Highly bright alternating-current (AC) driven quantum-dot light-emitting diodes (QLEDs) are demonstrated based on a single dielectric layer structure.

Quantum-dot light-emitting-diodes (QLEDs) can be fabricated by low-cost solution processes, such as spin-coating or inkjet printing, making them strong rivals to their organic LED counterparts. However, the top electrodes, which are usually based on metallic thin-films, such as Al or Ag, have to be deposited by a costly vacuum process, which is incompatible with the low-cost solution process. In this work, an InSnBi alloy, which has a low-melting-point of 47 °C, is developed as a laminated top cathode for the QLEDs. Because of the presence of the native oxides that serve as an electron blocking layer, the resultant vacuum-free fabricated QLEDs exhibit an improved performance, with a peak external quantum efficiency of 12.3%, 9.15%, and 2.5% for red, green, and blue devices, respectively, which is 1.5-, 1-, and 1.1-fold higher than that of QLEDs with evaporated Al cathodes. The elimination of the costly vacuum process allows rapid high throughput, and low-cost fabrication of QLEDs for material screening purpose.

Quantum-dot light-emitting diodes (QLEDs) with tandem structures are expected to be one of the candidate technologies for next generation display due to their advantages of high efficiency and long lifetime. In this work, highly efficient tandem red QLEDs with current efficiency (CE) of 44.91 cd/A and external quantum efficiency (EQE) of 30.10 % are successfully demonstrated by using inter-connecting layer (ICL) based on Al/HATCN/MoO 3 . The efficiencies are further improved to 51.44 cd/A and 34.4 % by using the liquid metal EGaIn cathode. The developed ICL is stable and reproducible. The demonstrated tandem QLEDs, with high efficiency and long lifetime, would be promising candidates for next generation displays and lighting applications.

Top-emitting white quantum-dot light-emitting diodes (QLEDs) have great promise for the active-matrix display applications because the light emitting from the top electrodes greatly increases the aperture ratio of the display, while by working with color filters, they could enable the realization of high resolution, large area and full color display. However, it is difficult to achieve white emission in a conventional top-emitting structure due to the microcavity effect. In this work, we develop white and top-emitting QLEDs by using indium-tin-oxide (ITO) as the top electrodes, which greatly alleviate the undesired microcavity effect. To enhance hole injection from bottom Al anode to the TFB hole transport layer, the double hole injection layers MoO3/PEDOT:PSS are utilized, and to protect the quantum dots (QDs) from damaging by the plasma, a compact electron transport layer based on ZnMgO:PVP composite is used. As a consequence, the demonstrated devices exhibit a high brightness of 12980 cd m -2 , a pure white color with a 1931 Commission International de I'Eclairage (CIE) coordinate of (0.33, 0.33) and a high color stability. The demonstrated white and top-emitting QLEDs, with high brightness and high color stability, would be ideal candidates for next generation active-matrix display and solid-state lighting applications.