N-Type Water/Alcohol-Soluble Naphthalene Diimide-Based Conjugated Polymers for High-Performance Polymer Solar Cells

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Zhihong Wu
  • Chen Sun
  • Sheng Dong
  • Xiao-Fang Jiang
  • Siping Wu
  • Hongbin Wu
  • Fei Huang
  • Yong Cao

Detail(s)

Original languageEnglish
Pages (from-to)2004-2013
Journal / PublicationJournal of the American Chemical Society
Volume138
Issue number6
Publication statusPublished - 17 Feb 2016
Externally publishedYes

Abstract

With the demonstration of small-area, single-junction polymer solar cells (PSCs) with power conversion efficiencies (PCEs) over the 10% performance milestone, the manufacturing of high-performance large-area PSC modules is becoming the most critical issue for commercial applications. However, materials and processes that are optimized for fabricating small-area devices may not be applicable for the production of high-performance large-area PSC modules. One of the challenges is to develop new conductive interfacial materials that can be easily processed with a wide range of thicknesses without significantly affecting the performance of the PSCs. Toward this goal, we report two novel naphthalene diimide-based, self-doped, n-type water/alcohol-soluble conjugated polymers (WSCPs) that can be processed with a broad thickness range of 5 to 100 nm as efficient electron transporting layers (ETLs) for high-performance PSCs. Space charge limited current and electron spin resonance spectroscopy studies confirm that the presence of amine or ammonium bromide groups on the side chains of the WSCP can n-dope PC71BM at the bulk heterojunction (BHJ)/ETL interface, which improves the electron extraction properties at the cathode. In addition, both amino functional groups can induce self-doping to the WSCPs, although by different doping mechanisms, which leads to highly conductive ETLs with reduced ohmic loss for electron transport and extraction. Ultimately, PSCs based on the self-doped WSCP ETLs exhibit significantly improved device performance, yielding PCEs as high as 9.7% and 10.11% for PTB7-Th/PC71BM and PffBT4T-2OD/PC71BM systems, respectively. More importantly, with PffBT4T-2OD/PC71BM BHJ as an active layer, a prominent PCE of over 8% was achieved even when a thick ETL of 100 nm was used. To the best of our knowledge, this is the highest efficiency demonstrated for PSCs with a thick interlayer and light-harvesting layer, which are important criteria for eventually making organic photovoltaic modules based on roll-to-roll coating processes.

Bibliographic Note

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Citation Format(s)

N-Type Water/Alcohol-Soluble Naphthalene Diimide-Based Conjugated Polymers for High-Performance Polymer Solar Cells. / Wu, Zhihong; Sun, Chen; Dong, Sheng et al.

In: Journal of the American Chemical Society, Vol. 138, No. 6, 17.02.2016, p. 2004-2013.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review