An Overview of OLED Display Technology

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1 page:1 An Overview of OLED Display Technology Homer Antoniadis OSRAM Opto Semiconductors Inc. San Jose, CA

2 page:2 Outline! OLED device structure and operation! OLED materials (polymers and small molecules)! Evolution of OLED performance! OLED process and fabrication technologies! White emitting OLEDs! Color capabilities! Products and demonstrators

3 page:3 OLED display and pixel structure Display Pixel Cover glass Cathode Conducting polymer layer Emissive polymer layer Cathode (Ba,Ca/Al 2000 Å) Emissive polymer layer ~ 800 Å Conducting polymer layer ~ 1200 Å Epoxy Anode (ITO 1500 Å) Anode Single pixel structure Glass substrate Human hair is 200X the thickness of the OLED layers

4 page:4 OLED Device Operation Principles + + _ Cathode Emissive polymer Conducting polymer Anode+ + V OLEDs rely on organic materials (polymers or small molecules) that give off light when tweaked with an electrical current! Electrons injected from cathode! Holes injected from anode! Transport and radiative recombination of electron hole pairs at the emissive polymer OLED device operation (energy diagram) light Transparent substrate Anode (ITO) Conducting polymer LUMO Emissive polymer e - e - LUMO Cathodelayer (s) Light HOMO h + h + h + HOMO ca. 100 nm 10 - >100 nm <100 nm >100 nm

5 page:5 Optoelectronic Device Characteristics Luminance-Current-Voltage Efficiency-Luminance-Voltage 12 Luminance (cd/m 2 ) Current Density (A/cm 2 ) Voltage (Volts) Efficiency (cd/a) Luminance (cd/m 2 ) Efficiency (cd/a) Voltage (V) LUMINANCE is the luminous intensity per unit area projected in a given direction The SI unit is the candela per square meter (cd/m 2 ), which is still sometimes called a nit The footlambert (fl) is also in common use: 1 fl = cd/m Voltage (Volts)

6 page:6 Evolution of LED performance SM OLED Polymer OLED Courtesy of Agilent Technologies

page:7 Electroluminescent Conjugated Polymers Conducting polymers! Polyaniline (PANI:PSS) NH! Polyethylenedioxythiophene (PDOT:PSS) PANI PDOT PSS Emissive polymers!

7 page:7 Electroluminescent Conjugated Polymers Conducting polymers! Polyaniline (PANI:PSS) NH! Polyethylenedioxythiophene (PDOT:PSS) PANI PDOT PSS Emissive polymers! Polyphenylenevinylene (R-PPV) R 1! Polyfluorene (PF) Processed by : Spin casting, Printing, Roll-to-roll web coating R 1 R-PPV n R 1 R 1 PF n IP owned by Cambridge Display Technology

8 page:8 Multiple emission colors achieved by Covion Different emission colors can be obtained with a variety of chemical structures PPP n 300 nm 500 nm 700 nm PPV PT or CN-PPV S RO OR CN

9 page:9 Multiple emission colors achieved by Dow Chemical R 1 R 1 PF n

10 Polymer OLED display fabrication steps Deposit and pattern anode (ITO) Pattern polymer layers (first conducting then emissive) Spin coating Ink Jet printing Screen printing Web coating Vacuum deposit and pattern cathode (Ba,Ca/Al) Homer Antoniadis OLED Product Development page:10

11 Ink Jet Printing to Pattern Polymers (Full Color Applications) Homer Antoniadis OLED Product Development page:11 Ink Jet Head Red emitter Green emitter Blue emitter Substrate Ink Jet printing to define and pattern R, G, B emitting subpixels

12 page:12 The Holy Grail: Flexible OLEDs Sheila Kennedy, Harvard Univ., 1999

13 page:13 Polymer and Small Molecule Device Structures Small molecule Polymer Cathode -Li/Al ETL -Alq 3 Cathode Ba, Ca/Al ETL - PPV, PF EML - doped Alq 3 HTL -NPB HIL -CuPc Anode -ITO Substrate -glass HIL - PDOT, Pani Anode -ITO Substrate - glass Multi-layer structure made all in vacuum Bilayer structure made from solution

14 page:14 Electroluminescent Small Molecules Hole transport small molecules! Metal-phthalocyanines N N! Arylamines, starburst amines NPD Emissive small molecules! Metal chelates, distyrylbenzenes! Fluorescent dyes N O Al O N O N Processed and deposited by : thermal evaporation in vacuum Alq 3 IP owned by Eastman Kodak

