Sequential Fluorination on Napthaleneamide-Based Conjugated Polymers and Their Impact on Charge Transport Properties

다국어 초록 (Multilingual Abstract)

<P>Improving π-conjugated polymer electron transport and injection efficiency are important to realize high performance n-channel organic field-effect transistors (OFETs). This paper reports a series of naphthalene diimide (NDI-) based n-type π-conjugated polymers, NDI-T-1FP-T, NDI-T-2FP-T, and NDI-T-4FP-T, with varioulis amounts of fluorine atoms (1F, 2F, and 4F) in their backbones. We found notable differences in energy levels, ground and excited state dipole moments (Δμ<SUB>ge</SUB>), exciton lifetimes, dihedral angles, and charge transport properties by varying the fluorine content: Δμ<SUB>ge</SUB> and charge transport properties reduced with increasing fluorine content. Electron mobility of optimized top gate bottom contact OFETs using the n-type π-conjugated polymers were 0.35, 0.18, and 0.16 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP>, respectively. OFET performances were further improved further by low concentration polyethylenimine (PEI) doping, significantly improving field-effect mobility to (maximum) 0.51, 0.34, and 0.26 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP>, respectively. Doped NDI-T-4FP-T with 4F in particular showed unipolar n-channel behavior by depletion of the hole current.</P>
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