Origin of Extended UV Stability of 2D Atomic Layer Titania-Based Perovskite Solar Cells Unveiled by Ultrafast Spectroscopy

Anusha Puliparambil Thilakan, Jia Xing Li, Tzu Pei Chen, Shao Sian Li, Chun Wei Chen, Minoru Osada, Kazuhito Tsukagoshi, Takayoshi Sasaki, Atsushi Yabushita, Kaung Hsiung Wu, Chih Wei Luo

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The inherent instability of UV-induced degradation in TiO2-based perovskite solar cells was largely improved by replacing the anatase-phase compact TiO2 layer with an atomic sheet transport layer (ASTL) of two-dimensional (2D) Ti1-δO2. The vital role of microscopic carrier dynamics that govern the UV stability of perovskite solar cells was comprehensively examined in this work by performing time-resolved pump-probe spectroscopy. In conventional perovskite solar cells, the presence of a UV-active oxygen vacancy in compact TiO2 prohibits current generation by heavily trapping electrons after UV degradation. Conversely, the dominant vacancy type in the 2D Ti1-δO2 ASTL is a titanium vacancy, which is a shallow acceptor and is not UV-sensitive. Therefore, it significantly suppresses carrier recombination and extends UV stability in perovskite solar cells with a 2D Ti1-δO2 ASTL. Other carrier dynamics, such as electron diffusion, electron injection, and hot hole transfer processes, were found to be less affected by UV irradiation. Quantitative pump-probe data clearly show a correlation between the carrier dynamics and UV aging of perovskite solar cells, thus providing a profound insight into the factors driving UV-induced degradation in perovskite solar cells and the origin of its performance.

Original languageEnglish
Pages (from-to)21473-21480
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number24
Publication statusPublished - Jun 19 2019


  • electron transport layer
  • perovskite solar cell
  • pump-probe technique
  • two-dimensional metal oxide
  • ultrafast mechanism
  • UV degradation

ASJC Scopus subject areas

  • Materials Science(all)


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