Suppressing Ion Migration across Perovskite Grain Boundaries by Polymer Additives

Yuhui Ma, Yuanhang Cheng, Xiuwen Xu, Menglin Li, Chujun Zhang, Sin Hang CHEUNG, Zixin Zeng, Dong Shen, Yue Min Xie, Ka Lok Chiu, Fen Lin, Shu Kong SO, Chun Sing Lee, Sai Wing Tsang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Passivation of organometal halide perovskites with polar molecules has been recently demonstrated to improve the photovoltaic device efficiency and stability. However, the mechanism is still elusive. Here, it is found that both polymers with large and small dipole moment of 3.7 D and 0.6 D have negligible defect passivation effect on the MAPbI3 perovskite films as evidenced by photothermal deflection spectroscopy. The photovoltaic devices with and without the polymer additives also have comparable power conversion efficiencies around 19%. However, devices with the additives have noticeable improvement in stability under continuous light irradiation. It is found that although the initial mobile ion concentrations are comparable in both devices with and without the additives, the additives can strongly suppress the ion migration during the device operation. This contributes to the significantly enhanced electrical-field stress tolerance of the perovskite solar cells (PVSCs). The PVSCs with polymer additives can operate up to −2 V reverse voltage bias which is much larger than the breakdown voltage of −0.5 V that has been commonly observed. This study provides insight into the role of additives in perovskites and the corresponding device degradation mechanism.

Original languageEnglish
Article number2006802
JournalAdvanced Functional Materials
Volume31
Issue number3
DOIs
Publication statusPublished - 18 Jan 2021

Scopus Subject Areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

User-Defined Keywords

  • grain boundaries
  • ion dissociation
  • ion migration
  • perovskite
  • polymer additives

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