Pressure-Dependent Relaxation Dynamics of Excitons in Conjugated Polymer Film
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- 作者：Dong-Xiao Lu ; Ying-Hui Wang ; Fang-Fei Li ; Xiao-Li Huang ; Ling-Yun Pan ; Yuan-Bo Gong ; Bo Han ; Qiang Zhou ; Tian Cui
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：June 11, 2015
- 年：2015
- 卷：119
- 期：23
- 页码：13194-13199
- 全文大小：321K
- ISSN：1932-7455
文摘
Conjugated polymers have been widely used in polymer solar cells (PSC). The transient absorption spectra on conjugated polymer poly{2,7鈥?9,9-dioctylfluorene-alt-5-diethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione} (PDPP-F) film are measured under pressure, and the pressure-dependent relaxation dynamics of excitons in PDPP-F film are investigated. It is found that the relaxation dynamics of excitons under high pressure could be divided into a fast relaxation process that is attributed to the exciton鈥揺xciton annihilation (EEA) and a slow relaxation process that is assigned to the diffusion of free excitons. As a result of pressure-induced delocalization of excitons and extension of lifetime of free excitons, both the EEA process and the free exciton diffusion are enhanced upon compression. Moreover, the delocalization extent of excitons under different pressures is quantitatively calculated, indicating that the scale of exciton delocalization at 30 GPa is tripled compared with that at 1 atm. These results are very important to understand the photophysical property of polymer and to optimize the efficiency of PSC.