OLED 구조 및 구동원리

OLED 구조및구동원리 (2006 년 2 월 FPD 전문가양성세미나 ) 20.1, 1280X800, AMOLED LPL/LGE, 2004 2006. 02. 08 김광영 kykim@lge.com OLED Business Team Digital Display Company LG Electronics Inc.

Contents - OLED 발광원리 - OLED Display 구조및재료 - 제조공정및기술 (Panel 및Module) - 구동기술 2/54

Terminology from IEC/TC 110/PT 62341, Terminology and letter symbols 3.1.28 organic electroluminescence emission of light from organic materials by injecting current 3.1.29 organic electroluminescent display display showing visual information in which organic electroluminescence occurs 3.1.30 organic light emitting diode light emitting device in which light is emitted from organic materials, possessing properties of diode 3.1.31 organic light emitting diode display display showing visual information in which organic light emitting diode is applied 3.1.32 organic light emitting diode display device generic term for organic light emitting diode display panel and organic light emitting diode display module 3.1.33 organic light emitting diode display module organic light emitting diode display panel and its driving electronics 3.1.34 organic light emitting diode (display) panel display panel of an organic light emitting diode display without external drivers 3/54

OLED 발광원리 4/54

OLED 발광 Mechanism Conduction Band (LUMO) 기판양극 (ITO) HTL EML ETL 정공주입층 (HIL) HIL EIL Al 정공수송층 (HTL) Exciton 발광층 (EML) 전자수송층 (ETL) ITO + 전자주입층 (EIL) 음극 ITO : Indium Tin Oxide HIL : Hole Injection Layer HTL : Hole Transport Layer EML : Emitting Layer ETL : Electron Transport Layer EIL : Electron Injection Layer Valence Band (HOMO) LUMO : Lowest Unoccupied Molecular Orbital HOMO : Highest Occupied Molecular Orbital 5/54

형광 & 인광 hole electron exciton Charge transfer or Triplets 1 2 > > ( > + > ) 인광 Singlet 1 2 ( > - > ) 형광 6/54

Emission Mechanism Electron - hole Charge separation (Photoconductivity) Charge separation Charge recombination Charge injection 25% Singlet Exciton Triplet Exciton 75% hν Fluorescence ( 螢光, 수명 ~nsec) Intersystem crossing Thermal deactivation Ground State hν Thermal deactivation Phosphorescence ( 隣光, 수명 ~1sec) 7/54

Emission Mechanism 8/54

Emission Efficiency Power efficiency (unit: lm /W) Φ power = γη r Φ PL V(λ) η ext Internal quantum efficiency External quantum efficiency where γ : charge balancing factor (~100%) η r : fraction of neutral excited states formed as singlet excitons via the electrical current ( 형광재료 25%, 인광재료 100%) Φ PL : photoluminescence (PL) quantum efficiency, the fraction of energy released from fluorescent or phosphorescent material as light (~100%) V(λ) : eye response curve (At peak visual response 555nm, 1W=683lm) η ext : the fraction of emitted photons that are coupled out of the device. ~1/ (2n 2 ) ( <20%) n : refractive index 9/54

Out-coupling 31.5% waveguided or emitted from sides 51% waveguided cathode 전자주입전극 유기발광층 (n ~ 1.7) 정공주입전극 ( ITO: n = 1.8 ~ 2.1) Internal QE 투명기판 ( 유리 : n =1.46 ) External QE 17.5% coupled out 10/54

Emission Efficiency of OLED Flourescence Charge injection & transfer e-h Pair(Exciton) formation(γ) Max. γ = 100% 인광재료 G: 19% R: 7% B: 5~6% Phosphorescence Singlet Exciton formation(r s ) Max. r s = 25% O X Triplet Exciton formation (r t ) Max. r t + Max. r s = 75% + 25% = 100% Fluorescence Emission(q f ) Max. q f = 100% Phosphorescence Emission (q p ) Max. q p = 100% Optical Coupling(η coupling ) η coupling = 20% Optical Coupling(η coupling ) η coupling = 20% External quantum efficiency(η ext ) Max. η ext = γ r s q f η coupling = 5% External quantum efficiency(η ext ) Max. η ext = γ r t q p η coupling = 20% 11/54

