Margreet de Kok / TNO-Holst Centre

10 november 2011Foil technology for conformable electronicsMargreet de Kok TNO/ Holst Centre10 november 2011

10 november 2011Contents1. Holst Centre2. Introduction OLED3. Application of OLED4. Lifetime of OLEDs5. Conformable technology6. Conclusions

31. Holst Centre

4Holst Centre FingerprintWho we are Independent research organization co-founded by IMEC (1300 fte, Belgium) and TNO (4500 fte, the Netherlands) in 2005 Global network of industrial and academic partners 150 researchers and 60 resident researchers from industry and universityWhat we do Creating generic technologies, time to market 3..10 years Research Focus on wireless, autonomous micro-systems and flexible electronicsHow we work Open Innovation through precompetitive research programs Roadmaps defined along with partners Day to day interaction with industrial residents Results are shared between partners

5 5 Large Area Electronics market applications Flexible displays Plastic solar cells Touch screens Plastic batteries Smart packaging SignageRFID tags OLEDs Sensors Disposable bio-sensors Smart bandage Electronic textiles

6Important Enabler:Organic Semiconductors New ways of MicroDrop processing Inkjet printingSoluble Semiconductors Roll to Roll coating

7Access to Unique Set of Infrastructures and Process Labs High Tech Campus, Eindhoven Life Sciences 8000 m 2 cleanroom facilities O LED Device Processing Materials Analysis Photonics T hin Film cleanroom clean room EMC lab Electronic measurement Reliability lab H olst O ffices Amsterdam Equipment H olst Electronic Engineering R2R lab Prototyping Netherlands Eindhoven Clean room 2 IMEC 4 Office building Clean room 1 Düsseldorf 5200 m2 clean room 1750 m2 class 1 3200 m2 clean room cleanroom 200 mm pilot line 2200 m2 vibration controlled Nano- Cleanroom 300 mm pilot line elektronicalab Continuous operation: 200mm silicium 24hrs / 7 days Aachen Ball room, clean sub-FAB pilootlijn FOUP wafer transport Leuven Belgium IMEC 2 & 3 offices and labs IMEC 1 Main entrance IMECEXPO visitor Cafeteria center Training Offices and labs infrastructure

8 8Industrial partners from across the value chain

92. Introduction to OLED

10OLED BasicsTwo types of OLEDs: cathode Organic layers anodePolymer LED Small molecule LED

11OLED: Electroluminescence (Fluorescent emitter) Typical Light Emitting Polymers: PPV (polyphenylene vinylene) PF (polyfluorene)

12OLED: Injection scheme SrO BaO Cs LiF GdB6 2 Work function (eV) Ba Li,K Ca TiN 3 Mg Hf 4 In 4 Al Ag 5 PEDOTNi Au ITO Pt Se TiO2 6 High workfunction Low workfunction anode materials cathode materials

13IVL• Vbi ~Vturnon 10000 BL102• Dependent on band gap material 1000• Dependent on work function 100 10 difference of the contacts J (A/m ) 2 1 0.1• Blue and white 5-10 lum/W 0.01 1E-3• Record: 100 lum/W 1E-4 -2 0 2 4 6 8 Bias (V) 2 BL102 Ba/Al LUMOPF (2.2 eV) (2.7 eV) PEDOT: Efficacy (lm/W) 1 PSS HOMOHT (5.2 eV) (5.1 eV) 0 -2 0 2 4 6 8 Energies with respect to the vacuum Bias (V) level

14Possibilities to prevent voltage drop• Metal grid 12x6 cm2 top emission white OLED on SS12x12 cm2 top emission white OLED on SS

15Application in OLED144 cm2 white PLED without ITO using high conductivity PEDOT withAg printed shunting lines (submitted for SPIE 2009)

163. Applications for OLEDs

17OLED Applications & Expectations Signaling Signage Lighting Displays

18 But also:Company logo Automotive Healthcare Add-VisionAdvertising Automotive

19Flexible OLEDs• Only prototypes, no commercial products Add-Vision Sony Samsung Novaled/Assilor-Mital UDC GE• Showstopper: barrier films

20Next Application for OLED: Solid State Lighting LED (SM/P)OLED

21Solid State Lighting Small-molecular Inorganic Organic Macromolecular OSRAM

22 Comparison Inorganic – Organic LEDs• Inorganic LEDs • Organic LEDs• Products on the market with • First lighting products on high efficiency and long the market lifetime • Large area possible and• Small area and high therefore low luminance luminance (no large area enough possible) • Thin• Thermal management needs • Thermal management less attention problematic• (Colour stability of • Colour better controllable production leads to binning • Cost per area effective of LEDs) Application and design freedom (and price) make the difference

