Development of air-stable organic semiconductors for p-channel thin-film transistors

Recent developments on heteroarene-based organic semiconductors applicable to high-performance, air-stable thin-film p-channel transistors are described. First, a molecular design strategy for effectively using chalcogen atoms (sulfur or selenium), where molecular orbital calculations play an important role, was proposed, which was followed by the syntheses of target molecules, including development of new synthetic methods. Then, new molecules thus developed, i.e. benzo[l,2-b:4,5-b′]chalcogenophenes (BDXs), [1]benzochalcogenopheno[3,2-b] [1]benzochalcogenophenes (BXBXs), and dinaphtho[2,3-b:2′,3′-f] chalcogenopheno[3,2-b] chalcogenophenes (DNXXs), were evaluated as an active semiconducting materials of organic thin film transistors (OTFTs). In the present work, molecular factors (molecular structures, energy levels and shapes of HOMO, molecular arrangements in the thin film) and the device performances were correlated and discussed to understand a structure-properties relationship. As a consequence of this approach, several air-stable and high-performance semiconductors for the OTFTs were successfully developed. For example, vapor-processable DNTT and solution-processable alkylated-BTBTs showing field-effect mobility as high as 3.0 cm² V^-1 s ^-1 and with 2.8 cm² V^-1 s^-1 respectively, are among the best for recently developed new materials.