由於石化能源的供不應求以及核能發電的核廢料處理等能源相關問題，尋找或改進替代能源的重要性日益增加，而太陽能電池是目前替代能源的主要選項。在這許多太陽能電池種類中，矽晶太陽能電池一直是研究主流，並且具有相當好的光電轉換效率。但近年來，另一種結晶材料 – 「有機-無機混成鈣鈦礦結構」所製作而成的太陽能電池，光電轉換效率逐年快速增加，且製作上不需如矽晶太陽能電池等高溫長晶設備，製作成本可大幅度降低，因此受到相當大的矚目。

而本研究主要有兩個研究項目，一是透過化學溶液法製備鈣鈦礦單晶並進行不同量測以了解所得到的單晶品質。二是透過空間限制法來製備鈣鈦礦單晶薄膜，探討不同實驗參數以控制薄膜厚度，希望透過單晶材料的晶界比較少來增加電子遷移率進而增加光電轉換效率。

在第一項工作，我們使用逆向溫度成長方式在溶液中成功製備出鈣鈦礦晶體，透過X-Ray繞射分析確認其為單晶，並透過紫外/可見光吸收光譜儀來分析其光吸收性質及了解其能隙，並了解逆向溫度成長法的長晶機制。在第二項工作，我們成功製備出大縱橫比的鈣鈦礦單晶薄膜，但後續須要進一步克服基板的強力附著力，將這些小單晶薄膜從基板上取出，並且將它們聚合。

Alternative energy is the energy resources do not consume the fossil fuels. Searching for alternative energy resources is important for the sustainable development. Currently, due to the issues such as shortage of fossil fuels, nuclear wastes, global warming and so on, to find new alternative energy sources as well as to improve the inherent ones becomes an important task for humans. Due to the abundant and continuous supply from the sun, the solar cell is one of the best choices in the alternative energy source. Silicon-based solar cells are the most widely used because of the remarkable power conversion efficiency and relatively low cost. However, there are new types of solar cells, perovskite solar cells, which are attractive because of their rapid growth of power conversion efficiency (PCE) and lower processing temperature, hence can have the potential to further reduce the cost of the energy conversion by sunlight.

This study contains two parts. In the first part, single crystals of perovskite were grown by the inverse temperature crystallization method. The optical and electrical properties were investigated. Moreover, the mechanism for the inverse temperature crystallization method was studied. It is expected that perovskite single crystals can have better electrical and optical properties and hence to have higher PCE than the polycrystalline counterparts, for the avoiding of the grain boundaries in the polycrystalline films. In the second part, we fabricate single-crystalline thin films of perovskite by space-confined fabrication and study the relationship between thickness and experimental parameters. It is hopeful that the small flakes can be further merged into larger ones, which is suitable for the fabrication of high-quality solar cells.

In the first study, we fabricate crystals of perovskite successfully. The crystalline structures are confirmed by the X-ray diffraction analysis, and their optical properties are investigated by the ultraviolet—visible absorption spectroscopy. The mechanism for the inverse temperature crystallization was also investigated. In the second study, it aims to fabricate single-crystalline thin films of perovskite by space-confined fabrication technique. We successfully fabricate thin flakes with a thickness in the order of ten micrometers. It further needs to merge these small films to larger area ones for the photovoltaic devices.

致謝 i
摘要 iv
Abstract vi
List of tables x
List of figures xi
Chapter 1 Introduction 1
Chapter 2 Background and literature review 4
2.1 Solar cell fundamentals 4
2.1.1 Current–voltage characteristic (IV curve) 4
2.1.2 Short-circuit current and open-circuit voltage 7
2.1.3 Power conversion efficiency and fill factor 7
2.1.4 Series resistance and shunt resistance 8
2.1.5 The sunlight 10
2.1.6 Air mass 10
2.1.7 Shockley–Queisser limit 10
2.1.8 Perovskite solar cells 12
2.2 History of perovskites 13
2.2.1 Inorganic perovskites 13
2.2.2 Halide-based perovskites 14
2.2.3 Hybrid organic-inorganic perovskites 14
2.3 Material properties of perovskites 15
2.3.1 Tolerance factor (t) and Octahedral factor(u) 15

2.3.2 Composition of perovskites 16
2.3.3 Crystal structures of perovskites 18
2.3.4 Tunable band gaps 19
2.4 Fabrications of perovskite solar cells 19
2.4.1 Perovskite thin film solar cells 19
2.4.2 Perovskite single crystals 21
2.4.3 Single-crystalline thin film perovskites 22
2.5 The mechanism for the growth of hybrid organic-inorganic hybrid perovskites
by inverse temperature crystallization Research motivation 22
2.6 Research motivation 23
Chapter 3 Experimental procedures 25
3.1 Materials 25
3.2 Fabricating procedures 25
3.2.1 Single crystals 25
3.2.2 Single-crystalline thin films 27
3.2.3 Mechanism for the growth of hybrid organic-inorganic hybrid perovskites
by inverse temperature crystallization 28
3.3 Property measurements and analyses 29
3.3.1 X-ray diffraction (XRD) 29
3.3.2 Optical microscopy (OM) 30
3.3.3 Scanning electron microscopy (SEM) 30
3.3.4 Ultraviolet–visible spectroscopy (UV–Vis) 30
3.3.5 3D alpha-step profilometer (α-step) 32
Chapter 4 Results and discussion 33
4.1 Crystal growth 33
4.2 X-ray analysis 35
4.3 Morphology analysis 36
4.4 Optical property analysis 38
Chapter 5 Conclusions 40
References 41
Tables 46
Figures 48

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