Type Semiconductors with Fused Thiophenes

In most organic semiconductors, the % conjugation is extended through a linear condensation of aromatic rings. On the other hand, 2-D ir-extension systems with It stacking structures, which have not been extensively developed, are expected to afford unusual nano or microribbons. However, their OFET performances are relatively low compared to other series. 

Micro/nanoribbons of 58 and 59 were applied for OFETs to give high mobilities of 2.1 and 0.42 cm s, respectively. 

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Figure 11.12 Structures of n-type semiconductors with fused thiophenes.

The cyclic voltammetry measurements of both polymers in thin films showed that IIDDT owned HOMO/LUMO level of -5.7/-3.7 eV, and IIDT had HOMO/ LUMO level of -5.8/-3.S eV. Both polymers showed much stronger oxidative peaks than their reductive peaks, and the oxidative peak of IIDDT seems more reversible than that of IIDT (Tig. 2.2c). This result is consistent with the device performance that both the polymers are typical p-type semiconductors and IIDDT exhibited a better performance. Compared with traditional thiophene or fused thiophene based polymers, both polymers showed much deeper HOMO levels, which is attributed to the strong election-withdrawing ability of the isoindigo core. Computational results indicate that the HOMO of the polymers are well delocalized... 

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