Fabrication of a Patterned Assembly of Semiconducting Organic Nanowires

Abstract

The current interest in organic semiconductors arises from their synthetic facility, their solution processability, and their potential applications for the fabrication of electrical devices. Among semiconductors of this type, those based on organic nanowires are particularly interesting because of their outstanding self-assembly characteristics and anisotropic optical properties. Several research groups have reported various kinds of functional organic nanowires. While some of these wires exhibit electrical conductivity and mobility, others emit polarized photoluminescence (PL). In spite of these special characteristics, nanowires often form entangled coil-like structures. Therefore, much effort has been made to align the wires in a better way. Various methods, such as electric-field assembly, Langmuir–Blodgett process, and soft lithography have been applied for this purpose. However, it is still difficult to manipulate these randomly generated nanowires one-dimensionally and direct them to the desired position, for example, toward electrode channels for fabricating electrical or optical devices with polarized emission. Among these methods, soft lithography is considered one of the most promising patterning tools because of its simplicity and high efficiency. While inorganic nanowires are frequently patterned by means of soft lithography, only a few organic semiconducting nanowires have been aligned using this process due to their unsatisfactory fluidic selfassembling and structure-forming characteristics. Thus, the kernel of organic nanowire patterning via soft lithography is the development of nanowires with high self-assembly capability. It should be meaningful to align these developed semiconducting nanowires for measuring their electrical and optical properties by the MIMIC (micromolding in capillaries) method, which is one of the effective soft lithography processes. In the present study, we used 1-cyano-trans-1,2-bis-(30,50bis-trifluoromethyl-biphenyl)ethylene (CN-TFMBE) for nanowire patterning. CN-TFMBE was chosen because some of