Organic Light Emitting DiodesMaterial Science

Stephen Clemmet CEng MSc BEng MIET

Oxford - Great Britain

Topics

Organic Light Emitting Diode Devices

1. Overview of OLED technology2. Fluid material science3. Lifetime and degradation

Ultraviolet Curing

4. UV-inkjet curing technology5. Material science6. Curing techniques7. Curing challenges

Technology Overview

Organic Light Emitting Diodes

OLED System

OLED Driver

Channels

PWM

Current

Battery

Device

EncapsulationUV

Cathode

ETL

EmissiveUV

HTL

MaskUV

Anode

Substrate

Organic Electronics Literature

Organic Electronics

Hagen Klauk

Wiley- VCHISBN 978-3-527-31264-1£126 / €146

Organic Electronics Literature

Organic Light-Emitting Devices

Joseph Shinar

SpringerISBN 0-387-95343-4£87 / €100

Material Science

Lifetime

Oxygen Pin holesTemperature Water vapour

OLED Structure

Encapsulation

Power

Mask Mask

Hole Transport

Emissive

Electron Transport

Cathode

Substrate

Anode

Light

Substrates

Substrate

Material Malleability Thicknessµm

WVTRml/m2/24hr

O2TRcm3/m2/24hr

Glass Rigid 1110 - -

PET Flexible 160 1.6 1.5

PET = Polyethylene terephthalateWVTR = Water vapour transmission rateO2TR = Oxygen transmission rate

www.norner.no/bcalc/model/wvtr/film

Anode Materials

Anode

Parameter ITO on glass ITO on PET PANI PW

Malleability Rigid Flexible Flexible Flexible

Resistivity Ω/m2 10 / 45 / 85 60 / 200 / 300 4 <0.1

ITO = Indium tin oxidePANI = PolyanilinePW = Printed wire

Printed Wire

Track width = 0.05mTrack pitch = 0.5mmResistivity ≤ 0.1 Ω/m2

Mask Materials

Mask

Deposition Colours Curing Performance

UV-inkjet CYMK / BW Seconds Excellent

Screen-print CYMK / BW minutes Excellent

UV = Ultraviolet

Hole Transport Layer

Hole Transport

Material Deposition Colour ResistivityΩ/m2

PEDOT:PSS Spin-coat Dark blue 500

PEDOT:PSS Inkjet Dark blue 75-120

PEDOT:PSS = Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)

Emissive Layer

Emissive

Material Deposition Solvent Colour Performance

Ruthenium complex Spin-coat Acetonitrile Red Good

Ruthenium complex Inkjet DMF Red Good

DMF = N,N-Dimethylformamide

Polymertronics’ Red Diamond 620s Deposition

Inkjet on ITO

Red Diamond Emission Spectra

Electron Transport Materials

Electron Transport

Material Solvent Colour Performance

Alq3 Chloroform Green Good

PBD Toluene Clear Fair

Butyl-PBD Toluene Clear Fair

Alq3 = Tris-(8-hydroxyquinoline)aluminumPBD = 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazoleButyl-PBD = 2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazol

Material DepositionWork

FunctioneV

ResistivityΩm

TempºC Performance

Aluminium Sputter 4.08 2.7 x10-8 500 Excellent

Indium-Gallium Liquid 4.15 29.4 x10-8 16 Good (Lab)

Indium Foil Heat 4.12 8.4 x10-8 157 Fair

Silver Particles Liquid 4.26 1.2 x10-8 25 Fair

Gold Sputter 5.10 2.4 x10-8 500 Useless

Cathode Materials

Cathode

Indium-Gallium

Encapsulation Materials

Material Malleability Thicknessµm

WVTRml/m2/24hr

Glass Rigid 1100 -

PET Flexible 160 1.6

PEN Flexible 160 0.5

CA Flexible 110 77

PET = Polyethylene terephthalatePEN = Polyethylene nitrideCA = Cellulose Acetate

Encapsulation

UV-Inkjet

UV-Inkjet

www.cyan-tec.com

Advantages of UV-Inkjet

Fast printing4s curing timeHigh durability

High dot-registrationInkjet on non-pourous surfaces

Print electronics with CYMK graphics

UV Bands

BAND Wavelength nm Curing Source

UVA 380-315 CYMK HgPb

UVB 315-280 - -

UVC 280-200 GMA HgFe

VUV 200-100 - -

HgPb = Mercury - LeadHgFe = Mercury – IronCYMK = Cyan, yellow, magenta, black colour inksGMA = Poly(tert-butyl methacrylate-co-glycidyl methacrylate)

400nm 700nm

Mercury-Lead Spectra

Mercury-Iron Spectra

Red Diamond 620 Emissive Layer

Emissive

Material Deposition Solvent Wavelengthnm Polymer Initiator

Ruthenium complex Inkjet DMF 260 GMA PDT

DMF = N,N-DimethylformamideGMA = Poly(tert-butyl methacrylate-co-glycidyl methacrylate)PDT = (4-Phenoxyphenyl)diphenylsulfonium triflate

Electron Scans

Organic Light Emitting DiodesMaterial Science

Stephen Clemmet CEng MSc BEng MIET

Oxford - Great Britain