Charge Generation Dynamics in Efficient All-Polymer Solar Cells: Influence of Polymer Packing and Morphology

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• 作者：Bhoj R. Gautam ; Changyeon Lee ; Robert Younts ; Wonho Lee ; Evgeny Danilov ; Bumjoon J. Kim ; Kenan Gundogdu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 23, 2015
• 年：2015
• 卷：7
• 期：50
• 页码：27586-27591
• 全文大小：352K
• ISSN：1944-8252

文摘

All-polymer solar cells exhibit rapid progress in power conversion efficiency (PCE) from 2 to 7.7% over the past few years. While this improvement is primarily attributed to efficient charge transport and balanced mobility between the carriers, not much is known about the charge generation dynamics in these systems. Here we measured exciton relaxation and charge separation dynamics using ultrafast spectroscopy in polymer/polymer blends with different molecular packing and morphology. These measurements indicate that preferential face-on configuration with intermixed nanomorphology increases the charge generation efficiency. In fact, there is a direct quantitative correlation between the free charge population in the ultrafast time scales and the external quantum efficiency, suggesting not only the transport but also charge generation is key for the design of high performance all polymer solar cells.