1,10-Phenanthroline as an Efficient Bifunctional Passivating Agent for MAPbI3Perovskite Solar Cells

Ali Buyruk, Dominic Blätte, Marcella Günther, Manuel A. Scheel, Nicolai F. Hartmann, Markus Döblinger, Andreas Weis, Achim Hartschuh, Peter Müller-Buschbaum, Thomas Bein, Tayebeh Ameri*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Passivation is one of the most promising concepts to heal defects created at the surface and grain boundaries of polycrystalline perovskite thin films, which significantly deteriorate the photovoltaic performance and stability of corresponding devices. Here, 1,10-phenanthroline, known as a bidentate chelating ligand, is implemented between the methylammonium lead iodide (MAPbI3) film and the hole-transport layer for both passivating the lead-based surface defects (undercoordinated lead ions) and converting the excess/unreacted lead iodide (PbI2) buried at interfaces, which is problematic for the long-term stability, into "neutralized"and beneficial species (PbI2(1,10-phen)x, x = 1, 2) for efficient hole transfer at the modified interface. The defect healing ability of 1,10-phenanthroline is verified with a set of complementary techniques including photoluminescence (steady-state and time-resolved), space-charge-limited current (SCLC) measurements, light intensity dependent JV measurements, and Fourier-transform photocurrent spectroscopy (FTPS). In addition to these analytical methods, we employ advanced X-ray scattering techniques, nano-Fourier transform infrared (nano-FTIR) spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to further analyze the structure and chemical composition at the perovskite surface after treatment at nanoscale spatial resolution. On the basis of our experimental results, we conclude that 1,10-phenanthroline treatment induces the formation of different morphologies with distinct chemical compositions on the surface of the perovskite film such that surface defects are effectively passivated, and excess/unreacted PbI2 is converted into beneficial complex species at the modified interface. As a result, an improved power conversion efficiency (20.16%) and significantly more stable unencapsulated perovskite solar cells are obtained with the 1,10-phenanthroline treatment compared to the MAPbI3 reference device (18.03%).

Original languageEnglish
Pages (from-to)32894-32905
Number of pages12
JournalACS Applied Materials and Interfaces
Volume13
Issue number28
Early online date9 Jul 2021
DOIs
Publication statusPublished - 21 Jul 2021

Keywords

  • 1,10-phenanthroline
  • defects passivation
  • lead iodide
  • multiple ligands
  • perovskite solar cells

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