Interplay between Interfacial Structures and Device Performance in Organic Solar Cells: A Case Study with the Low Work Function Metal, Calcium

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• 作者：Huanxin Ju ; Kristina M. Knesting ; Wei Zhang ; Xiao Pan ; Chia-Hsin Wang ; Yaw-Wen Yang ; David S. Ginger ; Junfa Zhu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：January 27, 2016
• 年：2016
• 卷：8
• 期：3
• 页码：2125-2131
• 全文大小：439K
• ISSN：1944-8252

文摘

A better understanding of how interfacial structure affects charge carrier recombination would benefit the development of highly efficient organic photovoltaic (OPV) devices. In this paper, transient photovoltage (TPV) and charge extraction (CE) measurements are used in combination with synchrotron radiation photoemission spectroscopy (SRPES) to gain insight into the correlation between interfacial properties and device performance. OPV devices based on PCDTBT/PC₇₁BM with a Ca interlayer were studied as a reference system to investigate the interfacial effects on device performance. Devices with a Ca interlayer exhibit a lower recombination than devices with only an Al cathode at a given charge carrier density (n). In addition, the interfacial band structures indicate that the strong dipole moment produced by the Ca interlayer can facilitate the extraction of electrons and drive holes away from the cathode/polymer interface, resulting in beneficial reduction in interfacial recombination losses. These results help explain the higher efficiencies of devices made with Ca interlayers compared to that without the Ca interlayer.