Magnetic coupling for highly efficient and tunable emission in CsCdX3:Mn perovskites

All-inorganic ABX3 (X = Cl,Br,I) can work as an ionic luminescence material in optoelectronic field. Here Mn-doped CsCdCl3 hexagonal perovskite powders were synthesized and found to give bright orange-yellow colored emission at room temperature with an astonishingly quantum yield close to 100% at successful incorporation of 2.1% atomic ratio Mn ions. This enhanced emission comes from the local magnetic polaron—combined STEs with ferromagnetic Mn–Mn pair d-d transition (4T1→6A1) in replacement of Cd dimers in the CsCdCl3 lattice. Compared with CsCdBr3, this local magnetic polaron rely on the magnetic couplings, for example, in the Mn ions in the octahedral point and edge alternately connected 1-d chain and between 1-d chains, upon Mn concentrations. The magnetic coupling can modify the optical absorption edge and photoluminescence quantum yield (PLQY), and tune emission color from yellow to red. The PLQY maximum occurs at 350 K. The more Mn–Mn FM coupling in denser Mn-X octahedra face-shared chains in the bromides lead to a larger emission redshift than in the chloride. The magnetic coupling in the perovskite out of local Mn connection styles (separated, or point, edge and face shared TM ions) can determine its PLQY and emission color, which is useful in the future material design and optoelectronic or spintronic devices.