Effects of 1,2-ethanedithiol concentration on performance improvement of quantum-dot LEDs

Abstract

We report systematic efficiency improvement of green-emitting CdSe@ZnS quantum-dot LEDs with respect to the concentration of a 1,2-ethanedithiol solution used for in situ treatment.

Flexible CdSe/ZnS Quantum-Dot Light-Emitting Diodes with Higher Efficiency than Rigid Devices

“…The current efficiencies of QLEDs with WO X and MoO X oxide layers were 19.4 and 30.3 cd/A, respectively. These are equal to or larger than the values of previous reports using QLEDs with CdSe/ZnS QD EMLs and ZnO ETLs [26][27][28][29]. The EML and ETL materials greatly affect device performance; we therefore evaluated the effects of the transparent bottom cathode and substrate planarization layer on performance compared to those of QLEDs fabricated from the same EML and ETL materials employed in our study.…”

Suppression of non-radiative recombination to improve performance of colloidal quantum-dot LEDs with a Cs2CO3 solution treatment

“…The sheet resistance of a 140-nm-thick ITO layer was 9 Ω sq −1 . Similar to other devices in our previous works, a ZnO ETL, a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (CBP) hole-transport layer (HTL), and a MoO 3 hole-injection layer (HIL) were used to make devices with a multilayer structure of ITO/ZnO/QD/CBP/MoO 3 /Al [40,41]. An extra step of treating a ZnO ETL with a 2-ethoxyethanol solution of Cs 2 CO 3 was added to alter electronic states related to the ZnO ETL with the aim of improving device performance while a control device was fabricated without Cs 2 CO 3 treatment.…”

“…In order to manifest the contributions of Cs 2 CO 3 treatment to improvements of QLED performance, we analyzed current versus voltage characteristics of QLEDs by representing measured currents as a sum of two modified Shockley functions, similar to a double-diode model [39]. Previously, we used a two-current model to separate different variations of electron and hole currents [40,41]. However, in this work, we interpreted two modified Shockley functions as radiative and non-radiative recombination current components to elucidate the discrepancy in current and luminance variations with respect to bias voltages.…”

Tailored ZnO Functional Nanomaterials for Solution‐Processed Quantum‐Dot Light‐Emitting Diodes

“…Nguyen et al investigated the effect of EDT concentration on the performance of QLED devices using 3, 4, and 6 mM of EDT on a CdSe/ZnS QDs EML spin coated on a ZnO ETL. [ 96 ] The QLED device performance parameters are shown in Figure . The authors claimed that a shift in the vacuum level was induced due to the EDT dipole moments, both at the EML/ETL interface and at the EML surface.…”

“…a) Current density, b) luminance versus voltage,and c) luminance efficiency versus luminance for the device with and without EDT treatment. Reproduced with permission [96]. Copyright 2019, Royal Society of Chemistry.…”