LEDs: High‐Efficiency and Stable Quantum Dot Light‐Emitting Diodes Enabled by a Solution‐Processed Metal‐Doped Nickel Oxide Hole Injection Interfacial Layer (Adv. Funct. Mater. 42/2017)

Abstract

A Cu‐doped, NiO‐based quantum dot light‐emitting diode (QLED) reported by Xuyong Yang and co‐workers in article number https://doi.org/10.1002/adfm.201704278 exhibits a significant operating lifetime enhancement compared with organic PEDOT:PSS‐based QLEDs. Relying on an inorganic hole transport layer, the device's quantum dots retain their brightness for an extended time period. This is in contrast to light from a PEDOT:PSS‐based QLED shown in the upper‐left corner of the image.

Ten‐Gram‐Scale Synthesis of FAPbX3 Perovskite Nanocrystals by a High‐Power Room‐Temperature Ultrasonic‐Assisted Strategy and Their Electroluminescence

“…An ≈4 nm redshift for the electroluminescence (EL) emission peak as compared to the PLEM peak is observed (Figure 4d), which is attributed to inner NCs interaction and Stark effect induced by the external electric field . The current density–voltage ( J – V ), luminance–voltage ( L – V ), current efficiency–luminance ( C – L ), and EQE–luminance (EQE–L) characteristics are shown in Figure 4e,f.…”

High‐Performance Quantum‐Dot Light‐Emitting Diodes Using NiOx Hole‐Injection Layers with a High and Stable Work Function

“…It is of interest to exploit the excellent stability of oxide materials to increase the operational lifetime of QLEDs. For this purpose, high‐performance solution‐processed oxide HILs have been actively pursued in the QLED field . Recently, Yang and co‐workers introduced solution‐processed Cu:NiO HILs in QLEDs, leading to devices with a maximum external quantum efficiency (EQE) of 10.5% and a half operational lifetime of 87 h at an initial brightness of 5000 cd m −2 .…”

“…For this purpose, high‐performance solution‐processed oxide HILs have been actively pursued in the QLED field . Recently, Yang and co‐workers introduced solution‐processed Cu:NiO HILs in QLEDs, leading to devices with a maximum external quantum efficiency (EQE) of 10.5% and a half operational lifetime of 87 h at an initial brightness of 5000 cd m −2 . Sun et al reported a flexible QLED using solution‐processed NiO as HILs, demonstrating a maximum current efficiency of 45.8 cd A −1 , a maximum EQE of 10.9%, and a half operational lifetime of 49.3 h at an initial brightness of 7182 cd m −2 .…”

“…Sun et al reported a flexible QLED using solution‐processed NiO as HILs, demonstrating a maximum current efficiency of 45.8 cd A −1 , a maximum EQE of 10.9%, and a half operational lifetime of 49.3 h at an initial brightness of 7182 cd m −2 . Nevertheless, operational stability of the QLEDs based on solution‐processed oxide HILs (see Table S1 of the Supporting Information for details) is far inferior to that of the state‐of‐the‐art device, which shows a T 95 lifetime (the time required for the luminance drops to 95% of its initial value) of ≈2000 h at an initial brightness of 1000 cd m −2…”

“…We propose that one of the main challenges for developing solution‐processed oxide HILs in high‐performance QLEDs is to simultaneously achieve high and stable work functions. In general, the work functions of the pristine solution‐processed oxide films are lower than 5.2 eV, which cannot form low‐resistance contact with the organic HTLs with high ionization potentials . A few postdeposition treatments, such as ozone treatment and oxygen‐plasma treatment, were applied to increase the work function of the oxide HILs .…”