LAUSR

Abstract Thin blend films of the diblock copolymer poly(3-hexylthiophene-2,5-diyl)- block -polystyrene (P3HT- b -PS) and phenyl-C61-butyric acid methyl ester (PCBM) are prepared and investigated. The morphology of films with 9, 25, 33, 50, 58 and 67% PCBM weight fraction is determined. The surface topography is probed with optical microscopy and atomic force microscopy whereas the lateral inner structures are determined using grazing incidence small angle neutron scattering (GISANS). Grazing incidence X-ray diffraction (GI-XRD) shows a blend ratio dependence of the P3HT crystallites orientation within the block copolymer films. The thermodynamically favoured P3HT edge-on orientation is suppressed upon increasing the PCBM content from 9% till 33% while it recovers in samples with a PCBM weight fraction above 50%. PCBM tends to interact with the PS block at low PCBM fractions and forms segregated domains at a PCBM weight fraction higher than 50%. The addition of PCBM decreases the degree of lamellar structure order and well-ordered hexagonal packed cylindrical structures emerge in at a PCBM weight fraction of 67%. Absorbance and photoluminescence measurements show the relationship between morphology transformation and optoelectronic properties. The phenomena reported here could provide an alternative view for potential nanotechnology applications.