Temperature-Tunable 2D Assembly of PTCDA on Fe-Intercalated TaS₂

By controlling the postannealing temperature, atomically flat supramolecular assemblies of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) with tunable structural and electronic properties were synthesized on an intercalated quasi-two-dimensional crystal, Fe_0.24TaS₂, and characterized using scanning tunneling microscopy and spectroscopy (STM/STS). At 100 °C, a coexistence of a herringbone PTCDA assembly with p-type-like HOMO-LUMO alignment and a pseudosquare Fe-PTCDA structure were observed on the surface. Upon further annealing at 150 °C, a new dominant Fe-PTCDA honeycomb-kagome framework with chirality emerged, exhibiting n-type-like HOMO-LUMO characteristics. This transition in the types of HOMO-LUMO alignments, along with spatial variations in Fermi level shifting, is attributed to charge transfer from Fe atoms. These findings highlight the potential for designing functional materials, engineering interfacial properties, and constructing exotic low-dimensional structuressuch as kagome metal-organic frameworks (MOFs) and chiral nanostructuresthrough the controlled synthesis of organic heterostructures with emergent crystal phases.