Improved Efficiency in Dithieno[3,2-b:2鈥?3鈥?d]silole-Based Polymer Solar Cells by the Insertion of ZnO Optical Spacer

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• 作者：Shanpeng Wen ; Chen Wang ; Pengfei Ma ; Ge Wang ; Wei Dong ; Yajun Gao ; Shengping Ruan
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 10, 2015
• 年：2015
• 卷：119
• 期：36
• 页码：20817-20822
• 全文大小：371K
• ISSN：1932-7455

文摘

The insertion of a ZnO optical spacer between the active layer and the cathode significantly improves the power conversion efficiency of the PDTS-DTffBT:PC₇₁BM-based polymer solar cell up to 5.5%, which is 48% higher than the control device. The functionality of the ZnO optical spacer is embodied from a variety of aspects. First, the AFM image shows that it can optimize the surface morphology of the active layer, leading to a better contact with the cathode and lower interfacial energy barrier for the electron extraction. Second, the normal incident reflection spectra and the external quantum efficiency curve indicate that the optical field distribution is effectively modulated such that the light harvesting capability is improved. Third, the analysis of the saturated photocurrent reveals the increase for both the generation efficiency of free charges and the dissociation probability of the exciton. Finally, the dark current voltage measurement demonstrates that the local leakage current is suppressed, and the transport property is improved meanwhile. All of these features make the ZnO optical spacer a promising interface layer for polymer solar cells.