Synergistic Effect of Fullerenes on the Laser-Induced Periodic Surface Structuring of Poly(3-Hexyl Thiophene)

Ordered and homogeneous laser-induced periodic surface structures (LIPSS) could be fabricated in poly(3-hexyl thiophene):[6,6]-phenyl C71-butyric acid methyl ester (P3HT:PC71BM) blends by using wavelengths in the ultraviolet (UV) range (266 nm). The absorption coefficient of PC71BM, which is maximum in its UV-Visible absorption spectrum around 266 nm, enhanced the overall absorption of the blend. In addition, PC71BM itself was capable of developing homogeneous LIPSS by laser irradiation at lambda(laser) = 266 nm. Therefore, we proposed that the synergistic effect of PC71BM on the LIPSS formation in P3HT:PC71BM (1:1) was due to a templating effect for the LIPSS formation of the PC71BM itself, which added to the overall increment of the absorption of the blend. LIPSS formation at ambient conditions in this wavelength range led to chemical modification of both P3HT and PC71BM, which rendered to non-conducting samples. Irradiation in vacuum significantly reduced radiation damage, rendering to the characteristic electrical conductivity pattern observed in P3HT LIPSS samples irradiated in the visible range. This effect could be of potential interest in order to obtain LIPSS in low absorbing polymers.