# Tuning charge transport by manipulating concentration dependent single-molecule absorption configurations

## TL;DR

This paper shows how changing concentration affects charge transport in molecular junctions by altering single-molecule absorption configurations.

## Contribution

A new method to control single-molecule adsorption configurations in molecular junctions using concentration is introduced.

## Key findings

- Molecular junctions show a transition from high to low conductance states with decreasing concentration.
- An additional conductance state was identified beyond previously known states.
- Flicker noise analysis and theory explain the concentration-dependent charge transport mechanisms.

## Abstract

Understanding and tuning charge transport in molecular junctions is pivotal for crafting molecular devices with tailored functionalities. Here, we report a novel approach to manipulate the absorption configuration within a 4,4′-bipyridine (4,4′-BPY) molecular junction, utilizing the scanning tunneling microscope break junction technique in a concentration-dependent manner. Single-molecule conductance measurements demonstrate that the molecular junctions exhibit a significant concentration dependence, with a transition from high conductance (HC) to low conductance (LC) states as the concentration decreases. Moreover, we identified an additional conductance state in the molecular junctions besides already known HC and LC states. Flicker noise analysis and theoretical calculations provided valuable insights into the underlying charge transport mechanisms and single-molecule absorption configurations concerning varying concentrations. These findings contribute to a fundamental comprehension of charge transport in concentration-dependent molecular junctions. Furthermore, they offer promising prospects for controlling single-molecule adsorption configurations, thereby paving the way for future molecular devices.

•Manipulation of single-molecule absorption configurations by concentration•Tunability of charge transport within molecular junction at the single-molecule scale•An additional conductance state is observed besides already known high and low states

Manipulation of single-molecule absorption configurations by concentration

Tunability of charge transport within molecular junction at the single-molecule scale

An additional conductance state is observed besides already known high and low states

Transport phenomena; Molecular electrochemistry