Latest development of polymer light-emitting material for ... · 4／60 Fine-tech Japan 2016 •...

1／60

Fine-tech Japan 2016

Apr 08, 2016

Takeshi Yamada

Sumitomo Chemical Co., Ltd.

Latest development of polymer light-emitting material

for printed OLED


FTJ-10

2／60


Contents

1. Proprietary material design

2. Efficiency

3. Lifetime

4. Features of printing

5. State-of-the-art OLED design

6. OLED Lighting

7. Summary

3／60


Sumitomo-CDT R&D

MaterialInk

Device

Scale up

Process

Tsukuba Material Development Lab.

Electronic DeviceDevelopment Centre

Tsukuba Material Development Lab.(Osaka site)Industrial Technology & Research Lab.

CDT (Godmanchester)

ITOHILIL

EML

Low-WF cathode

ITO

HiLiLLEP

Cathode

Glass

e-

h+

Best solution for p-OLED

Joint Development with Partners

Cambridge Display Technology (CDT)(Godmanchester)

4／60


• Proprietary conjugated polymer system• Integrated function in polymer-chain via copolymerization instead of multi-layered stacks

Hole affinitive

Electron affinitive

Emissive

Other functions

Single-stackIntegrated in polymer

Integrated in conjugation system

EaEa

HaEa

EMEa

SM-evap

Multi-stackFunctional layers

Ea

Ha

EM

Proprietary OLED design

P-OLED

5／60


Backbone ETU HTU Emitter Other functions

Fluorenes

Phenylenes

Hetero-atomAromatic system

AminesAmines

Dendrimers

Other condensed-rings

HydrocarbonCondensed-ring emitter

Cross-linkers

Other functional units

Soluble Polymer system : Advantages

- Very soluble and ink-stable materials- Uniform film formation without significant phase-separation or aggregation of materials- Distinctive layer formation by thermally cross-linked polymeric-HTL layer

Every monomer has its function and integrated into one polymer chain with keeping conjugation

: show composition of RGBIL polymers respectively

Proprietary polymer design

Other HTU

6／60


Sumitomo’s material portfolio

Anode

HIL

HTL (IL)

LEP

Cathode

Cathode Selected from various kind of materialsNaF/Al would be preferred as model.

Blue LEP • Proprietary fluorescent polymer system with high efficiency and deep blue.

Green LEP • Proprietary phosphorescent system• Emitter embedded in high T1 polymer

Red LEP • Proprietary phosphorescent system• Emitter embedded in polymer

Polymer HTL • Proprietary X-linking polymer system with high hole mobility, high T1 and stable layer formation

HIL Selected from various kind of 3rd party’s HIL

Printed ETL • Proprietary soluble-ETL system specially for lighting White devices (for all-phos material)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

350 450 550 650 750wavelength(nm)

Nor

mal

ized

inte

nsity

RedGreenBlueIL

PL spectrum

7／60


Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

8／60


• Mobility / energy level offsets• Singlet Yield (Fs:t, cTTA )• PLQE at RZ (krad, knrad)• Recombination Zone profile• Dipole orientation (kx, ky, kz)• Optical constants (n, k)• Layer thicknesses• PL spectrum

TTAHigh S1/T1 ILCharge balance and RZDipole orientationBest optimized n,k

Efficiency of commercial p-OLED material improved

through these studies.

…

Efficiency improvement in commercial material

9／60


0%

10%

20%

30%

40%

0 20 40 60

Outc

oupl

ing e

fficie

ncy (

%)

nm from cathode

1

1.2

1.4

1.6

1.8

0 0.2 0.4 0.6 0.8 1

rela

tive c

d/A

α = kz/kxplanar isotropic

(1,1,0) - inplane

(0,0,1) - perpendicular

(1,1,0) (1,1,1) Perpendicular dipole energy is absorbed by cathode, or channelled into cavity modes

Dipole orientation plays a key role in efficiency.How about polymer materials?

