Has the Achilles' heel of QD-LEDs been resolved? They become up to 5,000 times more durable
Quantum dot-based displays have long been one of the most promising technologies for achieving images characterized by extremely pure colors, high brightness, and reduced energy consumption. Despite these potentials, the spread of electrically powered QD-LEDs (Quantum Dot LED) has remained limited by a fundamental problem: an insufficient operational lifetime, especially for devices emitting blue light.
A group of researchers from the Massachusetts Institute of Technology (MIT), in collaboration with the Samsung Advanced Institute of Technology (SAIT), has now identified both the causes of the phenomenon and a possible practical solution. The results, published in the journal Science Advances, show how the encapsulation of QD-LEDs using an acrylic-based resin can significantly increase their stability and longevity, achieving improvements of over 5,000 times in some cases.
Quantum dots are semiconductor nanoparticles designed to emit light at an extremely precise wavelength. This characteristic allows for richer and more accurate colors compared to conventional technologies, making them key players in some high-end televisions and monitors today. However, in commercial displays, quantum dots are generally excited through backlighting, while the more advanced version, where each quantum dot is powered directly by electric current, has not yet reached the market.
The main obstacle concerns the limited reliability of blue QD-LEDs, which are 50 to 100 times less stable than their red and green equivalents. Such a short lifespan prevents them from meeting the requirements for televisions, smartphones, augmented and virtual reality headsets, or other devices expected to operate for years.
To understand the causes of degradation, the researchers developed a technique capable of sectioning devices into ultra-thin nanometric slices, analyzing their structure using advanced microscopes available at MIT.nano. The comparison between new devices and samples subjected to intensive operation allowed for observation of structural changes in the three functional layers responsible for the light emission of blue QD-LEDs. During operation, these layers tend to thin out and alter their morphology, while individual quantum dots lose their original shape and merge together. According to the authors, the phenomenon is exacerbated by the release of hydrogen and oxygen within the structure, elements that accelerate device deterioration.
To counter this process, a technique already known in the electronics industry was adopted: encapsulation using an acrylic resin. The protective layer limits the release of gases responsible for degradation and reduces alterations in the internal structure of the device. The results show approximately an eight-fold increase in the lifespan of red QD-LEDs and over 5,000 times in blue ones, the component that has so far represented the main technological limitation.
According to the researchers, the resin could also help prevent the formation of moisture in the gases surrounding the quantum dots, further reducing deterioration phenomena. The encapsulation, while significantly improving performance, does not completely eliminate all causes of degradation, which is why the research group is already evaluating the integration of additional functional layers to further enhance efficiency and reliability.
This study is part of a research trajectory that has involved MIT for over twenty years. Among the prominent figures is Moungi Bawendi, a Nobel Prize winner in Chemistry in 2023 for his work on quantum dots, along with Vladimir Bulović, who contributed to the development of QD-LED technologies and the creation of the startup QD Vision, later acquired by Samsung in 2016.
If the progress achieved is confirmed on an industrial scale, the technology could facilitate the creation of thinner, brighter, and more efficient displays, as well as open new applications in the fields of lighting, optical sensors, and quantum dot-based lasers.