Ultralong Copper Phthalocyanine Nanowires with New Crystal Structure and Broad Optical Absorption

TL;DR

This paper reports the synthesis of ultralong copper phthalocyanine nanowires with a novel crystal structure, exhibiting broad optical absorption and high directionality, advancing their potential in organic electronics.

Contribution

Introduction of a new eta-CuPc crystal phase enabling ultralong, highly directional nanowires with enhanced optical and electronic properties.

Findings

Nanowires have diameters of 10-100 nm.

Wires adopt a new eta-CuPc crystal structure.

Optical absorption spectrum is significantly broadened.

Abstract

The development of molecular nanostructures plays a major role in emerging organic electronic applications, as it leads to improved performance and is compatible with our increasing need for miniaturisation. In particular, nanowires have been obtained from solution or vapour phase and have displayed high conductivity, or large interfacial areas in solar cells. In all cases however, the crystal structure remains as in films or bulk, and the exploitation of wires requires extensive post-growth manipulation as their orientations are random. Here we report copper phthalocyanine (CuPc) nanowires with diameters of 10-100 nm, high directionality and unprecedented aspect ratios. We demonstrate that they adopt a new crystal phase, designated eta-CuPc, where the molecules stack along the long axis. The resulting high electronic overlap along the centimetre length stacks achieved in our wires mediates antiferromagnetic couplings and broadens the optical absorption spectrum. The ability to fabricate ultralong, flexible metal phthalocyanine nanowires opens new possibilities for applications of these simple molecules.