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Open Access Publications from the University of California

Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells.

  • Author(s): Li, Yanbo
  • Cooper, Jason K
  • Liu, Wenjun
  • Sutter-Fella, Carolin M
  • Amani, Matin
  • Beeman, Jeffrey W
  • Javey, Ali
  • Ager, Joel W
  • Liu, Yi
  • Toma, Francesca M
  • Sharp, Ian D
  • et al.
Abstract

Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h.

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