Dipole orientation

10／60


0

0.5

1

1.5

1

1.2

1.4

1.6

1.8

2

2.2

2.4

Extin

ctio

n co

effic

ient

k

Refra

ctiv

e in

dex n

Model blue PLED is anisotropic : scope for improvement

Small molecules

Spectroscopic ellipsometry - Yokoyama et al. Organic Electronics 10 (2009) p.127-137

Model Polymer

k

k

n

n

0.05C8H17 C8H17 n0.95

F8 PFB

k

k

n

n

Small molecule vs polymer

α=0.8 α=0.26 α=0.43α=0.56α=kz/kx

n

n

k

k

11／60


Justification: • Up to 60% boost in efficiency available by aligning phosphorescent emitter

• Up to 16% boost in efficiency available by further alignment of fluorescent blue

planar

Phosphorescent green model Fluorescent blue modelα = kz/kx cd/A EQE % factor

1 8.5 6.9 0.650.5 10.9 8.6 0.830.3 12.3 9.6 0.930.2 13.2 10.2 1.000.1 14.2 10.8 1.080 15.4 11.6 1.16

α = kz/kx cd/A EQE % factor1 91 21.5 1.00

0.8 98 23.2 1.080.6 106 25.1 1.170.5 111 26.2 1.230.2 129 30.3 1.420 144 33.9 1.60

isotropic

planar

isotropic

α=1.0 is current emitter α=0.2 is current emitter

Anisotropic emitter alignment

(1,1,0) – in plane (0,0,1) - perpendicular

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By using emitter alignment, up to 60% boost in efficiency available.

planar

α = kz/kx cd/A EQE % factor1 91 21.5 1.00

0.8 98 23.2 1.080.6 106 25.1 1.170.5 111 26.2 1.230.2 129 30.3 1.420 144 33.9 1.60

isotropic

α=1.0 is current emitter

Emitter

Alignment OLED performance

α(measured)

Estimated gain in EQE

EQE%

Measuredgain in EQE cd/A

Current 1.07 - 19.0 - 76.0

Aligned 0.33 1.3 23.0 1.21 97.0

- Efficiency gain was successfully confirmed.- This is confirmed by on-axis measurement

AND integral-sphere measurement.- Lambertian emission from aligned emitter

also confirmed- Colour is a little bit yellowish.

Colour tuning is on-going

Current emitter

Aligned emitter

Current emitter

Aligned emitter

Theory Experiment

Aligned emitter for higher efficiency

13／60


Emitting dipole orientation - fundamentals

αemit = 0.67

Orientation of emitting dipoles (aemit) can be measured by polarised angular PL

αemit = 1

αemit = 0

Fitting is sensitive to • Thickness (~20nm best)• Wavelength • Optical constants• Angular resolution

SM evaporated Red Ir-acac emitter in

CBP host

Eliminate uncertainty by controlling/measuring all key parameters Satisfied that we have an estimate of aabs and aemit with accuracy of +/- 0.05

Alignment vector = (kx, ky, kz), Orientation α = kz / kxα = 0 100% in-plane (1,1,0)α = 1 isotropic (1,1,1)α = 2 vertical bias (1,1,2)αabs = alignment of backbone/host @ absorption peakαemit = alignment of emitter @ emission peak

14／60


Isotropic emitter5% in polymer

Spherical

αabs = 0.53αemit = 1.07

Anisotropic emitter5% in polymer

Planar & linear

αabs = 0.53αemit = 0.70

Expected gain X1.10Expected gain ~1.0

Orientation depending on various designs 1

Emitter blended in polymer

Polymer is alignedin both cases

Anisotropic emitter shows emitting dipole orientation in polymer.

Schematic picture shows cross-sectional view of EML

15／60


Linearly attached emitterin-chain

αabs = 0.39αemit = 0.31

Zig-zag attached emitterin-chain

αabs = 0.24αemit = 1.78

Expected gain X0.79Expected gain X1.31


Emitter covalently attached in polymer chain

Polymer is alignedin both cases

Shape & style of emitter attachment in polymer is important for higher alignment.


