OLED AND THIN-FILM ENCAPSULATION TECHNOLOGIES FOR MICRODISPLAYS

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1 OLED AND THIN-FILM ENCAPSULATION TECHNOLOGIES FOR MICRODISPLAYS Tony Maindron, PhD, CEA-Leti, France London, February, 21-22, 2017

2 OUTLINE Introduction OLED technology OLED for microdisplays Thin-film encapsulation of OLED 2

3 CEA-Leti Grenoble, 8000 m² clean room facilities 200 and 300 mm wafers [Source : Leti] 3

HISTORY OF PHOTONIC COMPONENTS INDUSTRIALIZATION AT Leti

42 people + 6M revenue 2015 1983 2002 2007 2011 2014

Sensors OLED microdisplays Nanowire Solid-state lighting

2007 2009 2010 2012 2013 Xray spectrometric imaging

sapphire Optical MEMS for imaging Optical mobile

4 HISTORY OF PHOTONIC COMPONENTS INDUSTRIALIZATION AT Leti SOFRADIR today 750 people + 190M revenue MicroOLED today 42 people + 6M revenue Cooled Infrared Image Sensors Microbolometer Image Sensors OLED microdisplays Nanowire Solid-state lighting Ubiquitous gas sensors Mid Infrared Integrated Sensors Xray spectrometric imaging Real-time fluorescence imaging Microscopic engravings on sapphire Optical MEMS for imaging Optical mobile point-of-care device Photonics Dpt biggest subdivision of LETI, 260 people 4

DISPLAY LABORATORY OLED Display µled Display Transparent µlcd

full color, Color without filters Optical micro cavities at

resolution Smallest pixel in the world : 5µm pitch Huge

~1cm² Freeform optic, holographic film, customized optical

5 DISPLAY LABORATORY OLED Display µled Display Transparent µlcd Advanced Optical system Highest µoled resolution (> 2000 ppi) full color, Color without filters Optical micro cavities at the pixel level (5000 cd/m²) TFFC technology to fabricate LED arrays with small pitch. Background in hybridization on active matrix for high resolution Smallest pixel in the world : 5µm pitch Huge number of pixels/display: up to 1Mpixels Though very compact: ~1cm² Freeform optic, holographic film, customized optical projection for nomadic applications such as Head Mounted Display (HMD), Head-up Display (HuD), transparent display 5

6 HISTORICAL BACKGROUND 1987: EQE = 1 %, 1,5 lm/w, L > 1000 cd/m² [Source : C. W. Tang and S. A. Van Slyke 51 (1987) ] 6

7 WHAT IS AN OLED? Blue light-emitting OLED on Si 100 nm [Source : LETI] [Source : Universal Display Corporation] OLED = convert electrical charges to photons 7

8 WORKING PRINCIPLE AlQ 3 NPB [Source : Gilles Lerondel, journée Eclairage, Troyes (2013)] At least one electrodetransparent or semi-transparent to allow light extraction 8

9 FABRICATION PROCESSES DRY PROCESSING WET PROCESSING Ink-jet printer [source = Dymatix] Systèmed evaporationencluster [Source = LETI] Aixtron OVPD [Source = Aixtron] Ink-jet printing of RGB pixels [Source = Aixtron] Slot-dye coating(top) and nozzle printing (bottom) (Dupont) 9

10 MARKET FORECAST Display market [Source : Display Search, 2012] Example of OLED actors, non exhaustive list 10

11 SSL Time LED = point source; OLED = surface emission (intrinsic) 11

12 DISPLAY MARKET Commercial products High-end products NAS D-Link ShareCenter Quattro DNS- 345 (monochrome OLED passive matrix) Samsung GalaxyTab 10,5, 2560x1600, super AMOLED technology LG Flex 2, full HD OLED, 5, [Source: Reckon, Jet] Lumix GH3, eyepiece Cinemizer Gratical HD (Zacuto) [Source: MicroOLED] Microdisplay (HD) = component for video goggles, EVF, AR Sony PS Vita (2012) 5 16/9 (960x544, 16 millions colours) puis écran LCD à partir de 2013 Actual market = < 10 displays LG 77EG990V - CES x2160 4k, Flexible (marketing benefit only) 12

13 µdisplay WORLDWIDE MAP OLED display manufacturers: smartphone, TV, tablet OLED µdisplay manufacturers 13

14 EXAMPLE OF APP: FPV RACING Acquisition of Zeiss s Cinemizer division (2015) By MicroOLED Fully immersive experience 14

constraints high for OLED: top-emitting structures mandatory(white more

15 µdisplay ARCHITECTURE [Source: Emagin] OLED microdisplay architecture, from Si to color filters Performances of OLED > Performances of LCD, but constraints high for OLED: top-emitting structures mandatory(white more difficult to achieve) Transparent and chemically robust thin film encapsulation mandatory 15

