Precise control of PbI2 excess into grain boundary for efficacious charge extraction in off-stoichiometric perovskite solar cells

Jin-an YANG, Andong XIAO, Lisha XIE, Kejun LIAO, Xiaoyu DENG, Chengbo LI, Aili WANG, Yong XIANG, Tingshuai LI*, Feng HAO*

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)peer-review

25 Citations (Scopus)

Abstract

Excess PbI2 has been widely introduced in halide perovskite precursor solution to passivate the grain boundary defects in high efficient perovskite solar cells (PSCs). However, the passivation effect is highly sensitive to the PbI2 content and overmuch PbI2 affects the crystalline growth and charge transport. We report here a precious control of excess PbI2 into perovskite grain boundaries by methylamine treatment for efficacious defects passivation and charge extraction. The crystallization of the deposited perovskite films was carefully evaluated and the charge recombination dynamics were systematically analyzed through time-resolved photoluminescence spectroscopy, space charge limited current, electrochemical impedance spectroscopy and Mott-Schottky analysis. The precise PbI2 introduction to the grain boundaries results in a significantly lower defect state density, efficient charge extraction and prolonged carrier lifetime, causing a notable increase of short-circuit current density and negligible hysteresis in the corresponding device. Our work demonstrates a reliable method to alleviate the rigorous tolerance of PbI2 excess in high efficient PSCs.

Original languageEnglish
Article number135697
Number of pages10
JournalElectrochimica Acta
Volume338
Early online date14 Jan 2020
DOIs
Publication statusPublished - 1 Apr 2020
Externally publishedYes

Bibliographical note

The authors acknowledge the financial support from the National Natural Science Foundation of China (51702038) and the Recruitment Program for Young Professionals.

Keywords

  • Bimolecular recombination
  • Crystallinity
  • Monomolecular recombination
  • Redistribution

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