16／60


Linearly attached emitterIn highly-aligned chain

αabs = 0.26αemit = 0.17

Linearly attached emitterIn weakly-aligned chain

αabs = 0.39αemit = 0.31

Expected gain X1.31Expected gain X1.50


Emitter covalently attached in highly-aligned polymer chain

Higher alignment of polymer results in

higher alignment of emitter

Best case strategy for higher emitter alignment

Anisotropic emitterAttached linearly in Aligned polymer


“A3 strategy”

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State-of-the-art Green polymer

Expected gain X1.21

Combination of :Best emitting dipole alignment- Anisotropic emitter - Attached linearly in- Aligned polymer

Optimized charge-balance/RZUse of high S1/T1 IL

Now 100cd/A(EQE~24%)

with CIE-x,y=0.31,0.64achieved

Measured gain X1.15

18／60


Exciton confinement by high S1/T1 interlayer

IL HOMO[eV]

S1(FL peak)

[nm]

T1 soln[eV]

T1film[eV]

PLQY UV-stability(T80 hrs)

PLQYIL

only

PLQYwith

emitter

T60365nm

IL only

T60 365nm

with emitter

A 5.28 419 2.40 2.20 0.34 0.08 - -

B 5.29 419 2.47 2.38 0.19 0.36 - -

C 5.28 419 - - 0.19 0.32 0.3 3.0

New 5.50 417 2.43 2.34 0.52 0.50 10.5 9.5

Trends towards ;Higher S1Higher T1Better stabilitySame hole mobility Deeper HOMO

New IL has a great potential to further enhance device performance.

19／60


Summary of efficiency improvement

Charge Balance

Singlet yield PLQE Out-coupling

TTA or TADF Intrinsic PLQE

Excitonconfinement

Emitter alignment

RZ profile Best optimizedn, k & thickness

R Optimized - Need to improve

Done by high T1 IL

Next Scope

Optimized

G Optimized - (Little Space) Done by high T1 IL

Principleproved

Optimized

B Optimized Done by TTA (Little Space) Done by high S1 IL

Partially done(polymer alignment)

Optimized

EQE = ηexciton formation x ηsinglet formation x ηphoton emission x ηphoton escape

‘charge balance’ ‘Singlet Yield’ ‘PLQE’ ‘outcoupling’

Efficiency

EQE IQE

21% 70%

24% 80%

13% 43%

ITO

HiLiLLEP

Cathode

Glass

e-

h+

~50-100nm ~15nm

IQE estimated from assumption of 30% light out-coupling

Re-assessment

necessary for wider range

of HIL/IL/EML

20／60


Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

21／60


Current Elucidation of p-OLED degradation

Bipolar device

0

0.2

0.4

0.6

0.8

1

400 450 500 550 600nm

Inte

nsity

Hole only device

0

0.2

0.4

0.6

0.8

1

400 450 500 550 600nm

Inte

nsity

Electron only device

0

0.2

0.4

0.6

0.8

1

400 450 500 550 600nm

Inte

nsity

drivenundriven

drivenundriven

drivenundriven

Quenching site formation is dominant degradation mechanism.The PL decay from single carrier devices is shown to be remarkably stable.This strongly suggests that excitons are required to generate quenching sites.

22／60


Process BEFORE exciton formation Process AFTER exciton formation

ocphehext κηγη ×Φ××=

Φph ： PLQEγ ：Charge Balance ηeh ：Exciton formation ratio

Loss of Carrier Balance Decay of Photo Luminescence

ηext : External QuantumEff.γ : Charge Balanceηeh : Exciton Formation RatioΦph : PLQEκoc : Outcoupling

“Decay of Photo-Luminescence Quantum Efficiency” is our main focus.

Efficiency and degradation of p-OLED

23／60


Electron hole

Singlet exciton Triplet exciton

75%25%

Ground state

Sole- or inter-action

Emission

PolymerEfficient and fast emission from Singlet >higher PLQY material

Remove triplet exciton>Use T1 through TTA mechanism (TCP)

Suppress exciton-excitoninteraction (SSA etc)

• Degradation pathway ( ) exists.• To suppress this pathway and establish

longer T95, we need ;1) Reduce route of degradation pathway2) Highly durable material against exciton

energy

Reversible state

Irreversible state

PL quenching site

Introduce stable chemical structure(C-C, C-N bond)

Eliminate traps

Eliminate impurities/defects

Degradation pathway

24／60


Adv. Mater. 2013, 25, 2114–2129- This case is for amine, but generally C(sp3)-C(sp2) bond is weaker than C(sp2)-C(sp2) bond.

