Three-dimensional micropatterning of semiconducting polymers via capillary force-assisted evaporative self-assembly.

Controlled evaporative self-assembly of semiconducting polymers has mostly been studied on 2-dimensional flat substrates. In this study, we reported capillary-assisted evaporative self-assembly of poly(3-hexylthiophene 2,5-diyl) (P3HT) into 3-D micro-ring patterns through the stick-slip phenomenon within a 3-dimensional cylinder. We deconvoluted the well-known two-step stick-slip phenomenon into three regimes through in situ monitoring of the P3HT self-assembly process using a high-speed camera: pinning and deposition; depinning and slip; and retraction regimes. Furthermore, we investigated the effects of various parameters associated with the self-assembly, including polymer concentration, tilt angle, magnetic field, and evaporation temperature, thus achieving self-assembled microarchitectures with diverse dimensions ranging from dots to lines and networks. The self-assembled microstructures were analyzed qualitatively and quantitatively by evaluating the fast Fourier transform image, surface coverage, fractal dimension and lacunarity of the micropatterns.