Formation\nand Encapsulation of Lead Halide Perovskites in Lanthanide Metal–Organic\nFrameworks for Tunable Emission

Abstract

Improving\nthe stability of perovskite quantum dots and adjusting their optical\nproperties are essential for their application in advanced optoelectronic\nequipment. We provide a simple synthetic method to hybridize perovskite\nquantum dots and metal–organic frameworks (MOFs) into a polymer\nmatrix. The hybrid material is made by encapsulating perovskite CH₃NH₃PbBr₃ quantum dots in lanthanide-based\nmetal–organic frameworks. A series of lanthanide-based metal–organic\nframeworks (LnMOFs), namely, [Ln­(tpob)­(DMF)­(H₂O)]<i>_n</i> (<b>Lntpob</b>, Ln = Nd, Sm, Eu, Gd,\nTb, Dy, H₃tpob = 1,3,5-tris­(4-carbonylphenyloxy)­benzene),\nhave been synthesized under solvothermal conditions and fully characterized. <b>Lntpob</b>s display a three-dimensional (3D) <b>pcu</b> network\nwith central-symmetric [Eu₂(COO)₄] structural\nbuilding units (SBUs) linked by one-dimensional (1D) chains. <b>CH</b>_<b>3</b><b>NH</b>_<b>3</b><b>PbBr</b>_<b>3</b><b>@Eutpob</b> hybrids were developed through a three-step process, in which the\nprecursor <b>PbBr</b>_<b>2</b><b>@Eutpob</b> was formed by immersing the <b>Eutpob</b> crystal synthesized\nin the first step into a PbBr₂ solution; then the composite\nmaterials could form quickly when CH₃NH₃Br was\nadded to the precursor. Therefore, the hybrid composite material exhibits\nluminescent properties related to the excitation wavelength in the\nform of powders or thin films. In addition, the photoluminescence\nof the <b>CH</b>_<b>3</b><b>NH</b>_<b>3</b><b>PbBr</b>_<b>3</b><b>@Eutpob</b> composite can be improved and maintained for a long\ntime after it is introduced into the poly­(methyl methacrylate) (PMMA)\nmatrix. Moreover, the emission peak based on the perovskite quantum\ndots can still maintain about 85% of the original intensity after\nbeing left for 30 days. Also, the obtained PMMA films can achieve\ntunable emission from red to green.