| This thesis studies the influence of solvent evaporation speed on the nanostructure and carrier mobility of related OTFT devices.In the first part, the P3HT thin films were made by spin-coating from Chloroform solution in different concentration. The out-of-plane GIXRD patterns demonstrate that relative intensity of (100) peak increase with concentration while (010) peak increase. This phenomenon is due to that orientation change from face-on to edge-on when the concentration decrease, which is demonstrated by2D GIXRD. Related performance of thin film transistor indicates that face-on orientation will lead to higher carrier mobility. The results are similar with the sample of the preparation of high boiling point solvents.In the second part, novel solvent vapor assisted spin-coating method, which also can control the solvent evaporation speed, was used to prepare P3HT thin film and related OTFT devices. Thin films made by using normal spin-coating (SP), solvent vapor assisted spin-coating (SVASP) and solvent vapor annealing after normal spin-coating (SPSV). The1DGIXRD patterns and UV absorption spectra demonstrate that P3HT thin film made by solvent vapor assisted spin-coating directly has broader absorption and higher crystallinity. The corresponding thin film transistor also had higher mobility of0.041cm2/vs contrasting to0.007cm2/vs of device based on P3HT thin film made by normal spin-coating. Compared with the solvent vapor annealed P3HT thin film made by normal spin-coating, the thin film made by solvent vapor assisted spin-coating has similar absorption spectrum, X-ray diffraction and device performance which demonstrates that such novel method is equivalent to the combination of normal spin-coating and solvent vapor annealing. However the fabrication is simpler and the process time is reduced from several hours to several tens of seconds, which is more beneficial for actual mass production. |
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