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Organic semiconductor/insulator polymer blends have been widely used in the manufacturing process of field-effect transistors (FETs) to overcome the disadvantages of FETs based on organic semiconductor. In this study, phase-separation characteristics and structural developments of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene)/insulating polymers were examined to enhance electrical properties of their blends for uses in active layers of FETs. Especially, phase-separation characteristics of TIPS-pentacene/insulating polymer blends were greatly affected by the processing condition such as spin coating time. Although TIPS-pentacene-top/insulating polymer-bottom vertically phase separated structures were formed onto the substrate regardless of spin-time, spin coating time governed growth mode of phase-separated TIPS-pentacene onto phase-separated insulating polymer. Excess residual solvent in short spin-coating time induces convective flow in a drying droplet, thereby resulted in one-dimensional (1D) growth of TIPS-pentacene crystals. On the other hand, optimum residual solvent in moderate spin coating time led to two-dimensional (2D) growth of TIPS-pentacene crystals. These 2D spherulites onto insulating polymer was quite advantageous for increasing field-effect mobility of FETs because of higher perfectness and coverage of TIPS-pentacene crystals compared to those of 1D crystals. In addition, when TIPS-pentacene was blended with various types of insulating polymers, critical spin-coating time was changed due to the different surface energy of the insulating polymers. Insulating polymer with lower surface energy was advantageous for increasing film formation time, thereby increasing time for phase-separation and crystallization.
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