Excess Ion-Induced Efficiency Roll-Off in High-Efficiency Perovskite Light-Emitting Diodes

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Yongheng Jia
  • Hui Yu
  • Yang Zhou
  • Yuwei Guo
  • Fangyan Xie
  • Zhaotong Qin
  • Xinhui Lu
  • Ni Zhao

Detail(s)

Original languageEnglish
Pages (from-to)28546-28554
Journal / PublicationACS Applied Materials and Interfaces
Volume13
Issue number24
Online published10 Jun 2021
Publication statusPublished - 23 Jun 2021
Externally publishedYes

Abstract

Applying extensively excess ammonium halides in forming perovskites is a widely used approach to achieve high-performance perovskite light-emitting diodes (PeLEDs). However, most of these PeLEDs suffer from severe external quantum efficiency (EQE) roll-off at high current densities, thereby restricting the realization of high-brightness PeLEDs and laser diodes. In this work, we explore the underlying mechanism of the EQE roll-off in high-efficiency formamidinium lead iodide (FAPbI3)-based PeLEDs. By combining voltage-dependent electrical stress measurements and ex situ ion distribution analysis of PeLEDs, we found that the electric field-driven migration and local segregation of excess iodide ions, originated from nonstoichiometric precursors, trigger the EQE roll-off via promoting imbalanced charge injection. Based on this discovery, we introduced a simple wash-off treatment with chloroform to remove the excess iodides from the perovskite surface and demonstrated that the treatment is highly effective in suppressing the roll-off behavior. By combining the treatment and the use of an ultrathin poly(methyl methacrylate) (PMMA) interlayer, we achieved a high-brightness PeLED with an EQEmax of 19.6%, a critical current density of 1550 mA cm-2, and a radiancemax of 875 W sr-1 m-2. The study reveals the double-edge sword effect of precursor nonstoichiometry and highlights the importance of managing excess ions in perovskite films. © 2021 American Chemical Society.

Research Area(s)

  • charge injection balance, efficiency roll-off, ion migration, perovskite light-emitting diodes, solvent treatment

Citation Format(s)

Excess Ion-Induced Efficiency Roll-Off in High-Efficiency Perovskite Light-Emitting Diodes. / Jia, Yongheng; Yu, Hui; Zhou, Yang et al.
In: ACS Applied Materials and Interfaces, Vol. 13, No. 24, 23.06.2021, p. 28546-28554.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review