Solid-Surface Modification with Two-Dimensionally Ordered Oriented Molecular Films

Abstract

The surface properties of solid substrates have a considerable impact on many physical, chemical, and electrochemical events occurring at a materials interface, and thus the control of chemical and physical properties of solid surfaces (e.g., surface morphology and energy, wettability, and adhesiveness) provides a key technology in many practical applications. As a useful approach for this purpose, the formation of self-assembled monolayers (SAMs) has widely been used, which relies on specific bonding between polar functional groups of organic molecules and outermost surface elements of inorganic substrates. However, this approach cannot be applied for the modification of polymer substrate surfaces, which are devoid of any effective binding site against polar functional groups. Here we report a new type of organic surface modifier consisting of a paraffinic tripodal triptycene, which undergoes controlled self-assembly not only on inorganic substrates but also on polymer substrates, resulting in a completely oriented molecular thin film like SAMs. The formation of this molecular film does not rely on specific chemical bonding but on a unique assembling property of the molecular building block capable of forming 2D (hexagonal triptycene array) + 1D (layer stacking) structure regardless of the types of substrates. In this presentation, an application of this molecular film to organic electronic devices, which can enhance device performances, will also be described.