| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 104 === The effect of spatial confinement on the structure and phase transition behavior of polymer has been a subject of extensive interest. This study is centered on resolving the preferred orientation of poly(3-hexylthiophene) (P3HT) crystallites formed within the 2D nanoconfined space of Anodic Aluminum Oxide Template (AAO) nanochannels. P3HT is a crystalline semiconduting polymer which has attracted significant attention due to its potential in the application as the active material for bulk heterojunction solar cell and organic field-effect transistors (OFETS). The opto-electronic properties of P3HT are expected to strongly depend on its degree of crystallinity and the gobal arrangement of the crystallites; therefore, controlling these two morphological paraemeters is important for tailoring the photophysical properties of the material. In this work, we incorporated P3HT into AAO nanochannels with the diameter of 20 and 100 nm and examined the crystal orientation within the channels as a function of the post treatment condition Tc by means of 2D wide angle X-ray diffraction patterns collected at BL01C2 and BL17A1 at the National Synchrotron Radiation Research Center (NSRRC). The P3HT crystallites predominantly adopted the edge-on orientation with the crystalline backbone aligning perpendicularly to the long axis of the cylindrical pores since this type of orientation was kinetically favored for the long range crystal growth along the channel axis. However, using AAO nanochannels with smaller diameter and an annealing or recrystallization treatment at 160˚C induced the formation of a small fraction of the face-on orientation. It was also found that the as-cast P3HT in the confined space with smaller pore size exhibited higher degree of crystallinity and better orientation. The samples prepared from the xylene solution generally possessed better orientation and higher crystallinity than those prepared from the THF solution. However, we found that melt recrystallization removed the nucleus in the samples, which hindered the crystal growth, resulting in a decrease in the degree of crystallinity.
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