Improvement of Photophysical Properties of CsPbBr3 and Mn2+:CsPb(Br,Cl)3 Perovskite Nanocrystals by Sr2+ Doping for White Light-Emitting Diodes

All-inorganic metal halide perovskite
nanocrystals (NCs) having
the general formula ABX3, where A is a monovalent cation,
for example, Cs+, B is a divalent cation, typically Pb2+, and X is Cl–, Br–,
I–, or their binary mixture, show potential in optoelectronic
devices. In this work, we explore the effect of B-site doping on the
optoelectronic properties of CsPbX3 NCs (X = Br, Cl). First,
the Pb2+ ions in the pristine CsPbBr3 NC are
partially substituted by Mn2+ ions. The alkaline earth
metal strontium is then doped on both pristine and the Mn2+-substituted NCs. We found that a small percentage of Sr2+ doping remarkably improves the photoluminescence quantum yield of
CsPbBr3 and Mn2+-state emission in Mn2+:CsPb­(Br,Cl)3 NCs. Perovskite NC film/poly­(methyl methacrylate)
composites with all four NC variants were used in a white light-emitting
diode (WLED), where Sr2+ doping increased the luminous
efficiency of the WLED by ∼4.7%. We attribute this performance
enhancement to a reduced defect density and an attenuated microstrain
in the local NC structure.

所有无机金属卤化物钙钛矿纳米晶体（NCs），其通式为ABX3，其中A为单价阳离子，例如Cs+，B为二价阳离子，通常为Pb2+，而X为Cl–、Br–、I–或其二元混合物，在光电子器件领域展现出巨大潜力。在本研究中，我们探讨了B位掺杂对CsPbX3 NCs（X = Br, Cl）的光电子性能的影响。首先，在原始CsPbBr3 NC中，Pb2+离子部分被Mn2+离子替代。随后，对原始和Mn2+-替代的NCs进行了碱土金属锶的掺杂。我们发现，少量Sr2+的掺杂显著提高了CsPbBr3以及Mn2+:CsPb(Br,Cl)3 NCs中的Mn2+-态发光的光致发光量子产率。包含四种NC变种的钙钛矿NC薄膜/聚甲基丙烯酸甲酯复合材料被用于白色发光二极管（WLED）中，其中Sr2+掺杂使得WLED的发光效率提高了约4.7%。我们归因于这种性能提升的原因是缺陷密度的降低和局部NC结构微应力的减弱。