Nanomaterials (Apr 2020)

Yb:MoO<sub>3</sub>/Ag/MoO<sub>3</sub> Multilayer Transparent Top Cathode for Top-Emitting Green Quantum Dot Light-Emitting Diodes

  • Chun-Yu Lee,
  • Yi-Min Chen,
  • Yao-Zong Deng,
  • Ya-Pei Kuo,
  • Peng-Yu Chen,
  • Leo Tsai,
  • Ming-Yi Lin

DOI
https://doi.org/10.3390/nano10040663
Journal volume & issue
Vol. 10, no. 4
p. 663

Abstract

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In this study, we report on the application of a dielectric/ultra-thin metal/dielectric (DMD) multilayer consisting of ytterbium (Yb)-doped molybdenum oxide (MoO3)/silver (Ag)/MoO3 stacked as the transparent cathode in top-emitting green quantum dot light-emitting diodes (QLED). By optimizing the Yb doping ratio, we have highly improved the electron injection ability from 0.01 to 0.35. In addition, the dielectric/ultra-thin metal/dielectric (DMD) cathode also shows a low sheet resistance of only 12.2 Ω/sq, which is superior to the resistance of the commercially-available indium tin oxide (ITO) electrode (~15 Ω/sq). The DMD multilayer exhibits a maximum transmittance of 75% and an average transmittance of 70% over the visible range of 400–700 nm. The optimized DMD-based G-QLED has a smaller current leakage at low driving voltage. The optimized DMD-based G-QLED enhances the current density than that of G-QLED with indium zinc oxide (IZO) as a cathode. The fabricated DMD-based G-QLED shows a low turn-on voltage of 2.2 V, a high current efficiency of 38 cd/A, and external quantum efficiency of 9.8. These findings support the fabricated DMD multilayer as a promising cathode for transparent top-emitting diodes.

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