Flexible OLEDs for consumer products - CDT Ltd · Performance table of current material set. ... Performance of EIL devices opens up further opportunities for ... heat (IR) and sound

Flexible OLEDs for consumer products

Dr. Alexander Doust

Cambridge Display Technology Limited (Company Number 02672530)

Introduction to CDT

Cambridge Display Technology (CDT) is a spin-out Company from the Cavendish Laboratory,

University of Cambridge

Since 2007, CDT is part of Sumitomo Chemical Group (SCC), as a Research and

Development subsidiary in Europe.

CDT is recognised for its activities on the development of light emitting polymer technology

(POLEDs) for Displays (TV’s) and Lighting, as well as some activities in Printed electronics.

We are now expanding our activities to cover other topics such biosensors, energy harvesting

and storage solutions and organic photodetectors.

2


Outline Flexible OLEDs for Consumer Products

3

Recent Improvements

Reduction in drive Voltage

Reduction in takt time – moving towards manufacturing processes

Air stable cathode

Straightforward encapsulation process (lamination) with an off-the-shelf material, offering

improved shelf life

Current portfolio of prototypes

Working with CDT / Sumitomo Chemical


Flexible OLED device structure and processing

4

Evaporation of non

low work-function

cathode

Organic layers printed, dried

and annealed in normal

atmospheric conditions

Processes in vacuum or inert

environment (dry nitrogen)

Electron injection

layer

Light emitting

polymer layer

Hole Injection /

transport layer

ITO Anode

Preparation and

lamination of off

the shelf flexible

encapsulation

In addition to Materials for Displays, CDT has been developing low-cost Flexible OLEDs

These are flexible low information content displays based on solution processed polymer

light emitting materials


Fully printed and flexible OLEDs

5

Green Red Blue White

Luminance turn-on < 20 msec < 20 msec < 20 msec < 20 msec

Operating voltage <5V ~5V <5V <5V

Luminance ~400cd/m2 ~400cd/m2 ~400cd/m2 ~400cd/m2

Operating lifetime > 5,000 hrs > 5,000 hrs > 5,000 hrs > 5,000 hrs

Drive current density ~3 mA/cm2 ~70 mA/cm2 ~5 mA/cm2 ~5 mA/cm2

Power requirement <10 mW/cm2 <400 mW/cm2 <15 mW/cm2 <25 mW/cm2

Shelf life > 5 years > 5 years > 5 years > 5 years

CIE Colour 0.30, 0.64 0.68, 0.31 0.14, 0.17 0.35, 0.38

Performance table of current material set.


Materials Development enabling Low Voltage Platform

6

CDT have developed new air-processable electron-injection layer (EIL) to aid injection

in our FlexOLED structure when using an air-stable cathode (not low-work-function).

Performance of EIL devices opens up further opportunities for FlexOLED applications,

given the ease of manufacturing and the lower drive voltage.

The EIL is compatible with RGBW devices leading to T50 lifetime > 5,000 hours.

New EIL with Air stable cathode

Low work-function cathode – not Air stable

Previous EIL with Air stable cathode

0.00

0.00

0.00

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0.01

0.10

1.00

10.00

100.00

-5.00 -3.00 -1.00 1.00 3.00 5.00 7.00

Cu

rre

nt

De

nsi

ty (

mA

/cm

2)

Voltage (V)

Current Density vs Voltage PlotSelect Multiple

Series1

Series2

Series3

Series4

Series5

Series6

Series7

Series8

Series9

Series10

Series11

Series12

Series13

Series14

Series15

Series16

Series17

Series18

0.50

0.55

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0.65

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1.00

0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00 7000.00

Re

lati

ve L

um

inan

ce (

Arb

. Un

its)

Time (hrs)

Normalised Luminance vs Time Plot

4) iL+GREEN+vac/Al

1) G - EIL/Al

1) G - EIL/Al

4) iL+GREEN+vac/Al>5000 hrs to LT50 for both

previous EIL and current EIL


Flexible OLEDs – Compatibility with manufacturing processes

7

IR baking enables a takt time of

<90seconds for all OLED layers.

No change in electrical performance

compared to standard hot plate baking.

Opens up possibility for lower-cost

substrates to be used.

