In this work, we report on the promising photoluminescent behavior of the cubic double perovskite Cs 2 NaBiCl 6 doped with Mn 2+ ions. Localized excitations centered on Bi 3+ ions in the host lattice strongly absorb near-UV light. In the undoped host compound, only very weak photoluminescence is observed, but in manganese-doped samples, energy transfer from Bi 3+ to Mn 2+ leads to intense orange-red photoluminescence. A broad emission peak centered at 590 nm is assigned to the 4 T 1 → 6 A 1 transition of octahedrally coordinated Mn 2+ . The excitation spectrum contains peaks at 294 and 354 nm that arise from 6s 2 → 6s 1 6p 1 excitations of Bi 3+ ions. If the chloride ions are partially replaced by bromide ions, the strongest excitation peak red-shifts to 375 nm. The lack of expensive reagents and toxic elements and the ability to tune the excitation and emission spectra through chemical substitution make Cs 2 NaBiCl 6−x Br x :Mn 2+ a promising phosphor system.

The halide double perovskite Cs2NaInCl6 doped with Sb3+ is shown to be a promising blue phosphor.

The structural, optical, and magnetic properties of the vacancy-ordered quadruple perovskites Cs 4 CdBi 2 Cl 12 and Cs 4 MnBi 2 Cl 12 and their solid solution have been investigated. Both compounds crystallize with the R3̅ m space group symmetry that arises from the ordering of Bi 3+ , Mn 2+ /Cd 2+ , and cation vacancies into layers that run perpendicular to the ⟨111⟩ direction of the cubic perovskite structure. Cs 4 MnBi 2 Cl 12 is paramagnetic down to 2 K with a Weiss constant of −2.88(3) K and an effective moment of 5.840(1) μ B . This compound exhibits weak orange-red luminescence, which involves Bi 3+ ions absorbing near-UV photons, followed by energy transfer to Mn 2+ ions and finally radiative decay that is attributed to a spin-forbidden 4 T 1 (G) → 6 A 1 (S) d−d transition. The emission peak is centered near 605 nm with a fullwidth at half-maximum of ∼90 nm and a photoluminescence quantum yield (PLQY) of ∼4%. The isostructural Cs 4 CdBi 2 Cl 12 is neither magnetic nor does it show detectable PL at room temperature. Replacing Mn 2+ with Cd 2+ to form Cs 4 Cd 1−x Mn x Bi 2 Cl 12 leads to a zero-dimensional electronic structure that inhibits energy migration to defect sites where nonradiative decay can occur, increasing the room temperature PLQY to 57% in the x = 0.27 sample. Cs 4 Cd 1−x Mn x Bi 2 Cl 12 phosphors are easily synthesized from solution, do not contain rare-earth ions, and possess emission spectra that compare favorably to narrow band, red phosphors containing Eu 2+ .