Year: 2019
Type: article
Abstract: We report how the electron transport through a solid-state metal/Gly-Gly-His (GGH) tripeptide monolayer/metal junction and the metal/GGH work function (WF) are modified by the GGH complexation with Cu 2+ ions. Conducting atomic force microscopy is used to measure the current–voltage histograms. The WF is characterized by combining macroscopic Kelvin probe and Kelvin probe force microscopy at the nanoscale. We observe that the complexation of Cu 2+ ions with the GGH monolayer is highly dependent on the molecular surface density and results in opposite trends. In the case of a high-density monolayer the conformational changes are hindered by the proximity of the neighboring peptides, hence forming an insulating layer in response to copper complexation. However, the monolayers of a slightly lower density allow for the conformational change to a looped peptide wrapping the Cu-ion, which results in a more conductive monolayer. Copper-ion complexation to the high- and low-density monolayers systematically induces an increase of the WFs. Copper-ion complexation to the low-density monolayer induces an increase of electron-transport efficiency, whereas the copper-ion complexation to the high-density monolayer results in a slight decrease of electron transport. Both of the observed trends agree with first-principle calculations. Complexation of copper to the low-density GGH monolayer induces a new gap state slightly above the Au Fermi energy that is absent in the high-density monolayer.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Award: G1610650801
OpenAlex ID: W2951366356