Cs4Cd1–xMnxBi2Cl12A Vacancy-Ordered Halide Perovskite Phosphor with High-Efficiency Orange-Red Emission

The structural, optical, and magnetic properties of the vacancy-ordered quadruple perovskites Cs4CdBi2Cl12 and Cs4MnBi2Cl12 and their solid solution have been investigated. Both compounds crystallize with the R3̅m space group symmetry that arises from the ordering of Bi3+, Mn2+/Cd2+, and cation vacancies into layers that run perpendicular to the ⟨111⟩ direction of the cubic perovskite structure. Cs4MnBi2Cl12 is paramagnetic down to 2 K with a Weiss constant of −2.88(3) K and an effective moment of 5.840(1) μB. This compound exhibits weak orange-red luminescence, which involves Bi3+ ions absorbing near-UV photons, followed by energy transfer to Mn2+ ions and finally radiative decay that is attributed to a spin-forbidden 4T1(G) → 6A1(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 Cs4CdBi2Cl12 is neither magnetic nor does it show detectable PL at room temperature. Replacing Mn2+ with Cd2+ to form Cs4Cd1–xMnxBi2Cl12 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. Cs4Cd1–xMnxBi2Cl12 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 Eu2+.

本研究针对空位有序四重钙钛矿Cs₄CdBi₂Cl₁₂、Cs₄MnBi₂Cl₁₂及其固溶体的结构、光学与磁学性质开展了系统性研究。两种化合物均以R3̅m空间群结晶，该空间群对称性源自Bi³+、Mn²+/Cd²+与阳离子空位有序排列形成的、垂直于立方钙钛矿结构⟨111⟩方向的层状结构。Cs₄MnBi₂Cl₁₂在低至2 K的温度下仍表现出顺磁性，其外斯常数为−2.88(3) K，有效磁矩为5.840(1) μB。该化合物呈现弱橙红色发光，发光过程为Bi³+离子吸收近紫外光子，随后将能量传递至Mn²+离子，最终通过自旋禁阻的⁴T₁(G) → ⁶A₁(S) d-d跃迁引发辐射衰减。其发射峰中心位于605 nm附近，半高全宽约为90 nm，光致发光量子产率（photoluminescence quantum yield, PLQY）约为4%。同结构的Cs₄CdBi₂Cl₁₂既无磁性，在室温下也未检测到可观测的光致发光。通过Cd²+取代Mn²+制备Cs₄Cd₁₋ₓMnₓBi₂Cl₁₂固溶体，可获得零维电子结构，该结构能够抑制能量迁移至易发生非辐射衰减的缺陷位点，使得x=0.27的样品在室温下的PLQY提升至57%。Cs₄Cd₁₋ₓMnₓBi₂Cl₁₂荧光粉可通过溶液法简便合成，且不含稀土离子，其发射光谱性能可与含Eu²+的窄带红色荧光粉相媲美。