Efficient and Stable Red-Orange Emission from Polaronic Magnetic Excitons in Mn (II)-Doped 0D All-Inorganic Rb4CdCl6

The impact of magnetic coupling effects on the luminescence of 0D (zero-dimensional) perovskite materials doped with TM (transition metal) ions remains underexplored. This study synthesizes Mn 2+ -doped 0D Rb 4 CdCl 6 halide structures using a solvent-based method, with Rb + ions systematically arranged around isolated [CdCl 6 ] 4− octahedra. The resulting Rb 4 Cd 1- x Mn x Cl 6 powder exhibits stable orange-red luminescence under UV (ultraviolet) excitation, achieving a PLQY (photoluminescence quantum yield) of 88.96%. The parent Rb 4 CdCl 6 is non-luminescent, but doping with Mn 2+ induces strong luminescence due to combined emissions from d-d transitions of Mn 2+ , weakly ferromagnetically coupled Mn 2+ pairs, and STEs (self-trapped excitons). Characterization via XRD (X-ray diffraction) and DFT (density functional theory) reveals that Mn 2+ doping occurs through both substitutional and interstitial processes, facilitating magnetic coupling. Raman spectroscopy identifies strong electron-phonon coupling at a phonon mode of 112 cm −1 , supporting STEs generation. Magnetic property analysis shows significant ferromagnetic coupling between Mn 2+ pairs and paramagnetic single Mn 2+ ions, enhancing luminescence. The material demonstrates remarkable structural and thermal stability, positioning Rb 4 Cd 1- x Mn x Cl 6 as a promising candidate for optoelectronic applications.