Solution-crystallized n-type organic thin-film transistors: An impact of branched alkyl chain on high electron mobility and thermal durability

Single-crystal organic thin-film field-effect transistors (OTFTs) have been actively studied because they are regarded as an ideal platform for charge carrier transport phenomena in small-molecule organic materials. Moreover, recently developed solution-based techniques to grow single-crystalline thin films have attracted industrial attention beyond fundamental physics. In this work, one of the solution-based techniques, namely, the edgecasting method, was employed to study single-crystal OTFTs of n-type organic semiconductors, dimerized naphtho[2,3-b]thiophene diimides, with linear and branched alkyl chains. A high electron mobility of >1 cm(2)V(-1)s(-1) and an excellent thermal durability were observed in the branched alkyl-chain derivative, while the OTFT based on linear alkyl-substituted one showed clear degradation of mobility after thermal annealing. Therefore, this work will demonstrate a potential availability of branched alkyl chains for improving carrier mobility and thermal durability with large-scalable printing methods.