Conference article

The polymer solar cells were fabricated by a novel solution coating process; the roller painting. The roller painted film composed of poly(3-hexylthiophene) (P3HT) and [6;6]-phenyl-C61-butyric acid methyl ester (PCBM) has smoother surface than the spin coated film. Since the roller painting is accompanied with shear and normal stresses and is also a slow drying process; the process induces effectively crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller painted active layer contribute to enhanced and balanced charge carrier mobility. Consequently; the roller painting process results in higher power conversion efficiency (PCE) of 4.6% as compared to that of the spin coating (3.9%). Furthermore; the annealing-free polymer solar cell (PSC) with high PCE were fabricated by the roller painting process with addition of a small amount of 1;8-octanedithiol. Since the addition of 1;8-octanedithiol induces phase separation between P3HT and PCBM and the roller painting process induces crystallization of P3HT and PCBM; the PCE of roller painted PSC is achieved up to 3.8% without post-annealing.

Roller Painting; Thin Films; Polymer Solar Cells; Device Performance