23Organic light sources and detectors: opportunities and challenges• Form freedom• Large area possible• Flexibility (bendability)• Very thin features• Fine tuning of optical properties possible• Integration with multiple functionalities possible in foil• Production technology versatile• Cost aspect positive• Challenges:• Processing thin layers - shorts• Encapsulation and intrinsic lifetime• Efficiency• Current density distribution• Design of combination of building blocks

24Why flexible?• Enhanced functionality for the end user: bendable, rollable devicesBut also• Integration of foil devices in products & systems: conformal application?; convenient feeding into assembly system• Efficient large area production of foil devices (e.g. roll-to-roll; no manual assembly) -> cost aspect Source: GE Source: Metsuo

25State-of-the-art in white OLED

26OLED Trends Materials Substrates: flexible plastic or metal substrates combined with R2R processing Barrier: strong focus on developing flexible thin film barriers (Holst Centre, Vitex, General Electrics, Dow, ..) with WVTR < 10-6 g/m2.day Emitters: phosphorescent emitters (UDC, Sumation, Merck, Novaled, ..) Transport layers: doping of transport layers (Novaled, ..) Cathodes: top emitting/transparent OLEDs with transparent cathodes Anodes: high conductive organic materials and/or or introduction of support structures (evaporated or other) (GE, OLLA, Holst Centre, ..) Processing: Roll-to-roll processing on flexible plastic or metallic substrates Printing or coating of functional materials in general (as opposed to spin-coating) Printing or coating of small molecules (Dupont, UDC, ..) Devices: Innovative OLED designs / Intelligent Lighting >100 cm2 lighting tiles (Lumiotec, GE, Philips, OSRAM, UDC, Konica Minolta, ..) OLED display driving: AMOLED as opposed to PMOLED (SDI, LGE, SONY, ..) TFT towards oxide TFT as opposed to OTFT / LTPS (Dai Nippon Printing) Place-it: conformable electronic systems comprising OLEDs

274. Lifetime of OLEDs

28OLED Degradation 150 150 luminance (%) voltage (%) intrinsic 100 100 voltage increase 50 50 0 0 0 50 100 0 50 100 150 time time 150 luminance (%) luminance (%) 100 leak 100 short 50 50 0 0 0 50 100 0 50 100 time time 150 150 voltage (%) voltage (%) 100 100 50 50 0 0 0 50 100 0 50 100 time time

29OLED Degradation

30 OLED Degradation: black spots • Intrinsic: homogeneous degradation • Cathode oxidation: local degradation leading to black spots H2O, not O2Right after processing ~10h at 20 °C / 50% RH

31Focus is on water penetration, not oxygen • oxygen analysis (RBS) • exposed calcium layer • DA = dry air • AA = atmospheric Cros et al. Nucl. Instr. Meth. Phys. Res. B 2006, 251, 257-260

32EL vs PL electroluminescence (EL) photoluminescence (PL)• black spots visible in EL, not in PL• no degradation of the active (emitting) material(s)• formation of a charge injection barrier due to cathode interface oxidation• light spots in PL: enhanced out-coupling due to scattering

33 black spot formation: pinholes in Alcathode 1 2 - shelf effect !! E3140201, SiN shelf 100organics 90 80 black spot area (a.u.) 70 60 50 40 30 20 10 0 0 200 400 600 800 1000 1200 tim e (hrs) ~106-107 pinholes / m2 in cathode Al-cathode = very good intrinsic barrier properties Linear growth of circular black spots: diffusion controlled process Shelf Effect

34Standard Encapsulation State-of-the-art encapsulation using metal or glass lid with cavity containing getters no hermetic seal (getter!) 40,000 hrs at 80 °C without black spot formation cathode getter organics ITO substrateBut, it is not applicable for: Fast production Large area devices Flexible (foil-based) devices

35 Requirements for (TF) barrier/encapsulation• Intrinsic WVTR < 10-6 g.m-2.day-1• No black spots >5 years @ 20/50 >504 h @ 60/90• Feasibility for R2R Barriers should be rollable over d=20cm• Low cost High deposition ratesBarrier on foil specific:• Transparency for visible light >90%• Uniform light output Extremely uniform layers over large areas• Light outcoupling• Abrasion resistance, UV protection, etc.

