Nanoscale quantitative chemical mapping of conjugated polymer blends.

Utilizing scanning transmission X-ray microscopy (STXM), we present a quantitative chemical analysis of the bulk composition of spin-coated blends of poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) and poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) used in efficient polymer light emitting diodes. With a lateral resolution of 50 nm, we reveal nanoscale subsurface chemical structure and show that in particular while blend composition remains constant within the TFB-rich domain, in the F8BT-rich phase there is an enrichment of F8BT at the domain interface.