Effect of Fabrication Parameters on Three-Dimensional Nanostructures of Bulk Heterojunctions Imaged by High-Resolution Scanning ToF-SIMS

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• 作者：Bang-Ying Yu ; Wei-Chun Lin ; Wei-Ben Wang ; Shin-ichi Iida ; Sun-Zen Chen ; Chia-Yi Liu ; Che-Hung Kuo ; Szu-Hsian Lee ; Wei-Lun Kao ; Guo-Ji Yen ; Yun-Wen You ; Chi-Ping Liu ; Jwo-Huei Jou ; Jing-Jong Shyue
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：February 23, 2010
• 年：2010
• 卷：4
• 期：2
• 页码：833-840
• 全文大小：699K
• 年卷期：0
• ISSN：1936-086X

文摘

Solution processable fullerene and copolymer bulk heterojunctions are widely used as the active layers of solar cells. In this work, scanning time-of-flight secondary ion mass spectrometry (ToF-SIMS) is used to examine the distribution of [6,6]phenyl-C61-butyric acid methyl ester (PCBM) and regio-regular poly(3-hexylthiophene) (rrP3HT) that forms the bulk heterojunction. The planar phase separation of P3HT:PCBM is observed by ToF-SIMS imaging. The depth profile of the fragment distribution that reflects the molecular distribution is achieved by low energy Cs⁺ ion sputtering. The depth profile clearly shows a vertical phase separation of P3HT:PCBM before annealing, and hence, the inverted device architecture is beneficial. After annealing, the phase segregation is suppressed, and the device efficiency is dramatically enhanced with a normal device structure. The 3D image is obtained by stacking the 2D ToF-SIMS images acquired at different sputtering times, and 50 nm features are clearly differentiated. The whole imaging process requires less than 2 h, making it both rapid and versatile.