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  • 09월 10일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제124회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Structure Studies of Poly(3-hexylthiophene-2,5-diyl) (P3HT) Using Femtosecond Stimulated Raman Spectroscopies

2019년 8월 27일 15시 14분 31초
PHYS.P-205 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 17일 (목요일) 11:00~12:30
Physical Chemistry
저자 및
Juwon Kim, Mingyeong Shin, Myeongkee Park1,*
Chemistry, Dong-A University, Korea
1Department of Chemistry, Dong-A University, Korea

Highly pi-conjugated poly(3-hexylthiophene) (P3HT) shows an effective formation of polaron, which is critical in organic photovoltaic performance. In our theoretical and experimental studies, this polaron generation can be stimulated by a highly oscillating vibrational motion of C=C. We exploited excited-state femtosecond stimulated Raman spectroscopy (FSRS) and found the two prominent Raman peaks at ~1450 cm-1(C=C stretching) and 1350 cm-1 (C-C stretching) which are ~20 cm-1 red-shifted from ground-state Raman peak locations. This red-shift dynamics is a pure excited-state reaction which occurs within 5 picoseconds after the excitation. Using density functional theory, we have correlated the redshifts to asymmetric or half-symmetric C=C and C-C stretches, not the entire symmetric stretching modes vibrating along the whole chain. Additionally, we also have found the elongated C=C motion can effectively increase the electron density localization and shortened C=C does vice versa. Thus, this motion can effectively initiate the formation of intramolecular polarons, supporting that the nuclear wave packet motions and electron densities are strongly correlated in P3HT. In addition, we have studied vibrational Raman modes and depolarization ratios of annealed and non-annealed P3HT films to account for the structural dependence on intermolecular interactions.