유기 박막 트랜지스터 기반 AMOLED 픽셀 구동 회로 설계에 관한 연구
A Study on the Design of Pixel Driving Circuit for Organic Thin Film Transistor based AMOLED Display
- 주제(키워드) AMOLED , OTFT
- 발행기관 고려대학교 대학원
- 지도교수 성만영
- 발행년도 2009
- 학위수여년월 2009. 8
- 학위명 석사
- 학과 일반대학원 미세소자공학협동과정
- 세부전공 반도체소자전공
- 원문페이지 91 p
- 실제URI http://www.dcollection.net/handler/korea/000000008651
- 본문언어 한국어
- 제출원본 000045551804
초록/요약
Active matrix organic light emitting diode(AMOLED) display has considerable advantages for realizing flat panel displays such as wide viewing angle, fast response, light weight, high contrast ratio and low power consumption. For driving AMOLED pixel circuit, thin film transistors(TFTs) based on silicon such as hydrogenated amorphous silicon(a-Si:H) and low temperature polycrystalline silicon(LTPS) have been used typically. Organic thin film transistors(OTFTs) as well as silicon-based TFTs have been made remarkable progress. As the driving device for AMOLED pixel circuit, OTFTs have many attractive characteristics in terms of possibility for realizing flexible display and fabricating with reduced temperature, low cost, etc. However, the threshold voltage(Vth) of OTFTs varies with applied DC bias, which causes reduction of OLED current after long time. First of all, in this study, as applying soluble-processed P-type OTFT to conventional 2-TFTs and 1-Capacitor(2T1C) pixel structure through HSPICE simulation, it is determined whether the fabricated OTFT is feasible or not for small and large AMOLED pixel structure respectively. As a result of simulation, it is demonstrated that the fabricated OTFT which has mobility of 0.2 cm2/Vs is available to drive small panel pixel circuit but not feasible for large panel display. And it is verified that the required mobility to drive large panel such as 40 inch HDTV is at least 0.7 cm2/Vs. Finally, the new pixel structure for compensating Vth shift of OTFT is proposed. It consists of five OTFTs and one storage capacitor and three signal lines. The proposed structure compensates output current degradation effectively through the Vth programming stage by diode- connected P-type OTFT. As a result of simulation, it is demonstrated that the variation of OLED current corresponding to Vth shift of 2.5 V is decreased by maximum 55 % compared to the conventional 2T1C structure. Through this result, it can be verified that the proposed pixel structure has much more stable output current than that of conventional 2T1C structure.
more목차
1. 서론 1
2. AMOLED 픽셀 구동 회로 5
2.1 박막 트랜지스터의 특성 비교 7
2.1.1 실리콘 기반의 박막 트랜지스터 7
2.1.2 유기물 기반의 박막 트랜지스터 8
2.2 AMOLED 픽셀 보상회로 11
2.2.1 전압구동 방식 13
2.2.2 전류구동 방식 17
3. 제작된 OTFT 의 AMOLED 픽셀 회로 구동 가능성 검증 21
3.1 소자 모델링 21
3.1.1 OTFT 모델링 21
3.1.2 OLED 모델링 26
3.2 제작된 OTFT 의 2T1C 픽셀 구조에 대한 구동 가능성 검증 29
3.2.1 픽셀 구동의 적합성 판단 기준 및 시뮬레이션 조건 설정 29
3.2.2 제작된 OTFT 의 2T1C 구조에 대한 구동 가능성 분석 33
3.2.3 OTFT 의 문턱전압 변화에 의한 영향 분석 37
4. 대면적 패널 구현을 위한 OTFT 파라미터의 검토 및 고찰 40
4.1 RC 지연을 고려한 시뮬레이션 조건의 고찰 40
4.2 시뮬레이션 및 결과 분석 43
5. 새로운 구조의 OTFT 기반 AMOLED 픽셀 보상회로 설계 52
5.1 제안한 AMOLED 픽셀 보상회로의 동작 원리 53
5.2 시뮬레이션 및 결과 분석 59
6. 결 론 67
참고문헌 69