15 page:15 Full color patterning with small molecules substrate R emission layer Cathode separator Shadow mask ITO G emission layer Shadow mask NPD Alq 3 ITO B emission layer Shadow mask ITO Small molecules are thermally evaporated in vacuum R, G, B pattering is defined by shadow masking in vacuum

16 page:16 White emitting small molecule OLEDs Initial Luminance 1000nits

17 Phosphorescent small molecule OLED (both singlets and triplets are harvested) Homer Antoniadis OLED Product Development page:17 η ext =19% and η int =87%

18 page:18 Full-color/Multi-color Approaches RGB- polymer emitters Color filters White emitter Color Changing Media (CCMs) Advantages: - power efficient - lower production cost - mature ITO technology Disadvantages: - emitters have to be optimized separately (common cathode?) - differential aging of emitters - patterning of emitters necessary Advantages: - well-established technology (LCD) - no patterning of emitter necessary - homogeneous aging of emitter (?) Disadvantages: - power inefficient - ITO sputtering on filters - efficient white emitter necessary Advantages: homogeneous aging of emitter (?) more efficient than filters no patterning of emitter necessary Disadvantages: ITO Sputtering on CCMs stable blue emitter necessary aging of CCMs

0 400 450 500 550 600 650 700 750 Wavelength (nm) Ink Jet printing of R,G,B

19 page:19 Obtaining a Full Color OLED Display AM TFT screen Blue polymer Green polymer Red polymer EL Intensity (normalized) Wavelength (nm) Ink Jet printing of R,G,B emissive polymers defines the R,G,B subpixels (x R, y R ) (x G, y G ) (x B, y B ) R G B

20 page:20 Device Color, Efficiency and Lifetime Polymers Small Molecules Color Efficiency (cd/a) Half-Life* nits, RT Efficiency (cd/a) Half-Life* nits, RT Red 1-2 >20, >40,000 Green , >40,000 Blue 4 3, ,000 Yellow 8-10 >30,000 8 >30,000 White 2-4 5, ,000 *Extrapolated Lifetime under constant current conditions

21 page:21 Small Molecule Passive Matrix Display Products Motorola (by Appeal) Samsung Electronics 96x64 Full Color PM Display Kodak Licensed SNMD to Manufacture PM OLED Displays Lucky Goldstar (LG)

22 page:22 Small Molecule Active Matrix Display Products Eastman Kodak: Digital camera Sanyo: Cell Phone with Digital camera

A 13-inch full-color AMOLED using poly-si TFT was made where the light emits through the transparent cathode and thus, the filling

23 page:23 Top Emitting Active Matrix OLED Display Top Emission Adaptive Current Drive technology, allows OLEDs to be larger and higher in brightness and resolution. A 13-inch full-color AMOLED using poly-si TFT was made where the light emits through the transparent cathode and thus, the filling factor does not depend on the TFT structure. The schematic vertical structure of the device is substrate/tft/metal anode/organic layers/transparent cathode/passivation layer/transparent sealing. Display format: 800 x 600 (SVGA); pixel pitch 0.33x0.33mm 2

24 page:24 Polymer Passive Matrix Display Products Philips: Electrical Shaver Delta Electronics: Display for MP3 player

page:25 OSRAM Opto Semiconductors evaluation kit San Jose, CA May 15, 2003 -- Osram Opto Semiconductors, a global leader of solid-state lighting devices, today announced its Pictiva Evaluation Kit.

25 page:25 OSRAM Opto Semiconductors evaluation kit San Jose, CA May 15, Osram Opto Semiconductors, a global leader of solid-state lighting devices, today announced its Pictiva Evaluation Kit. Announced earlier this week, the Pictiva brand is Osram s suite of organic light emitting diode (OLED) technologies. Pictiva displays offer a high level of brightness and contrast, video capabilities, wide viewing angles and a thin-profile, enabling developers and engineers to have greater design flexibility when developing the next-generation state-of-the-art electronics products.

[1.9] AMOLED 공정 Introduction OLED Materials Patterning Process Process Equipments

[1.9] AMOLED 공정 Introduction OLED Materials Patterning Process Process Equipments [1.9] AMOLED 공정 1.9.1. Introduction 1.9.2. OLED Materials 1.9.3. Patterning Process 1.9.4. Process Equipments OLED : Organic Light Emitting Diode Organic EL : Organic Electroluminescent 재료및공정 재료의발광메카니즘