A double perovskite Sr 2 ZnMoO 6 :Mn 4+ (SZM:Mn 4+ ) phosphor is synthesized by high-temperature solid-state reaction method in air. Emission band peaking at ∼705 nm of SZM:Mn 4+ phosphor in the range of 650–790 nm is attributed to the 2 E → 4 A 2 transition of Mn 4+ ion with activated different lattice vibration modes. Three excitation bands in the range of 210–610 nm are assigned to the O 2− → Mn 4+ charge transfer and the 4 A 2 → ( 4 T 1 , 2 T 2 , and 4 T 2 ) transition of Mn 4+ ion. The optimal Mn 4+ ion concentration is ∼0.8 mol% in SZM:Mn 4+ phosphor. Fluorescence lifetime of SZM:Mn 4+ phosphor decreases from ∼132 μs to 108 μs with increasing Mn 4+ ion concentration in the range of 0.2–1.0 mol%. Time-resolved spectra and fluorescence lifetime data indicate that luminescent center is caused by Mn 4+ ion. The luminous mechanism of SZM:Mn 4+ phosphor is explained by Tanabe-Sugano energy level diagram of Mn 4+ ion. The results are useful to understand the influences of the neighboring coordination environment around Mn 4+ and host crystal structure to the luminescence properties of Mn 4+ ion and develop other novel Mn 4+ -doped materials.
Lead-free double perovskites (DPs), characterized by their low toxicity, broad emission spectra and excellent stability, have emerged as highly promising doped hosts with significant potential for visible light applications. However, achieving rich and distinctive multiple photoluminescent (PL) emission through doping with various lanthanide (Ln 3+ ) ions remains a formidable challenge. In this work, we explored the luminescent properties of Cs 2 KInCl 6 , which exhibits intrinsic broad self-trapped excitons (STEs) emission centered at 500 nm. By doping Ln 3+ ions (Dy 3+ , Sm 3+ , and Tb 3+ ) into Cs 2 KInCl 6 , multiple emission could be realized, along with energy transfer (ET) from the intrinsic STEs to Tb 3+ and Sm 3+ ions. Notably, the incorporation of Tb 3+ ions enhanced exciton-phonon coupling and lattice vibrations , resulting in strengthened STEs emission. Furthermore, tunable emission from green to yellow was achieved through multiple ET processes in Cs 2 KInCl 6 :Tb 3+ ,Sm 3+ by co-doping Tb 3+ and Sm 3+ . This work not only offers new insights into enhancing STEs emission in DPs, but also imparts Cs 2 KInCl 6 with tunable PL properties, which makes it a promising candidate for multicolor light-emitting devices.
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