Cathodic multilayer transparent electrodes for ITO-free inverted organic solar cells

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• 作者：Donggeon Han^a ; Soohyun Lee^a ; Hoyeon Kim^a ; Seonju Jeong^b ; Seunghyup Yoo^a ; ^{syoo@ee.kaist.ac.kr}
• 关键词：Metal based transparent cathode ; Titanium oxide ; Tungsten oxide ; Inverted organic solar cell
• 刊名：Organic Electronics
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：14
• 期：6
• 页码：1477-1482
• 全文大小：646 K

文摘

We demonstrate cathodic multilayer transparent electrodes based on a ZnS/Ag/TiO_x (ZAT) structure for ITO-free inverted organic solar cells. A quality solution-based TiO_x layer is adopted as an inner dielectric layer to modify the effective work function of Ag, ensuring the ZAT electrode works as a cathode. The effect of the TiO_x layer is seen on the open-circuit voltage of a solar cell incorporating this layer, increasing to 900 mV from 600 mV in the case of a cell with a bare Ag layer for a bulk-heterojunction of poly[N-9¡å-hepta-decanyl-2,7-carbazole-alt-5,5-(4¡ä,7¡ä-di-2-thienyl-2¡ä,1¡ä,3¡ä-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C₇₀-butyric acid methyl ester (PCBM70). The results of a joint theoretical and experimental study indicate that the photocurrent of a ZAT-based solar cell can be significantly enhanced by carefully balancing the optical-spacer and cavity-resonance effects, both of which are modulated by the thickness of the WO₃ layer used as a hole-collection layer at the top anode side. ZAT-based inverted solar cells with an optimized structure exhibit a power conversion efficiency as high as 5.1 % , which is comparable to that of the ITO-based equivalent.