm3+ co-doped zinc pyrophosphate

Abstract

A series of new phosphors Zn2(0.97-x)P2O7:0.06Tm(3+),2xMn(2+) (0 ≤ x ≤ 0.05) were synthesized and their luminescence properties were investigated. The results showed that the defects in all the phosphors were related to Tm(3+), and Mn(2+) merely served as the emission centres. Tm(3+) also acted as an emission centre and yielded blue phosphorescence corresponding to its characteristic f-f emissions in the phosphors where the Mn(2+) concentration was low (x ≤ 0.001), while in the phosphors with high concentrations of Mn(2+) it mainly served as a defect by forming Tm. The electrons thermally released from defects selectively transferred to Mn(2+) centres mainly through thermally-assisted tunnelling and this resulted in their red to near-infrared phosphorescence. By adjusting the ratio of Mn(2+) to Tm(3+) to control the spectral distribution, tunable long lasting phosphorescence from blue to near-infrared was achieved.

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

“…On the contrary, codoping of cations with larger ionization potentials correspondingly results in higher numbers and deeper depth of the deep traps (578 K). The same was observed in almost all of the other examples.Table 3shows a summary of the ionization potentials of ions and the influences of co-dopants on the TL peaks previously reported for some phosphors 23,24,32,[54][55][56][57][58][59][60][61][62][63][64][65]. It is obvious that when the ionization potentials of co-dopants such as Yb 3+ cations are lower than that of Mn2+ , the intensity of the TL peak at low temperature is increased and is shifted to a lower temperature.…”

Role of oxygen vacancies in long persistent phosphor Ca2Ga2GeO7: Zn2+

“…Traps usually do not emit radiation by themselves, instead they store excitation energy, which can be gradually released and transferred to the emitters owing to thermal or other physical stimulations. These centers nowadays, are usually focused on the discrete ions, i.e., rare‐earth ions or some vacancy defects . Oxygen vacancy () acting as electron trap is of great importance to LPL materials.…”

Enhancing the luminescent properites of Zn2P2O7: Ce3+, Dy3+ via efficient energy transfer

“…Zinc pyrophosphate is considered to be an ideal luminescent host due to its easy synthesis, low cost, high chemical and thermal stabilities, and environmental friendliness. Several RE doped Zinc pyrophosphate, such as Zn 2 P 2 O 7 : Tm 3+ , Zn 2 P 2 O 7 : Eu 3+ , Zn 2 P 2 O 7 : Tm 3+ , Mn 2+ , have been reported [21][22][23]. In order to enrich the color of the emitted light and improve the luminescent performance, it is necessary to choose other dopant ions for Zn 2 P 2 O 7 phosphor materials.…”