Erfan Mohammadi, Chuankai Zhao, Fengjiao Zhang, Ge Qu, Seok-Heon Jung, Qiujie Zhao, Christopher M. Evans, Jin-Kyun Lee, Diwakar Shukla and Ying Diao.
ACS Applied Material and Interfaces, Volume 11(25), Pages 22561-22574, 2019.
Publication year: 2019

Dynamic surfaces play a critical role in templating highly ordered complex structures in living systems but are rarely employed for directing assembly of synthetic functional materials. We design ion gel templates with widely tunable dynamics (Tg) to template solution-coated conjugated polymers. We hypothesize that the ion gel expedites polymer nucleation by reconfiguring its surface to facilitate cooperative multivalent interactions with the conjugated polymer, validated using both experimental and computational approaches. Varying ion gel dynamics enables large modulation of alignment, molecular orientation, and crystallinity in templated polymer thin films. At the optimal conditions, ion-gel-templated films exhibit 55 times higher dichroic ratio (grazing incidence X-ray diffraction) and 49% increase in the relative degree of crystallinity compared to those templated by the neat polymer matrix. As a result, the maximum hole mobilities increase by factors of 4 and 11 along the π–π stacking and the backbone directions. Intriguingly, we observe a synergistic effect between the gel matrix and the ionic liquid that produces markedly enhanced templating effect than either component alone. Molecular dynamics simulations suggest that complementary multivalent interactions facilitated by template reconfigurability underlie the observed synergy. We further demonstrate field-effect transistors both templated and gated by ion gels with average mobility exceeding 7 cm2 V–1 s–1.

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