Understanding the Influence of Anion Exchange on the Hole Transport Layer for Efficient and Humidity-Stable Perovskite Solar Cells

Sukyoung Goh, Gyumin Jang, Sunihl Ma, Jaemin Park, Hayeon Ban, Chan Uk Lee, Junwoo Lee, Jooho Moon

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8 Citations (Scopus)


High-performance perovskite solar cells (PSCs) are readily degradable by moisture, leading to high demand for a water-repelling efficient hole transport layer (HTL). In this study, we proposed an anion-exchange approach to replace the conventional hygroscopic dopant anion-bis(trifluoromethanesulfonyl)imide (TFSI-)-with a hydrophobic dopant anion capable of effectively doping into a 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) matrix. By varying the size of dopant anions, we successfully controlled electrostatic interactions between spiro-OMeTAD and the dopant anion. Hexafluorophosphate (PF6-) demonstrated the highest p-doping anion-exchange capability because the optimal-sized PF6- enabled a strong electrostatic interaction between spiro-OMeTAD•+ and PF6- while resulting in poor affinity between Li+ and PF6-. The resulting PF6-doped spiro-OMeTAD HTL not only produced favorable energy band alignment with perovskite but also improved film conductivity. Correspondingly, the PSCs based on the PF6-doped HTL exhibited a higher power conversion efficiency (PCE) of 20.78% than the reference TFSI-based PSCs of 19.04%. Besides device performance, the superior hydrophobic nature of PF6- enabled the HTL to prevent water penetration into the perovskite layer, improving long-term stability against moisture. The PF6-based PSCs exhibited enhanced humidity stability while maintaining 92% of the initial PCE for 1180 h at a relative humidity of 25% under ambient conditions.

Original languageEnglish
Pages (from-to)16730-16740
Number of pages11
JournalACS Sustainable Chemistry and Engineering
Issue number49
Publication statusPublished - 2021 Dec 13

Bibliographical note

Funding Information:
This research was supported by the National R&D Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (no. 2018M3D1A1058793, 2021R1A3B1068920, and 2021M3H4A1A03049662). This research was also supported by the Yonsei Signature Research Cluster Program of 2021 (2021-22-0002).

Publisher Copyright:
© 2021 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment


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