Understanding and Improving Solid-State Polymer/C60-Fullerene Bulk-Heterojunction Solar Cells Using Ternary Porphyrin Blends

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• 作者：Paul C. Dastoor ; Christopher R. McNeill ; Holger Frohne ; Christopher J. Foster ; Benjamin Dean ; Christopher J. Fell ; Warwick J. Belcher ; Wayne M. Campbell ; David L. Officer ; Iain M. Blake ; Pall Thordars
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：October 25, 2007
• 年：2007
• 卷：111
• 期：42
• 页码：15415 - 15426
• 全文大小：363K
• 年卷期：v.111,no.42(October 25, 2007)
• ISSN：1932-7455

文摘

Solid-state heterojunction solar cells formed from binary blends of conjugated polymers and fullerenes providea promising class of organic devices. We demonstrate that ternary blends incorporating porphyrins can be ofsimilar morphology to the binary mixture and retain full device functionality. They allow, for the first time,the construction of efficient devices containing less than 10% polymer. By analyzing the absorption spectraas a function of concentration, we determine the proportion of light absorbed by each individual componentin both binary and ternary mixtures. This analysis reveals that the majority of the light is absorbed by thefullerene in 1:4 polymer/C₆₀-fullerene blends, with over 50% of the photocurrent produced under AM 1.5conditions occurring subsequent to C₆₀-fullerene absorption. This result provides for a consistent understandingof the origin of primary charge separation in general polymer/C₆₀-fullerene blends, polymer/C₇₀-fullereneblends, and polymer-fullerene dyad molecules. Porphyrins are demonstrated to add broad-band character tothe device and may be used to tune for particular wavelengths; they also are shown to initiate primary chargeseparation through electron-transfer to the fullerene. Finally, addition of the porphyrin is shown to increasethe internal quantum efficiency following polymer absorption from ca. 60 to 80%.