Cs₄Cd_1–xMn_xBi₂Cl₁₂—A Vacancy-Ordered Halide Perovskite Phosphor with High-Efficiency Orange-Red Emission

Abstract

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+ .

Efficient Luminescent Halide Quadruple‐Perovskite Nanocrystals via Trap‐Engineering for Highly Sensitive Photodetectors

“…[ 31 ] Using the Tanabe−Sugano diagram for a high‐spin d5 ion, one can see that the 4 T 1 (G) → 6 A 1 (S) transition energy decreases as crystal‐field‐splitting Δ increases. [ 31–35 ] The structural analysis indicates that the MnCl bond is 2.256 Å in Cs 4 MnSb 2 Cl 12 NCs but 2.760 Å in Cs 4 MnBi 2 Cl 12 NCs. The red‐shifted PL of Cs 4 MnSb 2 Cl 12 is due to the shortening of the MnCl bond, i.e., the increase in MnCl bond covalency and Δ.…”

“…This phenomenon is similar to that in bulk samples, in which the incorporation of Cd 2+ into Cs 4 MnBi 2 Cl 12 may cause Mn 2+ dilution, thereby weaken the Mn–Mn coupling. [ 32 ] The measured PLQY of Cs 4 Mn 0.25 Cd 0.75 Bi 2 Cl 12 NCs was 47.9% (Figure S9, Supporting Information). This represents a 96‐fold enhancement compared to Cs 4 MnBi 2 Cl 12 NCs (0.5%).…”

“…[31] Using the Tanabe−Sugano diagram for a high-spin d5 ion, one can see that the 4 T 1 (G) → 6 A 1 (S) transition energy decreases as crystal-field-splitting Δ increases. [31][32][33][34][35] given that the six-coordinate ionic radius of Sb 3+ (0.90 Å) is smaller than for Bi 3+ (1.17 Å), which condenses the crystal structure. We also studied the Bi/Sb-alloyed Cs 4 MnBi x Sb 2−x Cl 12 NCs (XRD patterns of the alloyed NCs can be found in Figure S6a, Supporting Information).…”

Crystal structure, luminescence properties and application performance of color tuning Y2Mg2Al2Si2O12:Ce3+,Mn2+ phosphors for warm white light-emitting diodes

“…Even though the luminescence of Mn 2+ is very weak due to the forbidden transition, the luminous intensity can be effectively enhanced through the sensitizing effect of Ce 3+ . 29,30 As shown in Fig. 7a-c, the PL spectra of YMAS:0.06Ce 3+ ,yMn 2+ samples exhibit a significant red shift with increase in Mn 2+ doping concentration.…”

Efficient Emission in Halide Layered Double Perovskites: The Role of Sb3+ Substitution in Cs4Cd1–xMnxBi2Cl12 Phosphors

“…Variations in bond lengths and bond angles for several structures. The data for BiCl6 octahedra were obtained from the SCXRD data from Woodward 2. …”