Abstract
In this paper, the performance of quantum dot-based light-emitting diodes (QLEDs) comprising ZnCdSe/ZnS core-shell QDs as an emitting layer were enhanced by employing Au-doped poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) hole injection layer (HIL). By varying the concentration and dimension of Au nanoparticle (NP) dopants in PEDOT:PSS, the optimal devices were obtained with ~22-nm-sized Au NP dopant at the concentration with an optical density (OD) of 0.21. Highly bright green QLEDs with a maximum external quantum efficiency (EQE) of 8.2 % and a current efficiency of 29.1 cd/A exhibit 80 % improvement compared with devices without Au NP dopants. The improved performance may be attributed to the significant increase in the hole injection rate as a result of the introduction of Au NPs and the good matching between the resonance frequency of the localized surface plasmon resonance (LSPR) generated by the Au NPs and the emission band of QD layer, as well as the suppressed Auger recombination of QD layer due to the LSPR-induced near-field enhanced radiative recombination rate of excitons. These results are helpful for fabricating high-performance QD-based applications, such as full-color displays and solid-state lighting.Graphical 80 % enhancement of efficency of quantum dot-based light-emitting diodes with gold nanoparticle doped hole-injection-layer.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1573-8) contains supplementary material, which is available to authorized users.
Highlights
Colloidal quantum dots (QDs) are promising lightemitting materials because of their color purity, color stability, and color tunability
The improved performance might be attributed to the significant increase in the hole injection, which benefits from the good conductivity of Au and balances the injected charge and produces more excitons within the emitting layer, and the matching between the resonance frequency of the localized surface plasmon resonance (LSPR) generated by the Au NPs and the emission band of QDs layer, as well as the suppressed Auger recombination of QD layer due to the LSPR-induced near-field enhanced radiative recombination rate of excitons
transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images of ZnCdSe cores and ZnCdSe/ZnS core/shell QDs are shown in Fig. 1b and Additional file 1: Figure S3
Summary
Colloidal quantum dots (QDs) are promising lightemitting materials because of their color purity, color stability, and color tunability. [8] In addition, the electrical conductivity of PEDOT:PSS film was improved by adding dimethyl sulfoxide (DMSO) or doping sorbitol, grapheme, iron oxidant-hemin and Au-doped SWCNTs, etc [18,19,20,21,22]. These above methods have been applied to OLEDs, polymer light-emitting diodes (PLEDs), and organic photovoltaic devices (OPVs) with the improvements of the lower surface roughness of anode, higher work function, and electrical conductivity of HIL [23, 24]. Plasma-enhanced green QLEDs by incorporating solution processable Au NPs into devices demonstrated a significant enhancement of 116 % for both luminance and current efficiency [37]
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