In Situ Studies on the Solidification Mechanism of Conjugated Polymer Films Processed by Blade Coating

Abstract

The device performance of organic field-effect transistors (OFETs) using conjugated polymers are highly dependent on the polymer domain size and molecular ordering in polymer films. Due to the importance of thin film morphology, deeper understanding of film formation mechanism during film deposition process in real time has been required to monitor the evolution of polymer packing structures. For this reason, in situ measurements of blade coated conjugated polymers can help reveal the insights into evolution of film morphology. In this study, in situ UV-visible spectroscopy and in situ GIWAXS were performed to elucidate the development of thin film morphology and crystallinity. Thermally controlled thin film formation rate in solution-shearing blade coating can bring drastic variation of the polymer domain size and packing structure. With optimized coating temperature, we can improve the electron mobility in OFETs over 50 times compared to its coating at room temperature.