OLED Display 구조및재료 12/54

OLED Panel Structure : PM, Bottom Emission Cathode (metal) Getter 절연막 (Insulator) Glass Substrate 전자주입층 (EIL) 전자수송층 (ETL) 발광층 (EML) 정공수송층 (HTL) 정공주입층 (HIL) 격벽 (Cathode Separator) RGB (Full Color) Anode (ITO) Sealant Polarizer Glass ITO Organic EL Separator Cathode Encapsulation 13/54

OLED Device Materials 두께 : 100 ~ 200 nm Light output Anode + 정공수송층 (HTL) 발광층 (EML) + - Exciton 전자수송층 (ETL) 전자 - Cathode 정공 (from KETI, 2005) 14/54

Organic Materials N N NC CN O N DCJTB(Red) NDNTPD(HIL) N N α-npd(htl) N S N O O mqd (Green) 15/54 NUV UV UV NNOOAlNOAlq3(ETL) DPVBi(Blue)

Fluorescence & Phosphorescence Emitter 인광재료의이론적효율은형광재료대비 4 배로 R, G 는실용화수준임. 전하 ( 전자 & 정공 ) 주입및이동 전자 - 정공 Pair(Exciton) 형성 (γ) Max. γ = 100% S 1 Singlet Excited State Triplet Excited State 형광 (Fluorescence) 재료 인광 (Phosphorescence) 재료 S 1 T 1 T 1 hυ ( 형광 ) Thermal Decay Singlet Exciton 형성 Max. η s = 25% Singlet/Triplet Exciton 형성 Max. (η s + η t )=25% +75% =100% hυ ( 형광 ) hυ ( 인광 ) S 0 Singlet Exciton Ground State 이론적내부양자효율 25% 이론적내부양자효율 100% S 0 Singlet Exciton Triplet Exciton Radiative Non-radiative Radiative Radiative 16/54

Fluorescence & Phosphorescence Emitter Excited State Singlet (25%) Triplet(75%) Ground state 형광형 OLED (25%) 인광형 OLED(100%) 특성 당면과제 형광 ( 저분자 & 고분자 ) Fast decay time(<1 μs ) 내전류특성우수 PM-OLED 에적당 상대적으로낮은효율 Green 수명향상 인광 ( 저분자 ) 높은발광효율 ( 이론적최대효율 100%) AM-OLED 에적당 Blue 수명 < 1,000 시간 Hole blocking layer 가추가로필요하여구동전압 1~2V 상승 17/54

Comparison of power consumption in Ph. & Fl. Efficiency (lm/w) Life time(hr) (@ Full White 100 nit) Red Fl. 2.0 Ph. 6.6 46,700 (@ 520 nit/pixel) 13,000 (@ 520 nit/pixel) Green Fl. 5.9 Ph. 15.5 32,000 (@ 960 nit/pixel) 4,000 (@ 960 nit/pixel) Fl. 2.6 11,000 (@ 390 nit./pixel) Blue Ph. 3.1 300 (@ 390 nit./pixel) 18/54

Phosphorescence Emitter - EML Dopant : Ir based metal complex - Hole Blocking Layer(HBL) - Identical charge transfer layer with flourescence N N N N Cu N N N N N N Ir emiierndevice 구조 ITO/CuPc/NPD/CBP+Dopant/BAlq/Alq3/Cathode(B:MgAg, RG:LiF/Al) - 전하수송재료 발광재료 구분주요내용 HIL(CuPc) HNO N N O O Al O N Al O N N NNO C3C비고 HTL(NPD) HBL ETL(Alq3) N O O O S Ir O F Ir Ir F N O N N O N 3NBCP BAlq 하는추세임 Host G Dopant R Dopant B Dopant F CBP Ir(ppy) (ppy) 2 Ir (acac) (btp) 2 Ir (acac) Firpic 3 2 2 F H3 HBL 재료로서 BCP 는결정화의문제로인하여수명에영향을준다는설이있으나검증된 Data 는없음. 이러한이유로현재는 BAlq 를사용 Green 의경우기존 Ir(ppy)3 보다특성이우수한 (ppy) 2 Ir(acac) 가개발됨 Red 의경우 HTL, ETL 물질을 Codep. 하여수명만시간달성 기존 Red 로알려진 PtOEP(x=0.71, y=0.29, η ext =2.2%, 70 cd/m 2 ) 보다특성이우수한 (btp) 2 Ir(acac) 개발 Blue 의경우는현재사용이어려울정도로특성저조 19/54

