Title Page
Abstract
Contents
Chapter 1. Introduction 9
1.1. Perovskite structure 9
1.2. Physics in lanthanide and photon upconversion 10
References 15
Chapter 2. Site-symmetry dependence of upconversion in BaTiO₃:Er³⁺ 18
2.1. Introduction 18
2.2. Experimental methods 19
2.2.1. Synthesis of Er³⁺ incorporated barium titanate 19
2.2.2. Experimental details 19
2.3. Results and Discussions 21
2.3.1. Characterization and X-ray diffraction patterns analysis at BaTiO₃:Er³⁺ phase transition 21
2.3.2. Effect of tetragonal to cubic phase transition on upconversion properties in BaTiO₃:Er³⁺ 28
2.4. Conclusions 34
References 35
Chapter 3. Excitation power of NIR-II dependence in upconversion of BaTiO₃:Er³⁺ 37
3.1. Introduction 37
3.2. Experimental methods 38
3.2.1. Synthesis of Er³⁺ incorporated barium titanate 38
3.2.2. Experimental details 38
3.3. Results and discussions 39
3.3.1. Characterization of BaTiO₃:Er³⁺ 39
3.3.2. Proposed photophysical pathways for upconversion under NIR-II irradiation 40
3.4. Conclusions 46
References 47
Chapter 4. Non-centrosymmetric site in CsBiNb₂O₇ and upconversion properties 48
4.1. Introduction 48
4.2. Experimental methods 50
4.2.1. Synthesis of SrTiO₃, BaTiO₃, CsBiNb₂O₇, and NaYF₄ 50
4.2.2. Experimental details 52
4.3. Results and discussions 53
4.3.1. Characterization of CsBiNb₂O₇:Er³⁺ 53
4.3.2. Comparison of upconversion efficiency and upconversion properties in CsBiNb₂O₇:Er³⁺ 55
4.4. Conclusions 66
References 67
Chapter 5. Broadband upconversion in Er₂O₃ with NIR-II irradiation 68
5.1. Introduction 68
5.2. Experimental methods 69
5.2.1. Synthesis of Er₂O₃ with oxygen vacancy 69
5.2.2. Density functional theory calculations 69
5.2.3. Experimental details 70
5.3. Results and Discussions 71
5.3.1. Characterization and density functional theory calculations of Er₂O₃ 71
5.3.2. Broadband upconversion in Er₂O₃ 77
5.4. Conclusions 89
References 90
Chapter 6. Re-absorption and re-emission properteis in Cs₄PbBr₆ 91
6.1. Introduction 91
6.2. Experimental methods 94
6.2.1. Synthesis of Cs₄PbBr₆ polycrystalline with inhomogeneous interface reaction 94
6.2.2. Experimental details 95
6.3. Results and discussions 96
6.3.1. Characterization of Cs₄PbBr₆ 96
6.3.2. Photophysical properties and photon-recycling properties in Cs₄PbBr₆ 100
6.4. Conclusions 111
References 112
Curriculum Vitae 115