Evolvement of Quantum dot Light Emitting Diode (QLED) Technology: An Overview

Television is amongst many other technologies which evolved rapidly in 20^th century as a result of market competition. Currently, this evolution has landed from huge boxes to flat screens with high definition display, which give more colorful experience than reality itself.

It was late before 1940s when people enjoyed Black and White Television, which worked merely on the basis of white phosphor coated screen which represented an image, when an electron beam painted that image on it resulting into a black and white image. Later on, CRT (Cathode Ray Tube) Technology for generation of colored images in television came up with three electron beams one for each additive primary color (red, green, and blue).

As technology evolved, Plasma Technology came into existence in televisions, which consists of tiny cells coated inside with phosphor which were then coated to the interior of a glass tube, which was filled up with a gas. Once current flows through the gas and the gas atoms bombard on cells, there occurs generation of ultraviolet light, ultimately generating an image on screen. This ultimately reduced the size, as the cathode tube is absent in this case.

Further Evolution of LCD (Liquid Crystal Display) Technology came into existence in televisions, which utilizes a backlight source to illuminate, which includes CCFL(Cold Cathode Fluorescence Lamps), etc. as this technology doesn’t include electron beams like CRT and these are much thinner than Plasma television and are available in variety of sizes.

Advancement in technology led to utilization of LED (Light Emitting Diode) as a backlight source for the display. In case of LCD, where the backlight needed to be blocked in order to represent a darker zone in display, LED provided a facility wherein the light can be dimmed (LED can be manufactured in very small sizes). LED television are of two types white and RGB, where white uses white CCFL and RGB utilizes three colors(red, green, blue).

In recent times market has flushed with OLED (Organic Light Emitting Diode) technology televisions, which refers to Organic Light Emitting Diode Technology which utilizes Organic Semiconductors, to create a digital display on activation by two electrodes, one of which is transparent.

Currently market is hit by a newer technology utilizing Quantum Dots or Semi-conductor nanocrystals called as QLED (quantum dot light emitting diode) Technology. QLED TV offers high and dynamic brightness levels, best viewing angle and produces more colours than any LED TV. QLED is supposed to be a so-called emissive technology. QLED basically means quantum dot technology + LED = QLED. QLED technology utilizes a quantum dots as a light source or light emitting device. Quantum dots are very small semiconductor particles, only several nanometers in size, so small that their optical and electronic properties differ from those of larger particles. The quantum dots are really tiny particles that, when hit with light, can deliver extremely high-intensity light means basically quantum dots may emit light, or just convert it. QLEDs are characterized by pure and saturated emission colors with narrow bandwidth. Quantum dots are tiny, and their size determines their color. LED TVs with quantum dots such as cadmium selenide (CdSe) nanocrystals, considered as “QLED” use BLU (Back-Light Unit) and produce enhanced colors utilizing quantum dots. The quantum dots can be used as a tube adjacent to the LEDs or in a sheet of film. QLED TV technology utilizes quantum dot with LED display. The quantum dot can be utilized to experience extremely bright and intensely dark colors on the QLED TV, just as real life. QLED TV technology places a layer or film of quantum dots in front of a regular LED backlight panel. The layer or film is made up of quantum dots which are tiny particle seach of which emit its own individual color depending on its size (anywhere between 2 and 10 nanometers). In QLED TV quantum dots are arranged between the display and the LED lights i.e. behind the display and in front of the LED. When the quantum dot is struck by light, it glows with a very specific colour.

Conventional LCD TV mostly utilizes LED which emits white light butQLED TV can utilize any color, like blue LED which can emit blue light. A blue LED light emits the blue hues. When blue LED emits the blue hues then the different sized quantum dot emits different colors such as red, green, etc based on size of quantum. The quantum dot can have different size and each size producing a different hue to turn light into perfect expressions of color. For example, when a blue LED light is struck on the quantum dot which has 5 nm diameters, then that quantum dot will emit red hue to express red colour and likewise, different size quantum dots emit different hue to express different colors while producing a picture.

Recently Samsung has come up with QLED TV quantum dot technology paired with (high dynamic range) HDR technology to reproduce a greater dynamic range of luminosity with standard digital imaging or photographic techniques for experiencing full spectrum of real-life hues and clarity. Samsung has paired this QLED technology with precision black technology which automatically adjusts the brightness of every scene accordingly, in their QLED TV series. In QLED TV the quantum dot technology helps in experiencing true or real colour as real life event and HDR technology assists in expressing greater dynamic range of luminosity from any angle.

Samsung has recently filed a Patent application (application no. WO2017018713A1) on QLED technology which talks about a display apparatus and a display method, which consists of fixed number of light emitting elements and a controller to monitor and control the light emission of these elements as per the requirement of the display. Samsung filed Another Patent application (application no. WO2016175541A1), which describes presence of liquid crystal panel in the display, associated purpose and utilization of quantum dots as color filter in between polarizing components of liquid crystal panel. The quantum dots are adapted to filter light of preset colors.

REFERENCES

[1]. http://www.samsung.com/global/tv/qled/quantum-dot/

[2]. https://www.wired.com/2015/01/primerquantum-dot/

[3]. https://www.google.co.in/patents/WO2016175541A1?cl=en

[4]. https://www.google.co.in/patents/WO20170187A1? dq=WO2017018713A1&cl=en

[5]. http://www.pocket-lint.com/news/139867-what-is-qled-samsung-s-new-tv-tech-explained

ABOUT THE AUTHOR:

Ms. Shubhangi Dhakane, Patent Associate at Khurana & Khurana Advocates and IP Attorneys , along with Ms. Shalini Patil, Birla Institute of Technology & Science, Pilani (Rajasthan), intern at Khurana & Khurana and can be reached at: [email protected]