Lanthanide-based metal-organic frameworks (MOFs) exhibit highly promising photoluminescent properties as these materials can emit light from the visible to the near-infrared regions due to the unique 4f-orbital electronic structure of the lanthanide nodes. While down-shifting emission is the most common luminescence process in these systems, the development of MOFs for photon up-conversion luminescence is a challenging and actively investigated field. In this project, we aim to characterize novel Yb-based luminescent MOFs that enable photon up-conversion with varying dopant compositions. A combined XAS/PXRD characterization under both normal and photoluminescent conditions will be highly beneficial to shed light onto the multiple phases of these MOFs about which very little structural information is currently available. We expect our project to unravel the influence of structural parameters on the MOF luminescent properties.