Unraveling the Origin of Operational Instability of Quantum Dot Based Light-Emitting Diodes

Jun Hyuk Chang, Philip Park, Heeyoung Jung, Byeong Guk Jeong, Donghyo Hahm, Gabriel Nagamine, Jongkuk Ko, Jinhan Cho, Lazaro A. Padilha, Doh C. Lee, Changhee Lee, Kookheon Char, Wan Ki Bae

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

We investigate the operational instability of quantum dot (QD)-based light-emitting diodes (QLEDs). Spectroscopic analysis on the QD emissive layer within devices in chorus with the optoelectronic and electrical characteristics of devices discloses that the device efficiency of QLEDs under operation is indeed deteriorated by two main mechanisms. The first is the luminance efficiency drop of the QD emissive layer in the running devices owing to the accumulation of excess electrons in the QDs, which escalates the possibility of nonradiative Auger recombination processes in the QDs. The other is the electron leakage toward hole transport layers (HTLs) that accompanies irreversible physical damage to the HTL by creating nonradiative recombination centers. These processes are distinguishable in terms of the time scale and the reversibility, but both stem from a single origin, the discrepancy between electron versus hole injection rates into QDs. Based on experimental and calculation results, we propose mechanistic models for the operation of QLEDs in individual quantum dot levels and their degradation during operation and offer rational guidelines that promise the realization of high-performance QLEDs with proven operational stability.

Original languageEnglish
JournalACS Nano
DOIs
Publication statusAccepted/In press - 2018 Jan 1

Keywords

  • Auger recombination
  • charge injection balance
  • degradation of organic hole transport layer
  • operational stability
  • quantum dot based light-emitting diodes

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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    Chang, J. H., Park, P., Jung, H., Jeong, B. G., Hahm, D., Nagamine, G., Ko, J., Cho, J., Padilha, L. A., Lee, D. C., Lee, C., Char, K., & Bae, W. K. (Accepted/In press). Unraveling the Origin of Operational Instability of Quantum Dot Based Light-Emitting Diodes. ACS Nano. https://doi.org/10.1021/acsnano.8b03386