A Combined Theoretical and Experimental Study of Dissociation of Charge Transfer States at the Donor鈥揂cceptor Interface of Organic Solar Cells
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- 作者：Steffen Tscheuschner ; Heinz B盲ssler ; Katja Huber ; Anna K枚hler
- 刊名：Journal of Physical Chemistry B
- 出版年：2015
- 出版时间：August 13, 2015
- 年：2015
- 卷：119
- 期：32
- 页码：10359-10371
- 全文大小：687K
- ISSN：1520-5207
文摘
The observation that in efficient organic solar cells almost all electron鈥揾ole pairs generated at the donor鈥揳cceptor interface escape from their mutual coulomb potential remains to be a conceptual challenge. It has been argued that it is the excess energy dissipated in the course of electron or hole transfer at the interface that assists this escape process. The current work demonstrates that this concept is unnecessary to explain the field dependence of electron鈥揾ole dissociation. It is based upon the formalism developed by Arkhipov and co-workers as well as Baranovskii and co-workers. The key idea is that the binding energy of the dissociating 鈥渃old鈥?charge-transfer state is reduced by delocalization of the hole along the polymer chain, quantified in terms of an 鈥渆ffective mass鈥? as well as the fractional strength of dipoles existent at the interface in the dark. By covering a broad parameter space, we determine the conditions for efficient electron鈥揾ole dissociation. Spectroscopy of the charge-transfer state on bilayer solar cells as well as measurements of the field dependence of the dissociation yield over a broad temperature range support the theoretical predictions.