Chemisorption at hetero-organic interfaces
Organic hererojunctions, i.e., the interfaces between different organic materials, are very important for the field of organic electronics since interface properties are dominant for the functionality of the entire electronic device. We have recently achieved evidence for a partly chemisorptive bonding between single monolayers of different organic molecules, i.e., across an organic heterojunction. Copper-II phthalocyanine (CuPc) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules which are stacked on a Ag(111) surface show such an unexpectedly strong interaction. The finding manifests itself in (i) a commensurate registry between the two molecular layers, i.e., a common crystallographic lattice for CuPc and PTCDA films, (ii) a surprisingly small “bonding distance” between the molecules which is incompatible with mere van der Waals interaction, and (iii) a gradual filling of the lowest unoccupied molecular orbital of PTCDA due to CuPc adsorption which proves the chemisorptive character. The results are published in a recent research article in Physical Review Letters.
Contact: C. Kumpf
Original publication: Phys. Rev. Lett. 108, 106103 (2012)