Large-area, ensemble molecular electronics: Motivation and challenges

TL;DR

This review discusses charge transport in large-area molecular junctions, emphasizing interface formation, analysis of I-V characteristics, and the potential for functional device applications with built-in electric fields.

Contribution

It provides a comprehensive overview of charge transport in large-area molecular electronics, highlighting challenges in interface formation and analysis methods for device functionality.

Findings

Charge transport is highly sensitive to interface quality.

I-V traces often lack molecular specificity for chemical information.

Built-in electric fields can enable non-linear device functionalities.

Abstract

We review charge transport across molecular monolayers, which is central to molecular electronics (MoE) using large-area junctions (NmJ). We strive to provide a wide conceptual overview of three main sub-topics. First, a broad introduction places NmJ in perspective to related fields of research, and to single molecule junctions (1mJ), in addition to a brief historical account. As charge transport presents an ultra sensitive probe for the electronic perfection of interfaces, in the second part ways to form both the monolayer and the contacts are described to construct reliable, defect-free interfaces. The last part is dedicated to understanding and analyses of current-voltage (I-V) traces across molecular junctions. Notwithstanding the original motivation of MoE, I-V traces are often not very sensitive to molecular details and then provide a poor probe for chemical information. Instead we focus on how to analyse the net electrical performance of molecular junctions, from a functional device perspective. Finally, we shortly point to creation of a built-in electric field as a key to achieve functionality, including non-linear current-voltage characteristics that originate in the molecules or their contacts to the electrodes.