(553c) Fluidic-Directed Assembly of Highly Crystalline Semiconductor Supramolecular Structures with Enhanced Charge Transport

Continuous-flow microreactors have emerged as a new tool for both synthetic and process chemists, which provide several advantages compared to traditional batch reactors. For example, enhanced heat- and mass-transfer characteristics, safety of operation when using highly exothermic, explosive or toxic reagents, precise control over residence (reaction) time, isolation of sensitive reactions from air and moisture, high surface-to-volume ratio, the possibility of automation and the ease of scale-up or ability to operate several devices in parallel (numbering up). In addition, these microreactors allow for integration of several reaction steps into one single streamlined process, which results in a significant time-gain compared to traditional batch processes. Further, laminar flow is an important advantage for microfluidic technology, due to the possibility of tuning materials properties. Self-assembly of semiconducting polymers into ordered supramolecular structures commensurate with efficient charge transport has been achieved by tuning a range of processing parameters (e.g. film formation methods, different solvents (low or high boiling point), polymer-dielectric interface treatment, and solution treatment such as ultrasonication or UV irradiation). However, these strategies present limitations for achieving highly crystalline semiconducting polymers, including uniform, rapid processing, and continuous fabrication of devices.

Here, fluidic-directed assembly of highly crystalline semiconductor supramolecular polymer structures with enhanced charge transport characteristics is demonstrated. Fluid flow provides for enhanced intramolecular ordering of solubilized polymer chains, and thereby effects formation of anisotropic supramolecular polymer assemblies via favorable π–π stacking (intermolecular interaction). Molecular ordering is thus dramatically enhanced with concomitant, enhanced charge transport characteristics of corresponding films. Furthermore, we combine the microfluidic treatment strategy with a blade coating method to achieve continuous and large scale preparation of FET (field-effect transistor) devices with enhanced performance. The methodology exhibits great potential for application in flexible semiconductor device manufacturing.