Development of High-Performance Organic Thermoelectric Devices Using Thiazolothiazole and Diketopyrrolopyrrole Based Donor-Acceptor Conjugated Polymers
티아졸로티아졸 과 디케토피롤로피롤 골격을 기반으로 하는 도너-억셉터 공액고분자를 이용한 고성능 유기열전 소자 개발
- 주제(키워드) Conjugated polymer , Organic thermoelectric , Molecular doping
- 주제(DDC) 547
- 발행기관 아주대학교 일반대학원
- 지도교수 김종현
- 발행년도 2026
- 학위수여년월 2026. 2
- 학위명 석사
- 학과 및 전공 일반대학원 분자과학기술학과
- 실제URI http://www.dcollection.net/handler/ajou/000000035457
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Development of High-Performance Organic Thermoelectric Devices Using Thiazolothiazole and Diketopyrrolopyrrole-Based Donor-Acceptor Conjugated Polymers Yang Hun Nam Department of Molecular Science and Technology The Graduate School Ajou University Organic thermoelectric (OTE) materials based on conjugated polymers offer mechanical flexibility, solution processability, and intrinsically low thermal conductivity, yet their performance is constrained by the interplay among molecular structure, doping efficiency, and solid-state ordering. This dissertation establishes a systematic molecular design framework connecting these factors through the study of two donor–acceptor polymer families: (i) thiazolothiazole-based (TTz) copolymers incorporating a newly introduced acceptor core and (ii) diketopyrrolopyrrole-based (DPP) copolymers engineered through controlled backbone and side chain substitution. In Chapter 2, TTz copolymers were synthesized by pairing the rigid TTz acceptor with donors of different electron donating strengths. TTz-Th, possessing the highest HOMO level, exhibited strong charge transfer interaction with AuCl3 and maintained stable molecular ordering upon oxidation. Spectroscopic and structural analyses showed that TTz-Th preserved short range π–π stacking coherence even under strong doping, enabling high charge carrier mobility and yielding a peak power factor of 1000 μW m−1 K−2. These results identify TTz as a promising acceptor framework for organic thermoelectric applications. Chapter 3 investigated four DPP copolymers to clarify how the position of methyl substitution influences backbone conformation, molecular packing, and doping behavior. Methylation on the bithiophene donor unit increased local free volume while simultaneously enhancing backbone torsion, thereby perturbing intermolecular packing. whereas methylation near the DPP core caused minimal distortion and promoted more cohesive molecular packing. Systematic comparison of F4TCNQ and AuBr3 doping revealed distinct dopant dependent trends. With F4TCNQ, the series displayed a clear doping efficiency trend that aligned with their electrical characteristics, showing progressively improved charge generation from DPP-BT to MDPP-MBT. AuBr3 induced stronger oxidation but triggered severe structural disruption, particularly in the bithiophene methylated polymers, leading to reduced conductivity despite higher dopant uptake. This behavior demonstrates that effective doping requires polymers capable of maintaining structural integrity under oxidative conditions. Collectively, this dissertation establishes molecular level design principles linking backbone engineering, substitution-position control, and dopant strength to the balance between charge generation and structural integrity in donor–acceptor conjugated polymers. These insights provide guidelines for the development of next-generation high-performance organic thermoelectric materials. Keywords: Conjugated polymer, Organic thermoelectric, Molecular doping, Electrical conductivity
more목차
Chapter 1. Introduction 1
Chapter 2. Thiazolothiazole based conjugated polymer 3
2.1. Introduction 3
2.2. Experimental section 4
2.2.1. Device fabrication 4
2.2.2. Field effect transistor measurement 5
2.2.3. Thermoelectric measurement 5
2.2.4. Hall effect and conductivity measurement 5
2.2.5. Spectroscopic and structural analyses 6
2.3. Molecular structure and electronic structure 6
2.3.1. Molecular design of TTz based donor-acceptor copolymers 6
2.3.2. Optical characterization 7
2.4. Charge transport characteristics 9
2.4.1. Field effect transistor performance and mobility evaluation 9
2.4.2. Reliability Assessment of Field effect Characteristics 11
2.5. Chemical and structural characteristics 13
2.5.1. X-ray photoelectron spectroscopy (XPS) analysis 13
2.5.2. Raman spectroscopic analysis 14
2.5.3. Surface morphology analysis 16
2.5.4. Crystalline ordering and molecular orientation analysis 18
2.6. Doping induced transport characteristics 19
2.7. Thermoelectric characteristics 21
2.8. Conclusion 24
Chapter 3. Diketopyrrolopyrrole based conjugated polymer 25
3.1. Introduction 25
3.2. Experimental section 26
3.2.1. Device fabrication 26
3.2.2. Field effect transistor measurement 27
3.2.3. Thermoelectric measurement 27
3.2.4. Hall effect and conductivity measurement 27
3.2.5. Spectroscopic and structural analyses 28
3.3. Molecular structure and electronic characteristics 28
3.3.1. Molecular design of DPP based donor-acceptor copolymers 28
3.3.2. Optical characterization 29
3.4. Charge transport characteristics 32
3.5. Electrical conductivity and thermoelectric characteristics 33
3.6. X-ray photoelectron spectroscopy (XPS) analysis 37
3.7. Structural characteristics 39
3.8. Carrier transport and quantitative analysis 40
3.8.1. Quantitative analysis of charged dopant species 41
3.8.2. Vibrational signatures of charge transfer doping 42
3.8.3. Hall measurements of charge carrier density and mobility 44
3.8.4. Four-probe FET analysis of charge transport 46
3.9. Conclusions 47
Chapter 4. Conclusion 48
References 51
