Development of OLED Lighting Applications Using Phosphorescent Emission System

Development of OLED Lighting Applications Using Phosphorescent Emission System Kazuhiro Oikawa R&D Department OLED Lighting Business Center KONICA MINOLTA ADVANCED LAYERS, INC. October 10, 2012

Outline KONICA MINOLTA s OLED lighting development Evaporation and Solution Process OLED Efficiency Improvement Production Case Study of OLED Lighting World s first all-phosphorescent OLED product Proprietary blue phosphorescent emitter Roll-to-Roll process OLED technology Unique material technology and OLED structure for solution process Recent progress in solution-processed OLED device R2R OLEDs line Summary 1

OLED development at KONICA MINOLTA Evaporation Solution Process World-record performance presented in SID2007 Demonstration of OLED lighting by R2R process 2

Goals for OLED Development All phosphorescent Solution Process High efficiency High productivity Low greenhouse gas emission lightings Low cost to compete with conventional lightings 3

OLED Efficiency Improvement For lighting application, [ /lumen] tells the competitiveness of a luminaire. It is quite important to improve the luminous efficacy for lighting applications. OLED (external) quantum efficiency is given by the formula; n air Light extraction capability Ratio of emission per number of exciton Light n 3 n 2 Electron Carrier balance Hole Heat Ratio of emissive exciton Fluorescence: 25% Phosphorescence: 100% n 1 Phosphorescence has significant advantage over fluorescence 4

Productivity (m 2 /min.) Production Case Study of OLED Lighting 100 10 R2R Process Target (Past results: photographic material coating) G8,TACTs:60s Desired productivity for general lighting application 10 million m 2 /year G10,TACTs:45s Expected productivity by Evaporation G6,TACTs:60s 1 G4,TACTs:90s G6,TACTs:180s G8,TAKT:180s G10,TACTs:180s 0.1 0 G2.5,TACTs:180s G4,TACTs:180s 1 2 3 Substrate Width (m) R2R solution process has the potential to significantly reduce costs due to scalability through both the substrate width and the coating speed. 5

Outline KONICA MINOLTA s OLED lighting development Evaporation and Solution Process OLED Efficiency Improvement Production Case Study of OLED Lighting World s first all-phosphorescent OLED product Proprietary blue phosphorescent emitter Roll-to-Roll process OLED technology Unique material technology and OLED structure for solution process Recent progress in solution-processed OLED device R2R OLEDs line Summary 6

World s First All-phosphorescent OLED Product All-phosphorescent OLED lighting product using our proprietary blue emitter Items Luminous efficacy Thickness Performance 45 lm/w 1.9 mm Area 55 cm 2 Luminance 1000 cd/m 2 Current / Voltage Color coordinate Life time (LT50) Color temperature 71.5 ma / 3.6 V (x,y)=(0.45,0.41) 8,000 hrs 2800 K 7

Relative Lifetime Proprietary Blue Phosphorescent Emitter New type proprietary blue emitter 10 1 Ir(ppy) 3 0.1 0.01 Flrpic 0.001 Phenylpyridine-Ir metal Complex 0.0001 450 500 550 Emission Wavelength (nm) Conventional Phenylpyridine-Ir metal complex has no solution! 8

Wide Band-gap Materials Design Necessity of Host with high triplet energy for Phosphorescent emission S 1(H) S 1(H) S 0(H) Host Band Gap Emitter S 1(D) S 0(D) hν S 0(H) Host Wide Band Gap T 1(H) Emitter T 1(D) S 0(D) hν Fluorescent emission Phosphorescent emission Jablonski Level Diagrams Molecule Design Policy 1. High T 1 energy 2. High Tg 3. High carrier transport ability 4. Amorphous morphology 9

Outline KONICA MINOLTA s OLED lighting development Evaporation and Solution Process OLED Efficiency Improvement Production Case Study of OLED Lighting World s first all-phosphorescent OLED product Proprietary blue phosphorescent emitter Roll-to-Roll process OLED technology Unique material technology and OLED structure for solution process Recent progress in solution-processed OLED device R2R OLEDs line Summary 10

Overview of R2R Solution Process Work Cathode Organic Thin Layers Anode Adhesive Flexible Substrate High performance & low cost Materials Layer design Substrate Device design R2R Process Phosphorescent emitter and host materials HILs and HTLs ETLs Solvents Multilayer design Thickness Charge balance Film morphology Light out-coupling High-Barrier film Plastic substrate Metal substrate Ultra-thin glass Transparent conductive film Patterning Encapsulation Packaging Interconnection process environment Cleaning Coating & drying Web handling Lamination Quality inspection 11

