Organic light-emitting diodes(OLED)

PRESENTED BY:

PARITAM SONISID: 13207012M.E. ELECTRONICS

OUTLINE INTRODUCTION HISTORY STRUCTURE OF OLEDs HOW OLEDs EMIT LIGHT TYPES OF OLEDs APPLICATIONS ADVANTAGES DISADVANTAGES FUTURE USES FUTURE IMPROVEMENTS

INTRODUCTION OLED-Organic Light Emitting Diode Organic-Organic materials Definition- Emissive electroluminescent layer is a film

of organic compounds which emits light in response to an electric current

Electroluminescent layer – organic semiconductor material is sandwiched between two electrodes

One of these electrodes is transparent A device that is 100 to 500 nm thick or about 200

times smaller than a human hair.

HISTORY

First developed in the early 1950’s in France. Early technology would emit a short burst of light when a high-voltage alternating current field is applied to crystalline thin films of acridine orange and quinacrine

1960’s – AC – driven electroluminescent cells using doped anthracene was developed

The first diode device was invented at Eastman Kodak in the 1987 by Dr. Ching Tang and Steven Van Slyke

1990 – electroluminescence in polymers was discovered

2000 - Alan J.Heeger & Hideki Shrikawa received Nobel Prize in chemistry for “The discovery and development of conductive organic polymer”.

2008 – announced the creation of consortium including Sony, Toshiba to produce OLED screen

Cathode Emissive Layer Conductive Layer Anode Substrate

Structure of OLEDs

o Conducting layer - This layer is made of organic plastic molecules that transport "holes" from the anode.

o Eg: polyaniline. Polystyrene.

o Emissive layer - This layer is made of organic plastic molecules (different from that of conductive layer) that transport electrons from the cathode; this is where light is made.

Eg: polyfluorene, Alq3 

Organic layers:

Cathode (may or may not be transparent depending on the type of OLED) - The cathode injects electrons when a current flows through the device

Eg: Mg, Al, Ba, and Ca • • Substrate - The substrate supports the OLED Eg: clear plastic, glass, foil Anode (transparent) - The anode removes electrons (adds electron holes) when a current flows through the device Eg: Indium Tin Oxide

1. Voltage applied across Cathode and Anode

1. Typically 2V-10V

2. Electron current flows from cathode to anode

1. Electrons flow to emissive layer

2. Electrons removed from conductive layer leaving holes

3. Electrons from emissive layer jump into holes of conductive layer

3. Electron and hole recombine and light is emitted

How OLEDs Emit Light ?

TYPES OF OLEDs

1. Passive-matrix OLED2. Active-matrix OLED3. Transparent OLED4. Top-emitting OLED5. Flexible/Foldable OLED6. White OLED7. Phosphorescent OLED

1. Passive-Matrix OLED (PMOLED)

Perpendicular cathode/anode strip orientation

Light emitted at intersection (pixels)

Large power consumption

Used on 1-3 inch screens

2. Active-Matrix OLED (AMOLED)

Full layers of cathode, anode, organic molecules

Thin Film Transistor matrix (TFT) on top of anode

Less power consumed then PMOLED

Used for larger displays

DIFFERENCE

Passive OLEDs• The organic layer is between

strips of cathode and anode that run perpendicular

• The intersections form the pixels•  Easy to make• Use more power• Best for small screens

Active OLEDs• Full layers of cathode and

anode• Requires less power• Higher refresh rates• Suitable for large screens

3. Transparent OLED TOLED

Transparent substrate, cathode and anode

Bi-direction light emission Passive or Active Matrix

OLED Useful for heads-up

display Transparent projector

screen glasses

4. Top-emitting OLED (TEOLED)

Transparent Cathode Non Transparent or

Reflective Substrate Used with Active Matrix

Device Smart card displays

5. Foldable OLED

Flexiable metallic foil or plastic substrate

Light weight and ultra thin

Reduce display breaking

6. White OLED Emits bright white light Replace fluorescent lights Reduce energy cost for

lighting True Color Qualities Environmental friendly

7. Phosphorescent OLED

Use the principle of electroluminescence to convert 100% of electrical energy into light

Good energy efficiencies Reduce heat generation Operate at very low voltage Long operating life time Environmental friendly

APPLICATIONS

Portable device displays

Phillips Go Gear MP3 Player

Mobile phones

Keyboards

Digital watches

Light sources

Optimus Maximus Keyboard

• Small OLED screen on every

key

• 113 OLED screens total

• Each key can be programmed

to perform a series of functions

• Keys can be linked to

applications

• Display notes, numerals,

special symbols, etc...

OLED Televisions

• Released in Dec 2007 in Japan

• Released worldwide in Feb 2009. 

• First OLED TV sold in stores.

• 11'' screen, 3mm thin

• Rs.2,50,000

• Weighs approximately 1.9 kg

• Wide 178 degree viewing angle

• 1,000,000:1 Contrast ratio

Sony XEL-1

TVs almost as thin as a credit card

OLED Televisions

LG Display 19-inch OLED

Samsung’s 40 –inch OLED TV

ADVANTAGES OF OLEDs

Much faster response time Consume significantly less energy Wider viewing angles Thinner display No backlight required Better contrast ratio Safer for the environment Has potential to be mass produced inexpensively OLEDs refresh almost 1,000 times faster then LCDs

OLED Displays Vs. LCD and Plasma

Fast Response Time

Fast response time means full motion graphics can be displayed

Wide Viewing Angle

Cheaper way to create flexible lighting Requires less power Better quality of light New design concepts for interior lighting

OLED Lighting Vs. Incandescent and Fluorescent

DISADVANTAGES OF OLEDs

OLED Displays Vs. LCD and Plasma

• Cost to manufacture is high

• Constraints with lifespan

• Easily damaged by water

• Limited market availability

OLED Lighting Vs. Incandescent and Fluorescent

• Not as easy as changing a light bulb

 

    

In Direct Sunlight

Nokia N00 OLED Display Apple iPHONE LCD Display

Future Uses for OLEDLighting• Flexible / bendable lighting• Wallpaper lighting defining new ways to light a space• Transparent lighting doubles as a window

 Cell Phones• Nokia 888

    

    

• Curved OLED Displays, placed on non flat surfaces

Scroll Laptop: Nokia concept OLED laptop

Transparent Car Navigation System on Windshield• Using Samsungs' transparent OLED technology• Heads up display • GPS system 

    

Data GlassDeveloped by Students at the Fraunhofer Institute in Germany A pair of interactive data eyeglasses that can project an image onto the retina from an organic light-emitting diode (OLED) micro display, making the image appear as if it's a meter in front of the wearer. Similar headwear only throws up a static image, Just the movement of the eyeball, to scroll through information.

Future Improvements

 

    

Manufacturers focusing on finding a cheap way to produce “Roll-to-Roll” manufacturing Increasing efficiency of blue luminance Boosting overall lifespan

Roll-to-Roll Printing