제조공정및기술 (Panel 및 Module) 20/54

OLED Process(PM) AM 에서는제외 AM 에서는제외 PHOTO & ETCHING ITO sputtering ITO patterning Metal patterning 절연막형성격벽형성 O 2 R/G/B source PLASMA 증착공정 Evaporation Plasma 처리 Loading UV 조사 Encap. 공정 Sealing Seal 형성 Getter 주입 Canister 세척 후공정 Aging Cell 절단 Cell 검사 Pol 부착 TAB 공정 출하검사 21/54

OLED Process (AM) INPUT AM 용 TFT 유기 EL 층형성 HIL, HTL, RGB 용 EML ETL 증착 (shadow mask 이용 ) 상부전극형성 Al 증착 Encapsulation sealing SCRIBE & BREAKING Cutting the combined glass into screen units Module Factory FINAL INSPECTION Inspecting the TFT panel while regular display signal is applied 22/54

Separator( 격벽 ) 형성 Photo 증착 Encap. 후공정 Cathode 전극 (Al) 의 Patterning 공정, 감광성수지이용 격벽 Patterning 후의형상 격벽 절연층 격벽형성까지의단면형상 Metal Strip(Cathode) ITO Strip(anode) Buffer Layer 격벽유기막 23/54

Pre-treatment Photo 증착 Encap. 후공정 Plasma Treatment PRINCIPLE O 2, Ar Gas등불활성기체에 RF Power를인가시켜생성된 Plasma로기판의표면을화학적, 물리적반응에의해처리한다. Gas RF RAW MATERIAL O 2, Ar Gas PLASMA TARGET ITO 층의 Work Function 값을높여줌으로써 OELD Device 의특성을향상시켜준다. UV Cleaning PRINCIPLE O 2 Gas 에 UV 를조사시켜화학반응에의해생성된 Ozone 으로기판표면의불순물 ( 유기물 ) 을제거한다. RAW MATERIAL O 2, UV Lamp TARGET 기판표면의유기물제거로 Device 의효율을향상시킨다. UV 조사 O 2 24/54

Evaporation Photo 증착 Encap. 후공정 Thermal Evaporation E-beam Evaporation PRINCIPLE 도가니에원료물질을넣고 Termally Heating 시켜녹이면상부의기판으로날아가성막된다. RAW MATERIAL Alq 3, R/G/B dopant, CuPc, α-npd, LiF, Al APPLYING PROCESS 유기물질, 또는 Metal 증착시사용한다. PRINCIPLE Magnetic Field 에의해회절된 Electron Beam 으로원료물질을가열하여증착한다. RAW MATERIAL LiF, Al APPLYING PROCESS 유기물질, 또는 Metal 증착시사용한다. Glass Substrate Glass Substrate Flux Profile Shutter Molten Pool Electron Beam Cold trap Organic material Ingot Rod Crucible Electron Beam Source Crucible Vacuum Pump 25/54

OLED Pixellation : Full Color Photo 증착 Encap. 후공정 Side-by-Side Deposition White 발광 + Color Filter Color Change Medium (CCM) 소자구조 R G B R G B B B B R G B 색재현성 (Color Satu.) 우수 ( 발광재료에의존 ) 우수 (C/F 에의존 ) 우수 효율 우수 낮음 보통 제조공정 약간어려움 매우쉬움 쉬움 가격 높음 중간 중간 장점 현재상용화된방법 각색의특징 ( 효율 ) 을최대한활용가능 단순한유기막구조 R,G,B 형성용고정세 shadow mask 가필요없음 대형화, 고해상도유리 단순한유기막구조, R,G,B 형성용고정세 shadow mask 가필요없음 단점 Differential degra. 대형화, 고해상도곤란 공정중오염증가 R,G,B 모두개발필요 Color filter 통과후최종효율이 white 재료의 1/3 로낮아고효율재료가필요 CCM 색순도가낮아추가로 C/F 사용, CCM 효율이낮음 Application 소형기판, 소형 display 대형기판, 중대형 display 대형기판, 중대형 display 26/54

OLED 대면적증착기술 Photo 증착 Encap. 후공정 Thermal Evaporation (Shadow Mask) Ink-Jet LITI 현황 - 370x470mm 양산적용중 (Max. 20.1 inch Display) - 730x920 개발중 - 370x470mm 가능 - 2,000x2,000 개발 (for C/F) - 370x400mm 가능 - 550x650 개발 for C/F 장점 - 우수한 OLED 특성 - 기양산검증됨 - 기판대형화가능 - 단순하여경제적임 - 기판대형화용이 - 고해상도구현가능 - 건식 Patterning 공정 단점 - Shadow mask 정도 * 730x920 Glass 100~130 ppi (Max. 40 inch Wide) * 패턴균일도 < 23µm - 재료수명한계 - 격벽공정추가 - 패턴시성능저하요인 - 설비개발필요 (LITI: Laser Induced Thermal Imaging) 27/54

