Synthesis, characterization, and transistor applications of new linear small molecules: Naphthyl-ethynyl-anthracene-based small molecules containing different alkyl end group

• Two novel linear naphthalene-anthracene conjugated small molecules are described.
• The small molecule was combined with either a pentyl or decyl end group.
• We investigated the effects of different alkyl chain length on OFET performances.
• The suitable length of pentyl end group induce the more ordered packing structure.
• The pentyl substituted molecule promoted the higher mobility than the decyl one.

A novel small molecule consisting of triple bond-bridged naphthalene-anthracene core was synthesized with either a pentyl or decyl end group. The linear and planar shape of naphthalene-anthracene core allowed herringbone packing pattern with enhanced conjugation length and close molecular packing structure. The film morphology of naphthalene-anthracene based small molecules was also affected by the pentyl and decyl groups. The pentyl substituted molecule exhibited more unified and ordered packing patterns than did the decyl substituted example, which showed at least two polymorphs. The p-type semiconducting properties of the two new molecules were characterized by organic field-effect transistor measurements. In annealed devices at 80 °C, the field-effect mobility of pentyl analogue was 0.045 cm2/(V∙s), which was about 3 times higher than the decyl substituted compound.

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