36 Multilayer approach • Stacks of inorganic and organic layer used to decouple pinholes and get full coverage => time delay of black spot formation • Holst approach: SiN – OCP – SiN • OCP = organic coating for planarisation 100 SiN SiN-org-SiN planarizationblack spot area (a.u.) 10 4 layer 3 1 1 2 0.1 10 100 1000 10000 time (hrs)

37State of the Art for encapsulation• Wvtr: 10-6 g/m2day• >5000 hrs at 20/50 black spot free and still running Side leakage Black spots by pin holes

38Advanced systems by combined functionalities in Foil• Organic LEDs• Organic Photodetectors• Organic Photovoltaics• Embedded circuitry• Embedded chips• RFID• Memories• Sensors Electrochemical Optochemical Optical

39Device Design - laminated foil approach• Foil Double side processing Modular: diodes and LEDs printed on separate foils• Top emissive PLEDs, Bottom receptive OPDs: skin Photodiode LED• Bottom emissive PLEDs, Top receptive OPDs: skin 30 Spectral Radiance (10 W/sr m nm) 2 25 20 -3 15• Etc. 10 5 0 500 550 600 650 700 750 wavelength (nm)

40Printed devices• Foil Single side processing Diodes and OLEDs via printing Arrays of different devices on one substrate

41Foil Integration• Modular approach• Distribute functions over different layers -via technology combined with lamination• Silicon in Foil embedding

42First Organic Device Prototype: Proof of Principle• OPD • Works! Total measured current PPG comparable to commercial ca. 10 A pulse-oximeter (Nelcor N200) Signal ca. 50 nA• PLED I = 80 mA/cm2 V = 5.2 V L = 520 Cd/m2 Signal (a.u.) Organic Nelcor N200 0 1 2 3 4 5 Time (s)

435. Conformable technology

44 Example of OLED roadmap rigid –> flexible -> conformableGlass based OLED Flexible OLED Conformable LEDs on foilPhilips Lighting Holst Centre Holst Centre

45The vision: conformable electronic and photonic systems• Featuring Conformable, stretchable/flexible Thin and light weight Unobtrusive integration Wearable• Applications: Biomedical (sensors, phototherapy) Textile/fashion, Outdoor (biking, road safety) Architecture Displays Interior design (curtains, furniture)• Advantages organics c.t. inorganics: Large area: homogeneity Very thin Temperature management Combination inspiring

46Conformable electronicsT. Sekitani, T. Someya et al. Nature Materials 8, 2009 p. 494-499R. Kim, J. Rogers, et al. Nature Materials 9, 2010, p. 929-937

47 Stretchable systems• OLED structuring on rigid regions: printing technology• OLED / OPV need protection by barrier technology• Interspaces deliver stretchability and should contain electric circuitry: Ag nanoparticles in binder matrix pedot LEP Ba/Al foil anode cathode pedot Ba/Al Top barrier Bottom barrier foil anode cathode

48Structured deposition of active materials• Printing: Inkjetable ink formulation (halogen-free solvent): droplet formation Jetting and stable in time & speed Ink & substrate interaction Layer formation and homogeneity Device performance and efficiency

49Ink & substrate interaction• Pinning and de-wetting Plasma treatment Temperature treatment

50Solvents selective layer formation A 100% A:B=50:50 B 100%

51Inkjet printed OLED active layer development 2007 2011

52State of the art

53OPV cells bonded on textileSamples= 3 OPVs + drilled holes bondedPressure= very lowTemperature= 125°CAdhesive= CLocal encapsulation= None 3 OPVs gave 924 mV

54Healing power of sunlight : wearable phototherapyTBC treatment by sun therapy

55 55 Example - jaundice treatment of neonatals • Old treatment Static light sources necessitating eye protection of neonatal Jaundice treatment: photochemical conversion and excretion of bilirubine (yellow colour treatment) • New possibility Wearable light source less interfering with care including bonding with parents Philips BilitXTMSource flickr: 1542122226_5e43a1d008 and 2538039854_e67b67926c Blue LED based

56Other options for applications• Light in safety (traffic, working conditions)• Light harvesting (tents, outdoor sports, clothing)• Phototherapy: psoriasis, eczema, jaundice, wound healing, prevention decubitus, pain relief, skin rejuvenation• Camouflage• Textile design – fashion!• Bring light where no light was before

57Platform for Large AreaConformable Electronicsby InTegrationFP7 Place-it 57

586. Conclusions

59Conclusions• Organic electronics have a bright future• Technology development indispensable• Collaboration between disciplines necessary• Conformable electronics will change the world• Margreet.dekok@tno.nl• www.holstcentre.com• Thank you for your attention

Margreet de Kok / TNO-Holst Centre

by Themadagen on Nov 24, 2011

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Margreet de Kok / TNO-Holst Centre — Presentation Transcript