A Study on the Thermoelectric Properties of Conjugated Copolymers and Conjugated Terpolymer
공액 공중합체와 공액 삼원 공중합체의 열전 특성에 관한 연구
- 주제(키워드) 유기 고분자 , 열전 소자 , 도핑
- 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/000000035471
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
A Study on the Thermoelectric Properties of Conjugated Copolymers and Conjugated Terpolymer Kwangil Jo Department of Molecular Science and Technology The Graduate School Ajou University Organic thermoelectric (OTE) materials, based on π-conjugated polymers, are attracting significant attention for sustainable energy conversion. Their intrinsic advantages, such as mechanical flexibility, light weight, low thermal conductivity, and solution processability, make them promising candidates for applications like wearable devices and flexible electronics. Among various platforms, donor-acceptor (D-A) type conjugated polymers have emerged as particularly attractive systems. Their electronic structure, molecular packing, and doping behavior can be systematically tuned through rational molecular design. This thesis investigates three distinct D-A polymer systems—the PNTDT series, the PDPyD series, and the PBQx-TF/PM6 terpolymer series—to establish molecular-level design principles for achieving high thermoelectric performance. Chapter 1 presents a comprehensive study of the PNTD series, a new class of D–A conjugated copolymers incorporating a 1,5-naphthyridine-2,6-dione (NTD) acceptor core with systematically varied donor units (thiophene, selenophene, and bithiophene). Through detailed spectroscopic (UV–Vis–NIR, Raman, XPS) and structural (2D-GIWAXS) analyses, we demonstrate that the donor unit length dictates the polymer chain orientation—from a bimodal, face-on dominant arrangement in monothiophene/selenophene-based polymers to a highly ordered edge-on orientation in bithiophene-based polymers. Upon AuCl3 doping, a site-selective charge localization on the more electron-rich, extended donor segments was observed, leading to superior charge transport and thermoelectric properties. In particular, the bithiophene-containing polymer (PNTDT-BT) exhibited a high electrical conductivity of 2044.5 S cm-1 and a power factor of 1061.2 mW m-1 K-2, among the highest reported for D– A type OTE polymers. Chapter 2 investigates the thermoelectric properties of a newly designed PDPyD-based donor–acceptor polymer platform, in which the PDFD-T backbone was modified with a pyridal[2,1,3]thiadiazole (PDPyD) acceptor to enhance backbone planarity and intermolecular packing. Based on this optimized structure, chalcogen substitution at the terminal donor unit (thiophene, selenophene, tellurophene) was introduced to systematically tune the electronic structure. The resulting PDPyD-T, PDPyD-Se, and PDPyD-Te polymers were examined under two representative p-type dopants, F4-TCNQ and AuCl3, to evaluate how molecular design and dopant strength together influence doping behavior and charge transport. Under moderate F4-TCNQ doping, all polymers retained their crystalline order and showed the expected chalcogen-dependent enhancement in conductivity. However, under strong AuCl3 doping, PDPyD-Te—despite exhibiting the highest dopant uptake— underwent significant structural degradation, leading to reduced mobility and low conductivity. In contrast, PDPyD-Se maintained structural integrity while achieving a high carrier density, producing an electrical conductivity of 376 Scm-1 and a power factor of 272.8 mWm-1K-1, the highest values within the series. These results highlight the importance of preserving structural robustness during doping and demonstrate that backbone engineering combined with controlled heteroatom substitution can effectively optimize the thermoelectric properties of conjugated polymers. Chapter 3 investigates the PBQx-TF/PM6 terpolymer series, where a terpolymerization strategy was adopted to suppress phase separation typically observed in polymer blends. Random terpolymers were synthesized by polymerizing the acceptor monomers derived from PBQx-TF (dithienylquinoxaline, DTQx) and PM6 (dithiophenedione, BDD) together with a common donor monomer, benzodithiophene (BDT), in a single copolymerization step. By setting the DTQx:BDD feed ratio to 2:8, the resulting terpolymer contains a statistically random distribution of both acceptor fragments along a single covalently linked backbone. These terpolymers were directly compared with blend films of identical composition to clearly distinguish the impact of covalent linkage within a single backbone from the effects arising solely from physical mixing of two separate polymers. Upon AuCl3 doping, the 2:8 terpolymer achieved a power factor of 285.2 mW m-1 K-2, whereas the corresponding blend reached only 80.8 mW m-1 K-2. The substantial gap in performance demonstrates that molecular-level copolymerization can effectively relieve the morphological constraints associated with simple polymer blends.
more목차
Introduction 1
Experimental methods – Devices fabrication and Characterizations 3
Chapter 1. Donor-Unit-Dependent Polymer Chain Packing Dictates Site-Selective Doping and Charge Transport in High-Performance Naphthyridinedione-based Organic Thermoelectric Conjugated Polymers 6
1.1 Introduction 6
1.2 Results 8
1.2.1 Synthesis, and Optoelectronic and Structural Characterization 8
1.2.2 Site-Selective Doping Investigated by XPS 13
1.2.3 2D-GIWAXS Structural analysis 15
1.2.4 Electrical and Thermoelectric Properties 18
1.3 Conclusion 29
Chapter 2. Chalcogen-Substituted Pyridal[2,1,3]thiadiazole-Based Donor–Acceptor Polymers for Thermoelectric Applications. 30
2.1 Introduction 30
2.2 Results 31
2.2.1 Molecular Design, Electronic Structure, and Optical Properties 32
2.2.2 X-ray Photoelectron Spectroscopy (XPS) Analysis of Chemical State and Doping Efficiency 33
2.2.3 Doping-Induced Structural Evolution Probed by GIWAXS 35
2.2.4 Analysis of Film Surface Morphology 37
2.2.5 Electrical Transport Properties and Thermoelectric Performance 39
2.3 Conclusion 42
Chapter 3 Terpolymerization as a Strategy to Suppress Phase Separation and Enhance Charge Transport in Conjugated Polymers for High Performance Organic Thermoelectric Applications. 43
3.1 Introduction 43
3.2. Results 45
3.2.1 Material Design and Electronic Structure 45
3.2.2 Morphological and Structural Analysis 46
3.2.3 Charge Transport Characterization 48
3.2.4 Electrical and Thermoelectric Performance 51
3.3. Conclusion 56
References 57
Introduction Reference 57
Chater 1. References 58
Chater 2. References 61
Chater 3. References 63
