Molecular-Wetting Control by Ultrasmooth Pentacene Buffer for High-crystallinity Organic Field-Effect Transistors

<jats:title>ABSTRACT</jats:title><jats:p>Organic thin film devices are of interest for a variety of forthcoming ubiquitous electronics applications. In order to build ubiquitous high-performance devices, it is necessary to fabricate crystalline thin films of various organic materials onto “ubiquitous substrates” that are dictated by applications. However, many organic thin films crystallize only on a limited selection of substrates. Unfortunately, promising organic molecules, which have a large overlap of pi-orbitals between molecules, cannot migrate freely on a substrate because of stronger cohesion between molecules than interaction between the molecule and the substrate. Therefore, enhancement of the molecule-substrate interaction, <jats:italic>i.e.</jats:italic> ‘molecular wettability’ should promote crystallization. We found that an ultrasmooth monolayer of pentacene (C<jats:sub>22</jats:sub>H<jats:sub>14</jats:sub>), which can be grown on many general dielectric substrates, changes the molecular wettability of a substrate for other poorly wettable organic materials. We also demonstrate that a field effect transistor (FET) using a crystalline C<jats:sub>60</jats:sub> thin film on a pentacene-buffered substrate can have a mobility of 4.9 cm<jats:sup>2</jats:sup>/Vs, which is 5-fold higher than that of C<jats:sub>60</jats:sub> FETs without the buffer. Molecular wetting-controlled substrates can thus offer a general solution to the fabrication of high-performance crystalline plastic and molecular electronics.</jats:p>