Photo 증착 Encap. 후공정 28/54 삼성 SDI, KDC 2005

Thin Film Encapsulation Photo 증착 Encap. 후공정 기존 TFT- LCD 기존 OLED 박형 OLED Flexible OLED 상판 Glass TFT Glass Back Light 봉지용 Glass TFT Glass 현재 봉지용초박막 TFT Glass 2005 봉지용초박막 Flexible TFT Glass 2010 5mm 0.2mm Weight Thickness Breakage Cost 20 grams 5 mm 10% $18.00 29/54

후공정 Photo 증착 Encap. 후공정 Encapsulation 공정이끝난후샘플에전원을인가시켜 Panel 의양, 불을판별하고양품으로판별된 Panel 은아래와같은공정을거쳐제품으로만들어진다. Aging 양질의 Panel 각각에역전압을인가하여막안정성및막효율을향상시킨다. O/S 검사 Cell 전체화면을각각발광시켜소자내의결함여부를판정. Scribing 원판 Glass 를 Cell 단위로분할하기위하여일정한깊이로 Crack 을발생시킨다. Breaking Scribing 된 Glass 를자동내지는수동으로완전절단시킨다 Probe TEST 각 Panel Pad 에신호를입력하여점, Line, Open/ Short 또는기타불량을점검. Cleaning Polarizer 를부착하기전 Chip 이나유기물들을건식으로제거하는과정이다. Pol. 부착 시인성향상을위해외광의난반사를최소화하고, 입사자외선차단을위하여광학Film을부착시킨다. 30/54

Line Fail 과 Aging Line Fail 현상 Line Fail 이란? Pixel의上 - 下전극간의 Short에의해서 Panel 구동시세로방향으로밝은휘선이발생하는현상. - Pixel의上전극 (Anode, ITO) : Data Line에연결 - Pixel의下전극 (Cathode, Al) : Scan Line에연결 Scan Line (n-1) Scan Line ( n ) Scan Line (n+1) L H H Data Line ( m ) Line Fail 원인을제공하는 Short 된 Pixel 31/54 Driver IC 에서공급되는출력전류와는무관하게 Short 된 Pixel 에연결된 Scan Line 의 High Voltage 에의해서발광 Scan Line n 이 Select 된상태에서도비발광 Scan Line n+1 이 Select 된상태에서발광

Polarizer Attachment Photo 증착 Encap. 후공정 외부로부터들어오는광을차단하기위해 Glass View 면에 Polarizer 를부착한다. Alignment Panel 과 Polarizer 를 Align 한다. SUCTION BLOCK Pol Attaching * Protecting Film 제거 * Polarizer 를 Panel 에부착 Light Source polarizer Function of Polarizer Polarizer 는수직, 수평의양방향 빛의한쪽방향만을통과시키고 나머지방향은차단한다. Transmit Intercept 32/54

Circular Polarizer Photo 증착 Encap. 후공정 사용목적 : Contrast Ratio 를높여실외에서의시인성향상 문제점 : Panel 에서나오는광량감소 (50% 이상흡수 ) 원 리 33/54

후공정 Photo 증착 Encap. 후공정 ACF 부착 Panel 과 Module 을전기적으로도통시켜주는동시에부착성을지니는 ACF 를우선 Panel 의 PAD 에부착한다 TAB Panel 부위에접착되어있는 ACF 상에 COF 를 Panel Pad 와정확히정렬시켜열압착을한다. 최종검사 Panel 과 module 의연결상태와일정신호를입력하여 Pattern 검사를실시한다. Seal/Tape 부착제품의신뢰성향상을위해 TAB 된부위에 Seal 제도포후 Tape 를부착한다. Case 조립 Set 에유기 EL 제품탑재을용이하게하고, 내충격성을고려한외각 Case 에 Panel 을조립함. 외관 / 포장 / 출하최종외관검사후포장, 출하함. 34/54

