The merging mechanisms of poly(3-hexylthiophene) domains revealed through scanning tunneling microscopy and molecular dynamics simulations

Herein, we in situ track the merging processes of poly(3-hexylthiophene) (P3HT) domains physisorbed onto graphite while keeping the domain structures clearly resolved through scanning tunneling microscopy (STM). The domain shape-fixed, amoeba/worm-like and bridge-mediated merging mechanisms are revealed. In the domain shape-fixed diffusion, the moving domains obey the principle of the non-continuous random walks. Both diffusive and ballistic-like dynamics are disclosed. Additionally, the asymmetrical domains may show anisotropic movements. In the amoeba-like style, the pseudopodia are formed and changed stochastically while in the worm-like style two permanent parts (head and body) of the domains are formed prior movement and kept fixed in the motions. Finally, the integration of two domains is called a bridge-mediated one, if a small domain is bound to a bigger one directly through a dynamic bridge. The molecular dynamics simulations support the experimental findings of P3HT domain movements and rotations on the graphite surface. [Display omitted] •The shape-fixed, amoeba- and worm-like, and bridge-mediated surface motion of P3HT.•The shape-fixed style: a non-continuous random walk; diffusive and ballistic-like stage.•Revealing the anisotropic motion of asymmetrical domains in the shape-fixed style.•In the amoeba-like style, pseudopodia are formed and changed stochastically.•In the worm-like style, head and body part are kept fixed once formed during movements.