Close Encounters of the 3D Kind - Exploiting High Dimensionality in Molecular Semiconductors

• Published in: Advanced materials (Weinheim) Vol. 25; no. 13; pp. 1948 - 1954
• Main Authors: Skabara, Peter J., Arlin, Jean-Baptiste, Geerts, Yves H.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 04-04-2013; WILEY‐VCH Verlag
• Subjects: charge-transport; organic field effect transistors; organic semiconductors; organic solar cells; self-assembly
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201200862

In this Research News article we discuss the significance of dimensionality on the charge‐transport properties of organic semiconductors. Dimensionality is defined in two ways: as a function of (i) the π‐conjugated framework within the molecular structure, and (ii) the degree and direction of intermolecular close‐contacts between molecules in the bulk. In terms of dimensionality, silicon is a good role model for organic semiconductors, since it demonstrates 3D architecture in the bulk through covalent bonding. Achieving this for organics is challenging and requires not only a 3D molecular structure, but also a network of intermolecular short contacts in three dimensions. This review identifies the limitations of low dimensional materials and summarizes the challenges faced in progressing towards fully 3D organic semiconductors.
Charge‐transport behavior in organic semiconductors is highly dependent on intermolecular orbital overlap throughout the bulk solid. The latter arises from non‐covalent interactions, such as π‐π or heteroatom close contacts, and can take the form of 1D, 2D or 3D assemblies. The relationship between dimensionality and charge transport properties is considered for a range of molecular‐based organic semiconductors.