Selective Chain Alignment of Conducting Polymer Blend Films by an Ultrafast Laser

Abstract

Tunable and selective areal polymer chain alignment method is developed for spin‐cast blend films of poly(3‐hexylthiophene)(P3HT):[6,6]‐phenyl‐C61‐butlyric methyl ester (PCBM) system by a femtosecond laser process. The chain alignment, phase separation, and molecular structure of the laser exposed P3HT:PCBM films are investigated by grazing incidence wide angle X‐ray scattering and micro‐Raman analysis. The alkyl chains of P3HT polymer become highly ordered along the polarization axis of the laser. Thus, the amount of desirable face‐on configuration for solar cell application is largely enhanced with a subsequent postannealing process. Vertically expanded morphology up to 200 nm on P3HT:PCBM films is also prompted by the laser irradiation without deteriorating intramolecular structure and changing chemical composition. Simultaneously, vertical phase separation of PCBM toward surface is induced at exposed region. image