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OLED The Future in Display Technology

*Samsung OLED TV
Probably two of the biggest announces during the CES 2012 were the Samsung and LG's OLED TVs. Although, both vendors offers different characteristics that make their products unique, they have one thing in common: both use OLED technology. But, what is OLED? Well, OLED stands for Organic Light Emitting Diode, and even though this technology isn't very new, it has become stronger during the last years, and used, mainly because of its costs, in devices such as phones and tablets.
 
*LG OLED TV

OLED are semiconductor devices, which can be from 100 to 500 nanometers thick, that consist in two conductors separated by a carbon-derived material in form of films. Basically OLED work in a similar manner to LEDs, and this process is called electro phosphorescence. When voltage is applied between both conductors, one layer becomes negative charged (anode) and the other one positive charged (cathode) producing an electrical current inside the OLED. In consequence, the side of the organic material near the cathode, known as donor, is filled with electrons (atoms are provided with and additional electrons becoming negatively charged), and the other side, known as receiver, is filled with holes (electrons are removed from atoms becoming positively charged). In the middle of both charged layers, there is a neutral region, called depletion or junction region. When an electron from the donor side cross this barrier and reach the other side to fill one hole it gives up energy in the form of a photon of light, in consequence the OLED emits ligh. The color of the light depends on the type of the organic material on the emissive layer. Manufacturers place several types of organic films on the same OLED to make color displays, the intensity or brightness of the light depends on the amount of electrical current applied. The more the current, the brighter the light.

** OLED Structure
** How OLED works
OLEDs are made of several types of materials. The most basic division is between small molecules (SMOLEDs), and large molecules (Polymer OLEDs or POLEDs). Today, almost all OLEDs are made of SMOLED.
In addition, based its the properties, the materials used in the manufacture of OLEDs can be classified in two different types: fluorescent and phosphorescent (PHOLED). Flourescent materials last longer, but are much less efficient than phosphorescent materials. Some Manufacturers like Samsung combines these materials, and uses red PHOLED together with fluorescent green and blue.

Moreover, there are two methods for driving OLED displays: Passive-Matrix OLED (PMOLED) and Active-Matrix OLED (AMOLED).
Passive-matrix OLED or PMOLED consist in stripped films of conductor material, instead of just one layer, in the anode and cathode. The anode strips are arranged perpendicular to the cathode strips and the intersection of both creates a pixel. An external circuit is used to control which pixel will get turned on and which will remain turn off. The intensity of the light will depend only to the amount of the applied current. PMOLEDs are easy to make, but they consume more power than other types of OLED, mainly due to the external circuitry. Although, they consume even less battery power than LCDs so they are better used in applications such as cell  phones, PDAs and MP3 players.

** OLED Passive Matrix
 Active-Matrix OLED or AMOLED, contrarily to PMOLED, has full layers of cathode, organic molecules, and anode. To control the OLED, small TFT transistors are placed in an array that forms a matrix. This array determines which pixel get turned on to form and image. AMOLEDs consume less power than PMOLEDs, because the TFT array require less power than an external circuitry, so they are used for large displays. Moreover, AMOLED has faster refresh rates. AMOLEDs are mainly used in computer monitors, large screen TVs, and electronic signs or billboards.
Besides, the development of displays the future of OLED devices also covers applications such as light, transparent OLED and Flexible OLED.

** OLED Active Matrix

Some of the Advantages of OLED are:
  • Thinner, lighter and more flexible than LCD and LED
  • Don't require backlight like LCDs or LED because they generates light by themselves
  • Lower power consumption
  • Faster refresh and better contrast
  • Easy to produce and can be made in larger size because its made of plastic
  • Field of view of 170°
  • Operate in a broader temperature range
But, it also has some disadvantages:
  • Lifetime, red and green OLED films have longer lifetimes (46,000 to 230,000 hours), while blue reach up to 14,000 hours
  • Manufacturing process is still expensive
  • Easily damaged by water

OLEDs can also be used in another type of applications. For example, light applications. This market includes several companies like Phillips, OSRAM and Lumotech. Phillips panels, called Lumiblade, were the first to be released back in 2009. Actually, these companies are shipping OLED panels but they are small and expensive. Some of the benefits of OLED light are that they don’t contain bad metals such as CFLs, and are very efficient.
 

In addition, manufacturers are also developing a transparent and flexible OLED. Transparent OLED is made of transparent materials, so when it's turn on images can be seen in both sides.

* Samsunt OLED transparent window
Flexible OLEDs are made of flexible metallic materials or plastic. They are used in devices such as cell phones and PDAs due to its reduced breakage. Flexible OLEDs can also be attached to fabrics.

* Toshiba Flexible OLED prototype

This is  a short video released by Samsung, showing their idea of how tablet PCs will be in the future, if they are made of transparent and flexible OLED.


Flexible and transparent OLEDs will open up a whole world of innovative applications that only existed in our imagination. Corning release back in April 2011 a video named "A day made of glass". In the video, they show all the possible applications that can be developed in the future and how they will influence our lives.
 
 

Recently, Corning also released "A day made of glass 2", if you want to watch this video here is the link.

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