Stacking conjugated chains

However, in all these calculations, the conjugated chains bear H atoms only. As bulkier side groups are introduced, the overall interchain interaction decreases and it becomes more anisotropic. If chains form stacks, relatively strong two-dimensional coupling will persist and may still have consequences similar to those of three-dimensional coupling. The question remains open. But substituted CPs are generally even more disordered than the simple ones, and we shall see now that disorder will then have more important consequences than the details of interchain interaction. 

Comparing with conventional amorphous organic semiconductors [16], it is characteristic that conjugated polymer films consist of crystal-like domains, in which jt-conjugated chains are stacked closely, and an amorphous domain, in which polymer chains are disordered [115]. In crystal-like domains, band-like carrier transport that is similar to that of molecular crystals should be possible. However, hopping transport influenced by structural disorder is the dominant process in the amorphous domains. The total carrier transport process is dominated mainly by that in amorphous domains, resulting in bulk carrier transport characteristics similar to those of amorphous organic semiconductors. 

H. Hayasaka, T. Miyashita, K. Tamura, K. Akagi, Helically rt-stacked conjugated polymers bearing photoresponsive and chiral moieties in side chains reversible photoisomerization-enforced switching between emission and quenching of circularly polarized fluorescence. Adv. Fund. Mater. 20, 1243-1250 (2010)... 

The importance of interactions between conjugated chains is illustrated by the effect of orientation of poly(3-alkylthiophene)s on the mobility of charge carriers in field-effect transistors [12, 13]. Thin films in which the polythiophene backbone of a poly(3-alkylthiophene) is oriented perpendicular to the surface of the gate electrode (see Fig. 2) yield a higher measured hole mobility than the case in which the conjugated chains are primarily oriented parallel to the surface. This is interpreted in terms of the orientation of % stacks that define a pathway for facile charge... 

When a 7i-conjugated polymer has long alkyl or alkoxy side chains and forms the stacked structure, it tends to be aligned on the surface of substrates (e.g., Pt plate) with the alkyl or alkoxy chains oriented toward the surface of the substrate [95,128,134,135], presumably because of a strong tendency for the alkyl chain to stand upright on the surface of substrates [95,136]. Actually, the PAEs shown in No. 19 in Table 2 are aligned on a Pt plate with the OR chains oriented toward the surface of the Pt plate [95]. A model for the alignment is depicted in Fig. 1. 

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