Design for Four-layer Solution Process Cathode Solutionprocessed four layers EIL ETL EML(Host+Emitter) Phosphorescent small molecules system Anode HTL HIL 2010 White OLED with light out-coupling Luminance cd/m 2 1,000 Efficacy lm/w 52 Driving Voltage V 3.5 Life time (LT50) hrs 6,000 Color coordinate (x,y)=(0.46,0.42) CCT K 2,800 Key Items All phosphorescent system using proprietary solution processable blue emitter Unique material system to avoid lower layer wash-off Optimization of each layer s solution formulation Process condition to be compatible with plastic substrate 12

Analysis of Organic Multilayer Thin-film Cross-sectional observation by STEM Evaporation Solution Process Cathode Cathode ETL EML HTL HIL Anode ETL EML HTL HIL Anode 100 nm 100 nm Clear interfaces in multilayer structure as well as evaporation 13

Performance Comparison on an Identical Design All-Evaporation HIL only (Solution) HIL/HTL (Solution) HIL/HTL/EML (Solution) HIL/HTL/ETL (Solution) = EML only (Evaporation) All-Solution Process Major factor limiting the performance : Solution-processed EML 14

What is the difference in EML? EML s morphological properties can be a cause. Crystallization Molecular aggregation Film density Impurities Evaporation ETL HTL Solution Process ETL HTL Host Emitter Impurities 15

Film morphological improvement 1 XRD analysis using Synchrotron radiation (SPring-8) X-ray High brightness High directionality Variable polarization EML(Host+Emitter) Glass Small Angle X-ray Scattering(SAXS) Particle size I(counts) 20000 18000 16000 14000 12000 10000 8000 6000 4000 2000 0 Evaporation Solution Process 2 7 12 2θ Wide Angle X-ray Diffraction(WAXD) Molecular Orientation 16

Ln[I(q)] Number-size distribution Film morphological improvement 2 SAXS analysis by Guinier plot q ( 4 )sinq λ 2 2 q Rg I(q) I(0)exp(- ) 3 2 Ln I(q) Ln I(0)-( Rg )q 3 2 Guinier s Law q: Scattering vector Rg: Radius of gyration λ: Incident X-rays wavelength(nm) q: Scattering angle I(q): Scattering Intensity Incident radiation S 0 S 0 Scattering body q q S 2q Scattered radiation q:scatterign vector 11 Guinier plot 10 9 8 Evaporation Solution process Slope -( Rg 3 2 ) 2 Slope Rg Particle size analysis 1.2 Evaporation 1 Solution Process 0.8 0.6 7 0.4 6 0.2 5 0.000 0.002 0.004 0.006 0.008 q2 0 0 5 10 Particle diameter (nm) 17

Film morphological improvement 3 Performance degradation by molecular aggregation Solution Process ETL E E T-T annihilation Quenching Charge transfer loss Energy Residual solvent Assisting E-E aggregation Host HTL Emitter E No harmful effect Impurities 18

Number-size distribution Number-size distribution Film morphological improvement 4 1.2 1 Evaporation Solution Process 1.2 1 Evaporation Improved Solution Process SAXS 0.8 0.6 Improved effect 0.8 0.6 0.4 0.4 0.2 0.2 0 0 0 5 10 Particle diameter (nm) 0 5 10 Particle diameter (nm) Full width at half maximum (2θ degree) WAXD Solution process Improved solution process Evaporation 1.0 1.7 1.8 Adoption of new host material for solution process Optimization of drying condition 19

Current Performance All-Evaporation All-Solution Process in 2010 All-Solution Process in 2012 Our activities showed encouraging progress. 20

R2R OLEDs Line for R&D Patterning, Cleaning Wet coating & drying of organic layers Vacuum deposition for electrode layers Encapsulation, Packaging Quality inspection 21

Improvement of Defective Appearance Coating Failure Rate Key Focus Die Coating technology to form uniform coating a nanoscale organic layer Optimization of various parameters ; Slot die coater design with high accuracy Coating conditions for each layer Drying instruments and conditions Web handling 22

Outcome from R2R OLEDs Line Area : 94.5cm 2 (63mm X 150mm) Thickness : 500µm Weight : 14g / panel Feasibility demonstration of all-phosphorescent OLED lighting panel by solution-based R2R process technology 23

Summary All-phosphorescent OLED is a major breakthrough in OLED lighting. We have commercialized OLED lighting product by evaporation with the world s highest-level efficacy using all phosphorescent emitters for the first time in the world. Successful demonstration of the all R2R-processed OLED panel has opened a way to achieve commercially viable OLEDs for general lighting applications. To catch up with the state-of-the-art evaporated OLED lighting, we will accelerate the development of the solution-processed OLEDs by combining advanced materials and innovative process technologies. 24

Acknowledgements NEDO project (P09024) Philips Technologie GmbH for consignment production on the evaporated OLEDs Universal Display Corporation for Universal PHOLED Phosphorescent OLED technology GE Global Research for collaboration on the solution process technology (March 2007~March 2011) Japan Synchrotron Radiation Research Institute (JASRI) 25

Thank you for your attention! Kazuhiro.oikawa@konicaminolta.jp 26