(a) SEM image of the complete negative pattern (i.e., open-hole array) of P3HT, distinctly formed at a high concentration of 3.00 wt% using chloroform as a solvent. (b) SEM image of the negatively patterned P3HT layer formed at a concentration of 2.00 wt% using chloroform as a solvent. The solution was expelled from the mold before completing the formation of the pattern, and accordingly, a small amount of P3HT was aggregated along the corners of the pillars in comparison with (a). (c) Optical microscopy image of an exemplary P3HT pattern fabricated using the PDMS mold with a smaller pillar array (of ~1 μm thickness). A significant change in the overall tendency for the polymer patterning was not observed according to the size of the pillars. (d) SEM image of (c).