16 OLED, SPECIFICITY FOR MICRODISPLAY APP Standard architecture Color filters Encapsulation Encapsulation Al n-doped layer HBL EML EBL P-doped layer anode glass Exciton generation Optical cavity ( Fabry-Perrot) Capping layer Al n-doped layer HBL EML EBL P-doped layer Reflective anode Si Exciton generation z d Not ITO! Top emitting architectures higher aperture ratio onto driving backplane But cavity effect has to be managed 16

17 ENCAPSULATION : PRINCIPLE [Source : Novaled] [Source : Google, MicroOLED] Encapsulation mandatory from the raw material to the system 17

ENCAPSULATION : BACKGROUND [Source : I. F. Gavitt Society of vacuum coaters, 36th annual technical conference proceedings 1-878068-12-1 (1993) 254 ] mopp Stale point is < 2.

18 ENCAPSULATION : BACKGROUND [Source : I. F. Gavitt Society of vacuum coaters, 36th annual technical conference proceedings (1993) 254 ] mopp Stale point is < 2.5% HB mopp Finished moisture content is % Food and medicalpackaging have been driving the development of barrier-coated (Al, SiO x, AlO x, TiO x, Si 3 N 4 ) polymerfilms for years In 2001, about 11 billion square metersof Al-coatedPET and OPP were produced for snack food, beverages [Source : Flexible flat panel displays (2005) John Wiley & Sons Ltd] [Source : TopMet clear coater, Applied Materials] 18

19 2 TYPES OF ENCAPSULATION Cavity = N 2 -filled Y. Lai, Z. Chen, Y. Huang, J. Zhang IEEE (2012) Source: Materion Thin-film encapsulation mandatory for OLED-based microdisplays LETI thin-film development 19

20 BARRIER LEVELS WVTR = Water Vapor Transmission Rate OTR = Oxygen Transmission Rate Glass lid(laser frit) Multilayer (PECVD SiO 2, Si 3 N 4, multilayer(barix) Single layer (Métal ou oxyde par PVD) Single layer ALD, PECVD hybrid, PE e-beam WVTR (OLED) < 10-6 g/m²/day [Source : Cros, S. Propriétés barrières des polymères utilisés en emballage, Tech. Ing. AM 3160 (2007)

CONSEQUENCE OF DEFECTS ONTO OLED [Source :

2 OH - 4 Al + 3 O 2 2 Al 2 O 3 OLED, t +

21 CONSEQUENCE OF DEFECTS ONTO OLED [Source : LETI] [Source : Schaer, M. et al. Adv. Funct. Mat.11(2001) ] OLED, t h, pas de dark spots (bonne encapsulation) 2 Al + 3H 2 O Al 2 O H 2 g 2 H 2 O + 2e- H 2g + 2 OH - 4 Al + 3 O 2 2 Al 2 O 3 OLED, t h, dark spots (mauvaise encapsulation) Extrinsicsource of degradationh 2 O and O 2 21

with multilayer TFE However defects still present(r&d line with manual load) 1,0E+00 0,0 2,0 4,0 6,0 Applied potential (V) IV and LV characteristics of an

22 LETI TECHNOLOGY (BASED ON ALD) 1,0E+03 Current density (ma/cm²) 1,0E+01 1,0E-01 1,0E-03 1,0E-05 LETI thin-film encapsulation 1,0E-07-3,0-1,0 1,0 3,0 5,0 7,0 Applied potential (V) 1,0E+05 1,0E+04 Luminance (cd/m²) 1,0E+03 1,0E+02 1,0E+01 Blue OLED after 1516 h at 85 C/85% RH High reliability of OLED encapsulated with multilayer TFE However defects still present(r&d line with manual load) 1,0E+00 0,0 2,0 4,0 6,0 Applied potential (V) IV and LV characteristics of an OLED module (with Gen 1 TFE, no lid) at t0 (red line), after 504 h (blue line) and 1500 h (black line) at 85 C/85% RH [Source: Jean-Yves Simon PhD (2013), LETI] 22

CONCLUSIONS, OLED DREAMS [Source: LG] [Source:

23 CONCLUSIONS, OLED DREAMS [Source: LG] [Source: [Source: audi] [Source: [Source: [Source: [Source: 23

24 Thank you for your attention

OLED ON CMOS: WHAT ABOUT THINNING AND BENDING?

Large cost-effective OLED microdisplays and their applications OLED ON CMOS: WHAT ABOUT THINNING AND BENDING? IDW2017 tony.maindron@cea.fr T. Maindron, B. Chambion, A. Vandeneynde, S. Gétin, M. Provost,