Electrical Stress Influences the Efficiency of CH3NH3PbI3 Perovskite Light Emitting Devices

Lianfeng Zhao, Jia Gao, Yun Hui L. Lin, Yao Wen Yeh, Kyung Min Lee, Nan Yao, Yueh Lin Loo, Barry P. Rand

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

Organic–inorganic hybrid perovskite materials are emerging as semiconductors with potential application in optoelectronic devices. In particular, perovskites are very promising for light-emitting devices (LEDs) due to their high color purity, low nonradiative recombination rates, and tunable bandgap. Here, using pure CH3NH3PbI3 perovskite LEDs with an external quantum efficiency (EQE) of 5.9% as a platform, it is shown that electrical stress can influence device performance significantly, increasing the EQE from an initial 5.9% to as high as 7.4%. Consistent with the enhanced device performance, both the steady-state photoluminescence (PL) intensity and the time-resolved PL decay lifetime increase after electrical stress, indicating a reduction in nonradiative recombination in the perovskite film. By investigating the temperature-dependent characteristics of the perovskite LEDs and the cross-sectional elemental depth profile, it is proposed that trap reduction and resulting device-performance enhancement is due to local ionic motion of excess ions, likely excess mobile iodide, in the perovskite film that fills vacancies and reduces interstitial defects. On the other hand, it is found that overstressed LEDs show irreversibly degraded device performance, possibly because ions initially on the perovskite lattice are displaced during extended electrical stress and create defects such as vacancies.

Original languageEnglish (US)
Article number1605317
JournalAdvanced Materials
Volume29
Issue number24
DOIs
StatePublished - Jun 27 2017

All Science Journal Classification (ASJC) codes

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

Keywords

  • defect reduction
  • ion migration
  • light emitting diodes
  • perovskites

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