Abstract ix Acknowledgment xiii TABLE OF CONTENTS xv LIST OF FIGURES xix LIST OF TABLES xxiv LIST OF SCHEMES xxv LIST OF ACRYNOMES AND SYMBOLES xxvi 1. Research Background 1 1.1 Historical background 1 1.2 Perovskite Phenomena 3 1.3 CH3NH3PbI3 Perovskite and fundamental origin of this research 7 1.4 Optical characterization 13 1.5 Organization of this thesis 15 2. Thesis dissertation 17 2.1 Motivation of this study 17 2.2 Aims and objectives of the study 20 3. Literature review on Organometal halide perovskite solar cells: degradation and stability 23 3.1 Background 23 3.2. Overview of Omh-PSCs Devices 25 3.1.1 The need for Omh-PSCs 25 3.1.2 Mechanistic processes in Omh-PSCs 26 3.1.3. Current status of performance in Omh-PSCs 28 3.3 Causes of failure and associated mechanisms of degradation 39 3.3.1. Oxygen induced degradation 41 3.3.2 Light induced degradation 44 3.3.3 Moisture induced degradation 45 3. 3.4 Temperature induced degradation 48 3.3.5 Thermal and electric field induced intrinsic degradation 49 3.4. Origins for degradation of Omh-PSCs 53 3.4.1. Effects of device components 53 3.4.2 Effect of device architecture 64 3.4.3 Effect of interface 69 3.5. Suggested approaches to improve stability of Omh-PSCs 71 3.5.1 Omh-perovskite material aspects 71 3.5.2 Device architecture aspects 72 3.5.3 Interface aspect 74 3.5.4 Device operation aspect 77 3.6. Protocols and methods for studying degradation mechanisms 80 3.6.1 Possible methods for studying degradation of Omh-PSCs 80 3.7. Summary and prospects 84 4. Experimental section and characterization methods 89 4.1 CH3NH3PbI3 Film preparation: 89 4.2 Characterization methods 89 4.2.1 Steady State Photoluminescence (PL) and Time-Resolved PL (TRPL) Measurement 90 4.2.2 In-situ Micro-Raman Spectroscopy 92 4.2.3 In Situ synchrotron X-ray diffraction during heating process 94 4.2.4 Angle dispersive X-ray diffraction 94 4.2.5 In-situ X-ray Absorption Spectroscopy 95 4.2.6 X-ray Absorption Spectroscopy Data Analysis 97 4.2.7 Scanning electron microscopy 99 4.2.8 Atomic Force Microscopy 99 4.2.9 Computational method 99 5. Scalable Synthesis of Highly Crystalline CH3NH3PbI3 at Room Temperature in Acetonitrile: the Reactive crystallization of CH3NH3PbI3 101 5.1 Introduction 101 5.2 Optical properties 103 5.3 Nature, reaction and formation mechanism of the synthesized nanocrystals in Acetonitrile: 105 5.4 Nucleation and growth mechanisms of perovskite in DMSO and DMF solvents using acetonitrile as anti-solvent studied by Angle Dispersive X-ray Diffraction 111 5.5 Effect of CH3NH3+ cation on the preferred orientation of CH3NH3PbI3 121 5.6 Higher temperature structural coexistence and its impact on PL lifetime 124 5.7 Thermal behavior and degradation mechanisms of CH3NH3PbI3 129 5.8 Summary 131 6. Nanosecond Pulse Laser irradiation induced reduction of disorder, heterogeneity and non-radiative recombination in organolead halide hybrid perovskite thin film 133 6.1 Introduction 133 6.2 Physical origin behind disorder and film heterogeneity 134 6.3 Mechanisms of microstructure reconstruction and restructuring-Steady state PL 137 6.4 Mechanisms of microstructure reconstruction and restructuring-micro Raman and Angle dispersive X-ray diffraction 140 6.5 In-situ XAS study of local disorder and structural evolutions in thermal and laser light treated CH3NH3PbI3 thin films 148 6.6 CH3NH3PbI3 film morphology evolution by AFM and SEM 153 6.7 Summary 158 7. Development of Transition metal (I) cation based New Inorganic Perovskites for optimal light absorption 161 7.1 Introduction 161 4.3 Crystal structures/Geometric properties 163 7.3 Electronic and optical properties of APbX3 perovskites 166 7.4 Effect of A and X Size on optical bandgap of APbX3 perovskites 170 7.5 Summary 174 5 General conclusions 175 6 Perspectives 179 References 183 Appendix A Supplementary result for Chapter 5 211 Appendix B Supplementary result for Chapter 6 221 Appendix C Supplementary result for Chapter 7 235 Curriculum Vitae 241 Summary of research papers 243 List of conference papers 245 List of conference awards for this research 247