Material process Temp Time

iLHot Plate 160℃ 60min

IR 195℃ 90sec

HiL/LEP/

EIL

Hot Plate 150℃ 15min

IR 150℃ 90sec

Hot plate bake step:

Through substrate.

Substrate dependent

temperature limitations

IR bake step:

Direct annealing of organic

layers only. No thermal

impact on substrate.

tungsten

kanthal (Fe-Cr-Al alloy)



8

We have validated compatibility of fabrication with R2R processing of FlexOLED devices.

Slot die coating is the preferred route for fabrication and this process has been demonstrated at CDT for

prototype fabrication up to 6” in size scalable printing technique.

Ink jet printing has provided 2-colour demonstrators as shown below.

Large area slot die coating of all

organic layers

Ink Jet printing enables multiple

colours on the same device.



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We have demonstrated that screen printing can be used to print the pixel definition layers:

Metal Tracking

Insulator / Bank

Cambridge Display Technology Limited (Company Number 02672530) 10

Good encapsulation is important for FLEXOLED

applications.

Encapsulation of the OLED is by a lamination process of

primary and secondary layers.

Total thickness ~300µm.

There is no additional need for atomic layer deposition.

The primary encapsulation layer contains Al foil acting as a

primary barrier.

These materials have provided a “shelf life” in excess of 5

years – accelerated testing is ongoing.

No visual failure (black spots).

No impact upon performance.

Printed Flexible OLED - encapsulation

Organic solution

processed films ~100nm

Simple laminated

encapsulation – no atomic

layer deposition required

CDT 2016 Company confidential

Poor

encapsulationGood

encapsulation


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7

% o

f d

efe

ct f

ree

de

mo

nst

rato

rs

Shelf Life (years)

Long term Shelf Life

Reducing particles has led to significant improvements in shelf life and yield of devices

achieving >5 years.

Edge seal width for 5 years shelf life is 10mm – currently working on reducing this.

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Reduction in number of trapped

particles leading to defect sites

and moisture ingress

> 5 years

1mm


Simpler Manufacturing – R2R process compatibility

12

Additive processing techniques

Low cost tool set

Fast takt time for all processes

Organic layers printed and dried in air

Reduced encapsulation requirements simple lamination step.

Direct integration into production

For example plastic moulding processes

Ease of customization of smaller runs - can make bespoke OLEDs


10s mW would equate to a few cm2 per application, colour dependent.

Household

Appliances,

White Goods

Smart card,

Promotional

Signage,

Security

Consumer

(Medical)

Devices,

Toys, Wearables

Application Space

13

Thin, lightweight, flexible and

distributed OLED icons over

large area

No need for pick and place or

diffusers

Direct integration into

production

Wide array of designs possible


CDT’s flexible OLED Prototypes

14

Current array of demonstrators highlight the possibilities of this technology, each

demonstrating different features.

1. Human Machine Interface – mock-up of domestic energy management unit

Large area with distributed icons of various shapes/sizes.

Integrated capacitive touch sensor

2. Near Field communication – mock-up of business/transport/event/security card

Low voltage OLED platform enables NFC functionality

Fully flexible

3. Passive Matrix

30ppi (800µm pixel pitch) demonstrator with 400 pixels of scrolling text.

4. Multiple colours

Ink Jet Printing can be used for limited colours, but gives best efficiency.

Use of single white OLED with colour filters can be used for wider colour palette

and simple fabrication.


1. Human Machine Interface: HMI Prototype

15

Slot Die Coated at 6” (150mm) size.

Total thickness of OLED 300µm – fully flexible

Integrated capacitive touch sensors


2. NFC – OLED Prototype

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Credit card size flexible PCB with integrated

NFC antenna and flexible OLED.

Enabled by low V platform

Website information sent and OLED icons

light up.


3. Flexible Passive Matrix 4. Multiple Colours

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30 ppi x400 pixels on flexible substrate

Scrolling text

Use of Ink Jet

Printer and/or colour

filters on common

printed emissive

layer colour.


Working with CDT

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CDT can design and fabricate prototypes to meet your application needs.

Sampling of CDT’s Flexible OLEDs to trial in your product, application or processing.

Full life-cycle testing facilities on-site.

Technology transfer options available for manufacturing partners.

