High Performance White OLEDs Technologies for Lighting 10 October, 2012 Takuya Komoda Core Technologies Development Center Panasonic Corporation
Contents 2 1. Expectation to the Next Generation Lighting 2.Recent Progress of White OLED Technologies for Lighting Application 3.Examples of the OLED Lighting 4.Summary
Various Lighting Devices 3
Worldwide power Consumption Global Environmental Issue 4 Lighting Consumes about 20 % of Total Power Consumption Worldwide [1,000 TWh] Lighting ~ 3,300 TWh 18 16 14 = 12 10 8 6 ~ 17,000 TWh 4 2 0 75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 05 07 Year Reference: Energy white paper 2010 issued by Agency for Natural Resources and Energy
Next Generation Solid State Lighting... OLED vs LED 5 Diffusive Light Source Directional Light Source Thin Thick Point <1 mm 10 mm 100 mm OLED LED Surface Light LED Array LED Bulb Highly comfortable and energy saving lighting environment should be realized by well mixing up both Diffusive and Directional light sources. Not OLED OR LED But OLED AND LED
Features of OLED lighting 6 Advantages potentiality of low power consumption no toxic material (e.g., mercury) very thin, light weight low voltage DC drive high response / easy modulation no UV, IR emission gentle surface emission with high CRI (color rendering index) environmental friendliness appearance shape control --- expression quality of light
2. Two-unit structure Concept and features of Panasonic white OLEDs 7 Comfort: High quality High CRI High color spatial uniformity Eco-friendliness: High specification High efficiency Long lifetime High reliability 1. Deep blue fluorescent and red/green phosphorescent hybrid structure 2. Two-unit structure 3. Wet coated HIL 1. R/G phosphorescent unit (Connecting layer) 1. Deep B fluorescent unit 3. Wet coated HIL Light outcoupling structure luminous efficiency 42 lm/w CRI 90 luminance 1,000 cd/m 2 color coordinate (0.41,0.39) color temperature half decay lifetime 3,400 K > 100,000 h with light outcoupling enhancement sheet efficiency was corrected by emission pattern
low high Requirements for solid-state lightings (SSL) as Luminaires 8 Energy Star Program Requirements - Color rendering index (CRI) > 75 (for indoor luminaires) * CRI of fluorescent tubes : 84 better CRI: over 90 - Color spatial uniformity (i.e., chromaticity variation in viewing angle) < 0.004 in CIE 1976 (u,v ) coordinates - Color maintenance < 0.007 in CIE 1976 (u,v ) coordinates - Corrected colour temperatures ex. 5000K : 5028+/-283 CRI
CIE-y CIE-y CIE-y Achievement of high color rendering index (CRI) 9 design of color combination 0.9 0.9 0.9 0.8 0.7 0.6 0.5 yellow 0.8 0.7 0.6 0.5 green 0.8 0.7 0.6 0.5 bluish-green green 0.4 0.3 white 0.4 0.3 white red 0.4 0.3 white red 0.2 0.2 0.2 0.1 blue 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 blue 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 blue 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 CIE-x CIE-x CIE-x simpler structure better CRI easier optical design What is the best combination for Lighting?
Features of our white device 10 1. 2-unit structure for the better electrical and optical performance - lifetime - excellent color spatial uniformity connecting layer HIL (wet coated) 2. high color rendering index (CRI) and long-lifetime - new deep blue fluorescent emitters (by Idemitsu Kosan) - high performance R/G phosphorescent emitters - high mobility and high T1 organic materials light outcoupling structure 3. wet coated HIL layer for the better reliability (short reduction) (very thin, uniform layer was slit-coated developed by TAZMO) Thanks to Universal Display Corporation and Nippon Steel Chemical Co., Ltd for green and red phosphorescent emitters and host materials. Nissan Chemical industries for coatable HIL materials.
Emission Intensity (arb. units) intensity Emission Intensity (arb. units) Design of high CRI white emission 11 < 460 nm 525 nm 615 nm 460 nm CRI 90 ~50 nm Wavelength 400 500 600 700 800 Wavelength (nm) CRI 95 for high CRI white emission... - combination of several colors - wavelengths of R/G/B - appropriate spectra of R/G/B novel deep blue emitters were developed ~90 nm 400 500 600 700 800 Wavelength (nm)
Optical design Typical optical design method (2n+1) l / 4 (m+1) l / 2 cathode anode 12 Not available for multi-unit devices!! - No value satisfies those relationships at the same time. - The efficiency, emission color and emission patterns after light out-coupling enhancement should be considered. Optimization of - the order of emissive layers - the emissive region - width of emission site - interference Out-coupling structure
Efficacy Efficacy Design Strategy of High Efficacy and High Quality Light Source 13 High Device Structure Nil HIgh Light Outcoupling Nil Angular Dependence Angular Dependence Emitting Position Low Light Scattering Property High In order to realize both high efficacy and small angular dependence, relationship of device and light out-coupling structure should be considered.
