Surface optimization to eliminate hysteresis for record efficiency planar perovskite solar cells

Dong Yang, Xin Zhou, Ruixia Yang, Zhou Yang, Wei Yu, Xiuli Wang, Can Li, Shengzhong Liu, Robert P.H. Chang

Research output: Contribution to journalArticlepeer-review

681 Scopus citations


The electron-transport layer (ETL) between the active perovskite material and the cathode plays a critical role in planar perovskite solar cells. Herein, we report a drastically improved solar cell efficiency via surface optimization of the TiO2 ETL using a special ionic-liquid (IL) that shows high optical transparency and superior electron mobility. As a consequence, the efficiency is promoted to as high as 19.62% (the certified efficiency is 19.42%), exceeding the previous highest efficiency recorded for planar CH3NH3PbI3 perovskite solar cells. Surprisingly, the notorious hysteresis is completely eliminated, likely due to the improved ETL quality that has effectively suppressed ion migration in the perovskite layer and charge accumulation at the interfaces, higher electron mobility to balance the hole flux at the anode, and a better growth platform for the high quality perovskite absorber. Both experimental analyses and theoretical calculations reveal that the anion group of the IL bonds to TiO2, leading to a higher electron mobility and a well-matched work function. Meanwhile, the cation group interfaces with adjacent perovskite grains to provide an effective channel for electron transport and a suitable setting to grow low trap-state density perovskite for improved device performance.

Original languageEnglish (US)
Pages (from-to)3071-3078
Number of pages8
JournalEnergy and Environmental Science
Issue number10
StatePublished - Oct 2016

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution


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