cours mit oled

Slide 1Lecture 76.976 Flat Panel Display Devices – Spring 2001 • types of organic materials • growth of organic materials • organic light emitting devices • OLED-based displays Lecture 7 6.976 Flat Panel Display Devices Emissive Displays – Organic Electroluminescence Flexible OLED Slide 2Lecture 76.976 Flat Panel Display Devices – Spring 2001 Organic Materials Alq 3 PPV MOLECULAR MATERIALS POLYMERS Attractive due to: Attractive due to: • • Integrability with inorganic semiconductors • • Low cost (fabric dyes, biologically derived materials) • • Large area bulk processing possible • • Tailor molecules for specific electronic or optical properties • • Unusual properties not easily attainable with conventional materials But problems exist: But problems exist: • • Stability • • Patterning • • Thickness control of polymers • • Low carrier mobility n Slide 3Lecture 76.976 Flat Panel Display Devices – Spring 2001 Scientific Interest in Organic Materials • 1828 - Wöhler first synthesized urea without the assistance of a living organism • 1950’s - steady work on crystalline organics starts • 1970’s - organic photoconductors (xerography) • 1980’s - organic non-linear optical materials • 1987 - Kodak group published the first efficient organic light emitting device (OLED) • Since then, the field has dramatically expanded both commercially and scientifically (OLEDs, transistors, solar cells, lasers, modulators, ) to date, about two million organic compounds have been made to date, about two million organic compounds have been made - this constitutes nearly 90% of all known materials - - this constitutes nearly 90% of all known materials - Slide 4Lecture 76.976 Flat Panel Display Devices – Spring 2001 VACUUM CHAMBER TURBO PUMP COLD TRAP ROUGHING PUMP substrate holder thickness monitor shutter GND substrate POWER SUPPLIES source boats Device Preparation and Growth • Glass substrates precoated with ITO - 94% transparent - 15 Ω/square • Precleaning Tergitol, TCE Acetone, 2-Propanol • Growth - 5 x 10 -7 Torr - Room T - 20 to 2000 Å layer thickness Slide 5Lecture 76.976 Flat Panel Display Devices – Spring 2001 OMBD II OMBD I Sputtering Analysis Chamber Load Lock Materials Growth Laboratory III-V MBE Load Lock Transfer Chamber Metal e-Beam Base Pressure 10 -9 ~ 10 -11 torr Princeton Princeton University University Slide 6Lecture 76.976 Flat Panel Display Devices – Spring 2001 Integrated Materials Growth System Evaporative Deposition • molecular organics (amorphous and crystalline) • metals Sputtering • ITO • ceramics Wet N2 Glove Box Load Lock with Sample Storage Ante Chamber and Oven Laminar Flow Hood Dry N2 Glove Box Shadow Mask Storage Probe Station with Cryostat AFM STM Physical & Vapor Phase Dep. • molecular organics • nano-dots ** • solvated polymers ** • colloids ** Slide 7Lecture 76.976 Flat Panel Display Devices – Spring 2001 • Spin-on • Langmuir-Blodgett • Inkjet Printing • Dye Diffusion • Silkscreen Other Growth Methods glass substrate ITO doped polymer film highly doped polymer film glass substrate } } DIFFUSION SOURCE SHADOW MASK DEVICE Slide 8Lecture 76.976 Flat Panel Display Devices – Spring 2001 Development of Organic LEDs • Conventional, Transparent, Inverted, Metal-Free, Flexible, Stacked ~ OLED, TOLED, OILED, MF-TOLED, FOLED, SOLED ~ • Displays Slide 9Lecture 76.976 Flat Panel Display Devices – Spring 2001 Personal Organizer, Personal Organizer, Notebook Notebook Rugged, high resolution, full-color, video-rate displays Slide 10Lecture 76.976 Flat Panel Display Devices – Spring 2001 Multi-Function Multi-Function Video Watch Video Watch Rugged, high resolution, full-color, video-rate displays enable a multitude of applications Automotive Automotive Dashboard displays, external indicator lights, and road signs [...]