Technologies Shaping the Future of Displays – Part 2

Angie Kellen, Director, Client Services, Open Sky Communications

Building on my previous blog “Technologies Shaping the Future of Displays – Part 1”, which reviewed micro light-emitting diodes (microLEDs) and how they are transforming the display landscape, I will take a deeper dive with this blog into another emerging display technology, called quantum dots. These nanocrystals,

(Source: Coherent)

typically composed of semiconductor materials, possess unique optical properties that have enabled significant advancements in display performance. From enhancing color accuracy and brightness to improving energy efficiency, quantum dots have revolutionized the way we experience visual content on a variety of devices, including TVs, monitors, and smartphones. This blog will explore the impact that quantum dots are having on the display industry, their key benefits, challenges, and future prospects.

Quantum dots have been a buzzword in the display industry for years. Interestingly, the concept of quantum dots was first introduced in the 1980s. The initial focus was on their potential use in medical imaging and solar cells. It wasn’t until the 2000s that researchers realized that their unique optical properties could be the key to improving display technology. And, the 2023 Nobel Prize in Chemistry was awarded to Moungi Bawendi, Louis Brus, and Alexei Ekimov for their discovery and development of quantum dots. 

While the name ‘quantum dot’ has a cool factor to it, to be honest, their actual definition has always been a bit of a mystery to me. But through conversations and digging deeper into research, I’ve learned that quantum dots are nanoscale semiconductor particles, typically ranging from 2 to 10 nanometers in size. What makes them unique is their size-dependent optical properties. What does this mean?

(Source: Coherent)

When quantum dots are exposed to light, they can absorb photons and re-emit them at specific wavelengths, which is determined by the size of the quantum dot. A helpful analogy on how this works is to imagine a ‘light wave in a box’. The smaller the box, the shorter the wavelength, which will emit a blue light. The larger the box, the longer the wavelength, which will emit light on the red scale. This tunability of emission wavelengths makes quantum dots highly desirable for applications in displays where precise control over color is critical.

Quantum Dot Benefits

Now that we have a good idea of what quantum dots are, let’s explore the benefits they are contributing to display technology.

One of the most significant advantages of quantum dots in displays is their ability to produce highly accurate and vivid colors. Quantum dots can be engineered to emit light at very specific wavelengths, resulting in purer red, green, and blue colors. This leads to a much wider color gamut, which allows for more lifelike and vibrant images, particularly in content that demands high color fidelity, such as High Dynamic Range (HDR) video.

Quantum dots also contribute to increased brightness and energy efficiency in displays. They are highly efficient at converting light into specific colors, meaning that less backlight is needed to achieve the same level of brightness. This efficiency translates to lower power consumption, making quantum dot displays more energy-efficient compared to traditional LCDs. For portable devices like smartphones and tablets, this is particularly important as it can lead to longer battery life and prolong the lifespan of the display by reducing heat-related degradation.

Another advantage of quantum dot displays is their ability to maintain color accuracy and brightness across a wide range of viewing angles. Traditional LCDs often suffer from color and brightness shifts when viewed from off-center angles, which can detract from the viewing experience. Quantum dots help mitigate this issue by providing more uniform light distribution, resulting in consistent color performance even at wider angles.

Quantum Dot Challenges

With every revolutionary technology comes a few challenges and quantum dots are no exception.

One challenge associated with quantum dot displays is cost. Quantum dot technology, especially in its early stages, was more expensive to produce than traditional LCDs. This was due to the cost of the quantum dot materials themselves as well as the additional manufacturing steps required to integrate them into displays. As the technology has matured and economies of scale have been achieved, the cost of quantum dot displays has decreased, making them more accessible to a broader range of consumers.

While quantum dots have been highly effective in enhancing red and green colors, the development of stable and efficient blue quantum dots has proven to be more challenging. Blue light requires quantum dots with smaller sizes, which are more prone to issues such as degradation and lower quantum yield. This challenge has limited the ability to create full quantum dot-based displays, where all three primary colors are generated by quantum dots. Currently, most quantum dot displays still rely on conventional methods for blue light emission, with quantum dots primarily used for red and green.

Quantum dots face stiff competition from other advanced display technologies, particularly OLED and the emerging MicroLED technology. OLED displays, known for their deep blacks, high contrast ratios, and flexibility, have become popular in high-end smartphones and televisions. MicroLED technology, which promises even better performance with self-emissive pixels like OLED but without some of its drawbacks (such as burn-in), is also gaining attention.

While quantum dots offer advantages in terms of color accuracy and brightness, they must continue to evolve to stay competitive against these technologies. Innovations such as quantum dot OLED (QD-OLED) displays, which combine the best features of both quantum dots and OLED, represent one avenue for maintaining relevance in this rapidly evolving market.

Future of Quantum Dots

Even with the challenges above, the future of quantum dots in the display industry looks very promising with new applications and several exciting developments on the horizon.

There have been tremendous innovations around the key materials used in creating flexible and stretchable displays. Quantum Dot LEDs (QLEDs) provide precise color control, resulting in vibrant displays, and when paired with flexible substrates they can be used in bendable and foldable displays. The industries currently exploring or utilizing quantum dots for flexible displays include consumer electronics (particularly in high-end TVs and smartphones), automotive displays, wearable technology and medical imaging devices.

Future of flexible and wearable displays. a Smart glasses or smart lens. b Smart watch with wearable biosensors. c fabric display. d Ultrathin electronic tattoo. e Bendable and foldable display. f transparent smart windows (Source: npj Flexible Electronics in Nature.com article)

One of the most significant advancements in quantum dot technology is the development of QD-OLED displays. These displays combine the emissive qualities of OLED with the color-enhancing properties of quantum dots. In a QD-OLED display, blue OLEDs are used as the light source, and quantum dots are used to convert some of this blue light into red and green, resulting in a display that combines the deep blacks and high contrast of OLED with the wide color gamut and brightness of quantum dots. Samsung has been at the forefront of QD-OLED development, with commercial products expected to become more widespread in the coming years.

Another emerging technology is Quantum Dot Nanorod LED (QNED), which aims to replace traditional OLED or LCD structures with nanorod-based quantum dots that act as both the light source and color filter. This could lead to displays with even higher efficiency, better color performance, and longer lifespans than current technologies.

Another promising development is the advancement of printable quantum dots, which could revolutionize the manufacturing process for displays. Printable quantum dots can be deposited onto substrates using inkjet printing or other additive manufacturing techniques, potentially reducing production costs and enabling the creation of flexible or transparent displays. This could reveal new applications for quantum dot displays, such as in wearable devices, automotive displays, and even transparent windows.

Quantum dots with their ability to emit pure, saturated colors with high energy efficiency have made a profound impact on the display industry. As a result, quantum dots have become a key component in high-end televisions and monitors with their influence on new applications continuing to grow as the technology evolves. I hope that this blog provided you with a better understanding of quantum dots and their potential to enhance display technology. With the ongoing advancements in QD-OLED and printable quantum dots, this unique technology is poised to play a central role in the next generation of displays, ensuring that quantum dots remain at the forefront of visual innovation for years to come.

(Source: Stereo & Video Center in CEPro article)