Zinc Oxide Metacrystals: Design Principles, Electro-Optical Properties, and Device Applications

다국어 초록 (Multilingual Abstract)

Polarization, despite being a fundamental property of light, remains underexplored in optics. Most research to date has focused predominantly on detecting light intensity and wavelength, while often neglecting polarization. However, polarized light plays a crucial role in materials inspection, optical encryption, medical diagnostics, display technology, and quantum computing. To fully exploit polarized light in optoelectronic devices, reliable polarization detection is essential. Polarization-sensitive photodetectors can be broadly classified according to the polarization state of the incident light: linearly polarized light photodetectors and circularly polarized light photodetectors. Low-dimensional materials such as 1D and 2D materials are attractive for linearly polarized light photodetection owing to their intrinsically anisotropic geometry or crystal structure. In contrast, chiral materials are required to directly detect circularly polarized light. So far, research on materials for linear polarization photodetectors has mainly focused on single anisotropic nanoflakes or nanowires. Although these structures can provide strong polarization sensitivity, they typically suffer from extremely low photocurrent and require sophisticated, low-throughput fabrication techniques, which severely limit their practical applicability. Moreover, synthesizing highly anisotropic structures with large-area coverage and high crystalline quality remains a significant challenge. To meet the need for large-scale, controllably anisotropic architectures, the metacrystal concept has been developed. They can be micro- to meso-scale analogues of crystalline solids, in which larger building blocks are deliberately oriented and arranged to emulate the grain orientations. While nanocrystals are inherently anisotropic at the atomic level, metacrystals can amplify it, making them more suitable for practical applications.

목차 (Table of Contents)

• CHAPTER 1. Introduction 1
• 1.1 Material anisotropy 1
• 1.1.1 Anisotropy in nature 2
• 1.1.2 Anisotropy in engineering 4
• 1.2 Zinc oxide 5
• 1.3 Light polarization 10
• 1.3.1 Linearly polarized light 11
• 1.3.2 Circularly polarized light 12
• 1.3.3 Elliptically polarized light 13
• 1.3.4 Polarizers and Wave plates 14
• 1.3.5 Jones Calculus 15
• 1.4 Polarization-sensitive photodetector 19
• 1.4.1 Linearly polarized light photodetectors 21
• 1.4.2 Circularly polarized light photodetectors 24
• 1.5 Overview of the Dissertation 25
• CHAPTER 2. Materials and Methods 27
• 2.1 Material 27
• 2.2 Characterization methods. 28
• 2.2.1 Ultraviolet-Visible spectroscopy (UV-Vis spectroscopy) 28
• 2.2.2 Circular dichroism spectroscopy (CD) 29
• 2.2.3 Scanning electron microscopy 30
• 2.2.4 Powder X-ray diffraction 31
• 2.2.5 Transmission electron microscopy 32
• 2.2.6 Polarized Optical Microscopy 33
• 2.2.7 Electrical parameter analyzer 34
• CHAPTER 3. Design of ZnO metacrystal 35
• 3.1 Synthesis of Zinc oxide microrods 35
• 3.2 The linear relationship between linear dichroism (LD) and degree of alignment (DoA) 38
• 3.3 Metacrystal ZnO film for linearly polarized light photodetector 52
• 3.4 Conclusion 61
• CHAPTER 4. UV Linear Polarization Sensitive Photodetector 62
• 4.1 Device Fabrication 62
• 4.2 UV light photodetection of metacrystal ZnO film 65
• 4.3 UV light polarization photodetection of metacrystal ZnO film 70
• 4.4 Conclusion 77
• CHAPTER 5. Application of UV Linear Polarization Sensitive Photodetector 78
• 5.1 Chiral sensing and quantitative measurement of the sugar concentration 78
• 5.2 Identify the crystalline orientation of polymer and strain 86
• 5.2.1 Identify the stress distribution in stretched PDMS substrate 86
• 5.2.2 Identify the stress direction in transparent polymer 95
• 5.3 Detecting of UV circularly polarized light 99
• 5.4 Conclusion 103
• CHAPTER 6. Bouligand-structured ZnO Metacrystal 104
• 6.1 Experimental details 104
• 6.2 Results and discussion 106
• 6.3 Conclusion 108
• CHAPTER 7. Conclusion and future direction 109
• 7.1 Conclusion 109
• 7.2 Future direction 111
• References 112
• 국문초록 125