π-Conjugated oligothiophene is considered a chain segment of its polymeric counterpart, whose size and shape can be precisely controlled. Because of its simplified structure, it is possible to understand complex excited-state dynamics of the π-conjugated polymers by employing a bottom-up approach. We review theoretical and experimental aspects of π-conjugated oligothiophenes by summarizing recent works employing time-resolved spectroscopy. The extent of exciton delocalization, which is a prerequisite to efficient charge generation at organic heterojunctions, is described sequentially in model linear and cyclic oligothiophenes, and their analogues. The heterogeneous nature of these systems is highlighted by illustrating the results at both ensemble and single-molecule levels. Exciton dynamics that arise in the polymers are also covered and the signifcance of exciton and charge delocalization in photovoltaic materials is highlighted.
Bibliographical noteFunding Information:
First, we thank the colleagues with whom we have been collaborating on this subject, in particular Prof. Masahiko Iyoda (Tokyo Metropolitan University) and his research fellows. The work at Yonsei University was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (2016R1E1A1A01943379).
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