Post on 12-Aug-2015
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Lowering Barriers to Higher BarriersLowering Barriers to Higher Barriers
The purpose, potential and progress in barrier films or encapsulation systems for OLED — February 2014
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Outline of Encapsulation TopicsContext: bankability and no(know)opolyWhy encapsulation is important for flexible electronics§ Protections and poisons (oxygen, UV et cetera)§ Fabrication (preparation) and adhesion§ Operation and performance (optics)§ Formation, flexibility and elasticityHow barrier technologies developed § Evolution and variations§ Evaluation and potentials§ ExpectationsWhom is doing what and why§ Encapsulation§ LaminationConclusion: readings and resources
1/8/14David Barnes 2
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Overview: The Purpose of Barrier FilmsImpede permeation of Oxygen or other solutes into electrical or optical films:§ Protect device from damage§ Preserve performanceLike insurance, specifications are complicated and you know what you really have only after you need/claim the policy.Like insurance, it is a balance between what you think you need and what you can afford.
David Barnes 1/8/14 3
Water Vapor Transmission Rate or WVTR of 10-6 g m-2 day-1
(or E-6 for short) can oxidize several monolayers of cathode film in 50,000 hours.
Oxygen Transmission Rate (OTR) of 10-4 cc(atm) m-2 day-1 can be as destructive but we worry more about WVTR because of humidity (or coffee?).
Other solutes may be critical…
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Overview: Ideal Barrier FilmsWe want… But it can’t be…Flexible film Difficult to form or apply Impervious film Invasive or conductiveTransparent film Refractive or UV sensitiveAdhesive (not delaminating) film Highly stressful for other filmsHigh availability and quality High priced or too generic
David Barnes 1/8/14 4
§ Finding the right blend of materials and methods takes time.§ Few of the materials or methods used for mass-market
packaging are good enough for organic electronics.
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Bankability and No(know)opolyExperience from several barrier business valuations and transactions teaches two things§ Bankability will be less of a factor than it was in solar
§ Even OELighting will have shorter expected lifetimes§ Most OLED products are goods, not investments
§ No(know)olopy will remain an apt description of the market§ Suppliers will adjust prices based on perceived risk§ Customers will adjust specs based on perceived cost§ Both will find barrier reliability difficult to quantify§ No one will know product lifetimes anytime soon
1/8/14David Barnes 5
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Protection and PoisonsSubstrates, superstrates and seals vary by application and production§ Substrates may be fabricated
or purchased§ Superstrates may be fab’d or
laminated§ Seals may be formed or
dispensed (adhesives)Chemical, mechanical and optical factors vary by device and by application
David Barnes 1/8/14 6
SubstrateDevice
SuperstrateSealSeal
O2
H2ODelamin-
ation
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Operation and Performance Effects
Effect Emitter Side Back Side
Chemical Permeation rateInteraction with device
Permeation rateContamination (migration)
Mechanical Thermal excursion, CTELayer adhesion, strain
Adhesion, seal integrityExpansion/contractionStrain, delamination, etc.
OpticalRefraction, diffusion, etc.Reflection, UV protectionTransmission, extraction
Reflection or cancellationScratch, dirt resistanceCosmetics, etc.
David Barnes 1/8/14 7
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Fabrication or Lamination Effects
David Barnes 1/8/14 8
Sup
erst
rate
Sub
stra
te
Topemitter
Bottomemitter Deposition—Adhesion
Migration—Interaction
Work Function—MorphologyDeposition—Separation—Strain
Refraction—Diffusion—AbsorptionEmission—Migration—Interaction
Work Function—MorphologyDeposit/Remove—Optics, etc.
Condition—ContaminationAdhesion—Morphology
Condition—AdhesionRefraction—Diffusion, etc.
Refraction—Diffusion—AbsorptionAdhesion—Emission—Migration
Fabricated Laminated
Condition—ContaminationAdhesion—Interaction
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Formation—Deformation (bendy) Effects
Effect Formation Deformation (bendy)
FabricatedThermal excursion, distortionSheet: deposit, releaseWeb: stretching, scoring…
Thermal mismatching, strainCracking or shifting insideReflection (gap) changes
LaminatedContamination, strainSheet: adhesion, flatnessWeb: wavy edge seal
DelaminationCracking or shifting inside (e.g. nanoparticles in matrix)
Operation Haze formation, UV effectsOcclusions, particles
LifetimeBending radius
David Barnes 1/8/14 9
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Evolution of Barrier TechnologiesMany materials and methods used today started in the 1970’s as means for protecting thin-film capacitors
IP claims and counterclaims are possible, once there is a market to argue over… for now, inventions are becoming more specific
Evolution can be evaluated on three axes§ Better films—materials and methods§ Composite films—multiple layers, cross-links§ Reactive films—scavengers, hydrophobics
1/8/14David Barnes 10
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Basic ConceptsSolid or glassy metal foils make great, but opaque barriersTransparent barriers made of metallic oxides (e.g. sapphire) would be great if they had no holes or cracks… and if they didn’t get damaged so easilySo engineers make the best oxide “barrier layer” they can for a given cost, then protect it with a polymer coating
David Barnes 1/8/14 11
Protective PolymerOxide, Nitride, Carbide…
