OLED basics

Organic Light Emitting Diode
(OLED)
Presented by:
Muhammad Umar 2012-MS-EE-50
Waqar Mahboob 2012-MS-EE-96
Ahmed Bilal Hussain 2012-ME-EE-14
Iayan Khalid 2012-MS-EE-20

Contents
 Introduction
 History
 Structure of OLED
 How OLED works?
 Types of OLEDs
 Advantages and disadvantages
 Comparison
 Conclusion
 References
2

Introduction
 Emerging Technology for displays in devices.
 Main principle behind OLED technology is
electroluminescence. [1]
 Offers brighter, thinner, high contrast, flexible displays.
 OLEDs are solid state devices composed of thin films of
organic molecules that is 100 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.
3

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.
 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 for5

Structure of OLED
 Substrate( made up of Plastic or Glass)
 Anode. (made up of ITO)
 Organic Layer.
 Cathode. (made up of oxides of Calcium,
Aluminium or Magnesium)
7

Single Layer and Multilayer
OLEDs
 Single Layer:
◦ Contains only one organic layer between two
electrodes.
◦ Having Low Operation Efficiency.
 Multi-Layer:
◦ Two or more layers are between electrodes
depending on the application.
◦ Two most frequently used layers are HTL and ETL.
◦ Conductive layer (Hole Transport Layer).
made up of polyaniline or metal-phthalocyanine.
◦ Emissive layer( Electron Transport Layer).
made up of polyfluorene or metal chelates.
8

Working
 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
9

OLED device operation
Transparent
substrate
Anode
(ITO)
Conductive
layer
Emissive
layer
Cathode
LUMO
LUMO
HOMO
HOMO
eˉ
eˉ
h+
h+
h+
10
Energy Diagram

Types of OLED
Six types of OLEDs [3]
 Passive matrix OLED(PMOLED).
 Active matrix OLED(AMOLED).
 Transparent OLED(TOLED).
 Top emitting OLED.
 Flexible OLED(FOLED).
 White OLED(WOLED).
11

Flexible OLED
 Human hair is 200x the thickness of the OLED
layers. 16

Advantages[2]
 Lower Cost in the future.
 Light weight & flexible plastic substrates.
 Wider viewing angles.(178°)
 Improved brightness (25% more than LCD)
 Better power efficiency (40% less than
LCD)
 Response time (<0.01 ms)
17

Disadvantages[2]
 Current cost
 Life Span
 Colour Balance Issue
 Efficiency of Blue OLEDs
 Water Damage
 Outdoor Performance
 Power consumption for white display
 UV sensitivity.
18

Comparison between LCD,
Plasma and OLED[2]
19

Conclusion
 OLED contains stunning picture qualities and it
open a new era in display devices.
 Use of proper encapsulation to prevent device
from water.
 Outdoor performance can be increase by using
circular polarizer or anti-reflective coating on
cathode.
 Singlet excitons will migrate with an average
diffusion length of about 20 nm followed by a
radiative or irradiative decay in Single Layer
OLED. [4]
 Using Multilayer OLEDs migration and decay of
singlet excitons are also restricted resulting in
drastically improved luminous and quantum
efficiencies compared to simple single layer
devices [5] 20

References
[2] Srećko Kunić, Zoran Šego, OLED Technology and Displays,
54th International Symposium ELMAR-2012.
[4] C.W. Tang, S. A. VanSlyke, C. H. Chen: Electroluminescence of
doped organic thin films, J. Appl. Phys., 65, 3610–3616, 1989.
[5] Dirk Ammermann, Achim Böhler, Wolfgang Kowalsky, Multilayer
Organic Light Emitting Diodes for Flat Panel Displays, Annual
report 1995, Institut für Hochfrequenztechnik, TU Braunschweig
22

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