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)]n (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. CH3NH3PbBr3@Eutpob hybrids were developed through a three-step process, in which the
precursor PbBr2@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 CH3NH3PbBr3@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.