Improvement of PL stability : insights from literature

Chemical structure stability against exciton

25／60


At start

After initial decayT90

After longer term decayT50

Initial decay

Intrinsic decay

• Generally lifetime trace described as the sum of initial decay and longer-term intrinsic decay.• If the initial mode exists over 5%, T95 should be very short.• For longer T95 we should suppress the initial decay, then improve intrinsic decay.

Intrinsic decay

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400Driving time with constant current

Initial decay

Intrinsic decay

Observed lifetime trace

EL in

tens

ityDegradation mode

26／60


0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.000.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

Normalised TTA yield Linear Fit of Sheet1 Normalised TTA yield

Norm

alise

d TT

A yie

ld

Normalised Luminance

Equation y = a + b*x

Weight No Weighting

Residual Sum of Squares

4.95305E-4

Pearson's r 0.99393

Adj. R-Square 0.98763Value Standard Error

Normalised TTA Intercept 0.17124 0.01229

Normalised TTA Slope 0.83998 0.01371

10

In-situ %DF measurement

How T95 defined by efficiency factor ?In-situ PL&EL measurement

10

EL at T95 is totally proportional of PL> Suggest that origin of initial decay is loss of PL

TTA contribution at T95 is also proportional of EL> Suggest that no special decay occurred for TTA

27／60


Stability:ThermalElectrochemicalChemicalPhoto (=Exciton)

PL-stability

Excited

Absorption

Al 80nm

Polymer

Al 80nm

Polymer film

EL lifetimePL-stability

LEP-A

LEP-B

LEP-C

LEP-A

LEP-BLEP-C

One of good measures to estimate device stability

28／60


Case 1 2 3 4

Scheme

325nm Ex 365nm Ex 450nm Ex 450nm Ex

Excited Host Host/G-em G-em G-em/R-em

Emission Host G-em G-em R-em

PL-stability : real case

ISC

ISC

Host 1 1 1 1 1

Host 2 1.0 1.6 2.7 1.0

Host 3 1.2 1.8 5.1 1.1

Population of exciton on Host depends on:- Energy transfer efficiency from host to emitter- Back energy transfer probability from emitter to host

Case 2Case 3

Device T95

1

2.0

2.4

Energy transfer between host and emitter plays a critical role for photo-stability and device LT

Normalized stability (T80)

hostG-em

R-em

Significant host dependence

29／60


Green T50

Blue T50

Red T50

RGB T50 have already reached to commercially-viable level Now focusing on T95 (image sticking LT) , efficiency and deeper blue color.

History of Sumitomo’s material development

1981 Start conductive-polymer study1990 Find emission from PPV2000 Start RGB full-color material study2005 Purchase Dow’s PLED activity2007 Acquire CDT as subsidiary

30／60


Spin/BE deviceITO/HIL/IL/LEP/NaF/AlXylene ink

Dec/2015Achieved

2016Our Target

REfficiency cd/A 24 28CIE-x,y 0.66, 0.34 0.66, 0.34T95 hrs @1000nt 5800 6000

GEfficiency cd/A 75 90CIE-x,y 0.32, 0.63 0.32, 0.63T95 hrs @1000nt 9700 12000

BEfficiency cd/A 8.0 10.0 10CIE-x,y 0.14, 0.10 0.14, 0.12 0.14,0.10T95 hrs @1000nt 300 700 750

P-OLED RGB material performance

Device structureITO (45nm)/ soluble HIL (35-65nm)/ Interlayer (20nm)/ LEP (60-90nm) / low-WF cathode

RGB common and simple layer structure. Organics are fully solution-processed.

*Lifetime estimated from luminance acceleration test.*No electrical-ageing applied before lifetime test.

