Interface interaction of transition metal phthalocyanines with strontium titanate (100)

Abstract

We study interface properties of CoPcFx and FePcFx (x = 0 or 16) on niobium-doped SrTiO3(100) surfaces using mainly X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. For all studied molecules, a rather complex, bidirectional charge transfer with the oxide substrate was observed, involving both the macrocycle and the central metal atom. For molecules of the first monolayer, an electron transfer to the central metal atom is concluded from transition metal 2p core level photoemission spectra. The number of interacting molecules in the first monolayer on the oxide surface depends on the central metal atom of the phthalocyanine, whereas the substrate preparation has minor influence on the interaction between CoPc and SrTiO3(100). Differences of the interaction mechanism to related TiO2 surfaces are discussed.

Solution Adsorption of Fluorinated Zinc Phthalocyanines on Titania: Combined XPS, UV–Vis, and Contact Angle Study

“…Next, we will compare the results of this work with the published reports − on the XPS characterization of thin films of F 16 PcM (MCu, Co, Fe) prepared by vapor deposition on various inorganic substrates. In describing the state of the adsorbed F 16 PcM, most authors − referred to “strong coupling” between the adsorbed molecules and the substrate implying strong interactions, particularly notable for ultrathin, submonolayer PcM coverages.…”

“…20,21 Clearly, all of these pointed out to dissociative chemisorption of PcMs, although the authors 18−24 did not use this particular term. In the XPS of the ultrathin films, additional "interfacial peaks" 18,21,23 were fitted in the C 1s, N 1s, and F 1s corelevel spectra. These extra peaks were attributed to species produced due to dissociation of F 16 PcM on the surface.…”

“…In describing the state of the adsorbed F 16 PcM, most authors − referred to “strong coupling” between the adsorbed molecules and the substrate implying strong interactions, particularly notable for ultrathin, submonolayer PcM coverages. Specifically, the authors noted: distortion and breaking of PcM molecules, , cleavage of the C–F bonds, , and formation of layers depleted in fluorine and enriched in carbon. , Clearly, all of these pointed out to dissociative chemisorption of PcMs, although the authors − did not use this particular term. In the XPS of the ultrathin films, additional “interfacial peaks” ,, were fitted in the C 1s, N 1s, and F 1s core-level spectra.…”

“…Specifically, the authors noted: distortion and breaking of PcM molecules, , cleavage of the C–F bonds, , and formation of layers depleted in fluorine and enriched in carbon. , Clearly, all of these pointed out to dissociative chemisorption of PcMs, although the authors − did not use this particular term. In the XPS of the ultrathin films, additional “interfacial peaks” ,, were fitted in the C 1s, N 1s, and F 1s core-level spectra. These extra peaks were attributed to species produced due to dissociation of F 16 PcM on the surface.…”

“…Thus, for sparingly soluble F x PcM (M = Co, Cu, Zn, x = 4, 8, 16), physical vapor deposition is the method of choice, while for more soluble fluoroalkyl- and fluoroaryl-substituted PcM, drop cast, spin coating, and jet spray techniques have been reported . Multiple mechanistic and structural studies on the preparation and characterization of thin films of F 16 PcM (M = Zn, Cu, Co, Fe) supported on the surfaces of semiconductors, metals, and metal oxides have been reported. − Prone to aggregation, planar F 16 PcM platform, deposited under high vacuum conditions, produced relatively thick (several nanometers) films with a strong Pc-mineral surface coupling. Considering that the film thickness is essential for designing successful organic semiconductor devices, and the fact that submonolayer films act as a template on which future depositions, multilayer formation, take place, the study of submonolayer film formation and properties is of great interest .…”