Effects of the linker unit in naphthalene-diimide-based small molecules on device performances of organic field-effect transistors
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초록
내용
In this study, we investigated the effects of the linker unit in naphthalene-diimide (NDI)-based small molecules on device performances of organic field-effect transistors (OFETs). Three different chemical units (phenyl, xylene, and bithiophene) were introduced as a rotatable linker between two NDI cores to improve the solubility while maintaining their high field-effect mobility. We found that the crystallinity and molecular ordering of the NDI-based small molecule with a bithiophene linker could be improved by thermal annealing; a moderate annealing temperature of 120 °C appeared to be optimal for promoting self-organization among the small molecules. As a result, the resulting OFETs exhibited evident n-type OFET characteristics with high field-effect mobilities up to 0.016 cm2/Vs (for the NDI-based small molecule with a bithiophene linker) and 0.0426 (for the NDI-based small molecule with a phenyl linker) with high on/off ratios of ~106.