(Substrate)
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Better Barrier Film Layers
David Barnes 1/8/14 12
Goal PVD (sputter) CVD ALDFilm density Medium High High
Defect density GoodTime dependent
Better, no PVD bombardment Best
Stoichiometry Fixed by target Variable by precursor mix
Variable by precursor mix
Speed (rate) Fast Slower Slowest
Cost Best Good Challenged
Example SDI or Vitriflex UDC Beneq
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Composite FilmsThe NREL-Vitex multi-layer way to minimize effect of pin-holes continues with SDI efforts todayN-O-N R&D at the Holst Centre continues Philips approach
Cross-linked SiO-N (silazane) by Konica Minolta combined with SiO (siloxane) under UV cureNano-composite experiments with clay-like materials are still ongoing as a coated method
David Barnes 1/8/14 13
PolymerOxide, Nitride, Carbide…
(Substrate)
PolymerOxide, Nitride, Carbide…
Polymer
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Reactive (Scavenger) FilmsReactive films or particles in a matrix can delay permeation and hydrophobic surfaces can repel water, c.f.§ Tera-Barrier Films WO2013062486§ Vitriflex PCT/US2012/022809
CNT and other nanoparticles are of interest here with some graphene research, also§ Tera-Barrier Films US2012016443
§ Survey DOI:10.1002/app.39628
David Barnes 1/8/14 14
CaO, ZTO, CNT…Oxide, Nitride, Carbide…
(Substrate)
Polymer
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Advances in Barrier TechnologiesThe goal remains a permeation rate that matches product lifetime within an acceptable range of capital and operating costs
The central problem remains balancing film (barrier) quality with productivity for a wide range of mechanical and optical systems
The challenge remains one of developing a specific material-tool system without benefit of industry consensus or scale
Key areas of product development§ Thin Film Encapsulation (TFE)—SDC and new tools§ TFE Alternatives—LGD plus Dam & Fill§ Laminates—3M, Konica Minolta, Vitriflex, et alii
1/8/14David Barnes 15
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
-
1
2
3
4
5
6
7
8
9
5 15 25 35 45 55 65 75 85 95
50 ppi
100 ppi
200 ppi
400 ppi
Reviewing the Goal: Risk ReductionGiven a defect can be as small as 50 nm, and product lifetimes can range from 18–180 months, we can see risks for large panels as high as risks for small panels*Thus, barrier levels are important for both large and small panel makers considering OLEDScaling methods up to TV panel sizes is a major challenge
*Arbitrary units scaled relative to 50 ppi at 5” HD diagonal
David Barnes 1/8/14 16
50 nm Defect Sensitivityversus
Diagonal Inch (HD)
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Risk: Diffusion and Permeability of a SoluteThe pace of diffusion through a thin film is linear if the solubility is the similar inside the film.In this simple case, the time for a solute (e.g. water) to move through the barrier film depends on the thickness of the film.The concentration gradient between inside and outside depends on the solute, the film and temperature (energy)…It is called permeability.
David Barnes 1/8/14 17
C1
C0
Film
AbsorptionDiffusion
Desorption
Con
cent
ratio
n
Thickness or length
inside
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Thin Film Encapsulation, e.g. SDC
TFE Upside Downside
Application Proprietary tuning of film for optics, etc
Complex interactions;Immature supply base
Position Early stage production Cost challenge
WVTR* (10-x) E-6+ E-5 (fewer dyads)
Materials Polyacylate on AlO Cost per dyad
Processes PVD (SNU…) & Coating Throughput, quality
Alternates, Variations Kateeva, Veeco Universal Display
Futures Flexible mobile displays TV panel cost-price
David Barnes 1/8/14 18
*Nominal water-vapor transmission rate, indicative only
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Laminates, e.g. Konica Minolta
TFE Upside Downside
Application Scalable x-linking of coated polymers
Less differentiated in optical attributes
Position Production Si-O-N + NH
WVTR* (10-x) E-5+ E-4+
Materials Siloxane, Silazane Cost
Processes Coat and VUV Drying, purging
Alternates, Variations Mitsubishi 3M, LG Chem
Futures Flex substrates Market development
David Barnes 1/8/14 19
*Nominal water-vapor transmission rate, indicative only
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Laminates, e.g. Vitriflex
TFE Upside Downside
Application Cost-effective laminateusing scavenger layer
Unproven sealing methods
Position Pilot line production More PV than OLED
WVTR* (10-x) E-6? E-5+
Materials ZTO, CaO, acrylates… Reactive delay time?
Processes PVD and coat Need for ALD?
Alternates, Variations Tera-Barrier Films Beneq (ALD)
Futures Flex substrates PV market dynamics
David Barnes 1/8/14 20
*Nominal water-vapor transmission rate, indicative only
For Distribution to Flexible & Printed Electronics Conference attendees only. Content remains property of FlexTech Alliance
Readings and ResourcesPermeation and ReliabilityKempe—http://www.nrel.gov/pv/performance_reliability/research_staff.html#Kempehttp://www.nrel.gov/pv/performance_reliability/publications.html
Graff, Weaver et al—doi:10.1117/12.416878
Weaver—https://www.rti.org/pubs/ThinFilm_Flexible_OLEDS.pdf
Stanislav—doi:10.1080/00914030390224337
Colye—doi:10.1002/pip.1172Park—http://iopscience.iop.org/0268-1242/26/3/034001
David Barnes 1/8/14 21
Tools and MaterialsALD—http://dx.doi.org/10.1063/1.4757907CVD—https://www.google.com/patents/US8592253iCVD—http://onlinelibrary.wiley.com/doi/10.1002/adfm.200701479/abstractGraphene—http://onlinelibrary.wiley.com/doi/10.1002/app.39628/abstractCeramics—http://onlinelibrary.wiley.com/doi/10.1002/j.2168-0159.2013.tb06219.x/abstractDavid Barnes, BizWitz— db@bizwitz.com