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

Álvaro Rodríguez-Rodríguez,Tiberio A Ezquerra,Mari-Cruz García-Gutiérrez,Esther Rebollar,Aurora Nogales,Edgar Gutiérrez-Fernández

doi:10.3390/polym11020190

Abstract

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 λlaser = 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.

Highlights

Polymer surface nanostructures are gaining interest as functional elements for a broad range of applications, ranging from organic electronics [1] to self-cleaning [2] and energy harvesting [3], among others
In this paper we report on the synergistic effect of phenyl C71-butyric acid methyl ester (PC71 BM) in the laser-induced periodic surface structures (LIPSS) formation on P3HT: PC71 BM at UV wavelengths
We demonstrate that in addition to the improvement of the overall absorption obtained in P3HT:PC71 BM by incorporating the additive, the fullerene itself experiences an efficient nanostructuring upon irradiation at this wavelength

Summary

Introduction

Polymer surface nanostructures are gaining interest as functional elements for a broad range of applications, ranging from organic electronics [1] to self-cleaning [2] and energy harvesting [3], among others. The fabrication of nanostructured polymer surfaces remains in general, a challenge depending on the functionality it is aimed for. In addition to conventional lithographic methods, alternative procedures that simplify polymer nanostructuring are highly welcome, since the need for clean rooms, mask fabrication and complex equipment can be a burden, which is difficult to overcome in some cases. Use of laser-induced periodic surface structures (LIPSS) is a versatile method to create patterns in a great variety of materials, including polymers [4]. LIPSS in polymers appear by illumination with a pulsed laser of a solid smooth surface. Laser pulses in the range from nanoseconds to femtoseconds, with wavelengths from visible to infrared (IR), have been reported to produce LIPSS in polymers [4,5]. More complex structures have been described [9]

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Conclusion