Diketopyrrolopyrrole (DPP) which is a π-conjugated organic semiconducting molecule, is a high performing building block for organic field effect transistors (OFETs). In OFETs devices using a DPP-based material, it shows hole or ambipolar transport characteristics. But n-type has not been developed much compared with p-type due to problems to lower LUMO level. 2-(2,3-dihydro-3-oxo-1H-inden-1-ylidene)propanedinitrile (INCN) is well-known electron acceptor structure. It is a prospective structure that induces deep LUMO level, increases conjugation length, and has efficient intermolecular π-π interactions without distorting the backbone structure. commonly, high-crystalline materials do not dissolve well. This processing trouble can be solved by attaching an alkyl chain of proper length. So, we designed it to have sufficient solubility by attaching an alkyl chain at the INCN group end in different positions. This new INCN moiety was attached to the DPP core to synthesize small molecule, which has high crystallinity without solubility problem and low LUMO level below than -4.0 eV. Finally, an n-type organic semiconductor containing a DPP core shows high electron mobility (~0.8 cm2/Vs).

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