f-Block Element-Based MOF Thin Films: A Platform for Luminescence, Sensing, and Energy Applications

f-Block element-based metal-organic framework (f-MOF) thin films, incorporating lanthanides and actinides, have emerged as a promising class of materials due to their unique properties and potential in sensing, luminescence, and energy-related applications. While MOF powders have been widely explored, many advanced applications-particularly in optics, electronics, and heteroepitaxial integration-require the controlled architecture and substrate interface that only thin films can provide. This review comprehensively summarizes recent advances in the synthesis, characterization, and functional deployment of f-MOF thin films, highlighting diverse fabrication techniques such as composite MOF particle assembly, layer-by-layer deposition, in situ solvothermal deposition, and electrodeposition. Tabulated data covering polymeric matrices, self-supporting structures, substrates, and synthesis conditions are included to support comparative analysis. The wide range of demonstrated applications, including luminescence sensing, anti-counterfeiting, radiation detection, and catalysis, are critically assessed alongside challenges in film stability, scalability, and performance optimization. Finally, future research directions are proposed, emphasizing the need for innovative synthetic strategies, advanced characterization tools, and tailored functional designs to fully exploit the potential of f-MOF thin films in next-generation technologies.