Theoretical Study of Core Excitations of Fullerene-Based Polymer Solar Cell Acceptors
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- 作者：Xiuneng Song ; Weijie Hua ; Yong Ma ; Chuankui Wang ; Yi Luo
- 刊名：The Journal of Physical Chemistry C
- 出版年：2012
- 出版时间：November 15, 2012
- 年：2012
- 卷：116
- 期：45
- 页码：23938-23944
- 全文大小：410K
- 年卷期：v.116,no.45(November 15, 2012)
- ISSN：1932-7455
文摘
First-principles simulations for the C K-edge X-ray photoelectron (XPS) and near-edge X-ray fine-structure (NEXAFS) spectra of representative polymer solar cell acceptor (PSCA) molecules have been carried out with special focuses on the [6,6]-phenyl-Cn+1-butyric acid methyl ester (PCnBM, n = 60, 70, 84). In the XPS spectra, evident red shift of core binding energies are observed in PCnBM as compared to the corresponding fullerene Cn, which is due to weak electronic charge transfer from the side chain to the fullerene backbone and consequently increased electron screening. Special emphasis is paid to a spectral peak at ca. 284.7 eV, which is caused by resonances of phenyl-ring carbons in the side chain and is important in characterizing the electronic structures of different PSCA molecules. Additionally, we propose a modified version of the building block (MBB) approach for quick estimation of the NEXAFS spectra, which is useful when computational resources are limited or massive systems are under study. This method is based on our component analysis on the side chain and fullerene backbone parts and adds only a further empirical fine-tuning after the conventional BB approach. Our calculated results are in good agreement with available experiments.