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Influence of Molecular Weight on the Solidification of a Semiconducting Polymer during Time-Controlled Spin-Coating

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journal contribution
posted on 05.07.2019, 20:43 by Jin Yeong Na, Boseok Kang, Yeong Don Park
Molecular weight (Mw) is a key material parameter governing a variety of interesting characteristics of macromolecules. Here, we systematically studied the effects of the Mw of a semiconducting polymer, poly­(3-hexylthiophene) (P3HT), on the microstructure, morphology, and optical and electrical properties of the thin films prepared using a time-controlled spin-coating method. Short spinning times significantly improved the structural and electrical characteristics of all P3HT thin films prepared with different Mws. Notably, greater chain entanglement in the high Mw-P3HT delayed solidification during spin-coating and provided more uniform and slightly thicker films. The crystallinity of high Mw-P3HT thin films prepared with short spinning times less than 10 s were comparable to that of low Mw films, and the hole mobilities of the former films reached to 0.076 cm2 V–1 s–1, 2.7 times the values obtained from films cast over a spinning time of 60 s. These results revealed that the structural disorder due to chain entanglement could be overcome to some extent by using short spinning times.