Effects of ZnMgO Electron Transport Layer on the Performance of InP-Based Inverted Quantum Dot Light-Emitting Diodes

Abstract

An environment-friendly inverted indium phosphide red quantum dot light-emitting diode (InP QLED) was fabricated using Mg-doped zinc oxide (ZnMgO) as the electron transport layer (ETL). The effects of ZnMgO ETL on the performance of InP QLED were investigated. X-ray diffraction (XRD) analysis indicated that ZnMgO film has an amorphous structure, which is similar to zinc oxide (ZnO) film. Comparison of morphology between ZnO film and ZnMgO film demonstrated that Mg-doped ZnO film remains a high-quality surface (root mean square roughness: 0.86 nm) as smooth as ZnO film. The optical band gap and ultraviolet photoelectron spectroscopy (UPS) analysis revealed that the conduction band of ZnO shifts to a more matched position with InP quantum dot after Mg-doping, resulting in the decrease in turn-on voltage from 2.51 to 2.32 V. In addition, the ratio of irradiation recombination of QLED increases from 7% to 25% using ZnMgO ETL, which can be attributed to reduction in trap state by introducing Mg ions into ZnO lattices. As a result, ZnMgO is a promising material to enhance the performance of inverted InP QLED. This work suggests that ZnMgO has the potential to improve the performance of QLED, which consists of the ITO/ETL/InP QDs/TCTA/MoO3/Al, and Mg-doping strategy is an efficient route to directionally regulate ZnO conduction bands.

Understanding the Origin of Degradation of InP‐Quantum Dot Light‐Emitting Diodes

“…[1][2][3][4][5][6] There have been many reports on the high efficiency and good lifetime of InP-QLEDs, but the reported device lifetime is inferior compared to the CdSe-QLEDs and organic LEDs (OLEDs). [7][8][9][10][11] The main degradation cause of InP-QLED is unknown compared to the OLED. In addition, lesser experimental results are published on the degradation of InP-QLED and therefore, we analyzed the origin of degradation in the red InP-QLED by comparing it with the red OLED.…”

Localized surface plasmon-enhanced blue electroluminescent device based on ZnSeTe quantum dots and AuAg nanoparticles

“…The faster components ( τ 1 and τ 2 ) represent the decays associated with negatively charged exciton and/or trap-assisted recombinations, while the slow component ( τ 3 ) corresponds to single exciton radiative channel. 42,43 The average exciton lifetime of the sample with AuAg NPs was shorter (∼25.5 ns) compared with that without AuAg NPs (∼33.4 ns). Supplementary time-resolved PL measurements with varied compositions of AuAg NPs, while maintaining the low concentration in PVK, were carried out.…”

Highly Efficient Double‐Side‐Emitting Electroluminescent Quantum Dot Thin Film with Transparent MoO3/Ag:Cu/MoO3 Electrode Prepared by Thermal Co‐Evaporation

“…Figure a–c shows transmittance spectra of Ag thin film with different thicknesses deposited on ZnMgO substrates, which is used as an electron transport layer (ETL) because ZnMgO has a better‐matched energy band to that of Ag, lower turn‐on voltage for EL devices, and relatively smooth film surface compared with that of conventional pure ZnO ETL. [ 16,17 ] As the Ag film thickness increases from 10 to 30 nm, the transmittance at 550 nm decreases from 61.2% to 25.8%, while the sheet resistance decreases from 10.0 to 1.6 Ω sq −1 because of better film morphology and continuity. The thinnest 10 nm thin film has the most considerable sheet resistance caused by the discontinuous film morphology that seriously affects the electronic properties of electrodes and devices.…”