TCNQ Interlayers for Colloidal Quantum Dot Light‐Emitting Diodes

Abstract

CdSe/CdS/ZnS quantum dot light-emitting diodes (QD-LEDs) show increased brightness (from ca. 18 000 to 27 000 cd m(-2) ) with 7,7,8,8-tetracyanoquinodimethane (TCNQ) between the QD and electron-transfer layers of ZnO nanoparticles. As QD/ZnO layers are known to have interface defects, our finding leads to the importance of interface engineering for QD-LEDs. Although the photoluminescent intensity and decay lifetime of ZnO/TCNQ/QD layers are similar to those of ZnO/QD layers, cyclic voltammetry suggests improved charge transfer of TCNQ/ZnO layers compared to that of pure ZnO layers. This helps us to understand the mechanism of electrically driven QD-LED behavior, which differs from that of conventional solid-state LEDs, and enables the rational design of QD-based optoelectronic devices.

Phosphonic Acid Stabilized Colloidal CsPbX3 (X=Br, I) Perovskite Nanocrystals and Their Surface Chemistry

“…One important challenge of those perovskite materials is their notable degradation process under ambient conditions, in which their instability and device performance can be improved by adopting stabilizing chemicals, such as formamidinium, phenylethylamine, and phosphonic acid . In general, the surface chemistry of colloidal NCs is critical in determining their properties such as NC growth, photophysics, and charge transport . Especially the surface chemistry of colloidal NCs is important for their stability, so it would be the key to understand the surface chemistry of CsPbX 3 perovskite NCs to enhance their stability.…”

Quantum Dot-Based Light Emitting Diodes (QDLEDs): New Progress

“…In 2016, Koh et al investigated these traps in the presence of TCNQ between charge transfer layer and quantum dots. With the introduction of TCNQ, the electroluminescent efficiency (EL) in QDLED has been improved by increasing the charge injection into the QD layer [61].…”

Ultrathin Colloidal Quantum Dot Films for Optical Amplification: The Role of Modal Confinement and Heat Dissipation

“…CdSe/CdS/ZnS QDs are synthesized according to an earlier reported procedure, and Figure a shows the schematic of the layer‐by‐layer technique to produce QD films using polyethylene imine (PEI) as a cross‐linker. Previously, drop‐cast or spin‐coating methods have been used to fabricate QD films, but these procedures can lead to random aggregation of QDs during their solvent evaporation and poor reproducibility .…”

“…CdSe/CdS/ZnS QDs were prepared using the same method reported previously, with a 4.0 nm diameter for the cores, 1.5‐nm‐thick inner shells, and 1.3‐nm‐thick outer shells . The QDs in cyclohexane (10 mg mL −1 ) were deposited layer by layer on the glass substrates by spin coating at 1000–2000 rpm for 30 s. After the deposition of each layer, 1 % of polyethyleneimine (PEI, Aldrich, average Mw ≈25,000) in ethanol was dispensed and spun dried at 2000 rpm for 30 s, followed by rinsing twice with ethanol at the same speed.…”

“…The refractivei ndex of the gain mediump lays an important role in modal confinement of the lasing process, and the waveguides with ah igh refractive index provideastrong light confinement in the gain media enhancing their optical amplification. [11] Along with engineering the modal confinement of the hybrid QD structures, their possible roles in heat dissipation in terms of gain and loss of optical amplification in QD solids are also discussed.CdSe/CdS/ZnS QDsa re synthesized according to an earlier reported procedure, [12] and Figure 1a shows the schematic of the layer-by-layer technique to produce QD films using polyethylene imine (PEI) as ac ross-linker. Previously,d rop-cast or spin-coating methods have been used to fabricate QD films, but these procedures can lead to random aggregation of QDs during their solvent evaporation and poor reproducibility.…”