1. OLEDs – Introductory Concepts and
Current Research
C. Coward
OEM Group
Supervisors – Prof. A.P. Monkman & Dr. F.B. Dias

2. Talk Outline
1. OLEDs – What they are, where and why they’re used, where they
came from and how they work.
2. Device Efficiency – What controls efficiency, and previously tested
ways to increase it.
3. Current Research – New methods being explored to improve OLED
performance.
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3. What is an OLED?
An OLED is a device that emits light in response to an electric current.
http://community.dur.ac.uk/oem.group
http://en.wikipedia.org/wiki/Oled

4. OLED Applications
http://community.dur.ac.uk/oem.group
www.siemens.com/innovation
http://www.hashslush.com
An OLED TV display (left), and
a solid-state OLED lighting
setup (below).

5. Advantages of OLEDs
http://community.dur.ac.uk/oem.group
www.oled-info.com/oled-tv
http://www.smallhd.com/prod
ucts/dp7-pro/display.html

6. History
C.W. Tang (left) and Steven Van Slyke (right) created the first ever
OLED in 1987.
http://community.dur.ac.uk/oem.group
http://www.oled-info.com/steven-van-slykehttp://en.scut.edu.cn/

7. Working Principles
Anode (e.g. Indium Tin Oxide)
~ 3-5V DC
Light
Emissive Layer
Cathode (e.g. Calcium or
Sodium)
http://community.dur.ac.uk/oem.group
Glass
E.F. Schubert – Light-Emitting Diodes
(Cambridge Univ. Press).

8. Material Technologies
The two competing material architectures used in OLEDs are small
molecules (left), and polymers (right).
http://community.dur.ac.uk/oem.group
VS.
ALQ3 PPV

9. Quantum Considerations
http://community.dur.ac.uk/oem.group
F. Dias – Optical Spectroscopy – PG
Lecture Course, Lecture 1.

10. Device Efficiency
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(i) Injection of electron and hole
(ii) Capture to form exciton
(iii) Radiative decay
(iv) Light emission eff =  rst q ext
Optical outcoupling.
Ratio of excitons to
charge injected.
Fraction of excitons that can
radiatively decay (i.e. Singlets).
Efficiency of radiative decay of
singlet excitons (PL efficiency).
Quantum efficiency = eff =
photons out
charges flowing in circuit

11. The Photopic Response
http://community.dur.ac.uk/oem.group
http://www.maximintegrated.com/
http://dot-color.com/2012/08/14/color-space-confusion/

12. Spin-Orbit Coupling
http://community.dur.ac.uk/oem.group
http://www.nature.com/srep/2013/1309
13/srep02653/full/srep02653.html

13. P-type Fluorescence (TTA)
P-type fluorescence is so called due to it first being observed in pyrene.
http://community.dur.ac.uk/oem.group
http://chemwiki.ucdavis.edu/

14. E-type Fluorescence (TADF)
E-type fluorescence is so called due to it first being observed in eosin.
http://community.dur.ac.uk/oem.group
http://www.nature.com/nature/journal/v492/
n7428/fig_tab/nature11687_ft.html

15. Talk Summary
1. OLEDs are organic, light-emitting diodes that produce
electroluminescence in response to current. They can be printed
onto ultra-thin, flexible substrates.
2. OLEDs are currently used in many display containing devices such
as TV’s and mobile phones, as well as being used in solid-state
lighting systems.
3. New research hopes to increase the efficiency of OLEDs closer to its
maximum theoretical limit of 100%.
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16. Thank you for listening.
Any questions?
http://community.dur.ac.uk/oem.group
http://ww3.oled-display.net/
http://www.ecubedventures.
com/oled-lighting