Charge Transport in a Zn-Porphyrin single molecule junction

TL;DR

This study explores charge transport in Zn-porphyrin molecular junctions, revealing multiple stable configurations and emphasizing the importance of combining conductance measurements with spectroscopy for detailed analysis.

Contribution

It introduces a combined approach of low-bias conductance and I(V) spectroscopy to better characterize charge transport in complex molecular junctions.

Findings

Multiple stable junction configurations can be achieved by adjusting electrode distance.

Different configurations can produce distinct spectroscopic features despite similar conductance.

Combining conductance measurements with spectroscopy enhances understanding of molecular charge transport.

Abstract

We have investigated charge transport in ZnTPPdT-Pyr molecular junctions using the lithographic MCBJ technique at room temperature and cryogenic temperature (6K). We combined low-bias statistical measurements with spectroscopy of the molecular levels using I(V) characteristics. This combination allows us to characterize the transport in a molecular junction in detail. This complex molecule can form different junction configurations, which is observed in trace histograms and in current-voltage (I(V)) measurements. Both methods show that multiple stable single-molecule junction configurations can be obtained by modulating the inter-electrode distance. In addition we demonstrate that different ZnTPPdT-Pyr junction configurations can lead to completely different spectroscopic features with the same conductance values. We show that statistical low-bias conductance measurements should be interpreted with care, and that the combination with I(V) spectroscopy represents an essential tool for a more detailed characterization of the charge transport in a single molecule.