First-principles study of hybrid nanostructures formed by deposited phthalocyanine/porphyrin metal complexes on phosphorene

Abstract

Porphyrin and phthalocyanine metal complexes are organic semiconductor molecules, also known as MN4 macrocyclic compounds, widely implemented as photosensitizers and electrocatalysts in solution. In this regard, phosphorene, an emerging layered material entirely composed of phosphorous atoms, shows excellent potential features to act as a building block of novel hybrid nanostructures with organic molecules. Here, we perform a first-principles study of hybrid nanostructures formed by phosphorene nanosheets and deposition of MN4 compounds (where M: Fe, Co, Ni, Zn). It is found that the MN4-phosphorene hybrids have remarkable stability in the gas phase and aqueous solution, comparable to that achieved with carbonaceous and metallic-based substrates. In terms of structure, the hybrid structures display non-degenerated adsorption patterns at room temperature, denoting the formation of stable ordered flat MN4 layers (self-assembly). To understand the origin of the binding stability, we conducted further analysis of binding and energy decomposition (ALMO-EDA). It is revealed that the stability is driven by the interplay between permanent electrostatic and dispersion physical effects, which stand for up to 90% of the stabilizing interaction energy. In terms of electronic properties, on the one hand, spin-polarized complexes do not show either switching in their spin state or substrate magnetization. On the other hand, all MN4 complexes act as mild n-dopants, slightly decreasing the phosphorene bandgap but retaining the topology of frontier orbitals concerning the free complexes for orbital-controlled reactions, e.g., electrochemical reactions in solution. In terms of optical properties, phosphorene induces shifting in the Q-band of phthalocyanines to longer wavelengths, which turns (metal)phthalocyanine-phosphorene hybrid materials into excellent candidates for the design of light-harvesting devices.