| Autor: |
Kynaston EL; Lash Miller Chemical Labs , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada., Winchell KJ; Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California 90095-1569 , United States., Yee PY; Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California 90095-1569 , United States., Manion JG; Lash Miller Chemical Labs , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada., Hendsbee AD; Department of Chemical Engineering , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada., Li Y; Department of Chemical Engineering , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada., Huettner S; Department of Chemistry , Universität Bayreuth , Universitätsstrasse 30 , 95447 Bayreuth , Germany., Tolbert SH; Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California 90095-1569 , United States., Seferos DS; Lash Miller Chemical Labs , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada.; Department of Chemical Engineering and Applied Chemistry , University of Toronto , 200 College Street , Toronto , Ontario M5S 3E5 , Canada. |
| Abstrakt: |
Understanding self-assembly behavior and resulting morphologies in block co-polymer films is an essential aspect of chemistry and materials science. Although the self-assembly of amorphous coil-coil block co-polymers is relatively well understood, that of semicrystalline block co-polymers where each block has distinct crystallization properties remains unclear. Here, we report a detailed study to elucidate the rich self-assembly behavior of conjugated thiophene-selenophene (P3AT- b-P3AS) block co-polymers. Using a combination of microscopy and synchrotron-based X-ray techniques, we show that three different film morphologies, denoted as lamellae, co-crystallized fibers, and patchy fibers, arise from the self-assembly of these block co-polymers over a relatively narrow range of overall degrees of polymerization (30 < N < 90). Crystallization-driven phase separation occurs at a very low N (<35), and lamellar films are formed. Conversely, at medium N (50-60) and high N (>80), the thiophene and selenophene blocks co-crystallize into nanofibers, where medium N leads to much more mixing than high N. The overall tendency for phase separation in these systems follows rather different trends than phase separation in amorphous polymers in that we observe the greatest degree of phase separation at the lowest N. Finally, we demonstrate how each morphology influences transport properties in organic thin-film transistors comprised of these conjugated polymers. |