CIE-y Optimization of device structures Emission patterns (Red, Green and Blue) (a) Red 60 o (b) 0 o 30 o 0 o 30 o (a) 60 o 60 o 0 o 30 o 30 o 60 o Green 60 o Blue 0 o (b) 30 o 30 o 60 o 30 o 30 o 14 0 (a) o Angular 30 dependence o of CIE coordinates 30 o from 0 deg to 80 deg 0.5 60 o 60 o 60 0.45 o 0.4 (b) 0.35 permissible variation 0 o 30 o 30 o 60 o black body radiation 60 o 0.3 60 o 0.3 0.35 0.4 0.45 0.5 CIE-x (c) 0 o 30 o 30 o (c) 60 o 0 o 30 o 30 o (c) 60 o 60 o 0 o 30 o 30 o 60 o 60 o 60 o
Approaches for light outcoupling improvement 15 Light confined in the high index layers Organic layers / electrode (n ~ 1.8) Glass substrate (n ~ 1.5) Light extraction efficiency : 20% - in glass substrate : confined - in organic layer : confined Light confined in the substrate air (n = 1.0) Conventional light outcoupling methods High refractive index substrate Scattering layer (e.g., micro lens array, diffusion sheet,...) High refractive index substrate High index scattering layer (e.g., micro lens array, diffusion sheet,...) Light extraction efficiency : 26% - in glass substrate : extracted - in organic layer : confined Developed light outcoupling substrate Light extraction efficiency Developed : 40% high refractice - in glass substrate index : extracted scattering layer - in organic layer Glass : extracted substrate - Cost of high index substrates is high
Schematic of OLED panel with light outcoupling substrate cavity glass for encapsulation 16 ~ 16 ~ cathode glass substrate with electrode pattern emissive area organic layer plastic film anode conductive paste bus electrode light outcoupling layer light Air-gap anti-reflection layer high-n plastic film High-n MLA glass substrate Detailed information will be presented at 51.4 in this conference
Approach for higher light out-coupling 17 (2) higher reflective electrode (3) optical modifications for - light out-coupling substrate - higher reflective electrode glass substrate (n ~ 1.5) transparent electrode (1) high refractive index light out-coupling layer between transparent electrode and glass substrate The structure of the light out-coupling layer and optical design for this device were simulated and designed by - ray tracing method - the other some optical ways with various optical parameters of such as refractive indices and extinction coefficients
Hybrid white OLED on the developed light out-coupling substrate 18 luminous efficiency cathode bus electrode at 1,000 cd/m 2 56 lm/w CRI 91 luminance 1,000 cd/m 2 color coordinate (0.42,0.41) color temperature 3,200 K by 25 cm 2 pixel higher reflective electrode half decay lifetime > 150,000 h glass substrate transparent electrode high refractive index light out-coupling layer substrate total reflection at the interface between transparent glass substrate is dramatically reduced by high refractive index light out-coupling layer outcoupling efficiency improves up to about 40% emission area light outcoupling area anode
CIE-y CIE-y Optically Designed Multi-unit OLEDs 19 5,000K 3,000K Please Come to the Author s Interview if you want to see Real Devices. Luminance: 3,000 cd/m 2 Size: 8 x 8 cm 2 0.8 0.7 0.6 0.5 0.45 0.5 0.4 0.3 0.4 5000K 4590K 3000K 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 CIE-x 0.35 permissible variation in Energy Star eligibility criteria 0.3 0.3 0.35 0.4 0.4 0.45 0.5 0.5 CIE-x
Development of High Speed Coating Process of HIL 20 Conventional Coating Process +20% Developed Process Coating HIL layer High reliability -20% Coating Speed:50mm/s Thickness :30nm±20% 200mm/s 30nm±3% Slit Coating System(Developed with Tazmo) Ultra Thin Film Coating Process Coated Film Nozzle Stage Substrate
film thickness(nm) Development of High Performance In-Line Evaporation Process 21 Schematic of In-Line evaporation Process Substrate Vacuum Chamber Evaporated Substrate Prototype of In-Line Evaporation Process Evapora tion gas Source1 Source2 Source3 Schematic of Hot Wall Source Hot wall CAE Simulation 200 Distribution Thickness Monitor 150 100 ±3% Crucible Valve 50 0 at 8 nm/s -120-90 -60-30 0 30 60 90 120 position(mm) Over 70 % Material Usage and High Speed Evaporation Process
CIE-y All phosphorescent vs. hybrid white OLEDs 22 all phosphorescent Features: - ultimate efficiency Challenges: - lifetime - color variation with high CRI - - deep blue is required for high color temperature and CRI obtainable color region (R-G-light blue) 5,000K 3,000K phosphorescent fluorescent hybrid Features: - better lifetime - color variation Challenges: - efficiency phosphorescent green / red fluorescent blue CIE-x
Structures of multi-unit all phosphorescent white OLED 23 device structure combination of emissive units example of white emission spectrum Blue Green Red single unit 3 colors RGB 2 colors R + GB G + RB 1 color B + RG 400 500 600 700 800 wavelength (nm) W avelength (nm) two units 2 colors 2 colors RG + RB RG + GB RB + GB RGB + RB 3 colors RGB + GB 3 colors RGB + RG RGB + RGB Various combination of emissive units are investigated and some candidates are selected.
