Alkyl chains are basic units in the design of organic semiconductors for purposes of enhancing solubility, tuning electronic energy levels, and tailoring molecular packing. This work demonstrates that the carrier mobilities of indeno[1,2-b]fluorene-6,12-dione (IFD)-based semiconductors can be dramatically enhanced by the incorporation of sulfur-or nitrogen-linked side chains. Three IFD derivatives possessing butyl, butylthio, and dibutylamino substituents are synthesized, and their organic field-effect transistors (OFET) are fabricated and characterized. The IFD possessing butyl substituents exhibits a very poor charge transport property with mobility lower than 10 −7 cm 2 V −1 s −1 . In contrast, the hole mobility is dramatically increased to 1.03 cm 2 V −1 s −1 by replacing the butyl units with dibutylamino groups (DBA-IFD), while the butylthio-modified IFD (BT-IFD) derivative exhibits a high and balanced ambipolar charge transport property with the maximum hole and electron mobilities up to 0.71 and 0.65 cm 2 V −1 s −1 , respectively. Moreover, the complementary metal-oxide-semiconductor-like inverters incorporated with the ambipolar OFETs shows sharp inversions with a maximum gain value up to 173. This work reveals that modification of the aromatic core with heteroatom-linked side chains, such as alkylthio or dialkylamino, can be an efficient strategy for the design of high-performance organic semiconductors.

We report herein the intriguing tautomerism behaviors of new dihydrohexaazapentacene derivatives. The dihydrohexaazapentacene molecules with 4n π electrons exist as two stable tautomers in solution and exhibits globe aromaticity.