A study on the degradation of flexible organic photovoltaic modules under accelerated conditions
- 주제(키워드) Organic solar cell , Accelerated Conditions , Flexible module , Degradation mechanism , Trigger , Holt transport layer
- 발행기관 고려대학교 그린스쿨대학원
- 지도교수 김동환
- 발행년도 2017
- 학위수여년월 2017. 2
- 학위구분 박사
- 학과 그린스쿨대학원 에너지·환경정책기술학과
- 원문페이지 130 p
- 실제URI http://www.dcollection.net/handler/korea/000000071608
- 본문언어 영어
- 제출원본 000045897220
초록/요약
Light weight, flexibility, abundant materials, low manufacturing cost, colorfulness and various applications such as building integrated photovoltaics (BIPV), portable power source and military, green house, interior, functional clothing and leisure goods can be enable organic photovoltaics (OPV) to be launched into renewable energy market and secure certain portion of generated energy from renewable sources in the near future. Although the efficiency of OPV is less than that of single crystalline silicon PV module, above mentioned advantages of OPV module make OPV to be one of potential energy sources Since the bulk heterojunction (BHJ) OPV was first demonstrated in 1995, many research groups have developed process and materials to improve the efficiency. The conversion efficiency of OPV was achieved 13.2% from Heliatek in 2016. But, compared with the Si solar cells, the lower efficiency and shorter lifetime of OPVs can be compensated by their low cost. Sometimes it is argued that if OPVs have the above mentioned potential. Hence, OPVs still have to have many developments to be available in the market. Even though lots of efforts have been devoted to improve both of efficiency and reliability, there are still more improvement to be carried out in order to realize wide commercialization. In this study, we wanted to discuss what the main issues regarding stability are in terms of industrial OPV modules and reveal degradation mechanism. Over several years of stability studies, we have learned an important fact; the printed Ag electrode and hole transport layer (HTL) are very critical to the stability of OPV module. Here, we conducted various tests to control acceleration factors such as heat and moisture for tracing the degradation sources of OPV, and then the interlayers were examined to figure out the specific degradation mechanism. The methodological aspect of experiment investigating the degradation factors of OPV by analyzing modification of interlayers via the acceleration factors is significant. As a result, it was proven that solvent from Ag electrode can diffuse by thermal stress and subsequently damage the organic materials. A printed back electrode is the only processing method until now for use in industrial scale production of OPV and hence it should be studied relative to modifying and degrading organic materials. Also, we revealed that Ag atoms migrated to the interlayers of the cell, resulting in the increase of shunt paths; this was the main reason underlying there reduction of Voc and FF of the OPV module under damp heat. The ZnO layer was also etched by the acidic molecules from the diffused PEDOT:PSS polymer by reacting with solvent. Thus, the proper selection of HTL (hole transport layer) like as PEDOT:PSS and Ag paste as a top electrode is very important to improve a reliability of OPV module for commercialization. Because critical degradation triggers of OPV modules were originated by PEDOT:PSS and Ag paste as a top electrode.
more목차
Chapter 1. Introduction 1
1.1 Overview 1
1.2 Outline of dissertation 4
Chapter 2. Theoretical Background 6
2.1 Basic theory of Solar Cells 6
2.1.1 Photovoltaic Effect 6
2.1.2 Principle of solar cells 6
2.1.3 Solar cells parameters 9
2.1.4 Current-Voltage characteristics 14
2.1.4.1 Illuminated current-Voltage characteristics 14
2.1.4.2 Dark current-Voltage characteristics 14
2.1.5 Quantum efficiency 18
2.1.6 Loss cells 19
2.1.6.1 Loss of short circuit current 19
2.1.6.2 Loss of open circuit voltage 19
2.1.6.3 Loss of fill factor 19
2.2 Organic photovoltaics 21
2.2.1 Classifications of OPVs 21
2.2.2 Development of bulk heterojunction solar cells 23
2.2.3 Degradation of OPVs 28
2.2.3.1 The history of the OPVs stability and degradation 28
2.2.3.2 Degradation of polymer as a donor 30
2.2.3.3 Degradation of fullerene derivatives as a acceptor 32
2.2.3.4 Degradation of metal electrode 33
2.2.3.5 Degradation of transparent conductive oxide 34
2.2.3.6 OPV module degradation 34
Chapter 3. Fabrication of flexible organic photovoltaic modules 36
3.1 Fabrication of flexible organic photovoltaic modules 36
3.2 Investigation of water vapor transmission rate 41
3.3 Characterization of OPV modules 43
Chapter 4. A study for degradation of flexible organic photovoltaic modules via damp-heat test: By accessing individual layers of the module 46
4.1 Introduction 46
4.2 Experimental procedure 47
4.3 Results and discussion 50
4.4 Conclusions 69
Chapter 5. Critical Impact of Hole Transporting Layers and Back Electrode on the Stability of Flexible Organic Photovoltaic Module 70
5.1 Introduction 70
5.2 Experimental procedure 75
5.3 Results and discussion 76
5.4 Conclusions 100
Chapter 6. Conclusion 101
6.1Summary of work 101
6.2 Future works 103
Reference 104
Acknowledgement 114
