Exploring Lateral and Vertical Phase Separation in SEBS and Dibenzochrysene Derivatives Polymer Blends

Abstract

In this work, stretchable semiconducting blend films for organic field-effect transistors (OFETs) are prepared using a conjugated polymer derived from the vat dye Vat Orange 1 (VO1) and the thermoplastic elastomer SEBS. While the atomic force microscopy (AFM) images of the pristine films showed smooth, featureless morphologies for VO1 and the characteristic fibrillar texture for SEBS, blending the two materials resulted in a progressive increase in surface roughness. Additionally, as the VO1 content increased, distinct aggregate domains became apparent, suggesting partial phase separation within the composite films. X-ray photoelectron spectroscopy (XPS) depth profiling further confirmed a vertical phase separation, showing VO1 enrichment at both the dielectric interface and the film surface, while SEBS was predominantly localised in the middle of the film. Mechanically, the blended films sustained deformation exceeding 100%, a fivefold improvement over pristine VO1 films. This morphology ensures continuous semiconducting pathways for charge transport while imparting exceptional mechanical resilience. Organic field-effect transistors (OFETs) fabricated from VO1:SEBS blends showed stable hole mobilities even at 10 wt% VO1 content, confirming preserved electronic connectivity despite significant dilution. The combination of intrinsic material stability, self-organized vertical morphology, and enhanced stretchability positions VO1:SEBS composites as a promising platform for deformable, solution-processable organic electronics.