Dynamical Transformation of Two-Dimensional Perovskites with Alternating Cations in the Interlayer Space for High-Performance Photovoltaics

Yalan Zhang, Peijun Wang, Ming Chun Tang, Dounya Barrit, Weijun Ke, Junxue Liu, Tao Luo, Yucheng Liu, Tianqi Niu, Detlef M. Smilgies, Zhou Yang, Zhike Liu, Shengye Jin, Mercouri G. Kanatzidis, Aram Amassian, Shengzhong Frank Liu, Kui Zhao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

187 Scopus citations


The two-dimensional (2D) perovskites stabilized by alternating cations in the interlayer space (ACI) define a new type of structure with different physical properties than the more common Ruddlesden-Popper counterparts. However, there is a lack of understanding of material crystallization in films and its influence on the morphological/optoelectronic properties and the final photovoltaic devices. Herein, we undertake in situ studies of the solidification process for ACI 2D perovskite (GA)(MA) n Pb n I 3n+1 (n = 3) from ink to solid-state semiconductor, using solvent mixture of DMSO:DMF (1:10 v/v) as the solvent and link this behavior to solar cell devices. The in situ grazing-incidence X-ray scattering (GIWAXS) analysis reveals a complex journey through disordered sol-gel precursors, intermediate phases, and ultimately to ACI perovskites. The intermediate phases, including a crystalline solvate compound and the 2D GA 2 PbI 4 perovskite, provide a scaffold for the growth of the ACI perovskites during thermal annealing. We identify 2D GA 2 PbI 4 to be the key intermediate phase, which is strongly influenced by the deposition technique and determines the formation of the 1D GAPbI 3 byproducts and the distribution of various n phases of ACI perovskites in the final films. We also confirm the presence of internal charge transfer between different n phases through transient absorption spectroscopy. The high quality ACI perovskite films deposited from solvent mixture of DMSO:DMF (1:10 v/v) deliver a record power conversion efficiency of 14.7% in planar solar cells and significantly enhanced long-term stability of devices in contrast to the 3D MAPbI 3 counterpart.

Original languageEnglish (US)
Pages (from-to)2684-2694
Number of pages11
JournalJournal of the American Chemical Society
Issue number6
StatePublished - Feb 13 2019

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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