Area-Selective Atomic/Molecular Layer Deposition of Photoluminescent Europium-Organic Thin Films for Graphene-Based Heterostructures

Developing area-selective atomic and molecular layer deposition (ALD/MLD) on 2D structures is crucial for optoelectronic and sensor applications yet remains challenging due to surface inertness. Here, we investigated the area-selective ALD/MLD of luminescent lanthanide-organic materials on graphene. To overcome the inherent chemical inertness of 2D materials, we utilized direct femtosecond laser two-photon oxidation to activate predefined regions on single-layer graphene, enabling area-selective deposition of europium-organic thin films. By optimizing the deposition parameters and carefully choosing a transfer polymer, we achieved over 90% selectivity and high film homogeneity in the activated areas. When excited with a green laser, the resulting films exhibited high photoluminescence emission at 612 nm and weaker emission bands at 579, 592, and 652 nm. In addition, graphene/Eu-organic thin films demonstrated green emission at ≈566 nm. The presence of graphene also shortened the photoluminescence lifetime due to quenching. Moreover, the Eu-organic layer reduced the work function of the oxidized graphene, indicating a strong electronic interaction in the graphene/Eu-organic heterostructures. This method enables the precise patterning of complex structures with submicron resolution, with potential for integration into multifunctional graphene-based optoelectronic and sensor systems on a single chip.