Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface Synthesized Organic Semiconducting Wires

TL;DR

This study demonstrates the on-surface synthesis of one-dimensional organic semiconducting nanowires with tunable energy levels and preserved carrier mobility, advancing the development of miniaturized molecular electronic devices.

Contribution

It introduces a method to synthesize and tune the electronic properties of organic nanowires via self-assembly without affecting charge mobility.

Findings

Tunable energy level alignment achieved through selective doping.

Preservation of charge carrier mobility in synthesized nanowires.

Detailed characterization of valence band dispersion.

Abstract

The tunable properties of molecular materials place them among the favorites for a variety of future generation devices. In addition, to maintain the current trend of miniaturization of those devices, a departure from the present top-down production methods may soon be required and self-assembly appears among the most promising alternatives. On-surface synthesis unites the promises of molecular materials and of self-assembly, with the sturdiness of covalently bonded structures: an ideal scenario for future applications. Following this idea, we report the synthesis of functional extended nanowires by self-assembly. In particular, the products correspond to one-dimensional organic semiconductors. The uniaxial alignment provided by our substrate templates allows us to access with exquisite detail their electronic properties, including the full valence band dispersion, by combining local probes with spatial averaging techniques. We show how, by selectively doping the molecular precursors, the product's energy level alignment can be tuned without compromising the charge carrier's mobility.