CDT has interest in a huge range of novel technologies and actively works with partners

to develop the potential for these technologies into marketable solutions


Technology Development at CDT / Sumitomo Chemical

19

Other areas of technology development at CDT include:

Energy Harvesting and Storage

Organic Thin Film Transistors

Organic Photodetectors

OLEDs for Lighting

Organic Photovoltaics


Energy Harvesting and Storage Solutions

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Hybrid batteries-supercapacitors

We are developing a new class of devices to address the increasing need in thin-film energy storage

solutions for existing and new applications.

These tuneable devices are hybrids that combine properties of supercapacitor (fast charge/discharge)

and batteries (current delivery).

Our technology builds upon the organic electronic materials and processes, allowing easy integration

with energy harvesting elements.

Printed Thermoelectric Generator

We are developing Printed Thermoelectric Generators (TEGs) to

provide a power source or battery life enhancement for autonomous

sensors and other low power systems.

Thin (<0.5 mm), flexible form factor, printable (scalable)

Suited to low temperature applications <400 K; small temperature

gradients with an expectation of outputs 5-20 mWcm-2 for low

temperature gradients, e.g. Δ5 K (industrial) and Δ 2 K (wearables)


Organic Photodetectors

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Pulse oximeter

Differential signal from two

OLEDs detected by OPD

Heart rate and

oxygenation level of the

blood is calculated

OLED and OPD can be

integrated on same

substrate

Optical Biosensor

OLED/OPD coupled devices

Quantitatively read out of

absorption or fluorescent

signals from biological

elements

Signal correlates with

biomarker concentration in

sample

Coloured

Test Line

Coloured

Control Line

OLEDs

OPDs

Lateral flow

or micro

fluidic

assay

Digital X-ray Imager

OLEDs

OPD

Large area imaging arrays

Potential for lower cost

than Si equivalent

technology

Light weight, potential for

increased robustness to

mechanical impact

Other addressable applications:

Proximity sensor

Gesture sensorFinger print sensor

Low cost spectrometer

Array sensor


OLEDs for Lighting

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Global market for OLED lighting set

to take off. Projection for 2023 is

$6.7B (ElectroniCast, 2016).

CDT and Sumitomo Chemical are

developing materials and

manufacturing capability for low cost,

OLED lighting.

Materials development focussed on

colour and improving efficiency &

lifetime.

2800 K to 4000 K white with high CRI.


Organic Photovoltaics

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BIPV – Building-Integrated Photovoltaics

CDT & Sumitomo Chemical are developing materials and processes for semi-transparent and coloured

photovoltaic modules that can provide diffused, natural lighting.

Single cell PV cell performances demonstrated with fullerene acceptor: 8.5% PCE

Action-spectra controllable with chemistry of polymers.

Multifunctional BIPV may additionally provide UV,

heat (IR) and sound insulation.

Manufacturing Process Developments to enable large

area modules, R2R processes for low cost & high throughput:

Less

absorption in

visible region

400 600 800 1000

Active

La

ye

r A

bso

rptio

n

Wavelength [nm]

0 5 10 15 200.0

0.1

0.2

0.3

0.4

0.5

0.6

Cur

rent

Den

sity

[mA

/cm

2]

Voltage [V]

Good for window

applicationsModule: 31740mm2

Absorption

over 900nm

Module: 5% PCE

Visible Transparency: 43%


Working with CDT

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CDT has interest in a huge range of novel

technologies and actively works with

partners to develop the potential for these

technologies into marketable solutions.

Supported by the financial strength and

market channels of Sumitomo Chemical

Co. Ltd., CDT is ideally placed to

accelerate research and development in

areas such as…


Working with CDT

25









areas such as…


Working with CDT

26









areas such as…


Conclusions

27

Recent Improvements in performance for Flexible OLEDs at CDT:

Reduction in drive Voltage

Reduction in takt time – moving towards manufacturing processes

Air stable cathode

Straightforward encapsulation process (lamination) with an off-the-shelf material, offering

improved shelf life

Current portfolio of prototypes – come and see these at the demonstrator street

Working with CDT / Sumitomo Chemical – come and talk to us at Printed Electronics USA 2016

Documents

Flexible OLEDs for consumer products - CDT Ltd · Performance table of current material set. ... Performance of EIL devices opens up further opportunities for ... heat (IR) and sound