“Face-on” oriented π-conjugated polymers containing 1,3,4-thiadiazole moiety investigated with synchrotron GIXS measurements: Relationship between morphology and PSC performance

Abstract

The detailed morphology was investigated on 1,3,4-oxadiazole (OXD) and 1,3,4-thiadiazole (TD) containing π-conjugated polymer films based on synchrotron GIXS measurements. Grazing-incidence wide-angle X-ray scattering (GIWAXS) proved that TD-containing polymers showed face-on orientation, which is, in general, favor for the polymer solar cell (PSC) application. Density function theory calculation suggests that the favorable orientation is probably induced by the curvature of TD-containing polymer main chains. In addition, the bulk-heterojunction structure were evaluated by grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscope (AFM). As a result, it was also found that the π-π stacking distance, correlation length and PC61BM cluster size had good relationship with the short circuit current density (Jsc) and fill factor (FF) in the PSC application.