Title Page
Abstract
Contents
1. Introduction 11
1.1. Growth of Metal halide perovskites (MHPs) 11
1.2. The background and objective of our research 14
2. Research 18
2.1. Experimental Details 18
2.1.1. Growth of PbI₂ thin film 18
2.1.2. MAPbI₃ conversion 19
2.1.3. Characterization 20
2.1.4. Device Characterization 20
2.1.5. Computational Fluid Dynamics simulation 21
2.2. Results & Discussion 23
2.2.1. Effect of substrate orientation on PbI₂ film uniformity 23
2.2.2. Substrate orientation-dependent methylammonium transport in vdW PbI₂ layer 27
2.2.3. Comparison of crystal structural uniformity via diffraction analysis 29
2.2.4. Optical homogeneity across the substrate 31
2.2.5. Comparison of optoelectronic device uniformity 33
2.3. Conclusion 36
2.5. Supporting note 62
2.5.1. Supporting note 1. CFD simulation strategy 62
2.5.2. Supporting note 2. Lattice structure-dependent diffusion coefficient of methylammonium species 66
2.5.3. Supporting note 3. Theoretical expansion ratio between PbI₂ and MAPbI₃ 67
2.6. Tables 68
2.6.1. Table 1. Average thickness of deposited PbI₂ thin film depicted in Figure 9 68
2.6.2. Table 2. Device performance comparison of perovskite photodetector arrays based on the preparation method and structures 69
2.6.3. Table 3. Light currents, on/off ratios, power law constants, responsivities, and detectivities of photoconductor arrays based on MAPbI₃ film fabrication sequence 70
2.6.4. Table 4. Closure equations for estimating the thermophysical properties of the gas species 71
2.7. References 72
Figure 1. Perovskite devices beyond photovoltaics: LEDs, lasers, memories, transistors, X-ray detectors, Li-ion batteries, piezoelectric... 12
Figure 2. Schematic illustration of spin coating and various large-scale perovskite deposition techniques, including blade coating, slot-die coating,... 13
Figure 3. Conversion of hexagonal PbI₂ (crystal structure shown on left) to tetragonal MAPbI₃ (shown on right) by addition of MAI. 17
Figure 4. CFD simulation of the CVD tube furnace system. 38
Figure 5. System pressure and substrate and precursor temperature profiles during (a) PbI₂ film deposition and (b) MAPbI₃ conversion process. 39
Figure 6. Effect of substrate orientation on surface temperature and velocity distribution. 40
Figure 7. Photographs depicting (a) vertical and (b) horizontal substrate orientations within a quartz tube of the CVD furnace. 42
Figure 8. Effect of substrate orientation on PbI₂ layer growth. 43
Figure 9. Distribution of PbI₂ layer thickness within the substrate according to deposition time and substrate orientation. 44
Figure 10. Comparison of perovskite film morphology based on the PbI₂ film orientation during conversion. 45
Figure 11. Characterization of the perovskite film produced with excess MAI. 47
Figure 12. CFD flow simulation of the conversion process from PbI₂ to MAPbI₃. 48
Figure 13. Degree of perovskite conversion according to the MAI intercalation routes. 49
Figure 14. XRD analysis of PbI₂ and MAPbI₃ films. 50
Figure 15. Schematic illustrations of the perovskite conversion process for (a) vertically and (b) horizontally oriented PbI₂ layers. 52
Figure 16. Comparison of optical uniformity between vertically- and horizontally-converted MAPbI₃. 53
Figure 17. PL distribution of MAPbI₃ films converted for 5 min. 54
Figure 18. Comparison of substrate surface coverage in PbI₂ and MAPbI₃ films based on substrate orientations. 55
Figure 19. Device performance uniformity dependent on substrate orientation. 56
Figure 20. Photodetector performance comparison for v→h and h→v perovskite films. 57
Figure 21. The control effect of substrate orientation on the device responsivity and detectivity of MAPbI₃ photodetector arrays. 58
Figure 22. Photodetector performance of the v→v perovskite film. 59
Figure 23. Device performance correlated with film thickness variation within the substrate. 61