Amorphous BaTiO3 Electron Transport Layer for Thermal Equilibrium-Governed γ-CsPbI3 Perovskite Solar Cell with High Power Conversion Efficiency of 19.96%

Changhyun Lee, Chanyong Lee, Kyungjin Chae, Taemin Kim, Seaeun Park, Yohan Ko, Yongseok Jun

Research output: Contribution to journalArticlepeer-review


Compared to organic–inorganic hybrid perovskites, the cesium-based all-inorganic lead halide perovskite (CsPbI3) is a promising light absorber for perovskite solar cells owing to its higher resistance to thermal stress. Nonetheless, additional research is required to reduce the nonradiative recombination to realize the full potential of CsPbI3. Here, the diffusion of Cs ions participating in ion exchange is proposed to be an important factor responsible for the bulk defects in γ-CsPbI3 perovskite. Calculations based on first-principles density functional theory reveal that the [PbI6]4− octahedral tilt modifies the perovskite crystallographic properties in γ-CsPbI3, leading to alterations in its bandgap and crystal strain. In addition, by substituting amorphous barium titanium oxide (a-BaTiO3) for TiO2 as the electron transport layer, interfacial defects caused by imperfect energy levels between the electron transport layer and perovskite are reduced. High-resolution transmission electron microscopy and electron energy loss spectroscopy demonstrate that a-BaTiO3 forms entirely as a single phase, as opposed to Ba-doped TiO2 hybrid nanoclusters or separate domains of TiO2 and BaTiO3 phases. Accordingly, inorganic perovskite solar cells based on the a-BaTiO3 electron transport layer achieved a power conversion efficiency of 19.96%.

Original languageEnglish
JournalEnergy and Environmental Materials
Publication statusAccepted/In press - 2023

Bibliographical note

Funding Information:
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20213091010020) and the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET) and Korea Smart Farm R&D Foundation (KosFarm) through Smart Farm Innovation Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) and Ministry of Science and ICT (MSIT), Rural Development Administration (RDA) (421036‐03). C.L. and C.L. contributed equally to this work.

Publisher Copyright:
© 2023 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.


  • amorphous BaTiO
  • electron transport layer
  • moisture
  • γ-CsPbI

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Water Science and Technology
  • Environmental Science (miscellaneous)
  • Waste Management and Disposal
  • Energy (miscellaneous)


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