Impact of Intermolecular Distance on Singlet Fission in a Series of TIPS Pentacene Compounds
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- 作者：Yishi Wu ; Ke Liu ; Huiying Liu ; Yi Zhang ; Haoli Zhang ; Jiannian Yao ; Hongbing Fu
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2014
- 出版时间：October 16, 2014
- 年：2014
- 卷：5
- 期：20
- 页码：3451-3455
- 全文大小：317K
- ISSN：1948-7185
文摘
Singlet fission has attracted considerable interest for its potential application in organic photovoltaics. However, the underlying microscopic mechanism is not well understood and the molecular parameters that govern SF efficiency remain unclear. We herein study the primary exciton photogeneration and evolution in the thin film of a series of pentacene derivatives (TIPS-Pn and ADPD-Pn) using femtosecond transient absorption spectroscopy. With a favorable 鈥渓ong-edge on鈥?packing motif, the singlet-excited slip-stacked TIPS-Pn and ADPD-Pn molecules undergo ultrafast fission to produce triplet excitonic states with time constants of 鈭?.3 ps. More importantly, the ADPD-Pn compound features a considerably higher triplet yield than TIPS-Pn (162 卤 10% vs 114 卤 15%). The enhanced electronic coupling as a result of closer interchromophore distance (3.33 脜 for ADPD-Pn vs 3.40 脜 for TIPS-Pn) is suggested to account for the much higher triplet yield for ADPD-Pn relative to that for TIPS-Pn, proving SF can be readily modulated by adjusting the intermolecular distance.