염료감응형 태양전지의 광전극 표면처리에 따른 광전효율 특성 = Photovoltaic Properties of Dye-sensitized Solar Cells with Surface Modified-Photoelectrodes

다국어 초록 (Multilingual Abstract)

Dye-sensitized solar cells(DSSCs) have attracted much attention and DSSCs are the subject of many research studies as a third-generation solar cell, because of their high efficiency and low cost of production. The DSSCs have a number of attractive features that it is easy to manufacture by using conventional printing techniques and it is semi-flexible, and semi-transparent which offers a variety of uses not applicable to glass-based systems, and most of the materials are used low cost. In this study, effects of surface modifiers on the performance of solar cells were systematically investigated to improve power conversion efficiency of DSSCs.
First, we investigated effects of valeric acid(VA) as a co-adsorbate on the photovoltaic performance of DSSCs. When the introduction of VA onto TiO2 surface was performed after dye adsorption, the DSSCs with VA showed an increase in short-circuit current(Jsc), open-circuit voltage(Voc) and fill factor (FF), resulting in a power conversion efficiency of 7.27 %, compared to that 6.20 % of reference device. It was confirmed that the improvements in both Jsc and Voc were attributed to the prolonged lifetime of electrons injected from dyes to conduction band of TiO2. This increased electron lifetime was probably due to a formation of the insulating layer by VA, which plays a role of energy barrier on free TiO2 surface.
Second, we investigated effects of lithium nitrate(LiNO3) as a co-adsorbate on the photovoltaic performance of DSSCs. Voc of DSSCs with a LiNO3 modified TiO2 layer was averagely improved by over 24 % compared to that of a reference device. It was revealed that the modification induced the formation of the surface dipole on the TiO2 electrode, leading to the conduction band edges shift of TiO2 to the negative direction, and thus a larger Voc.
We found that DSSCs with the surface modified photoelectrodes, which were treated with VA or LiNO3, showed an improved conversion efficiency, compared to that of conventional device without surface modification.

목차 (Table of Contents)

• Ⅰ. 서 론 1
• Ⅱ. 이 론 4
• 2.1 태양광에너지 4
• 2.2 태양전지의 분류 7
• 2.2.1 무기태양전지 8
• 2.2.2 유기태양전지 9
• 2.3 염료감응형 태양전지 10
• 2.3.1 염료감응형 태양전지의 구조 10
• 2.3.1.1 투명전극 11
• 2.3.1.2 나노입자 다공질산화물 14
• 2.3.1.3 염료 19
• 2.3.1.4 전해질 23
• 2.3.2 염료감응형 태양전지의 동작원리 25
• 2.3.3 염료감응형 태양전지의 계면반응 28
• 2.3.3.1 반도체-전해질 28
• 2.3.3.2 반도체-염료 30
• 2.3.3.3 반도체-투명전극 32
• 2.3.4 광전극층 화학적 흡착반응 33
• 2.3.4.1 염료흡착 33
• 2.3.4.2 광전극과 전해질의 계면변화 35
• 2.3.4.3 광전변환 특성 36
• Ⅲ. 실험 및 방법 42
• 3.1 광전극 제작 42
• 3.2 상대전극 제작 49
• 3.3 광전극과 상대전극 접합 50
• 3.4 전해질 주입 51
• 3.5 광전효율 측정 52
• Ⅳ. 결과 및 고찰 53
• 4.1 염료감응형 태양전지의 특성분석 53
• 4.1.1 광전극 표면의 에너지장벽 형성 53
• 4.1.1.1 VA 표면처리에 의한 광전효율 측정 54
• 4.1.1.2 단락전류밀도 향상 원인분석 57
• 4.1.1.3 개방전압 향상 원인분석 63
• 4.1.2 광전극 표면의 쌍극자 모멘트 작용 65
• 4.1.2.1 LiNO3 표면처리에 의한 광전효율 측정 66
• 4.1.2.2 단락전류밀도 및 개방전압 분석 70
• Ⅴ. 결 론 80
• 참고 문헌 82
• 영문 초록 92

참고문헌 (Reference)

1 김근배, "디스플레이공학?", 청범출판사, 청범출판사, pp. 193-203, 2000

2 이재형, 임동건, 이준신, "“태양전지 원론”", 홍릉과학출판사 : pp.182-188, 2005