Finely Controlled Synthesis of Zn_1–xMg_xO Nanoparticles with Uniform Size Distribution Used as Electron Transport Materials for Red QLEDs

Abstract

In this work, we report the finely controlled synthesis of Zn 1−x Mg x O nanoparticles (NPs) by a Corning advanced-flow reactor (AFR), which produced a uniform size distribution with 75% NPs in the range 3−4 nm with good reproducibility. The Zn 1−x Mg x O NPs have been applied as an electron transport layer (ETL) in red quantum light-emitting diodes (QLEDs). Different from the traditional method of one-pot synthesis which needs several hours to finish a synthetic cycle, the synthesis by AFR is much faster due to the fast heat and mass transport in the reaction chamber, and a typical synthetic cycle in the AFR needs only a few minutes. Optical properties of the NPs indicate that the Mg ion that substitutes the Zn ion in the ZnO matrix is almost linear with the doping concentration in the solution, which is consistent with the first-principles calculations. The Zn 1−x Mg x O NPs synthesized with the AFR were subsequently used as the ETL in fabricating red QLEDs, and the resultant performance exceeded that of the device based on the traditional one-pot synthesized NPs. For example, the external quantum efficiency, current efficiency, and power efficiency improved by 25.1%, 21.6%, and 26.9%, respectively. Moreover, better luminescence uniformity was observed in the QLED using the ZnMgO NPs synthesized with the AFR. The device reached an optimal performance when x is 15% in Zn 1−x Mg x O. The finely controlled synthesis of stable Zn 1−x Mg x O NPs has the potential in industry application to solve the critical issues of ETLs that impede progress in the mass production of QLEDs.

Molecular Design of Diazo Compound for Carbene-Mediated Cross-Linking of Hole-Transport Polymer in QLED with Reduced Energy Barrier and Improved Charge Balance

“…X1 was obtained by customized synthesis from Suzhou OPQ Display, Inc. Chlorobenzene and octane were purchased from Sigma-Aldrich Ltd. Indium tin oxide (ITO), PEDOT:PSS (AI4083, Clevios) and TFB (average molecular weight ∼ 66,000) were purchased from Jingzhitai Optoelectronic Technology Corp., Heraeus, and Xi’an Polymer Light Technology Corp., respectively. CdSe/ZnS QDs were purchased from Fullnano Technology Corp. Zn 0.85 Mg 0.15 O was synthesized by our previously reported methods …”

“…CdSe/ZnS QDs were purchased from Fullnano Technology Corp. Zn 0.85 Mg 0.15 O was synthesized by our previously reported methods. 49 DFT Calculations. The molecular geometry optimizations and electrostatic potential (ESP) of X1 and X1−Me were carried out by Gaussian 16 at the level of B3LYP/6-31G(d,p).…”

Side-Chain Engineering in Small-Molecule Hole Transport Layer Materials for High-Performance QD-LEDs

“…1 H NMR (400 MHz, Chloroform-d) δ 8.43 (s, 2H), 8.24 (d, J = 7.7 Hz, 2H), 7.86 (d, J = 7.9 Hz, 2H), 7.80 (s, 2H), 7.74 (d, J = 8.3 Hz, 4H), 7.66−7.56 (m, 8H), 7.49 (d, J = 8.5 Hz, 2H), 7.44 (d, J = 4.1 Hz, 4H), 7.32 (dt, J = 8.0, 4.1 Hz, 2H), 4.64 (s, 4H), 3.61 (t, J = 6.6 Hz, 4H), 1.69 (d, J = 6.1 Hz, 10H), 1.49 (dt, J = 14.9, 7.4 Hz, 4H), 0.98 (t, J = 7.4 Hz, 6H). 13 25 DFT Calculations. The molecular geometry optimization and electrostatic potential (ESP) of FLCZ-0, FLCZ, and FLCZ-2 were carried out using Gaussian 16 at the level of B3LYP/6-31G(d, p).…”

High-Throughput Screening of Hole Transport Materials for Quantum Dot Light-Emitting Diodes

“…Colloidal quantum dots (QDs) have shown immense potential in optoelectronics because of their unique properties, such as high luminescence quantum yields, tunable color coordinates, narrow emission bandwidths, solution processability, and compatibility with flexible substrates. − Ever since the first demonstration of QD light-emitting diodes (QLEDs), considerable efforts have been made to develop novel QDs and optimize the device architecture for higher performance. − Despite these advances, the widespread implementation of QLEDs for optoelectronic applications is limited due to the challenges in device fabrication (e.g., solution erosion) and the imbalance of carrier injection. − …”