Solution-Processed Narrowband Organic Light Emitting Diodes Using Customized Medium-Sized Molecular Hosts and Emitters
맞춤형 중간 크기 분자 호스트와 발광체를 사용한 좁은 반치폭을 가지는 용액공정 유기 발광 다이오드
- 주제(키워드) organic light emitting diodes , multiple resonance , solution-processed OLED , medium-sized molecule , narrowband
- 발행기관 고려대학교 대학원
- 지도교수 최동훈
- 발행년도 2024
- 학위수여년월 2024. 2
- 학위명 석사
- 학과 대학원 화학과
- 세부전공 고분자화학전공
- 원문페이지 96 p
- 실제URI http://www.dcollection.net/handler/korea/000000278257
- UCI I804:11009-000000278257
- DOI 10.23186/korea.000000278257.11009.0000395
- 본문언어 영어
초록/요약
Organic semiconductors have recently attracted significant attention due to their advantages, including lightweight, low-cost production, low-temperature processing, mechanical flexibility, and abundant availability. Among them, organic light emitting diodes (OLEDs) are the focus of extensive research in the display industry. These are being applied in various fields such as electric vehicles, computers, flexible displays, and transparent displays. In this study, new MR TADF emitters were synthesized and utilized for solution-processed OLEDs. This thesis includes two chapters. The first chapter provides an overview of the history and background of OLEDs. It discusses the photophysical processes of organic materials. In addition, the typical structure and materials used in OLEDs are discussed in this chapter. In the second chapter, based on the well-known BCzBN structure, two new multiple resonant (MR) emitters, namely DtCzBN and Cy-DtCzBN, were designed and synthesized for narrowband solution-processed organic light-emitting diodes (OLEDs). Cy-DtCzBN features a derived dimeric V-shaped structure by coupling two individual DtCzBNs through non-conjugated linkers. These medium-sized molecules maintain the optical properties of corresponding small molecules while exhibiting superior film-forming capabilities compared to small molecules. Furthermore, these medium-sized molecules demonstrate high thermal stability and excellent solubility due to their high molecular weight and bulky molecular structure. I applied these molecules, both small-molecule hosts and emitters (mCP and DtCzBN), as well as medium-sized molecule hosts and emitters (Cy-mCP and Cy-DtCzBN), to solution-processed OLEDs. Interestingly, devices using medium-sized emitters and hosts showed significantly improved reproducibility compared to those based on small-molecule counterparts. In summary, this study introduces a versatile molecular design approach for hosts and emitters that are well-suited for solution-processed OLEDs.
more목차
ABSTRACT i
국문 초록 iii
PREFACE v
TABLE OF CONTENTS vi
LIST OF SCHEMES ix
LIST OF FIGURES x
LIST OF TABLES xii
CHAPTER 1. Background of OLED 1
INTRODUCTION 2
1.1. Organic Light-Emitting Diodes (OLEDs) 2
1.2. Device Structure of OLED 4
1.3. Mechanism of Energy Transfer and Light Emission 6
1.4. OLED Materials 9
1.4.1 Hole and Electron Transporting Materials 9
1.4.2 Host Materials 13
1.4.3 Emitting Materials 15
1.5 Solution-Processed MR TADF materials 19
REFERENCE 21
CHAPTER 2. Precision-Engineered Medium-Sized Molecular Host and Emitter for Ensuring Consistent Performance in Solution-Processed Narrowband OLEDs 25
INTRODUCTION 26
EXPERIMENTAL SECTION 29
2.1. Materials 29
2.2. Synthesis 29
2.2.1 Synthesis of DtCzBN (3) 29
2.2.2 Synthesis of 9,9'-((cyclohexane-1,1-diylbis(9H-carbazole-3,9-diyl))bis(5-bromo-3,1-phenylene))bis(3,6-di-tert-butyl-9H-carbazole) (6) 30
2.2.3 Synthesis of Cy-DtCzBN (7) 31
2.3. Experimental 41
2.3.1 Instrumentation 41
2.3.2 Time-resolved photoluminescence (TR-PL) measurements 41
2.3.3 OLED device fabrication 42
RESULTS AND DISCUSSION 44
2.4. Design strategy, synthesis, and characterization 44
2.5. Photophysical Properties 45
2.6. Theoretical Calculation 53
2.7. Thermal stability and morphological properties 55
2.8. Electroluminescent Properties 66
CONCLUSION 76
REFERENCE 77
