OLED displays: From fundamental solid state physics to a multi-billion € industry
Uli Lemmer, Light Technology Institute, Karlsruhe Institute of Technology (KIT)
Outline
1. Beautiful pictures/introductory remarks 2. The beginnings in the 1960s and 1970s 3. Disruptive Discoveries/Pioneers
4. Battle of the technologies
5. From the laboratory to the living room
Looking for a new TV?
Size matters ...
88 inch/223 cm
OLEDs have arrived in everyday life
OLEDs have arrived in everyday life
Is your black black?
OLEDs vs. LED-LCDs
-generate the light of the right color at the right pixel
Structure of an Organic Light Emitting Diode (OLED)
Conjugated polymers
Materials for OLEDs
Production from the liquid phase
Polyfluorenes Sumitomo (Dow)
"Lumation"
Vacuum production
Merck (Covion) PPV Co-polymers
Small Molecules
Spin Coating Spin Coating
Rakeln Rakeln
Ink Jet Printing Ink Jet Printing
Dipping Dipping
Solution processing Evaporation of small molecules Doctor Blading
Conjugated polymers "Small" Molecules
OLED production
Roll-to-roll printing at InnovationLab
OLED production
Conjugated polymers "Small" Molecules
Source: T. Däubler, Schott
Mode of action of an OLED
1: Charge carrier injection 2. Transport
3: Exciton formation 4: Radiative decay
5-layer stack
OLED operation
Source: S. Stolz
Source: J. Blochwitz-Nimoth
Multi-layer-OLEDs
Single-layer-OLEDs
How to optimize OLEDs?
05.10.2021
Outline
1. Beautiful pictures/introductory remarks 2. 1960s and 1970s: The Beginnings 3. Disruptive Discoveries/Pioneers 4. Battle of the technologies
5. From the laboratory to the living room
Electroluminescence in Molecular Crystals.
Electroluminescence in an anthracene single
crystal The first
"OLEDs"
Talk to chemists (and engineers)!
Keep your eyes open for the unexpected!
Think disruptively!/Don't believe your boss!
Establish companies in an early stage of technology!
Network with Asia!
What can you learn from organic electronics?
From the oil crisis in the 1970ies to OLEDs
342 patents listed for Author= C. Tang and Applicant=Kodak
Cathode
ITO/Glass
Interfacial Layer
HTL ETL
Doped Layer Host
Guest
Die Tang-OLED
"Classical" work: Conjugated polymers
Measure the wrong thing and become rich
Soluble polymers for OLEDs
PROGRESS TOWARDS PROCESSIBLE MATERIALS FOR LIGHT-EMITTING DEVICES USING POLY(P-PHENYLPHENYLENEVINYLENE)
VESTWEBER H, GREINER A, LEMMER U, MAHRT RF, RICHERT R, HEITZ W, BASSLER H ADVANCED MATERIALS
4 (10): 661-662 OCT 1992.
Talk to chemists and engineers!
Keep your eyes open for the unexpected!
Think disruptively!/Don't believe your boss!
Establish companies at an early Stage of technology!
Network with Asia!
What can we learn from organic electronics?
Source: T. Däubler, Schott
-as a comparision:
-1 lm/W (CRT), -2 lm/W (AMLCD)
Ef ficienc y (lm/W)
Year
the triplet story
+
- – +
- – +
- –
+
- – +
- –
+
- – +
- – +
- – +
- –
Tx Ty Tz S - we need to form excitons from charge carriers
- if the statistics is completely random, three times more triplet excitons than singlet excitons are formed
Spin statistics
The triplet story
Often inefficient
The triplet story
Progress in OLEDs: Phosphorescence
$$$
$$$
Talk to chemists (and engineers)!
Keep your eyes open for the unexpected!
Think disruptively!/Don't believe your bosses!
Establish companies in a early stage of technology!
Network with Asia!
What can we learn from organic electronics?
Outline
1. Beautiful pictures/introductory remarks 2. The beginnings in the 1960s and 1970s 3. Disruptive Discoveries/Pioneers
4. Battle of the technologies
5. From the laboratory to the living room
Conjugated polymers
Materials for OLEDs
Production from the liquid phase
"Polymer LEDs (PLEDs)"
Polyfluorenes Sumitomo (Dow)
"Lumation"
Vacuum production
"Small molecule OLEDs (SMOLEDs)."
Merck (Covion) PPV Co-polymers
Small Molecules
OLED Products 1998-2006
OLED Performance: The failure of polymers in the first wave
Polymer LEDs (PLEDs) vs. Small Molecule Organic LEDs (SMOLEDs)
Source: Samsung SDI 2004
PLED SMOLED
(1 nit = 1 cd/m
2)
5.47
OLED Performance: Universal Display Corporation
Source: UDC 2009
OLED Performance: Example UDC
Source: UDC 2011
OLED Performance: Example UDC
5.50
UDC 2014
5.51
Color saturation is another performance factor: The real blue challenge
Outline
1. Beautiful pictures/introductory remarks 2. The beginnings in the 1960s and 1970s 3. Disruptive Discoveries/Pioneers
4. Battle of the technologies
5. From the laboratory to the living room
Introduction to display technology
Direct addressing
-this is impossible for 3840 × 2160 x 3 pixels
-actual driving schemes are much more complicated
to realize grey scale and fast switching times
Passive Matrix:
-signals are given to one row after the other
- duty cycle is given by 1/(# of rows)
A matrix is needed for driving the display
Active matrix liquid crystal displays
Pixel for LCD Pixel for OLED
Basic pixel for LCD and OLED display
Fabrication of multichrome OLED displays
- clogging of the masks is a problem in mass production
05.10.2021
Large area display fabrication
05.10.2021
Gen 8.5: 8 x 46 inch displays
Large area display fabrication
05.10.2021
Large area display fabrication
Multichrome OLED-Displays:
Ink jet printing of polymers
OLED displays: towards full color and active matrix displays
- Reproduzierbarkeit ?
- massenproduktionstauglich ? -...
...it is not yet clear whether this a technology for mass production
05.10.2021
Ink-Jet-Printed becomes increasingly important in OLED
mass fabrication
05.10.2021
• Tailored hole/electron transport and emission functionalities
• Lifetime for printed materials
• Multilayer printing
• Blue emitter
• Homogeneity
• Resolution
• …many more (performance/competition related) challenges for printed transistors
Challenges for printed OLED displays
05.10.2021
05.10.2021
Evolution of OLED display market
Source: DisplaySearch 2014