ITOHILIL

LEP

Low-WF cathode

Better color (0.68,0.32)Higher efficiency

Better color (0.30,0.64)Longer T95

Better color (0.15,0.08)Longer T95

Future Direction

31／60


Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

32／60


Well-established and well-understood

system

Much-attention paid to understand the difference from

Evaporative Material

Need to clarify differences from

Evaporative SM andSoluble SM

Evaporative Small-molecule

Soluble Small-molecule Polymer

Comparison of various OLED systems

Konika-Minolta, 2013 LOPE-CDupont, 2013 SPIEEMD, 2013 Printed Electronics USA

FMM evap

IJP

Nozzle

Flexography

33／60


Area Focus EvaporativeSmall-molecule

SolubleSmall-molecule Polymer

Material Charge injection / transport +

(Much attention paid here recently)

TBD

S1:T1 ratio including TTA + TBD

Molecular Orientation + +++Film Density + +++Morphology / crystallization + +Material impurity + ++

Structure Intermixing between layers + +++ +++Use of ETL + + +

Process Residual solvent - +++ +++Solvent impurity - +++ +++

Deposition condition +Vac

+++N2 or Air

+++N2 or Air

Ink viscosity vs conc. - Low dependency High dependency

Layer formation/ aggregation + +++ ++

Our focus on Polymer system

+++ Big difference (beneficial or problematic)++ Small difference+ Standard

34／60


IL/LEP interface detected by UPS

EML thickness Spin : % IL signal Evap : % IL signal

5nm 40% 8%

10nm 12% 4%

30nm 13% 2%

Very small intermixing at interface (~5nm) observed for polymer system.

UPS

IL signal IL signal

35／60


IL/LEP interface detected by TEM/TOF-SIMS

TOF-SIMS

Very clear interface between IL/LEP established- No significant intermixing- No significant penetration of LEP into IL

This originated from ;- Polymeric HTL (=IL) with reasonable Mw- Efficient thermal X-linking system

From UPS, TOF-SIMS and TEM measurement : TEM

EML IL HIL: polymer on IL: SM-evap on IL

Sulfur detected (polymer and SM-evap contain S)(IL contains no S)

At interface, there is no significant difference of S-profile between SM-evapand polymer.

36／60


Engineering of interface between layers

Engineering of IL/EML interface should be a key to “ideal stack”

Penetration Inter-mixing DissolutionObservedphenomena

EML material penetrates into IL while EML ink deposited on IL

EML material mixed with IL polymer at interface

Non X-linked IL polymer dissolves into EML

Issues Exciton migration into IL> low EQE, short LT

No distinctive layer formation results in possibility of lower EQE

Ourstrategy

EML should be polymer. Emitter should be embedded

into polymer chain.High S1/T1 IL to confine

exciton on emitter.

Highly X-linked IL polymer used

Parameters :-Activity of X-linker-Polymer formulation-Mw-Tg

= Ensemble to evaporated device stack

37／60


Process in “Good” Air

Red LEP spin-coated in AirBlue LEP spin-coated in N2

ITO/HIL/IL(20nm)/Blue-LEP(60nm)/cathode

There is no difference in performance between process in Air/N2

38／60


When exposed to O3 under dark, efficiency is not reduced but LT is dramatically reduced.

Process in “Bad” Air

ITO/HIL/IL(20nm)/G or R-LEP(80nm)/cathode

Green w/o O3 exposureO3:28ppb 5minO3:28ppb 10min

Red w/o O3 exposureO3:28ppb 5min O3:28ppb 10min

Accelerated LT test

EML exposed to controlled atmosphere after spin (under dark)

39／60


Intrinsic & extrinsic impurities

Genuine Material

Intrinsic damages Extrinsic damages

Impacts from material impurities

Quenching Site (QS) formation

Charge Trapping Site formation

Solid Ink Film

Impurities from Solvent

Impurities from Apparatus

Oxidative gas

Water

Light

Heat

Monomer Polymer

Terminal Halogen(insufficient end-cap)

Catalyst insertion to polymer

Ester converts to OH

Other elements

Material deterioration(oxidation, decomposition)

Impacts from deposition condition

Reduced Performance

To obtain higher performance, we need to - Improve genuine performance - Eliminate intrinsic damages- Eliminate extrinsic damages

40／60


PL Quenching Site/ Charge-carrier Trap Site

Polymer

Emitter

Solvent

O3

O2 + Excited energy

Oxidized material

N N

+・

QS

O O

Polymerhv

Polymer1*ISC

Polymer3*O2

Polymer3* O21*+

Polymer+・ O2-・+Charge separation

operation

+・

O2-・+ QS

O O

Mechanism hypothesis

- Organics are oxidized by O3 or O2/excited energy and generate oxidized material.- These oxidized material can act as PL Quenching Site and Charge-carrier Trap Site.

