Understanding S-Shaped Current鈥揤oltage Characteristics in Organic Solar Cells Containing a TiOx Interlayer with Impedance Spectroscopy and Equivalent Circuit Analysis

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• 作者：Bernhard Ecker ; Hans-Joachim Egelhaaf ; Roland Steim ; J眉rgen Parisi ; Elizabeth von Hauff
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：August 9, 2012
• 年：2012
• 卷：116
• 期：31
• 页码：16333-16337
• 全文大小：300K
• 年卷期：v.116,no.31(August 9, 2012)
• ISSN：1932-7455

文摘

In this study we propose an equivalent circuit model to describe S-shaped current鈥搗oltage (I鈥?i>V) characteristics in inverted solar cells with a TiO_x interlayer between the cathode and the poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester active layer. Initially the solar cells demonstrate S-shaped I鈥?i>V characteristics resulting in a low fill factor (FF). Upon light soaking with UV radiation, the resistance of the TiO_x interlayer decreases, the S-shape disappears, and the FF increases. Impedance spectroscopy was used to investigate the influence of the resistance of the TiO_x layer on the shape of the I鈥?i>V characteristics. We show that the equivalent circuit model can describe the voltage dependence of the data before and after light soaking in a range from 鈭? to +1.5 V well, demonstrating the robustness of the model. The equivalent circuit elements can be attributed to the distinct layers in the solar cell, therefore giving insight into the origin of the S-shape behavior in this solar cell architecture.