Reconstruction of the (EMIm) x MA1- xPb[(BF4) x I1- x]3 Interlayer for Efficient and Stable Perovskite Solar Cells

Zequn Zhang; Tonghui Guo; Haobo Yuan; Luting Yu; Rui Zhao; Zhiqiang Deng; Jing Zhang; Xiaohui Liu; Ziyang Hu; Yuejin Zhu

doi:10.1021/acsami.0c19784

Reconstruction of the (EMIm) _x MA_{1- x}Pb[(BF₄) _x I_{1- x}]₃ Interlayer for Efficient and Stable Perovskite Solar Cells

ACS Appl Mater Interfaces. 2021 Jan 13;13(1):727-733. doi: 10.1021/acsami.0c19784. Epub 2020 Dec 28.

Authors

Zequn Zhang¹, Tonghui Guo¹, Haobo Yuan¹, Luting Yu¹, Rui Zhao¹, Zhiqiang Deng¹, Jing Zhang¹, Xiaohui Liu¹, Ziyang Hu¹, Yuejin Zhu^{1

2}

Affiliations

¹ Department of Microelectronic Science and Engineering, Ningbo University, Ningbo, Zhejiang 315211, China.
² School of Science and Engineering, College of Science and Technology, Ningbo University, Ningbo 315300, China.

PMID: 33369383
DOI: 10.1021/acsami.0c19784

Abstract

Defective grain boundaries (GBs) and surface trap states are detrimental to the efficiency and stability of perovskite solar cells (PSCs). In this research, ionic liquid (IL) is used to control the defect states at the perovskite surface and GBs. The newly formed (EMIm)_xMA_1-xPb[(BF₄)_xI_1-x]₃ interlayer promotes secondary grain growth to diminish GBs; besides, EMIM⁺ and BF₄^- fill the vacancies of MA⁺ and I^- and also passivate undercoordinated Pb²⁺ trap states. The newly formed interface largely reduces the nonradiative recombination, thus enhancing the solar-cell performance to 19.0% (AM 1.5, 1 sun) with higher photovoltage and fill factor than the control device. Due to the hydrophobicity of the (EMIm)_xMA_1-xPb[(BF₄)_xI_1-x]₃ interlayer, the unencapsulated device stability in 30 days is much better than the control device under relative humidity (RH) = 20%. This work highlights IL-induced secondary grain growth and a defect passivation method for efficient and stable PSCs.

Keywords: crystal reconstruction; defect passivation; interface reconstruction; ionic liquid; perovskite solar cells.