π-Conjugated Lewis Base: Efficient Trap-Passivation and Charge-Extraction for Hybrid Perovskite Solar Cells

Yuze Lin, Liang Shen, Jun Dai, Yehao Deng, Yang Wu, Yang Bai, Xiaopeng Zheng, Jiayu Wang, Yanjun Fang, Haotong Wei, Wei Ma, Xiao Cheng Zeng, Xiaowei Zhan, Jinsong Huang

Research output: Contribution to journalArticle

258 Scopus citations

Abstract

A π-conjugated Lewis base with n-type semiconductor property was introduced to the MAPbI3 based solar cells as an interlayer between MAPbI3 and cathode. To confirm the formation of Lewis adducts of Pb and O or N, we firstly measured the UV-vis absorption spectra of IDIC neat solution and IDIC: PbI2 mixed solution. IDIC in N,N-dimethyl formamide (DMF) solution exhibits broad absorption in the 400-700 nm region with two peaks at 496 and 636 nm. IDIC: PbI2 mixed in DMF solution shows obviously stronger and blue shifted absorption relative to IDIC neat solution, which indicates the existence of a relatively strong interaction between PbI2 and IDIC. Then to further confirm the mechanism of interaction, the Fourier transform infrared (FTIR) spectroscopy measurement was conducted to analyze the IDIC powder and IDIC: MAPbI3 blend. The DFT calculation was also undertaken to investigate the function of IDIC, particularly the calculation of the density of states with and without IDIC on top of a MAPbI3 surface with partial loss of MAI. We also found direct evidences for the passivation effect of IDIC by measuring the trap density of the devices with and without IDIC. The reduction of trap states in MAPbI3 films by the passivation of the as-casted IDIC film was analyzed by using the thermal admittance spectroscopy (TAS) method. Since IDIC combines excellent trap passivation and good electron extraction of MAPbI3, the application of IDIC as the ETL is expected to yield high performance devices. MAPbI3 IDIC based solar cells yielded a 45% PCE enhancement relative to the control perovskite solar cells without IDIC.

Original languageEnglish (US)
Article number1604545
JournalAdvanced Materials
Volume29
Issue number7
DOIs
StatePublished - 2017

Keywords

  • charge extraction
  • perovskite solar cells
  • trap passivation
  • π-conjugated Lewis base

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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    Lin, Y., Shen, L., Dai, J., Deng, Y., Wu, Y., Bai, Y., Zheng, X., Wang, J., Fang, Y., Wei, H., Ma, W., Zeng, X. C., Zhan, X., & Huang, J. (2017). π-Conjugated Lewis Base: Efficient Trap-Passivation and Charge-Extraction for Hybrid Perovskite Solar Cells. Advanced Materials, 29(7), [1604545]. https://doi.org/10.1002/adma.201604545