Stepwise curing induced all-stretchable thermoelectric generator of high power density

국문 초록 (Abstract)

이 연구에서는 높은 전력 밀도를 가지는 착용형 고신축 유기 열전(TE) 발전기를 개발하였다. 탄성체와 전도 네트워크를 단계 경화 방식으로 형성하여 용액 공정 기반의 고신축 TE/전극 패턴을 구현하였다. 이후 후-활성화 처리(post-activation)를 통해 기존의 탄성 네트워크를 손상시키지 않으면서 장거리 전하 이동 경로가 형성되어 열전 및 전기적 성능이 크게 향상되었다.

TE와 전극 패턴은 신축 템플릿 위에 용액 공정으로 제작되어 완전 신축형 열전 발전기를 구현하였다. 제작된 발전기는 40% 인장 시 최대 출력의 90%를 유지하며, 200회 반복 신장 후에도 안정적인 출력을 보였다. 또한 고밀도 패턴에서도 높은 신축성을 유지하여 별도의 템플릿 의존도가 낮았다. 그 결과 발전기는 0.32 nW cm⁻² K⁻²의 높은 전력 밀도를 달성했으며, 이는 현재까지 보고된 신축형 열전 발전기 중 가장 높은 수준에 속한다.

다국어 초록 (Multilingual Abstract)

In this study, a wearable and highly stretchable organic thermoelectric (TE) generator with a notable power density is developed. A highly stretchable and solution-processable TE/electrode pattern is realized by stepwise-curing elastomeric and conducting network. Significant advances in the TE or electrical properties are obtained for these stretchable patterns through post-activation treatment, which creates long-range charge transport pathways without degrading pre-established elastomeric networks.

The TE and electrode patterns are solution-processed to a stretchable template, so that all-stretchable TE generator is realized. The fabricated TE generator maintains 90% of its maximum TE power output at 40% stretching stress and shows a stable TE power output after 200 stretching cycles. The TE generator maintains its stretchability in highly densified patterns, as the highly stretchable TE/electrode patterns enable good stretchability with little aid of the stretchable template. So, the TE generator has a high power density of 0.32 nW cm-2 K-2, one of the highest values among stretchable TE generators to date.

목차 (Table of Contents)

• List of Figures
• Abstract
• Chapter 1. Introduction 1
• 1.1 Background of Thermoelectric Energy Harvesting 2
• 1.2 Limitations of Inorganic Thermoelectric Generators for Wearables 3
• 1.3. Organic Thermoelectric Materials and Stretchable TEGs 4
• 1.4. Motivation and Objective of This Dissertation 6
• Chapter 2. Design and Fabrication of an All-Stretchable Thermoelectric Generator 7
• 2.1. Device Concept and Through-Plane Heat Transfer in Wearable TEGs 8
• 2.2. Mechanical Design and Stress Simulation of Stretchable Architectures 9
• 2.3. Stepwise Curing Strategy for Intrinsically Stretchable TE/Electrode Patterns 10
• 2.4. Continuous Fabrication of High-Aspect-Ratio TE Legs in PDMS Templates 12
• Chapter 3. Stepwise Network Formation in PEDOT:PSS/PVA Thermoelectric Legs 14
• 3.1. PEDOT:PSS/PVA System and Two-Step Curing Concept 15
• 3.2. Hydrogel Formation and Interface Engineering with PDMS Substrates 16
• 3.3. Acid-Induced Microstructural Rearrangement of PEDOT:PSS 18
• 3.4. Electrical, Thermoelectric, and Mechanical Properties of PPP Legs 19
• Chapter 4. Activation of SEBS/EGaIn Stretchable Electrodes 21
• 4.1. SEBS/EGaIn Composite Design and Initial Microstructure 22
• 4.2. Mechanical-Stress-Induced Network Formation 22
• 4.3. High-Voltage Pulse Activation and Liquid-Metal Reshaping 23
• Chapter 5. Device-Level Performance and Wearable Demonstration 25
• 5.1. Electrical Performance, Scalability, and Power Density of Stretchable TEGs 26
• 5.2. Mechanical Reliability and Human-Body-Heat Harvesting Performance 27
• Chapter 6. Conclusion 28
• 6.1 Summary of Key Findings 28
• 6.2 Future Directions for All-Stretchable Thermoelectric Systems 29
• References 31
• 논문요약 36