Project description
Quantum dots brighten the future of flat panel displays
Colloidal quantum dots are typically between 2 and 10 nm in diameter with applications in thin-film devices such as light-emitting diodes (LEDs). They have profound implications for flat-panel displays, promising to improve efficiency and power consumption with enhanced brightness and colour saturation. Despite their first appearing almost 40 years ago, colloidal quantum dots have yet to make significant headway in next-generation displays due to their low external quantum efficiency. The EU-funded CQWLED project will address this efficiency limitation with LEDs based on hybrid lead halide perovskites. Their unrivalled photophysical properties offer great potential for high-efficiency and long-lifetime in LED technology to produce displays that can fulfil the Rec. 2020 colour gamut, a milestone no company has been able to achieve.
Objective
The colloidal quantum dots (CQDs) are an emerging class of light-emitting compounds for solution-processed optoelectronics such as the light-emitting diodes (LEDs). Compared to the state-of-the-art compound semiconductors and organic light emitting diodes (OLED), the CQD-based LEDs possess extremely high color purity and low materials cost, representing the only feasible materials solution towards realization of the newly-defined Rec. 2020 standard for the next-generation displays. However, the theoretical upper limit of the device external quantum efficiency (EQE) is only ~20%, considerably lower than those in OLEDs and InGaN LEDs. The fundamental bottleneck is that it is not yet possible to control the emission directionality perpendicular to the substrate plane in the CQD superlattices, without compromising the photoluminescence quantum yield (PLQY). As a result, a lot of photons are wasted due to the total internal reflection (TIR) at the air/glass interface, as well as exciton quenching during interparticle energy transfer.
In order to overcome the efficiency limitation, my research group pioneers synthesis, physics, and LED device of layer-controlled colloidal quantum wells (CQWs) of organic-inorganic hybrid lead halide perovskites (OIHPs), the two-dimensional nanocrystals of OIHP in colloidal solution. Our results have suggested that the materials system might be the ultimate solution for the quantum-dot based LEDs. We found that the CQWs possess: (i) the aggregation-induced emission (AIE) characteristics, boosting the film PLQY up to 97%, and (ii) the emission directionality (ED) perpendicular to the substrate plane in their self-assembled superlattices. Based on the new photophysical properties that have never been found in any other CQD systems, in this proposal, we aim to optimally utilize the characteristics of the AIE and ED, in order to realize high-efficiency and long-lifetime LED technology that can fulfill 100% Rec. 2020 color gamut.
Fields of science
- natural sciencesphysical scienceselectromagnetism and electronicsoptoelectronics
- engineering and technologymaterials engineeringcolors
- engineering and technologynanotechnologynano-materialsnanocrystals
- natural sciencesphysical scienceselectromagnetism and electronicssemiconductivity
- natural sciencesphysical sciencestheoretical physicsparticle physicsphotons
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Funding Scheme
ERC-STG - Starting GrantHost institution
8092 Zuerich
Switzerland