Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics

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• 作者：George F. Burkhard ; Eric T. Hoke ; Zach M. Beiley ; Michael D. McGehee
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 20, 2012
• 年：2012
• 卷：116
• 期：50
• 页码：26674-26678
• 全文大小：263K
• 年卷期：v.116,no.50(December 20, 2012)
• ISSN：1932-7455

文摘

Early research on C₆₀ led to the discovery that the absorption of photons with energy greater than 2.35 eV by bulk C₆₀ produces free charge carriers at room temperature. We find that not only is this also true for many of the soluble fullerene derivatives commonly used in organic photovoltaics, but also that the presence of these free carriers has significant implications for the modeling, characterization, and performance of devices made with these materials. We demonstrate that the discrepancy between absorption and quantum efficiency spectra in P3HT:PCBM is due to recombination of such free carriers in large PCBM domains before they can be separated at a donor/acceptor interface. Since most theories assume that all free charges result from the separation of excitons at a donor/acceptor interface, the presence of free carrier generation in fullerenes can have a significant impact on the interpretation of data generated by numerous field-dependent techniques.