Thermal imprint of P3HT and PCPDTBT: Layer preparation and imprint temperature

Abstract

Conventional imprint (dry-imprint) requires a low polymer viscosity by means of thermal annealing to enhance sufficient flow. Nevertheless, NIL patterning of semiconducting polymers like P3HT and PCPDTBT demands for no or low heating to avoid degradation. Therefore, we tried different layer preparation (no soft bake and low temperature soft bake) and low imprint temperatures in order to maintain the patterning fidelity but to reduce degradation of the imprint polymer. Different patterns were investigated: relatively large sizes (50/100 μm pads) and relatively small sizes (5 μm grating). We achieved similar cavity filling with wet-NIL (no soft bake) imprinted at 110 °C and dry-NIL imprinted at 200 °C for the small pattern size. In addition, we found that the PCPCDTBT has higher viscosity than Reg-P3HT. Admittedly, the large pattern size suffered from non-uniformity and limited reproducibility due to the higher η of the semi-crystalline polymer Reg-P3HT (compared with amorphous polymer Ran-P3HT). © 2013SPST.