Synthesis and Characterisation of Perovskite and Chalcogenide Semiconductor Materials for Opto-Electrical Applications By Fiona McGrath Department of Chemical Sciences University of Limerick Academic Supervisor: Prof. Kevin M. Ryan Submitted to the University of Limerick in fulfilment of the requirements of Doctor of Philosophy (PhD) June 2021 ii Table of Contents Chapter 1 Introduction ...................................................................................................... 1-1 1.1 Research Questions ................................................................................................. 1-2 1.2 Hypothesis ............................................................................................................... 1-2 1.3 Scope of the Thesis ................................................................................................. 1-3 1.4 Bibliography ............................................................................................................ 1-4 Chapter 2 Introduction ...................................................................................................... 2-6 2.1 Electronic and Electro-optic Properties of NCs ...................................................... 2-8 2.1.1 Quantum Confinement Effects ...................................................................... 2-10 2.1.2 Spin-Orbit Coupling....................................................................................... 2-12 2.2 Solution Processing of Nanoparticles ................................................................... 2-12 2.2.1 Hot Injection Method ..................................................................................... 2-13 2.2.2 Ligand-Assisted Re-Precipitation (LARP) .................................................... 2-18 2.2.3 Other Perovskite Synthesis Techniquesructures ............................................ 2-21 2.2.4 Influencers to Nanoparticle Growth and Shape ............................................. 2-24 2.3 Crystal Structure .................................................................................................... 2-26 2.3.1 Crystal Nucleation and Growth Mechanisms ................................................ 2-33 2.3.2 2D chalcogenide semiconductor – Chapter 6 ................................................ 2-34 2.4 Nucleation and Growth of NPs ............................................................................. 2-38 2.5 Surface Chemistry of Semiconductor NPs ............................................................ 2-45 iii 2.5.1 Colloidal Stabilization and Purification ......................................................... 2-46 2.5.2 Ligand Types ................................................................................................. 2-48 2.5.3 Surface passivation of perovskite NCs – Chapter 3....................................... 2-61 2.5.4 Ligand Exchange ........................................................................................... 2-62 2.6 Potential applications of nanocrystals ................................................................... 2-66 2.7 Bibliography .......................................................................................................... 2-67 Chapter 3 Experimental Methods and Characterisation Techniques .............................. 3-89 3.1 Synthesis Techniques ............................................................................................ 3-89 3.2 Characterisation Techniques ................................................................................. 3-90 1.1.1 X-Ray Diffraction (XRD) .............................................................................. 3-90 1.1.2 Scanning Electron Microscopy (SEM) .......................................................... 3-92 1.1.3 Energy-Dispersive X-Ray Spectroscopy (EDX) ........................................... 3-93 1.1.4 Transmission Electron Microscopy (TEM) ................................................... 3-93 1.1.5 UV-Vis Absorption Spectroscopy (UV-Vis) ................................................. 3-96 1.1.6 Solid State Diffuse Reflectance UV-Visible Spectroscopy (DRS)................ 3-98 1.1.7 Photoluminescence Spectroscopy .................................................................. 3-99 1.1.8 XPS .............................................................................................................. 3-100 3.3 Bibliography ........................................................................................................ 3-101 Chapter 4 Synthesis and Dimensional Control of CsPbBr3 Perovskite Nanocrystals Using Phosphorous Based Ligands .............................................................................................. 4-103 4.1 Abstract ............................................................................................................... 4-103 iv 4.2 Introduction ......................................................................................................... 4-104 4.3 Experimental Section .......................................................................................... 4-107 4.4 Results and Discussion ........................................................................................ 4-108 4.5 Conclusion ........................................................................................................... 4-121 4.6 Bibliography ........................................................................................................ 4-122 Chapter 5 Colloidal Synthesis of 2D Monolayer Indium Chalcogenide Alloys Nanosheets 5-127 5.1 Abstract ............................................................................................................... 5-127 5.2 Introduction ......................................................................................................... 5-127 5.3 Experimental Section .......................................................................................... 5-129 5.4 Results and discussion ......................................................................................... 5-131 5.5 Conclusion ........................................................................................................... 5-141 5.6 Bibliography ........................................................................................................ 5-142 Chapter 6 Germanium-Tin Alloying at B site of Inorganic CsBX3 (X = Br, I) and Cs2BX6 Perovskite Systems. ........................................................................................................... 6-145 6.1 Abstract ............................................................................................................... 6-145 6.2 Introduction ......................................................................................................... 6-145 6.3 Experimental ....................................................................................................... 6-149 6.4 Results and discussion ......................................................................................... 6-149 6.5 Conclusion ........................................................................................................... 6-161 6.6 Bibliography ........................................................................................................ 6-161 v Chapter 7 Additive Effects on the Growth of Inorganic Caesium Germanium Bromide Perovskite 7-166 7.1 Abstract ............................................................................................................... 7-166 7.2 Introduction ......................................................................................................... 7-166 7.3 Experimental Section .......................................................................................... 7-169 7.4 Results ................................................................................................................. 7-171 7.4.1 Ammonium Additives .................................................................................. 7-175 7.4.2 Phosphorous Additives ................................................................................ 7-179 7.4.3 Polymer Additives ....................................................................................... 7-181 7.4.4 Silicon Additives .......................................................................................... 7-183 7.4.5 Sulphur Additives ........................................................................................ 7-185 7.5 Discussion ........................................................................................................... 7-186 7.6 Conclusion ........................................................................................................... 7-188 7.7 Bibliography ........................................................................................................ 7-188 Chapter 8 Conclusions and Perspectives ...................................................................... 8-194 8.1 Conclusion and Future Directions from Chapter 4 ............................................. 8-194 8.2 Conclusion and Future Directions from Chapter 5 ............................................. 8-195 8.3 Conclusion and Future Directions from Chapter 6 ............................................. 8-196 8.4 Conclusion and Future Directions from Chapter 7 ............................................. 8-196 8.5 Answering the research questions ......................................................................