Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics

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• 作者：Zhiqiang Guan ; Ho-Wa Li ; Jinfeng Zhang ; Yuanhang Cheng ; Qingdan Yang ; Ming-Fai Lo ; Tsz-Wai Ng ; Sai-Wing Tsang ; Chun-Sing Lee
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：August 24, 2016
• 年：2016
• 卷：8
• 期：33
• 页码：21798-21805
• 全文大小：562K
• 年卷期：0
• ISSN：1944-8252

文摘

How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the “hot” and the “relaxed” CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both “hot” and “relaxed” CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.