Fig. 1.

Arrangement of C16-IDTBT chains constrained to surfaces. (A) Chemical structure of C16-IDTBT. (B) STM image showing chains deposited on an atomically flat gold substrate. Overlaid colored lines indicate the local orientation of backbones. Their clustering reveals the existence of domains of locally parallel-orientated chains. Black lines highlight examples of chains bending and participating in multiple domains. Examples of interchain backbone contact are circled in red. (C) High-resolution STM image showing a crossing point between two polymers. The Inset shows a zoomed-in image with a geometry-optimized molecular model overlaid. Red represents the Bottom polymer, and blue the Top one. (D) An example MD structure resulting from simulation of C16-IDTBT chains deposited on substrate. The chains are colored red (Bottom) and blue (Top) to help distinguish them. (E) Stacked distributions of chain crossing angles from MD simulations. Crossing angles cluster around 90°. Each color represents contacts between particular types of moiety on the two backbones. Areas of colored regions represent occurrence of different moiety contacts, with larger areas indicating more contacts of this type.