LCD TFT LED-OLED CCD CMOS DISPLAY SYSTEMS AND PHOTOSENSORS (PART 3)

LCD

TFT

LED-OLED

CCD

CMOS

DISPLAY SYSTEMS AND PHOTOSENSORS (PART 3)

OLED

and PLED

Mehdi.SHarif

Introduction to:

Organic light-emitting diodes (OLEDs) have made great progress since the first presentation of thin film devices based on small molecule organic materials by Tang and VanSlyke in 1987.

The OLED performance and stability have been rapidly increased over the last years.

Also, the size of the devices is growing and several applications like displays and general lighting are produced.

The developments for lighting applications will reach high efficiencies and low cost production to replace fluorescent and phosphorescent lamps.

Because of very thin active layers (several 10–100 nm), the low material amount used for the production of OLED results in cheap and lightweight products

HISTORY

WHAT IS OLED?

• An organic light emitting diode (OLED) is a light emitting diode

• In OLED the emissive electroluminescent layer is a film of organic compounds .

• There are two main families of OLEDs: those based upon small molecules and those employing polymers.

• Adding mobile ions to an OLED creates a Light-emitting Electrochemical Cell or LEC, which has a slightly different mode of operation.

• An OLED display functions without a backlight. Thus, it can display deep black levels and can be thinner and lighter than liquid crystal display (LCD).

WORKING PRINCIPLE:

WORKING PRINCIPLE:

DEVICE ARCHITECTURES• Bottom or top emission:

• Transparent OLEDs: it much easier to view displays in bright sunlight

• Inverted OLED:

STACKED OLEDS :

Device Architectures

MATERIAL TECHNOLOGIES SMALL MOLECULES

Molecules commonly used in OLEDs include organometallic  chelates

PeryleneAlq3 Tris(8-hydroxyquinolinato)aluminium

 chelate

Alq3 has been used as a green emitter, electron transport material and as a host for yellow and red emitting dyes.

POLYMER LIGHT-EMITTING DIODES (PLED)

poly(p-phenylene vinylene)

Polymer light-emitting diodes (PLED), also light-emitting polymers (LEP), involve an electroluminescent conductive polymer that emits light when connected to an external voltage.

derivatives of poly(p-phenylene vinylene) and polyfluorene

The first blue light emitting polymer diode was produced with a substituted polyfluorene

polyfluorene

Patterning technologies

Organic vapour jet printing (OVJP)

vapor thermal evaporation (VTE)

Color patterning

• Vacuum deposition is not a suitable method for forming thin films of polymers.

• Polymers can be processed in solution, and spin coating is a common method of depositing thin polymer films. • The metal cathode may still need to be deposited by thermal evaporation in vacuum.

Patterning technologies

Lower cost in the future:

Light weight & flexible plastic substrates:

Wider viewing angles & improved brightness:

Better power efficiency: LCDs filter the light emitted

Response time

Advantages AND Disadvantages

Advantages

Disadvantages

Lifespan: The biggest technical problem for OLEDs was the limited lifetime of the organic materials

a lifetime of around 14,000

Color balance issues

Water damage

UV sensitivity

Advantages AND Disadvantages

MANUFACTURERS AND COMMERCIAL USES• Samsung applications

• Sony applications

• LG applications

15 inch 15EL9500

REFERENCES:

• http://en.wikipedia.org/wiki/Organic_light-emitting_diode

• http://en.wikipedia.org/wiki/Chelation

• http://electronics.howstuffworks.com/oled1.htm

• http://www.jbibbs.com/hdtutorial/futuretech.htm

• http://www.oled-display.net

• Sung-Jin Kim ,Yadong Zhang,Organic Electronics 12 (2011) 492–496

• M. Eritt , C. May a, K. Leo et al Thin Solid Films 518 (2010) 3042–3045