Solution-processed green and blue quantum-dot light-emitting diodes with eliminated charge leakage

Solution-processed colloidal quantum dots for light emission

“…One practical way is via using inorganic materials since these materials not only have ideal band gap energies and high carrier mobility, but also exhibit higher device stability than organic counter parts. To reduce the band gap energy mismatching between the layers and carrier mobility several strategies have been used, such as chemical doping or surface modification to alter the work function of electron transport materials (such as ZnO and ), band-TiO2 structure tailoring of QDs for hole-injection improvement and the use of buffer layers (such as TFB) which promote the electron transport and confine holes (47,48). Inorganic halide perovskite quantum dots (IPQDs) are alternatives to the colloidal dots discussed so far (Figure 3a-c) , however perovskite quantum dots are sometimes too large to be considered QDs and should instead be nanocrystals.…”

“…Lifetime of an LED is based on the time it takes for the luminescence intensity to decay to a specific level. 1,2,49 Electroluminescent QDs are especially good for use in LEDs as they produce pure monochromatic red, green, and blue light. Due to how humans perceive colour (RGB colour theory, Fig.…”

“…To reduce the band gap energy mismatch and carrier mobility between the layers several strategies have been used, such as chemical doping or surface modification to alter the work function of electron transport materials (such as ZnO and TiO 2 ), band-structure tailoring of QDs for hole-injection improvement and the use of buffer layers (such as TFB) which promote electron transport and confine holes. 49,50…”

“…Lifetime of an LED is based on the time it takes for the luminescence intensity to decay to a specific level. 1,2,49…”

ZnO-Based Electron-Transporting Layers for Perovskite Light-Emitting Diodes: Controlling the Interfacial Reactions

“…ZnO-based thin films are promising electron-transporting layers (ETLs) extensively used in solution-processed light-emitting diodes (LEDs) owing to their high electron mobility, excellent optical transparency, environmentally friendly nature, and ease of fabrication. − For example, the introduction of ZnO ETLs to replace organic ETLs in quantum-dot LEDs (QLEDs) has led to substantially enhanced electron injection and transport, and therefore lower turn-on voltage, higher current densities, and brighter emission. , To date, ZnO-based ETLs are the dominating choices for high-performance QLEDs. − The state-of-the-art CdSe-based QLEDs with ZnO ETLs demonstrate high efficiencies with external quantum efficiencies (EQEs) of >20% and long operational lifetimes ( T 50 at an initial brightness of 100 cd m –2 : 125 000 000 h for red devices and ∼2 570 000 h for green devices). Recently, ZnO-based ETLs have also been applied in high-performance InP-based and ZnSe-based QLEDs. ,, These results highlight the unique advantages of ZnO-based ETLs for high-performance electroluminescent (EL) devices.…”