Impact of the Solvation State of Lead Iodide on Its Two-Step Conversion to MAPbI3: An In Situ Investigation

Dounya Barrit, Peirui Cheng, Ming Chun Tang, Kai Wang, Hoang Dang, Detlef M. Smilgies, Shengzhong Liu, Thomas D. Anthopoulos*, Kui Zhao, Aram Amassian

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Producing high efficiency solar cells without high-temperature processing or use of additives still remains a challenge with the two-step process. Here, the solution processing of MAPbI3 from PbI2 films in N,N-dimethylformamide (DMF) is investigated. In-situ grazing incidence wide-angle X-ray scattering (GIWAXS) measurements reveal a sol–gel process involving three PbI2-DMF solvate complexes—disordered (P0) and ordered (P1, P2)—prior to PbI2 formation. When the appropriate solvated state of PbI2 is exposed to MAI (methylammonium Iodide), it can lead to rapid and complete room temperature conversion into MAPbI3 with higher quality films and improved solar cell performance. Complementary in-situ optical reflectance, absorbance, and quartz crystal microbalance with dissipation (QCM-D) measurements show that dry PbI2 can take up only one third of the MAI taken up by the solvated-crystalline P2 phase of PbI2, requiring additional annealing and yet still underperforming. The perovskite solar cells fabricated from the ordered P2 precursor show higher power conversion efficiency (PCE) and reproducibility than devices fabricated from other cases. The average PCE of the solar cells is greatly improved from 13.2(±0.53)% (from annealed PbI2) to 15.7(±0.35)% (from P2) reaching up to 16.2%. This work demonstrates the importance of controlling the solvation of PbI2 as an effective strategy for the growth of high-quality perovskite films and their application in high efficiency and reproducible solar cells.

Original languageEnglish (US)
Article number1807544
JournalAdvanced Functional Materials
Issue number47
StatePublished - Nov 1 2019


  • high performance
  • hybrid perovskite solar cells
  • in situ grazing incidence wide-angle X-ray scattering
  • solution processing
  • two-step conversion

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Chemistry
  • Condensed Matter Physics
  • General Materials Science
  • Electrochemistry
  • Biomaterials


Dive into the research topics of 'Impact of the Solvation State of Lead Iodide on Its Two-Step Conversion to MAPbI3: An In Situ Investigation'. Together they form a unique fingerprint.

Cite this