Elucidating the Roles of Precursor Impurity Control and Sputtered NiOx Layer Optimization for Stable and Efficient Perovskite Solar Cells
전구체 불순물 제어와 스퍼터링을 이용한 NiOx 층 최적화를 통한 안정적이고 고효율 페로브스카이트 태양전지 개발
- 주제(키워드) Perovskite solar cells , impurity engineering , stability enhancement , NiOx thin films , RF sputtering optimization , photovoltaic performance
- 발행기관 고려대학교 대학원
- 지도교수 김동환, 김지영
- 발행년도 2025
- 학위수여년월 2025. 8
- 학위명 석사
- 학과 및 전공 대학원 신소재공학과
- 원문페이지 96 p
- 실제URI http://www.dcollection.net/handler/korea/000000304518
- UCI I804:11009-000000304518
- DOI 10.23186/korea.000000304518.11009.0002944
- 본문언어 영어
초록/요약
The purity of perovskite precursors is a crucial factor that significantly impacts the performance and stability of perovskite solar cells (PSCs). In this study, we systematically investigate how variations in precursor impurity levels influence material properties and device efficiency. High-purity precursors are demonstrated to facilitate improved grain growth while suppressing the formation of intermediate phases. Thermogravimetric analysis (TGA) confirms that low-impurity precursors exhibit superior thermal stability compared to their high-impurity counterparts. Electrical and optical characterizations reveal that reducing impurity content effectively mitigates current-voltage hysteresis and decreases non-radiative recombination. Sodium (Na), identified as the most prevalent impurity, was found to adversely affect thermal stability, with its reduction correlating with enhanced device longevity. Notably, devices fabricated using low-impurity precursors achieved a power conversion efficiency (PCE) of 20.15% and retained 96.7% of their initial efficiency after two months of ambient exposure, while devices using higher impurity levels showed significant degradation. These results emphasize the critical role of precursor purity in improving both the efficiency and long-term stability of PSCs, providing valuable insights for the development of more reliable photovoltaic devices. Moreover, this study also focuses on optimizing NiOx thin films, utilized as the hole transport layer (HTL) in p-i-n structured PSCs. The optimization involved systematically varying RF power, film thickness, and annealing temperature to enhance device performance. Adjusting the RF power to 50 W resulted in improved film uniformity and consistent device efficiency, while a film thickness of 15 nm achieved a balanced combination of optical transmittance and electrical conductivity. Additionally, annealing at 300°C significantly increased film conductivity, albeit with a slight reduction in transmittance, likely due to oxygen incorporation into the NiOx matrix. Devices fabricated under these optimized conditions exhibited the highest PCE of 19.64% and maintained robust stability under ambient conditions. The comprehensive optimization of both precursor purity and NiOx deposition parameters contributes to the advancement of high-efficiency and stable PSCs, offering practical insights for future photovoltaic applications.
more목차
ABSTRACT i
국문 초록 iii
TABLE OF CONTENTS v
LIST OF TABLES vii
LIST OF FIGURES viii
Chapter 1. Introduction 1
1.1 Perovskite Solar Cells 1
1.1.1 Solar Cells 1
1.1.2 Perovskite Solar Cells (PSCs) 4
1.1.3 Architecture of PSCs 6
1.1.4 Working Mechanism of PSCs 8
1.1.5 Solar Cell Efficiency Parameters 9
1.2 Perovskite Single Crystals 13
1.2.1 Importance of Perovskite Single Crystals 13
1.2.2 Growth Methods of Perovskite Single Crystals 14
1.3 Impurity Engineering in PSCs 17
1.3.1 The Role of Impurities in Perovskite Solar Cells 17
1.3.2 Impurity Engineering Strategies 19
1.3.3 Impact of Impurity Control on Device Performance 20
1.4 NiOx as Hole Transport Layer (HTL) in PSCs 21
1.4.1 Role and Advantages of NiOx in PSCs 21
1.4.2 Challenges of NiOx in PSCs 22
Chapter 2. Experimental Section 24
2.1 Materials 24
2.2 Synthesis of FAPbI3 25
2.3 Device Fabrication 26
2.3.1 n-i-p Structure PSCs 26
2.3.2 p-i-n Structure PSCs 27
2.4 Characterization Methods 28
Chapter 3. Results and Discussion 30
3.1 Impurity Engineering 30
3.1.0 Motivation 30
3.1.1 Synthesis Method of Perovskite Precursors 31
3.1.2 Material Properties of Perovskite Precursors 36
3.1.3 Morphology and Crystallinity of Fabricated PSCs 39
3.1.4 Optical and Electrical Properties of Perovskite Thin Films with Different Impurities 42
3.1.5 Photovoltaic Performance of PSCs 47
3.2 NiOx RF Sputtering Optimization 52
3.2.0 Motivation 52
3.2.1 Optimization of RF Power for NiOx Films 53
3.2.2 Optimization of NiOx Film Thickness 59
3.2.3 Optimization of Annealing Temperature for NiOx Films 65
Chapter 4. Conclusions 74
Chapter 5. References 75