What’s happening ?

41／60


Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

42／60


HIL:Effective and stable hole injection intodeeper HOMO IL

New IL:-Higher S1/T1-Higher exciton stability-Good hole mobility-Deeper HOMO

EML:-Best RZ location-Exciton confinement on emitter

(energy transfer engineering)-Best material stability

(intrinsic, extrinsic)

Cathode:Effective and stable electron injection viaselected EIL/cathode system

ILHIL

EML

Best optical design to maximize out-coupling efficiency (layer thickness, n/k…)

A winning strategy leading to best performance

Emitting dipole alignment

Interface :Engineering to avoidenergy migration

Best fabrication condition commonly applied to mass-production (IJP)

43／60


Impressive result of latest printed p-OLED

Spin/BE deviceITO/HIL/IL/LEP/NaF/AlXylene ink

Dec/2015Achieved

REfficiency cd/A 22CIE-x,y 0.66, 0.34T95 hrs @1000nt 5800

GEfficiency cd/A 75CIE-x,y 0.32, 0.63T95 hrs @1000nt 9700

BEfficiency cd/A 7.9CIE-x,y 0.14, 0.11

T95 hrs @1000nt 270

Best practiceNow

280.66, 0.34

On-going

920.33, 0.62

170009.3

0.14, 0.11400

1120.33, 0.62

On-going

Aligned emitterin polymer

Winning strategy

Our winning strategy leads to impressively high p-OLED performance now.

G best practice

Over 25% EQE>90cd/AT95 17000hrs@1knt

44／60


Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

45／60


Transfer to White p-OLED

Anode

HIL

HTL (IL)

LEP

Cathode

Cathode Selected from various kind of materialsLow WF cathode would be preferred as model.

B

Green LEP

Red LEP

Polymer HTL

HIL In-house development or Selected from various kind of 3rd party’s HIL

Printed ETL • Proprietary soluble-ETL system specially for lighting White devices (for all-phos material)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

350 450 550 650 750wavelength(nm)

Nor

mal

ized

inte

nsity

RedGreenBlueIL

PL spectrum

WhiteHigh efficiency White

Phos BEffective electron injectionOptimized for White

Effective excitonconfinement

Effective hole injectionOptimized for White

46／60


Surface emission Thin, light, unbreakable

Soft emissionMulti colorPatterned

FlexibleSee-through

High efficiencyLow cost(R2Rproduction)

Model 2013

Flexible Glass substrate

Model 2015

Features of p-OLED lighting

Plastic Substrate

47／60


Performance Incandescent Fluorescenttube

Inorganic LED OLED

lm/W 20 60 80 70

T70 3000hr 10000hr 30000hr ＞30000hr

CRI 100 88 ＜90 ＞80

Features

Pros Low costGeneral use

Low costGeneral use

Long LifetimeLow power

consumption

Surface emission

Low power consumption

Cons Power consumption Use of Hg Point emission Cost

Lifetime

Comparison of lighting

48／60


Comparison of OLED stack

RGB Stripe Multi-stack Simple-stack

Devicestructure

Features Color-tuning High performance(efficiency & LT) Single layer emission

Material RG : phosB : Flu

RG : phosB : phos/Flu RGB : phos

Soluble process Can be used Cannot be used Can be used

Performance <30lm/W >50lm/W ～50lm/W

Cost High High Low

ETL

Cathode

ILEML

HIL

Anode

ETL

Cathode

IL

EML

HIL

Anode

ETL

Cathode

IL

EML

HIL

Anode

ETL

Cathode

IL

EML

HIL

Anode

ETL

Cathode

ILEML

HILAnode

EML

CGL

ILHIL

ETL

49／60


Solution-processed White-OLED for lighting

ETL

Cathode

ILEML

HIL

Anode

Solution processed

Emission

Base substrate

OLEDCathode

OLED stack Device Process

Simple stack• Solution-processed

4-layers• High performance

Simple device structure• High light out-coupling

efficiency• High durability

Simple R2R process• Good productivity

(Line speed)(Yield)

OLED printing

Cathode depo.