Module Process 1. Module 의정의 ; 자체로도동작을하는제품의단계이나그자체로는제품의가치가없고 SET로구성되었을경우제품으로써가치를발휘하는일종의반제품. 예 ) LCD Monitor의 LCD Module. Hand Phone의 STN LCD Module 등 2. OLED Module 의구성및역할 OEL Panel FPC : Driver/Controller IC 및각종회로부품을배치하고 Panel 에연결해주는일종의 PCB Driver/Controller IC 기타부품 FPC Driver IC : Panel 에공급되는파형을만들어주는 IC ( Scan 과 Data 로구분 ) Controller IC : Driver IC 를조정하고외부 MPU 로부터입력되는신호및 Data 를변경하는기능을가진 IC 35/54

Module Block Diagram CPU Data/ Synch. Controller Data Memory R,G,B Data Synch./ Control Signal Inter -face & DC/ DC Conv -erter R,G,B Data Frame, CLK.. Scan IC Synch./ Control Signal/ Power : : : : : : Data IC OLED Panel Power R,G,B Data Data IC ---- Extended Module ---- Synch./ Control Signal/ Power ---- General Module ---- 36/54

OLED Module 의구성 1. Module 주요공정용의의정의 1) TAB (Tape automatic bonding) : Film 성수지 Interface 상에 Drive IC 부착. 2) COG (Chip On Glass) : LCD Glass 에회로를구성하여그위에 IC 를부착. 3) COF (Chip On FPC) : LCD Interface 용 FPC 위에회로를구성하여 IC 부착. 4) COB (Chip On Board) : Main Board 나 Control PCB 를구성하여그 PCB 위에부착하는방식으로가장오래된방식 5) OLB(Out Lead Bonding) ; FPC 나 TCP 를 Panel 에 ACF 를이용하여전기적기구적으로접합시키는기술및방법 6) SMT(Soldering Mount Technique) ; FPC 나 PCB 에전기적부품을납을이용하여접합및실장하는기술및방법 7) Module Assembly (Module 조립 ) ; 위에서기술한 COF, OLB, SMT 의방법으로 Module 을조립완성시키고검사하는공정 2. Module 주요공정순서 COF or TCP OLED Panel OLB FOB 검사 PCB 37/54

OLED Product Assembly Process Sub-Unit Sub-KIT + FOG 공정 + FOB 공정 ILB 공정 SMT 공정 + Bare PCB + 부품 38/54

구동기술 (PM, AM) 39/54

OLED Display 특성 Opto-Electrical characteristics L [Cd/m 2 ] OEL C PIXEL Circuit model Current Imax I [A/cm 2 ] Approximate linear relationship between light intensity vs. current density. Easy gray scale realization with current control. Imin Voltage Vmin Vmax I-V characteristics like a diode 40/54

OLED 계조표현법 41/54

OLED 구동방법 구조 Passive Matrix (PM) Active Matrix (AM) Cathode Organic film TFT 1) Glass substrate Anode Glass substrate Matrix 전극사이에 EL device Line 선택구간만 Emission Matrix 전극사이에 EL 구동 TFT Frame time 동안 Emission 가능 1) TFT : Thin Film Transistor 42/54

Passive Matrix 구동 Scan Line이순차적으로선택될때, Data Line의신호에따라선택된 Pixel이순간적으로발광하는방식 Data Scan 1 Scan 2 1 2 3 4 5 6 Scan 3 Scan 4 1 Data 1 Data 2 Data 3 Data 4 Data 5 Data 6 Scan 2 3 4 t1 t2 t3 t4 t5 43/54

PMOLED Passive Matrix OLEDs Requires cathode patterning High pulsed drive currents (proportional to row counts) Higher drive voltage than active matrix display Higher power consumption Shorted pixels result in cross-talk or line defects Simple structure/fabrication (low fabrication cost) Small sized panel Programmable current source OEL C para Data Lines (Anodes) + + + + + + Scan Lines (Cathodes) 44/54

Active Matrix 구동 Scan Line이순차적으로선택될때, Data Line의신호에따라선택된 Pixel이다른신호 ( 다음 Frame) 가입력될때까지계속발광하는방식 Data Scan 1 Scan 2 1 2 3 4 5 6 Scan 3 Scan 4 Data 1 Data 2 Data 3 Data 4 Data 5 Data 6 Scan 1 2 3 4 t1 t2 t3 t4 t5 45/54

AMOLED Active Matrix OLEDs Common cathode, Display during frame time Low pixel drive voltage/current Low power consumption Full color capability Medium/large sized panel 46/54

