Cobalt Dopant with Deep Redox Potential for Organometal Halide Hybrid Solar Cells

Authors

  • Teck Ming Koh,

    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
    2. School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
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  • Sabba Dharani,

    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
    2. School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
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  • Dr. Hairong Li,

    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
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  • Rajiv Ramanujam Prabhakar,

    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
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  • Prof. Nripan Mathews,

    Corresponding author
    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
    2. School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
    3. Singapore-Berkeley Research Initiative for Sustainable Energy, 1 Create Way, Singapore, 138602 (Singapore)
    • Nripan Mathews, Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)===

      Andrew C. Grimsdale, School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)===

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  • Prof. Andrew C. Grimsdale,

    Corresponding author
    1. School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
    • Nripan Mathews, Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)===

      Andrew C. Grimsdale, School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)===

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  • Prof. Subodh G. Mhaisalkar

    1. Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Research Techno Plaza, Singapore 637553 (Singapore)
    2. School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
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Abstract

In this work, we report a new cobalt(III) complex, tris[2-(1H-pyrazol-1-yl)pyrimidine]cobalt(III) tris[bis(trifluoromethylsulfonyl)imide] (MY11), with deep redox potential (1.27 V vs NHE) as dopant for 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD). This dopant possesses, to the best of our knowledge, the deepest redox potential among all cobalt-based dopants used in solar cell applications, allowing it to dope a wide range of hole-conductors. We demonstrate the tuning of redox potential of the Co dopant by incorporating pyrimidine moiety in the ligand. We characterize the optical and electrochemical properties of the newly synthesized dopant and show impressive spiro-to-spiro+ conversion. Lastly, we fabricate high efficiency perovskite-based solar cells using MY11 as dopant for molecular hole-conductor, spiro-OMeTAD, to reveal the impact of this dopant in photovoltaic performance. An overall power conversion efficiency of 12 % is achieved using MY11 as p-type dopant to spiro-OMeTAD.

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