Formation of an interphase layer during deposition of cobalt onto tetraphenylporphyrin: a hard X-ray photoelectron spectroscopy (HAXPES) study. Issue 44 (28th October 2016)

• Record Type: Journal Article
• Authors: Chen, Min; Zhou, Han; Klein, Benedikt P.; Zugermeier, Malte; Krug, Claudio K.; Drescher, Hans-Jörg; Gorgoi, Mihaela; Schmid, Martin; Gottfried, J. Michael
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 44(2016)
• Page Start: 30643
• Page End: 30651
• Publication Date: 2016-10-28
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp05894a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Chemical depth profiling of a metal/porphyrin interface with Hard X-ray Photoelectron Spectroscopy (HAXPES) reveals the formation of a 1.6 nm thick interphase layer. Abstract : The interface formation upon vapor deposition of a metal onto a molecular organic semiconductor was studied using a well-defined complexation reaction between a metal and a porphyrin. Specifically, metallic cobalt (Co) was vapor deposited onto a thin film of 2 H -tetraphenylporphyrin (2HTPP) at room temperature. The resulting interface was probed with Hard X-ray Photoelectron Spectroscopy (HAXPES) using photon energies between 2 and 6 keV to obtain a detailed depth profile of the chemical composition. Characteristic changes in the N 1s core level signals reveal the formation of a cobalt tetraphenylporphyrin (CoTPP) layer between the Co and 2HTPP layers. Assuming an abrupt interface between CoTPP and 2HTPP (layer-by-layer model), analysis of the XPS data results in a thickness of the CoTPP reaction layer of 1.6 nm. However, a more advanced numerical analysis allowed us to reconstruct details of the actual depth distribution of the CoTPP interphase layer: up to a depth of 1.5 nm, all 2HTPP molecules were converted into CoTPP. Beyond this depth, the CoTPP concentration decreases sharply within 0.15 nm to zero.