PM & AM 구동방식비교 Driving method Passive Matrix Duty Driving (Scan 라인선택시점등 ) Active Matrix Static Driving ( 상시점등 ) 고휘도 Δ Scan Line 증가에따라높은순간휘도요구 Scan Line 수의한계 Scan Line 수에관계없이고휘도실현가능 저소비전력 Δ 순간휘도 = Scan Line 요구휘도 고전압구동 요구휘도의구동전압으로상시 발광 저전압구동 소형화 & Symmetry 구동 IC를외부장착 구동회로 Panel 내장가능 소자구조및 Cost Simple Process Low Cost Δ LTPS(TFT) + OLED 복잡한프로세스 응용제품 Δ 1) PM의경우높은순간휘도 (L p ) 가요구됨. L p = L o Scan Line 수 PM에서 1 Pixel 발광시간, t p = 1 Frame / Scan Line 수 AM에서 1 Pixel 발광시간 = 1 Frame 2 이하의 Mobile 용 Display 저해상도거치형제품 - Car Audio, 자동차용계기판, 가전제품용 Display 휘도 L p L o 47/54 다양한 Size 의 Display 에응용 (Mobile, CNS, Notebook, TV ) 1 Frame (AM) t p Time

LTPS (Low Temperature Poly-Si) TFT a-si TFT 보다이동도가 100 배이상인 poly-si TFT 를레이저結晶化技術을이용하여제작함으로써, 화소용 TFT 와구동회로를동시에유리기판상에일체화하여 compact 하고고화질의 TFT-LCD 제품을개발함. 이동도 (cm 2 /Vsec) 소자종류 결정특성 a-si:h poly-si Single-Si 0.5 ~ 1 50 ~ 200 ~ 600 NMOS 무질서 NMOS,PMOS NMOS,PMOS 결정립내규칙적임 전체적으로규칙적임 Gate PCB (DC-DC convert, Vcom) Source PCB (Controller, Υ-source ) a-si TFT LCD D-IC gate driver Controller, Interface circuit,υ-source, Amp, DC-DC data driver poly-si TFT LCD 레이저결정화기술 : 비정질실리콘박막을 depo. 한후결정화하여다결정질실리콘 (poly-si) film 을형성함으로써소자의이동도특성향상을가능하게함. Excimer Laser Scan poly-si 48/54

AMOLED Conventional 2T-1C Pixel Structure (from Professor Jin Jang, 2005) 49/54

AMOLED IR-Drop of VDD Line VDD Pixel Circuit I Pixel R Pixel R Pixel ( n ) I Pixel ( n-1 ) I Pixel V drop = I = I... ( n 1) I pixel pixel R R pixel pixel + 2I pixel R pixel pixel R pixel + ni pixel +... R pixel (1 + 2+... + ( n 1) + n) Pixel Circuit I Pixel Pixel Current = I pixel R pixel n ( n + 1) 2 Parastic Resistance of Pixel VDD Line RPixel 2 I Pixel Pixel Circuit I Pixel Worst Case Pixel RPixel I Pixel Pixel Circuit I Pixel VDD - V drop 50/54

AMOLED Pixel to Pixel Non-uniformity 17, 500cd/m 2, SXGA, 6bit-gray T1 : 20um/20um, T2 : 5um/10um Pixel Current : 20nA ~ 5.8uA VDD 12V V TH variation +/- 0.3V Mobility variation 10% Error Factors V TH Variation Mobility Variation VDD Line IR Drop Maximum Error (gray) 25 5 7 51/54

AMOLED Bottom Emission OLED Top Emission OLED Metal cap Getter Metal cathode Planarization layer Inert gas Semitransparent cathode Organic Layer Anode Glass cap or Film type cap Sealant 투명 getter Passivation Layer Planarization layer Glass Substrate Driving TR Glass Substrate Driving TR Pixel 구동회로부 Low Aperture Ratio Limitation circuit complexity High aperture ratio No Limitation circuit complexity High integral density High resolution 52/54

AMOLED Consideration for Driving Scheme Decision TFT Threshold Voltage & Mobility Variations IR-Drop of VDD line Pixel to Pixel Luminance Uniformity Data Programming Time Pre-charge Scheme (Driver LSI) OLED Pixel Current Power, OLED Life time Target Resolution (Line Time) Panel Size (Data Line Capacitance) Panel Brightness Aperture Ratio (# of Pixel Circuit TFT & Control Signal Line) 53/54

AMOLED History (2005. 2 월기준 ) (from Professor Jin Jang, 2005) 54/54

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