Yb:MoO3/Ag/MoO3 Multilayer Transparent Top Cathode for Top-Emitting Green Quantum Dot Light-Emitting Diodes

Abstract

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.

Conductive MoO3–PEDOT:PSS Composite Layer in MoO3/Au/MoO3–PEDOT:PSS Multilayer Electrode in ITO-Free Organic Solar Cells

“…Recently, one of the most common approaches applied to achieve the advantages of high optical transmittances of the metal oxides (MOs), band offsets in the energy diagram, and the magnificent conductivity of metals in the form of a thin metal layer between two metal oxide layers (MO/M/MO) has been used for the replacement of ITO [19][20][21][22][23][24]. Due to their high transparency, high hole affinity, high work function (WF), and easy as well as simple solution process ability, the poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) thin films have been commonly used as the hole transport layer (HTL) [25,26].…”

P‐114: Performance Improvement of Top‐Emitting Blue Quantum Dot Light‐Emitting Diodes by an Organic Capping Layer

“…In addition, the strong micro cavity effect of the top-emitting device can also help to improve the color purity, brightness and efficiency of the device to a certain extent. [11][12][13] More recently, an organic capping layer (CPL) on top of the thin top metal was introduced to improve the current efficiency of top-emitting OLEDs in forward direction by tuning the optical structure of the device.…”

Balanced electron and hole injection and transport in OLEDs by using transparent electrodes

“…In fact, DMD electrodes have been commonly used as an anode to extract electrons in top-emission OLEDs. 12,13) In this study, we modified a DMD cathode by doping one dielectric layer with cesium (Cs) for better electron injection. First, the new DMD electrode is composed of Cs:MoO x /Ag/MoO x layer as a cathode in a standard structure.…”