Sensitization of Mn²⁺ Luminescence by Eu²⁺: A Combined Study Using Optical Spectroscopy and Luminescence Dynamics Simulations

Abstract

Owing to the intriguing luminescent feature, Mn2+-doped materials have attracted a lot of attention. Unfortunately, their application potential is hampered by the parity-forbidden nature of Mn2+ 3d–3d transition, and the insufficient excitation light absorption is the main obstacle. Although the use of a sensitization strategy effectively addresses this issue, explicit knowledge of the sensitization mechanism is insufficient, severely limiting the improvement of Mn2+ luminescence performance in a wide range of materials. Herein, the sensitization of Mn2+ luminescence is investigated in Eu2+, Mn2+-codoped SrMgP2O7 which has the high luminescence efficiency upon UV excitation. The electronic transition properties of Eu2+ and Mn2+ are studied by VUV–UV–vis spectroscopy, and the sensitization mechanism is elucidated by luminescence dynamics simulations. Efforts are also made to evaluate the impact of temperature variation on the sensitization efficiency. Based on these discussions, the collaboration of high-efficiency Eu2+ → Mn2+ energy transfer via dipole–dipole interaction and suppression of Mn2+ luminescence loss results in the significant sensitization of Mn2+ luminescence in Eu2+, Mn2+-codoped materials, which are essentially associated with probable orbital hybridization and weak electron–vibration interaction, respectively. Current research provides a practical guideline for analyzing the luminescence sensitization effect in the donor–acceptor system, which facilitates the development of materials with unique optical features.

4f → 3d sensitization: a luminescent EuII–MnII heteronuclear complex with a near-unity quantum yield

“…In well-studied Eu II -Mn II co-doped inorganic phosphors, the sensitizerÀactivator energy transfer efficiency is mainly governed by the spatial distance between the two ions. 25 Both Dexter energy transfer 21,35 and electric dipole-quadrupole interaction have been proposed as the energy transfer mechanism. 24,36 As for [Eu(N2O6)]MnBr 4 , the shortest distance between Eu II and Mn II is 6.74 Å (Table 1), larger than the critical distance (5 Å) for an effective Dexter energy transfer, 37 and no aromatic group exists as an electron-transfer medium.…”

“…´forbidden 3d-3d transitions, is commonly sensitized by organic ligands cooperated by halide ions. Although Mn II -activated inorganic solid phosphors employing Eu II as the sensitizer were proposed since the 1970s, [20][21][22][23][24][25] incomplete energy transfer always hinders the performance improvements due to the relatively long distance between the activator and the sensitizer. In addition, a Eu II -Mn II bimetallic complex has not been reported and the corresponding energy transfer process has not been explored yet.…”

High performance of broad excitation and narrow emission green phosphor NaAl11O17:Eu2+, Mn2+for backlight displays

“…As an important parameter to assess the thermal quenching effect, the activation energy (Δ E ), was calculated using the Arrhenius formula. 50 Fig. 6c and d show the linear relationship between ln( I (0)/ I ( T ) − 1) and 1/ kT of NaAl 10.6 O 17 :0.40Mn 2+ and Na 0.8 Al 10.6 O 17 :0.20Eu 2+ , 0.40Mn 2+ samples.…”