Efficacy improvement of multi-unit white device 24 step 1 optical design of device structure Transparent electrode light outcoupling substrate multi-unit white OLED 1 cm 2 at 1,000 cd/m 2 step 3 introduction of highly reflective electrode and better electron injection layer step 2 introduction of high mobility, carrier transport materials luminous efficacy E.Q.E. voltage Ra estimated LT50 reference 48 lm/w 62 % 7.3 V 78 200 k h step 1 60 lm/w 72 % 7.7 V 85 200 k h step 2 74 lm/w 74 % 6.6 V 81 100 k h step 3 88 lm/w 80 % 6.2 V 85 140 k h Better light outcoupling and voltage reduction achieve higher efficacy
All phosphorescent white OLED panel (prototype: 25 cm 2 ) 25 ~ 25 ~ 25cm 2 at 1,000 cd/m 2 Efficacy Half-decay Lifetime 5cm Ra E.Q.E. Voltage L.E.E. (x,y) CIE1931 87 lm/w > 100,000 h 82 81 % 6.1 V > 41 % (0.46,0.42) Both high efficacy and long lifetime were achieved
Latest results on all phosphorescent white OLED Higher light outcoupling efficiency was achieved! Thanks to the reduction of light extinction by replacing some materials and further optical optimization. 26 all phosphorescent multi-unit device Transparent electrode light outcoupling substrate high-n hemispherical lens Glass at 1,000 cd/m 2 High refractive index hemisphere emission area: 4mm 2 Light outcoupling substrate emission area: 1cm 2 luminous efficiency 142 lm/w 101 lm/w EQE 123 % 84 % CRI 85 86 voltage 5.8 V 5.9 V light outcoupling efficiency over 62 % over 42 % color temperature 2700 K 3200 K color coordinate (0.46, 0.40) (0.44,0.44) half decay lifetime > 50,000 h > 30,000 h
Panasonic OLED Lighting 2011/09/01 First Product of Panasonic OLED Lighting was launched by Panasonic Idemitsu OLED Lighting Co.,Ltd. 27 Model number Color temperature Panel size OLED_Panel 3000K 97X90x2mm High CRI : >90 High luminance : 3,000cd/m 2 Long lifetime (LT70) : 10,000h Luminous efficiency : 30lm/W
News Release on October 13 th, 2011 (From the presentation on Oct. 28, 2011) 28 conceptual drawings OLED Panasonic s 30 OLED lightings and 1,200 LED lightings will be adopted for Jiyu-ga oka Station, Tokyu corporation until March 2012. LED OLED lightings: central entrance gate, commuter ticket counter LED lightings: platform, concourse, office, newsstand http://www2.panasonic.co.jp/es/archive/jp/corp/news/1110/1110-6.htm
OLED lighting at one of the railway station in Japan 29 at Jiyu-ga-oka Station, Tokyu Corporation ( 東京急行自由が丘駅 )
OLED Exhibition (Lighting Panel & Fixtures ) 30 Milano Salone Interni Legacy Date: April 16-18, 2012 Location: Milano, Italy Concept: Photosynthesis-Future Craft
Prototypes of OLED lighting with high CRI 31 Light for the Art Mirror Light Pendant Light Photo: Panasonic Shiodome Museum, Tokyo
Efficacy Future prospect of OLED lighting (lm/w) 140 120 New Results 142 lm/w (Hemisphire) R&D stage Production stage target of NEDO project For general use (130 lm/w at a larger panel) 32 100 80 Fluorescent lamps 101 lm/w (1cm 2 ) 87 lm/w (25cm 2 ) Outdoor lighting Office / for industrial use 60 40 20 0 Fluorescent compact lamps 56 lm/w For commercial use / indoor lighting Cathodeluminescent lamps For signature / decorative illumination 30 lm/w Incandescent lamps For niche market 2010 2015 2020
Summary 33 - Evolution of OLED is quite rapid all these years and OLED lighting has been just commercialized. - For the higher efficacy, light outcoupling technology and phosphorescent system are quite important but there exist many challenges. - Developed light outcoupling substrate with high-n structure achieved quite high outcoupling efficiency of over 40 %. - All phosphorescent white OLED on the light outcoupling substrate achieved high efficacy of over 100 lm/w. Well designed multi-unit device dramatically improved operation lifetime. - All phosphorescent system and light outcoupling technology will bring OLED lighting to the next stage.
Acknowledgements New Energy and Industrial Technology Development Organization (NEDO) - financial supports to several projects 34 Idemitsu Kosan Co. - High Efficiency Blue Emission materials / various materials - as a member of NEDO projects Tazmo Co. - Collaborative researches on innovative slit coating processes - as a member of NEDO projects Choshu Industries - Collaborative researches on innovative deposition processes - as a member of NEDO project Universal Display Corporation - Phosphorescent materials Nippon Steel Chemical Co. - Various materials for phosphorescent device
Thank you for your attention http://www2.panasonic.biz/es/lighting/device/oled/en/index.html 35 *1 Color rendering (no less than Ra90) and high luminance (3000 cd/m 2 ) among volume production OLED lighting panels as of August 31, 2011 (source: PIOL research).