Control of polymorphism in solution-processed organic thin film transistors by self-assembled monolayers

摘要

Polymorphism of organic semiconductor films is of key importance for the performance of organic thin film transistors(OTFTs).Herein,we demonstrate that the polymorphism of solution-processed organic semiconductors in thin film transistors can be controlled by finely tuning the surface nanostructures of substrates with self-assembled monolayers(SAMs).It is found that the SAMs of 12-cyclohexyldodecylphosphonic acid(CDPA)and 12-phenyldodecylphosphonic acid(Ph DPA)induce different polymorphs in the dip-coated films of 2-dodecyl[1]benzothieno[3,2-b][1]benzothiophene(BTBT-C12).The film of BTBT-C12 on CDPA exhibits field effect mobility as high as 28.1 cm2 V-1 s-1 for holes,which is higher than that of BTBT-C12 on Ph DPA by three times.The high mobility of BTBT-C12 on CDPA is attributable to the highly oriented films of BTBT-C12 with a reduced in-plane lattice and high molecular alignment.