Encapsulation

Our approach

50／60


OLED stack

ETL

Cathode

ILEML

HIL

Anode

Solution processed

Proprietary soluble-ETL• Soluble in orthogonal solvent to EML• Very conductive polymer with good

electron transport/injection function

Simple cathode system• Low WF cathode

Proprietary soluble-EML• Host + Green/Blue dopant• Oligo-/polymer host with high T1 enough for Blue

Proprietary soluble-IL• Polymeric-HTL with Red dopant• Thermally X-linked system• High intrinsic T1

HIL• Good hole injection• Thermally cured system• Appropriate n, k for higher out-coupling

Process and materials are compatibleto plastic substrates

Achievement of RGB well transferred to develop the system

All phosphorescent system

51／60


Scope of material development

Challenges for Material development Scope

Longer LT Blue phosphorescent material (1) Blue emitter / host

Higher lm/W by reduction of voltage (2) Soluble ETL

Appropriate energy transfer & distributionfrom B to GR (3) “Triplet management”

EMLIL CathodeETLAnode HIL＋ -

52／60


(1) Blue emitter and Host

Emitter Stability Emitter-Host Matching

For longer LT, we need 1) Emitter stability2) Best combination of host/emitter

53／60


(2) Soluble ETL

0

2

4

6

8

No ETL 10nmETL

30nmETL

40nmETL

Voltage

0

10

20

30

No ETL 10nmETL

30nmETL

40nmETL

lm/W

• Insertion of soluble ETL results in lower voltage and increased efficiency• No thickness dependence due to very high conductivity of ETL

Al

ETL

ITO

EML

HIL

ILe-

e-e-

AlITO

EML

HIL

ILe-

e-

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Interlayer for display RGBRGB 3-color EML

Red-emitting IL for whiteBG 2-color EML

Formation of Interlayer excited state• Non-radiative decay• Degradation from excited state

Energy in IL is transferred to Red• Red emits in IL efficiently• No additional layer

RGBEML

IL

White emission

Exciton energy on IL

(3) Triplet management

BGEMLIL-R

White emission

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Conventional ILRGB 3-color EML

BGEMLIL-R

RGBEML

ILStructure 1

Triplet management by Red-emitting IL gives higher efficiency and longer lifetime

(3) Triplet management

Red-emitting IL BG 2-color EML

Structure 2

Rela

tive

perf

orm

ance lm/W

LT

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ETL

EL

Cathode

HILIL

Glass

ITO

ETL

EL

Cathode

HILIL

Plastic Substrate

ITO

Intrinsic Material Performance 37lm/W

• Glass > Plastic substrate• OC film attachment• Optimization of every layer thickness• Higher reflectivity cathode• Index matching low-k HIL

Observed efficiency improved from 37 to 68lm/Wwith very simple architecture

×1.8Out-coupling enhancement

Out-couplinglm

/W e

ffici

ency

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ETL

Cathode

ILEML

HIL

Anode

Solution processed

EvaporatedKey development :•EML/IL material design and formulation•Technology to avoid intermixing between layers•Solution-processible ETL having EIL function

Coretechnologies

LT70 calculated to L0=1000 cd/m2 using AF (1.7-1.8)* estimated from T90 value

With 1.8x light out-coupling (estimation)

Latest p-OLED lighting material development

Current solution-processed White OLED without light out-coupling (Dec/2015)

Luminance cd/m2 1000

Efficiency lm/W 45 40 32

EQE % 21.0 20.3 19.0

Voltage V - 3.9 3.9

CCT K 3400 3140 2800

CRI - 62 70 74

T70 lifetime hrs 7400 10000 *18000

Efficiency lm/W 81 72 58

T70 hrs 21000 29000 52000

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Contents


2. Efficiency

3. Lifetime



6. OLED Lighting

7. Summary

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Summary

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Thank you for your attention.

[email protected]

Latest development of polymer light-emitting material for ... · 4／60 Fine-tech Japan 2016 •...

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