Tunable Emission in Heteroepitaxial Ln-SURMOFs

By using a layer-by-layer (LbL) approach, lanthanide-based, monolithic metal-organic framework (MOF) thin films are fabricated for optical applications. In particular, the LbL approach allows manufacturing of heteroepitaxial Tb(III)-Eu(III)(BTC) coatings with precise thickness control. Adjusting the Tb(III)-to-Eu(III) ratio allows tuning of the emission color. The hetero-multilayer architecture makes it possible to suppress the direct Tb(III)-to-Eu(III) energy transfer, an unwanted phenomenon present in the corresponding mixed-metal bulk MOF structures. The resulting Ln-MOF thin films, or Ln-surface-anchored MOFs (SURMOFs), are characterized by X-ray diffraction, infra-red reflection absorption spectroscopy, UV-vis, and photoluminescence measurements. The results demonstrate that the heteroepitaxial SURMOF architectures carry huge potential for fabricating optical coatings for a wide range of applications.