Formation and Encapsulation of Lead Halide Perovskites in Lanthanide Metal-Organic Frameworks for Tunable Emission

Improving the stability of perovskite quantum dots and adjusting their optical properties are essential for their application in advanced optoelectronic equipment. We provide a simple synthetic method to hybridize perovskite quantum dots and metal-organic frameworks (MOFs) into a polymer matrix. The hybrid material is made by encapsulating perovskite CH₃NH₃PbBr₃ quantum dots in lanthanide-based metal-organic frameworks. A series of lanthanide-based metal-organic frameworks (LnMOFs), namely, [Ln(tpob)(DMF)(H₂O)] (Lntpob, Ln = Nd, Sm, Eu, Gd, Tb, Dy, H₃tpob = 1,3,5-tris(4-carbonylphenyloxy)benzene), have been synthesized under solvothermal conditions and fully characterized. Lntpobs display a three-dimensional (3D) pcu network with central-symmetric [Eu₂(COO)₄] structural building units (SBUs) linked by one-dimensional (1D) chains. CHNHPbBr@Eutpob hybrids were developed through a three-step process, in which the precursor PbBr@Eutpob was formed by immersing the Eutpob crystal synthesized in the first step into a PbBr₂ solution; then the composite materials could form quickly when CH₃NH₃Br was added to the precursor. Therefore, the hybrid composite material exhibits luminescent properties related to the excitation wavelength in the form of powders or thin films. In addition, the photoluminescence of the CHNHPbBr@Eutpob composite can be improved and maintained for a long time after it is introduced into the poly(methyl methacrylate) (PMMA) matrix. Moreover, the emission peak based on the perovskite quantum dots can still maintain about 85% of the original intensity after being left for 30 days. Also, the obtained PMMA films can achieve tunable emission from red to green.