Fig. 5: Schematic illustration of assembly-controlled film-forming dynamic of Y6 analogs.

The assembly of molecules during a slot-die coating session happens stage by stage. The phases of molecule assembly, i.e., aggregation stages were laid horizontally. In each stage, configurations with lower electron configuration energy were laid at the lower position of the group. Starting from the same monomer (1) in upper left, the synergetic effect of electron delocalization and sidechain repulsion creates different populations of dimers in Y6, N3, and L8-BO systems, which we further classifies into weakly interacting(2a) dimers, A-X type interacting(2b) dimers, A-D,A′ type interacting dimers, and A′-A′ type interacting(2d) dimers. Following the arrows of different shapes, L8-BO mainly aggregates into chain like(3a) micro aggregates, gradually red shifts absorbing edge and finally creates fibril structure(4a) as observed in AFM characterization. Y6 mainly forms star-shaped trimer(3b), depicting the growing pattern in in-situ UV-Vis spectroscopy and forms the grain-like structure in AFM images. When these star-shaped dimers linked together and form network structure(4b), characteristic GIWAXS pattern was formed. While for N3, most dimers are in 2d type and forms dense aggregation(3c), which further grows into oversized crystals(4c), leading to the catastrophically poor device performance.