Multifunctional Dendrimer Ligands for High-Efficiency, Solution-Processed Quantum Dot Light-Emitting Diodes

Ikjun Cho, Heeyoung Jung, Byeong Guk Jeong, Jun Hyuk Chang, Younghoon Kim, Kookheon Char, Doh C. Lee, Changhee Lee, Jinhan Cho, Wan Ki Bae

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

We present multifunctional dendrimer ligands that serve as the charge injection controlling layer as well as the adhesive layer at the interfaces between quantum dots (QDs) and the electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs). Specifically, we use primary amine-functionalized dendrimer ligands (e.g., a series of poly(amidoamine) dendrimers (PADs, also referred to PAMAM)) that bind to the surface of QDs by replacing the native ligands (oleic acids) and also to the surface of ZnO ETL. PAD ligands control the electron injection rate from ZnO ETL into QDs by altering the electronic energy levels of the surface of ZnO ETL and thereby improve the charge balance within QDs in devices, leading to the enhancement of the device efficiency. As an ultimate achievement, the device efficiency (peak external quantum efficiency) improves by a factor of 3 by replacing the native ligands (3.86%) with PAD ligands (11.36%). In addition, multibranched dendrimer ligands keep the QD emissive layer intact during subsequent solution processing, enabling us to accomplish solution-processed QLEDs. The approach and results in the present study emphasize the importance of controlling the ligands of QDs to enhance QLED performance and also offer simple yet effective chemical mean toward all-solution-processed QLEDs.

Original languageEnglish
Pages (from-to)684-692
Number of pages9
JournalACS Nano
Volume11
Issue number1
DOIs
Publication statusPublished - 2017 Jan 24

Keywords

  • adhesive layer
  • charge injection
  • dendrimer ligands
  • interface engineering
  • quantum dot-based light-emitting diode

ASJC Scopus subject areas

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

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  • Cite this

    Cho, I., Jung, H., Jeong, B. G., Chang, J. H., Kim, Y., Char, K., Lee, D. C., Lee, C., Cho, J., & Bae, W. K. (2017). Multifunctional Dendrimer Ligands for High-Efficiency, Solution-Processed Quantum Dot Light-Emitting Diodes. ACS Nano, 11(1), 684-692. https://doi.org/10.1021/acsnano.6b07028