SONY OLED TV - WORLD FIRST

On 1st December, 2007, Sony released the world first OLED TV named XEL-1. Sony has been producing OLED display for mobile phones since 2004 but this is the first time OLED is used in TV consumer market. It is because the manufacturing process is still immature, the TV display screen is small and expensive compared with other technologies such as LCD or plasma TVs. This unit costs around $1700 US for a 11 inch TV 0_o

What is OLED?? OLED stands for Organic Light Emitting Diodes.

Diode is a type of electronic device that allows current to flow in one direction only.

Organic because it uses organic compound [molecules that contain carbon] as the Emissive Electronluminescent layer (basically a material that emits light when an electric current passes through it - Light Emitting)

The Emmissive Electroluminescene layer contains a polymer (a substance composed of molecules with large molecular mass [the weight of one molecule of a substance] and with repeating 'structural unit' [its sturcture pattern repeats itself. DNA, Protein and plastic are good examples of polymer]. This polymer allows the organic compound to be easily deposited on it. The matrix of screen pixels (rows and columns) can be "printed" on the polymer layer. The crossing-point of these printed rows and columns make one pixel that emits light.

How does it work?? Simplified descriptions are given below.

 

1) The OLED material contains two sublayers: Emissive layer and the Conductive layer. These two layers are made of two different polymer materials.The blue box is the Anode (+, postisive terminal) and the red box is the Cathode ( - , negative termimal)

2) When a postive voltage is applied to the anode and a negative voltage is applied to the cathode, electrons in the OLED material are attracted to the anode and leave behind the "holes" [holes are not physical but just space left behind by the electrons that occupied the space previously].

3) Eventually all electroncs are on one side of the material (Emissive layer) and the holes are on the other side of the OLED material (Conductive layer).

4) Due to electron-static force between Holes and Electrons, they attract each other and recombine. When electrons recombine with the holes, they lose energy. This energy is released as light (in the visible frequency range - our eyes can see it). The recombination occurs in the Emissive layer, so light emits at this layer , so it is called Emissive layer.

Why OLED??

1) The organic material can be printed on a flexible layer (polymer) , so you can have a display on a bendable surface. Also, it is theoretically cheaper to make than plasma or LCD (when the manufacturing process is mature).

2) Unlike LCD, each OLED pixel emits its own light, so no need for expensive back-lighting used in LCD technology. OLED produces "true black" ( when the room is in total darkness and the TV is still on, you won't be able to see whether the TV screen is on, because the black on the screen  is a true black). No backlight also means a thinner display.

3) OLED gets turned on faster.

4) OLED is lighter

5) OLED dispaly has a winder viewing angle

but.............

OLED materials have shorter life time. In the case of Sony XE-1, the operation hours are limited to about 30,000 hours.

Also, moisture can destroy organic material.

Samsung is also making an OLED high resolution display for the handheld market. Samples are available in the first quarter of 2008.