Controlled self-assembly of polymer semiconductors in solution using a solvent-vapor approach

A facile solution treatment strategy for controlling the microstructure of conjugated polymers using a non-solvent vapor is introduced. The content of well-ordered poly(3-hexylthiophene) (P3HT) aggregates in solution was precisely controlled by varying the non-solvent vapor exposure time. P3HT chains were self-assembled upon exposure to the non-solvent vapor to minimize the unfavorable interactions with the non-solvent molecules. The effect of solvent vapor on the molecular ordering and morphologies of P3HT films was investigated by UV-Vis spectroscopy, atomic force microscopy, and polarized optical microscopy. These studies reveal that the self-assembled P3HT aggregates have well-ordered nanofibrillar structures formed via I-I stacking. This strategy paves the way toward fabricating well-ordered polymeric structures, especially in the field of opto-electronic applications including FETs, LEDs, and lasers, where proper alignment or molecular assembly is in great demand.