Suppressing Defects Through the Synergistic Effect of a Lewis Base and a Lewis Acid for Highly Efficient and Stable Perovskite Solar Cells

Kai Zhu, Fei Zhang, Chuanxiao Xiao, Joseph Berry, Dongqin Bi, Norman Pellet, Shaik Zakeeruddin, Michael Gratzel, Zhen Li

Research output: Contribution to journalArticlepeer-review

274 Scopus Citations

Abstract

Achieving long-term operational stability at a high efficiency level for perovskite solar cells is the most challenging issue toward commercialization of this emerging photovoltaic technology. Here, we investigated the cooperation of a Lewis base and a Lewis acid by combining commercial bis-PCBM mixed isomers as the Lewis acid in the antisolvent and N-(4-bromophenyl)thiourea (BrPh-ThR) as the Lewis base in the perovskite solution precursor. The combination of the Lewis base and the Lewis acid synergistically passivates Pb 2+ and PbX 3- antisite defects, enlarges the perovskite grain size, and improves charge-carrier separation and transport, leading to improved device efficiency from 19.3% to 21.7%. In addition, this Lewis base and acid combination also suppresses moisture incursion and passivates pinholes generated in the hole-transporting layer. The unsealed devices remained at 93% of the initial efficiency value in ambient air (10-20% relative humidity) after 3600 h at 20-25 °C and dropped by 10% after 1500 h under continuous operation at 1-sun illumination and 55 °C in nitrogen with maximum power-point tracking.

Original languageAmerican English
Pages (from-to)3480-3490
Number of pages11
JournalEnergy and Environmental Science
Volume11
Issue number12
DOIs
StatePublished - Dec 2018

Bibliographical note

Publisher Copyright:
© 2018 The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5900-71829

Keywords

  • efficiency
  • Lewis acid
  • Lewis base
  • perovskite solar cells
  • photovoltaics
  • stability

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