11
Single molecular emitters
Cross-like excimer aggregate
Terthiophene monomer core Alternative terthiophene
(0.31, 0.42) 0.35% ITO/PEDOT:PSS/light emitting layer/LiF/Al
12
Single molecular emitters
Platinum complexs
Blue monomer/Red excimer Good transport properties Concentration of the emitter 10–20 wt% Incandescent lamps(15%)
It appears clear that research efforts focusing on new emitting molecular and polymeric compounds are at the heart of the progress of WOLED technology and advancements will largely rely on the ability of chemists to design and synthesise efficient materials and properly combine them.
14 lmW-1 20 wt% 2 wt% 0.5 wt% Direct charge recombination Low concentration
Host–guest energy transfer
10
Single molecular emitters
Simplified scheme
No device aging Difficult molecular design and colour purity Lower efficiency
Emission colour—voltage 14 V 3.7 cdA-1
8
Multiple emitters mixed in a single layer
Minimum intermolecular distance Encapsulated into functionalized cyclodextrins
5.75 lmW-1
22.62 cdA-1
17
Single molecular源自emittersBisindolylmaleimide (双吲哚马来酰亚胺) Polyfluorene Polycarbazole (聚咔唑)
P5 maleimide molar ratio：2% (0.33, 0.33) P6 Better hole transporting Efficiency
41.3 lmW-1
High energy gap mCP and TAZ
6
Stacked layers emitting different colours
Anode–cathode layer (ACL) 15. 1V (0.33, 0.38) 5.3%
11.2V (0.33, 0.31) 10.5%
Single molecular emitters
Molecular dyad
Ether linkage
No excimers
Excited-state intramolecular proton transfer Stoke shift
20
Conclution and outlook
The most important classes of organic and organometallic electroluminescent materials used to produce white light have been introduced in this tutorial review together with methods to combine emitters of different colours.
Electroluminescent materials for white organic light emitting diodes
Chemical Society Reviews, 2011, 40(7): 3467-3482.
By Kangbin Lin
1
Contents
Introduction Multiple emitters
(0.282, 0.336) 0.39 cdA-1
9
Multiple emitters mixed in a single layer
The host：charge transport；blue emission.
Second non emitting co-host polymer: PVK Hole mobility and Miscibility Microphase-separated 6.2V (0.33, 0.33) 12.5 cdA-1
Single molecular emitters
Conclution and outlook
2
Introduction
OLED schematic drawing
3
Introduction
1. CIE chromaticity coordinates (x, y) 2. Colour Rendering Index (CRI)
4
Introduction
Approaches to white electroluminescence from organic/organometallic emitters.
5
Stacked layers emitting different colours
10V (0.31, 0.41) 17 cdA-1 Same host compound
(0.298, 0.310) 8V
(0.304, 0.327) 15V
14
Single molecular emitters
Single organometallic complexe
Broad PL and EL emission
15
Single molecular emitters
ITO/PEDOT:PSS/P1(120 nm)/Ca/Ag
Block polymers
Benzothiadiazole (BT) 苯并噻二唑
Molar ratio 2% BT and 1% NTI
12.5 cdA-1
16
Single molecular emitters
0.005 molar ratio 2.0 lm/W-1
Alkyl spacer
0.003 molar ratio
18
Single molecular emitters
Supramolecular copolymer self assembly
pi-conjugated oligomers
(0.31, 0.45)
0.5 mol% red, 1.0 mol% green and 98.5 mol% blue
19
21
22
3. Correlated Colour Temperature (CCT)
4. Luminous power efficiency (lmW-1) 5. Luminous efficiency (cdA-1) 6. Internal quantum efficiency 7. External quantum efficiency 8. Lifetime
7
Multiple emitters mixed in a single layer
Blending polymers
Doping small molecular emitters in a wide energy gap host
MEH-PPV : 5–28 wt% range Phase segregated nanocrystalline PFO amorphous MEH-PPV domains
13
Single molecular emitters
Monomers and Electromers
PL and EL spectra of TECEB film Significant difference Blue emission peaked at 450 nm Singlet excitons Voltage independent