1. Organic Light Emitting Diodes Material Science Stephen Clemmet CEng MSc BEng MIET Oxford - Great Britain

2. Topics Organic Light Emitting Diode Devices 1.Overview of OLED technology 2.Fluid material science 3.Lifetime and degradation Ultraviolet Curing 1.UV-inkjet curing technology 2.Material science 3.Curing techniques 4.Curing challenges

3. Technology Overview

4. Organic Light Emitting Diodes

5. OLED System

6. Organic Electronics Literature Organic Electronics Hagen Klauk Wiley- VCH ISBN 978-3-527-31264-1 £126 / €146

7. Organic Electronics Literature Organic Light-Emitting Devices Joseph Shinar Springer ISBN 0-387-95343-4 £87 / €100

8. Material Science

9. Lifetime Oxygen Pin holes Temperature Water vapour

10. OLED Structure Encapsulation Power Mask Hole Transport Emissive Electron Transport Cathode Substrate Anode Light

11. Substrates Substrate MaterialMalleability Thickness µm WVTR ml/m 2 /24hr O 2 TR cm 3 /m 2 /24hr GlassRigid1110-- PETFlexible1601.61.5 PET = Polyethylene terephthalate WVTR= Water vapour transmission rate O 2 TR= Oxygen transmission rate www.norner.no/bcalc/model/wvtr/film

12. Anode Materials Anode ParameterITO on glassITO on PETPANIPW MalleabilityRigidFlexible Resistivity Ω/m 2 10 / 45 / 8560 / 200 / 3004<0.1 ITO= Indium tin oxide PANI= Polyaniline PW= Printed wire

13. Printed Wire Track width = 0.05m Track pitch = 0.5mm Resistivity ≤ 0.1 Ω/m 2

14. Mask Materials Mask DepositionColoursCuringPerformance UV-inkjetCYMK / BWSecondsExcellent Screen-printCYMK / BWminutesExcellent UV= Ultraviolet

15. Hole Transport Layer Hole Transport MaterialDepositionColour Resistivity Ω/m 2 PEDOT:PSSSpin-coatDark blue500 PEDOT:PSSInkjetDark blue75-120 PEDOT:PSS = Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)

16. Emissive Layer Emissive MaterialDepositionSolventColourPerformance Ruthenium complexSpin-coatAcetonitrileRedGood Ruthenium complexInkjetDMFRedGood DMF = N,N-Dimethylformamide

17. Polymertronics’ Red Diamond 620s Deposition

18. Inkjet on ITO

19. Red Diamond Emission Spectra

20. Electron Transport Materials Electron Transport MaterialSolventColourPerformance Alq 3 ChloroformGreenGood PBDTolueneClearFair Butyl-PBDTolueneClearFair Alq 3 = Tris-(8-hydroxyquinoline)aluminum PBD= 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole Butyl-PBD= 2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazol

21. MaterialDeposition Work Function eV Resistivity Ωm Temp ºC Performance AluminiumSputter4.082.7 x10 -8 500Excellent Indium-GalliumLiquid4.1529.4 x10 -8 16Good (Lab) Indium FoilHeat4.128.4 x10 -8 157Fair Silver ParticlesLiquid4.261.2 x10 -8 25Fair GoldSputter5.102.4 x10 -8 500Useless Cathode Materials Cathode

22. Indium-Gallium

23. Encapsulation Materials MaterialMalleability Thickness µm WVTR ml/m 2 /24hr GlassRigid1100- PETFlexible1601.6 PENFlexible1600.5 CAFlexible11077 PET = Polyethylene terephthalate PEN= Polyethylene nitride CA= Cellulose Acetate Encapsulation

24. UV-Inkjet

25. UV-Inkjet www.cyan-tec.com

26. Advantages of UV-Inkjet Fast printing 4s curing time High durability High dot-registration Inkjet on non-pourous surfaces Print electronics with CYMK graphics

27. UV Bands BAND Wavelength nm CuringSource UVA380-315CYMKHgPb UVB315-280-- UVC280-200GMAHgFe VUV200-100-- HgPb= Mercury - Lead HgFe= Mercury – Iron CYMK= Cyan, yellow, magenta, black colour inks GMA = Poly(tert-butyl methacrylate-co-glycidyl methacrylate) 400nm 700nm

28. Mercury-Lead Spectra

29. Mercury-Iron Spectra

30. Red Diamond 620 Emissive Layer Emissive MaterialDepositionSolvent Wavelength nm PolymerInitiator Ruthenium complexInkjetDMF260GMAPDT DMF= N,N-Dimethylformamide GMA = Poly(tert-butyl methacrylate-co-glycidyl methacrylate) PDT = (4-Phenoxyphenyl)diphenylsulfonium triflate

31. Electron Scans

32. Organic Light Emitting Diodes Material Science Stephen Clemmet CEng MSc BEng MIET Oxford - Great Britain