Self-emissive organic light-emitting diodes (OLEDs) are a new promising technology with high expected profitability on the display market, which is currently dominated by liquid crystals. They show low driving voltages in combination with unrestricted viewing angles, high color-brilliance, light weight, small film-thicknesses and low production costs. Because of the plasticity of the materials they can be deposited on flexible substrates. Nowadays, there are already OLED-display devices available such as PDAs, mp3 players, mobile phones, navigation-systems etc. One can distinguish two material-classes used in OLED: OLEDs based on small molecules, which are deposited by thermal evaporation and the low-cost polymeric OLEDs, which are processed from solution. Initially, it was difficult to realise polymeric multilayer OLEDs, since newly deposited layers dissolved the underlying layers, but are now easily accessible by the use of direct lithography in combination with oxetanefunctionalised polymers. Despite intense research efforts during the last decade there are still improvements to be made in OLED-lifetime and OLED-outcoupling. The light-outcoupling is limited by the refractive indices of the OLED building layers. Simple ray-optics allows to estimate the external quantum efficiency of a standard OLED to 20 % of the initially generated light. 80 %, however, are lost to total internal reflection. To overcome this problem many approaches have been introduced. They can be divided into modifications of the external OLED-architecture (e.g. mesa structures, micro-lenses) and modifications of the internal layer structure. It was demonstrated that diffraction elements, such as periodic structures, are highly suitable to improve light-outcoupling. Doubling of the efficiency and luminescence enhancements up to factors of five were reported with respect to the flat reference devices, but only in combination with very poor overall efficiencies. Subject of this thesis was to structure well-performing organic OLED-polymers by direct lithography (DL) and investigate their applications in electro-optic devices as diffraction elements. Additionally, photoembossing (PE) should be applied to access structured wellperforming oxetane functionalised OLED-materials without any wet-development step. The third method is a combination of direct lithography and photoembossing and is referred to as “combined DL-PE structuring” in this thesis

1. OLED Technology

2. Introduction
 Uses organic light emitting diode(OLED).
 Emerging Technology for displays in devices.
 Main principle behind OLED technology is
electroluminescence.
 Offers brighter, thinner, high contrast, flexible
displays.

3. What is an OLED?
 OLEDs are solid state devices composed of thin films
of organic molecules that is100 to 500 nanometres
thick.
 They emits light with the application of electricity.
 They doesn’t require any backlight. i.e., they are self
emitting.
 They are made from carbon and hydrogen.

4. History
 The first OLED device was developed by Eastman
Kodak in 1987.
 In 1996, pioneer produces the world’s first
commercial PMOLED.
 In 2000, many companies like Motorola, LG etc
developed various displays.
 In 2001, Sony developed world’s largest fullcolor
OLED.

5. History (contd.)
 In 2002, approximately 3.5 million passive matrix
OLED sub-displays were sold, and over 10 million
were sold in 2003.
 In 2010 and 2011, many companies announced
AMOLED displays.
 Many developments had take place in the year 2012.

6. Features
 Flexibility.
 Emissive Technology.
 Light weight and thin.
 Low power consumption.
 High contrast, brighter and perfect display from all
angles.

7. Structure of OLED
 Substrate.
 Anode.
 Organic layer.
-Conductive layer (Hole Transport Layer).
made up of polyaniline or metal-phthalocyanine.
-Emissive layer( Electron Transport Layer).
made up of polyfluorene or metal chelates.
 Cathode.

8. Structure of OLED(Figure)

9. OLED Fabrication
 Substrate preparation.
 Device deposition
 Deposit and pattern anode.
 Pattern organic layers.
 Vacuum deposit and pattern cathode.
 Encapsulation.
 Also involves making backplane.

10. Working Principle
 A voltage is applied across the anode and cathode.
 Current flows from cathode to anode through the organic
layers.
 Electrons flow to emissive layer from the cathode.
 Electrons are removed from conductive layer leaving holes.
 Holes jump into emissive layer .
 Electron and hole combine and light emitted.

11. Working Principle(figure)

12. OLED device operation
Transparent
substrate
Anode
(ITO)
Conductive
layer
Emissive
layer
Cathode
LUMO
LUMO
HOMO
HOMO
e
ˉ
e
ˉ
h+
h+h+
Light

13. Types of OLED
Six types of OLEDs
 Passive matrix OLED(PMOLED).
 Active matrix OLED(AMOLED).
 Transparent OLED(TOLED).
 Top emitting OLED.
 Flexible OLED(FOLED).
 White OLED(WOLED).

14. Passive Matrix OLED

15. Active Matrix OLED

16. Transparent OLED

17. Top Emitting OLED

18. Flexible OLED

19. White OLED

20. OLED Advantages
 Thinner, lighter and more flexible.
 Do not require backlighting like LCDs.
 Can be made to larger sizes.
 Large fields of view, about 170 degrees.
 Faster response time.
 Brighter.
 High resolution, <5μm pixel size.

21. OLED Disadvantages
 Expensive.
 Lifespan.
 Water damage.
 Colour balance issues .

22. OLED LCD
 Greater view angle.
 High contrast.
 Faster response time.
 Do not require
backlighting.
 Temperature(~50°C –
80°C).
 Limited view angle.
 Low contrast.
 Slow response time.
 Require backlighting.
 Temperature(~0°C-
100°C).
OLED vs. LCD

23. Applications
Major applications of OLED technology are
 OLED TV.
 Mobile phones with OLED screens.
 Rolltop Laptop.

24. OLED TV

25. Mobile phones with oled screen

26. Rolltop Laptop

27. Conclusion
 Organic Light Emitting Diodes are evolving as the
next generation displays.
 As OLED display technology matures, it will be
better able to improve upon certain existing
limitations of LCD including
 high power consumption
 limited viewing angles
 poor contrast ratios.