Micro-contact printing of poly(3-hexylthiophene) as a tool to improve orientation and ordering of the P3HT layer

The effect of the stamp stretching during micro-contact printing (?CP) onto the corresponding printed poly(3-hexylthiophene) (P3HT) layer has been analysed both from morphological (AFM) and structural (XRD) points of view. Results show an orienting effect of the stretching towards the P3HT ultimate morphological units (i.e. fibrils) along with the stretching direction. Other ?CP parameters leading to an overall P3HT crystallinity improvement such as ?CP mechanical pressure extent, substrate polarity, and post-annealing treatments are shown. Finally, preliminary results of ?CP of double polymer layers (DL) of P3HT/PCBM, used as active layer in organic photovoltaic cells, are presented. ?CP guarantees that each layer within the DL essentially maintains the morphological and structural features typical of the corresponding starting layer.