... Below Average Slide 33 Transparent OLEDs TOLEDs MF-TOLEDs EL Light 500 Å ITO - 50-100 Å Mg-Ag V ETL HTL ITO Glass + EL Light Alphanumeric TOLED Display > 70% transparent Bulovic et al., Nature 380, 29 (1996) ´ Parthasarathy et al., Appl Phys Lett 72, 2138 (1998) 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 34 I - V Characteristics of a Metal Free-TOLED 3 10 2 Current Density (mA/cm2... ground state (singlet) triplet exciton singlet exciton • triplet to ground state transition is not permitted • symmetry conserved fast process ~10-9s 6.976 Flat Panel Display Devices – Spring 2001 PHOSPHORESCENCE slow process ~ 1s Lecture 7 Slide 26 Phosphorescent OLED Performance Ir(ppy)3 6% Ir(ppy)3 in CBP OLED: N at 100 cd/m2 : 4.5 V, 19 lm/W at 10,000 cd/m2 : 7.2 V, 8 lm/W Ir 3 N N CBP 30 10,000 cd/m2... Current Density (mA/cm2 ) 10 1 10 0 10 -1 10 ITO CuPc Alq 3 α-NPD CuPc ITO Glass EL + V I ∝ V9 EL -2 10 -3 10 I ∝ V2 -4 10 10-5 MF-TOLED TOLED -6 10 0.1 6.976 Flat Panel Display Devices – Spring 2001 1 Voltage (V) Lecture 7 VT 10 Slide 35 Transparency/Reflection of a Metal Free-TOLED 1.0 Transmission Intensity (a.u) 0.8 0.6 0.4 Reflection CuPc Absorption 0.2 0.0 500 550 6.976 Flat Panel Display Devices –... Material Cell Material Equipment Depreciation Building Depreciation 50 AT SAME YIELDS 0 AMLCD 6.976 Flat Panel Display Devices – Spring 2001 LTPS /OLED Lecture 7 Source: DisplaySearch Slide 32 Technology Landscape TECHNOLGY/ FEATURES Brightness AMLCD PMLCD LED PDP FED OLED Good Good Good Good Resolution High High Very Good Low Medium High Very Good High Voltage Low Low High High High Low Viewing Angle Medium... m+1 V J ∝ NLUMO µnNt d m = Tt/T Nt=3.1x1018cm-3, µnNLUMO=4.8x1014/cm-V-s Slide 15 Progress in LED Efficiency OLEDs PLEDs ol M ec rS la u id ol s after Sheats et al., Science 273, 884 (1996) 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 16 Why Make Organic LEDs WE DEMONSTRATED OLEDs THAT ARE : • Bright - 100,000 cd/m2 (30,000 ft-L) • Efficient - >30 lm/W • Scalable Emissive Area - from...Active Wallpaper Large area displays Active Clothing Light, rugged, low voltage, flexible displays 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 11 Why do OLEDs Glow ? Alq3 PL OLED V Ag Mg:Ag + ~1000 Å ~500 Å ~500 Å Alq3 TPD electrons and holes form excitons (bound e h+ pairs) ITO E HTL Alq3 TPD N Al 6.976 Flat Panel Display Devices – Spring 2001 N O + 3 400 500 600... 2.4 eV PPV hν ν 6.976 Flat Panel Display Devices – Spring 2001 ITO Lecture 7 Slide 13 Exciton Recombination Zone C Adachi, et al 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 14 Trap Limited Conduction in Organic Materials charge trapping can dominate conduction _ ´ Shen, Burrows, Bulovic, McCarty, Thompson, Forrest, Jpn J Appl Phys 35, L401 (1996) _ free molecule molecule distorts _... – Spring 2001 Lecture 7 UDC,Slide 28 Inc Monochrome Passive-Matrix Polymer-LED Display Cambridge Display Technologies, Ltd 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 29 Full-Color OLED Display Kodak - Sanyo 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 30 Low Cost Potential Transparent Cathode Organic LED Multi-Color Icons ITO Anode Transparent Substrate: Glass,... • Low Cost Materials • Low Cost Substrates • Wide Viewing Angle - >160 deg • Reliability - 1,000,000 hrs (phosphorescent R half-life) 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 17 OLED Stability Relative luminance [L/L0] 1.0 0.9 MQA/Alq QA/Alq 0.8 0.7 Alq 0.6 0.5 1 5 10 50 100 1000 10000 Hours of operation Alq3 devices driven at 20 mA/cm2 Initial luminance for Alq3 is 510 cd/m2... molecules (charge transport material) 2 Excitons transfer to luminescent dye dopant molecule (luminescent dye) 6.976 Flat Panel Display Devices – Spring 2001 Lecture 7 Slide 19 Effect of Dopants on the OLED EL Spectrum N 1.0 Normalized EL Intensity O 0.8 N α-NPD N NC DCM2:Alq3 CN PtOEP:Alq3 0.6 Alq3 N 0.4 Al 0.2 N O N Pt N N 3 0.0 400 500 600 700 800 Wavelength [nm] 6.976 Flat Panel Display Devices – . LEDs • Conventional, Transparent, Inverted, Metal-Free, Flexible, Stacked ~ OLED, TOLED, OILED, MF-TOLED, FOLED, SOLED ~ • Displays Slide 9Lecture 76.976 Flat Panel Display Devices – Spring 2001 Personal. published the first efficient organic light emitting device (OLED) • Since then, the field has dramatically expanded both commercially and scientifically (OLEDs, transistors, solar cells, lasers,. materials • organic light emitting devices • OLED- based displays Lecture 7 6.976 Flat Panel Display Devices Emissive Displays – Organic Electroluminescence Flexible OLED Slide 2Lecture 76.976