A Unique Solution-Processable n-Type Semiconductor Material Design for High-Performance Organic Field-Effect Transistors

There have been only a limited number of reports on solution-processed n-channel organic thin-film transistor (OTFT) devices with high levels of electrical performance because the material design process for n-type organic semiconductors is relatively difficult compared with p-type semiconductors, and further chemical modification of the functional groups is required. As a result, the development of soluble n-type organic semiconductors with high carrier mobilities has remained a challenge. Our work addresses this by introducing a novel molecular design to realize soluble n-type organic semiconductors with high electron mobilities through the simple substitution of trifluoromethyl or trifluoromethoxy groups at the meta positions to support sufficient solubility, creating suitable LUMO energy levels and high crystallinity. These newly designed benzobis(thiadiazole) (BBT)-based molecules showed electron mobilities as high as 0.61 cm² V^-1 s^-1 in solution-processed OTFT devices. As a practical application in printed electronics, we demonstrated an organic complementary inverter circuit with OTFT devices using the developed soluble organic semiconductors. Because of their high solubility level and superior electrical properties compared with common para-substituted derivatives, the utilization of meta substituents is a new strategy for the design of soluble organic semiconductors in the field of OTFT device fabrication.