Effect of Spacer Length of Siloxane‐Terminated Side Chains on Charge Transport in Isoindigo‐Based Polymer Semiconductor Thin Films

• DOI: 10.1002/adfm.201500684
• Publication Date: 2015-05-07T16:46:00Z
• Authors: Jianguo Mei; Hung‐Chin Wu; Ying Diao; Anthony Appleton; Hong Wang; Yan Zhou; Wen‐Ya Lee; Tadanori Kurosawa; Wen‐Chang Chen; Zhenan Bao
• Keywords: Branching (polymer chemistry); Side chain; Siloxane; Organic semiconductor

A series of isoindigo‐based conjugated polymers (PII2F‐C m Si, = 3–11) with alkyl siloxane‐terminated side chains are prepared, in which the branching point is systematically “moved away” from backbone by one carbon atom. To investigate structure–property relationship, polymer thin film subsequently tested top‐contact field‐effect transistors, and further characterized both grazing incidence X‐ray diffraction atomic force microscopy. Hole mobilities over 1 cm 2 V −1 s exhibited for all soluble PII2F‐C Si ( 5–11) polymers, 10 times higher than reference same backbone. 9 shows highest mobility 4.8 , even though 11 exhibits smallest π–π stacking distance at 3.379 Å. In specific, when at, or beyond, third atoms, contribution to charge transport arising shortening becomes less significant. Other factors, such as thin‐film microstructure, crystallinity, domain size, become more important affecting resulting device's transport.