[14p-B11-1~13] 12.4 Organic light-emitting devices and organic transistors

△ [14p-B11-3] Fabrication of large-area, single-molecular layer organic semiconductor ultrathin films induced by interlayer frustration and their TFT operations

〇Shunto Arai¹, Satoru Inoue^2,3, Takamasa Hamai¹, Hiromi Minemawari², Reiji Kumai⁴, Tatsuo Hasegawa^1,2 (1.Univ. of Toyko, 2.AIST, 3.Nippon Kayaku, 4.KEK)

Keywords:organic semiconductor, large-area single crystalline thin films, thin film transistor

Layered crystallinity is quite essential for solution-based thin-film processing and thus for producing high performance organic thin-film transistors (OTFTs), as is demonstrated in some organic semiconductor molecules, such as benzothienobenzothiophene (BTBT) derivatives. It is also recently discussed that the device mobility depends crucially on the stacking number of the molecular layers. However, molecular-level thickness control or single molecular layer formation has been an enormous challenge in the materials so far. Here we report a simple method to produce wafer-scale-size single bilayer formation for asymmetrically substituted phenyl-BTBT (Ph-BTBT-Cn) with normal alkyl chains. We adopted to introduce length disorders in the component molecules by varying the alkyl-chain lengths. We found that the disorder is not effective to perturb the in-plane crystalline order of the molecules, but to avoid stacking additional molecular layers. We demonstrate that this method allows us to fabricate field effect transistors with highly reproducible values of device mobility.